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HE SPARKS 
 
 LIBRARY. 
 
 [MISCELLANY.] 
 Collected by 
 
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 President of Harvard College. 
 
 Purchased by the Cornell University, 
 
 1872. 
 
CORNELL UNIVERSITY LIBRARY 
 
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•THE 
 
 WORKS 
 
 THOMAS REID, D. D. F. R. S. 
 
 EDISTBUEGH. 
 
 KATE PROFESSOR OF MORAL PHILOSOPHY IN THE UNIVBRSITT OF GLASGOW. 
 
 With 
 
 ACCOUNT OF HIS LIFE AND WRITINGS, 
 
 BY DUGALD STEWART, F. R. Su 
 
 WITH NOTES, BY THE AMERICAN EDITORS. 
 
 IK rOUR VOLUMES VOX. I, 
 
 €liatle^to\on, 
 
 ^ROrrED AND rUBUSHED BY SAMCEI. ETHERISGE, Jt^T^^ 
 
 ♦♦♦♦♦♦♦♦*♦ 
 
 1813. 
 
THE 
 
 LIFE AND WRITINGS 
 
 THOMAS REID, D.D. FR S. 
 
 SECTION I. 
 
 FBOM DR. REID's BIRTH Tilt THE DATE OT HIS lATBST 
 PUBLICATION. 
 
 The life of which I am now to present to the Royal 
 Society a short account, although it fixes an era in the 
 history of modern philosophy, was uncommonly barren 
 of those incidents which furnish materials for biography j 
 strenuously devoted to truth, to virtue, and to the best 
 interests of mankind ; but spent in the obscurity of a 
 learned retirement, remote from the pursuits of ambi- 
 tion, and with little solicitude about literary fame. After 
 the agitation, however, of the political convulsions which 
 !Europe has witnessed for a course of years, the simple 
 record of such a life may derive an interest even from 
 its uniformity ; and, when contrasted with the events of 
 the passing scene, may lead the thoughts to some views 
 of human nature, on which it is not ungrateful to repose. 
 Thomas Reid, D.D. late professor of moral philosophy 
 in the university of Glasgow, was born on the 36th of 
 April, 1710, at Strachan in Kincardineshire, a country 
 parish situated about twenty miles from Aberdeen^ OQ the 
 north side of the Grampian mountains. 
 
4 ACCOUNT OF THE IIFE 
 
 His father, the Reverend Lewis Reid, was minister of 
 this parish for fifty years. He was a clergyman, accord- 
 ing to his son's account of him, respected by all who 
 knew him, for his piety, prudence, and benevolence ; in- 
 heriting from his ancestors, most of whom, from the lime 
 of the protestant establishment, had been ministers of 
 the church of Seotland, that purity and simplicity of 
 manners which became his station ; and a love of letters, 
 vhich. without attracting the notice of the world, amused 
 liis leisure, and dignified his retirement. 
 
 For some generations before his time, a propensity to 
 literature, and to the learned professions ; a propensity 
 which, wlien it is lias once become cbaracteristical of a 
 race, is peculiarly apt to be propagated by the influence 
 of early associations and habits, may be traced in several 
 individuals among his kindred. One of his ancestors, 
 James Reid. was the first minister of Banchory-Ternan 
 after the reformation; and transmitted to four sons a 
 predilection for those studious habits which formed his 
 own happiness. He was himself a younger son of Mr. 
 Reid of Pitfoddels, a gentleman of a very ancient and 
 respectable family in the county of Aberdeen. 
 
 James Reid was succeeded as minister of Banchory 
 by his son Robert, Another son, Thomas, rose to con- 
 siderable distinction both as a philosopher and a poet; 
 and seems to have wanted neither ability nor inclination 
 to turn his attainments to the best advantage. After 
 travelling over Europe, and maintaining, as was the cus- 
 tom of his age. public disputations in several universities, 
 lie collected into a volume, the theses and dissertations 
 which had been the subjects of his literary contests; 
 and also published some Latin poems, which may the 
 found in the eoMection entitled, Delitise Poetarum Sco- 
 torum. On his return to his native country, he fixed 
 liis residence in London, where he was appointed secre- 
 tary in the Greek and l^atin tongues to king James the 
 First of Engla;t!d. and lived in habits of intimacy with 
 some of the most distinguished characters of that period< 
 
AND AVEITIXGS OF DR. R£IB. 5 
 
 Litde more, I believe, is known of Thomas Reitl's history, 
 excepting that lie bequeathed to the Marischal college 
 of Aberdeen, a curious collection of books and manu- 
 scripts, with a fund for establishing a salary lo a librarian. 
 
 Alexander Reid, the third son, was ph_>sician to king 
 Charles the First, and jiublished several books on sur- 
 gery and mi>dicine. The fortune he acquired in the 
 course of his practice was considei-able, and enabled hira, 
 liesides many legacies to his relations and friends, to 
 leave various lasting and honourable memorials, both of 
 his benevolence, and of his attachment to letters. 
 
 A fourth son, whose name was Adam, translated into 
 ^English. Buchanan's History of Scotland. Of this trans- 
 lation, which was never published, there is a manuscript 
 copy in the possession of the university of Glasgow. 
 
 A grandson of Robert, the eldest of these sons, was 
 the third minister of Banchory after the reformation, and 
 was great-grandfather of Thomas Reid, the subject of 
 this memoir.* 
 
 The particulars hitherto mentioned, are stated on the 
 authority of some short memorandums written bv Dr. 
 Reid a few weeks before his death. In consequence of a 
 suggestion of his friend Dr. Gregory, he had resolved to 
 amuse himself with collecting such facts as his papers or 
 memory could supply, with respect to his life, and the 
 progress of his studies; but, unfortunately, before he had 
 fairly entered on the task, his design was interrupted by 
 his last illness. If he had lived to complete it, I might 
 have entertained hopes of presenting to the public some 
 details with respect to the history of his opinions and 
 speculations on those important subjects to which he ded- 
 icated his talents; the most interesting of all articles in 
 the biography of a philosopher, and of which it is to be 
 lamented, that so few authentic records are to be found 
 in the annals of letters. All the information, however, 
 which I have derived from these notes, is exhausted in 
 the foregoing pages | and I must content myself, in the 
 
 ^ ■» Note A/ 
 
6 ACCOUNT Oir THE IIFE 
 
 continuation of my narrative, with those indirect aids 
 which tradition, and the recollection of a few old acquaint- 
 ance, afford ; added to what I myself have learned from 
 Dr. ReJd's conversation, or collected from a careful peru- 
 sal of his writings. 
 
 His mother, Margaret Gregory, was a daughter of 
 David Gregory, Esq. of Kinnairdie, in Banffshire ; elder 
 brother of James Gregory, the inventor of the reflecting 
 telescope, and the antagonist of Huyghens. She was one 
 of twenty-nine children; the most remarkable of whom 
 was David Gregory, Savilian professor of astronomy at 
 Oxford, and an intimate friend of Sir Isaac Newton. 
 Two of her younger brothers were at the same time pro- 
 fessors of matheniatics ; the one at St. Andrew's, the 
 other at Edinburgh ; and were the first persons who 
 taught the Newtonian philosophy in our northern univer- 
 sities. Tlie hereditary worth and genius which have so 
 long distinguished, and which still distinguish, the de- 
 scendants of this memorable family, are well known to all 
 who have turned their attention to Scottish biography; 
 but it is not known so generally, that in the female line, 
 the same eliaiaeteristieal endowments have been conspic- 
 uous in various instances ; and that to the other monu- 
 ments which illustrate the race of the Gregories, is to 
 be added the Philosophy of Beid. 
 
 With respect to the earlier part of Dr. Reid's life, all 
 that I have been able to learn, amounts to this j that after 
 two years spent at the parish school of Kincardine, he 
 was sent to Aberdeen, where be had the advantage of 
 prosecuting his classical studies under an able and diligent 
 teacher ; that about the age of twelve or thirteen, he was 
 entered as a student in Marischal college ; and that his 
 master in philosophy, for three years, was Dr. George 
 Turnbull, who afterward attracted some degree of notice 
 as an author; particularly, by a book, entitled, Principles 
 of Moral Philosophy, and by a voluminous treatise, long 
 ago forgotten, on Ancient Painting.* The sessions of 
 
 • Note B. 
 
AND WKITIIfGS or DR.REID. 7 
 
 the college were, at that time, very short, and the 
 education, according to Dr. Keid's own accuun(, slight 
 and Muperticiai. 
 
 Il dues not appear from the infoi'matlon which I liave 
 received, that he gave any early indications of future 
 eininence. His industry, however, and modesty, were 
 conspicuous from his childhood ; and il was foretold of 
 him, hy ihe parish schoolmaster, who initiated him in the 
 first principles of learning, " that he would turn out to 
 be a man of good and well-wearing parts ;" a prediction 
 which, although it implied no flattering hopes of those 
 mure brilliant endowments which are commonly regarded 
 as the constituents of genius, touched, not unhappily, on 
 that capacity of "patient thought," which contrlhuted 
 so powerfully to the success of his philosophical re- 
 searches.* 
 
 His residence at the university was prolonged beyond 
 the usual term, in consequence of bis appointment to the 
 office of librarian, which had been endowed by one of his 
 ancestors about a century before. The situation was ac- 
 ceptable to him, as it afforded an oppoKunity of indulg- 
 ing his passion for study, and united the charms ufa 
 learned society, with the quiet of an academical retreat. 
 During this period he formed an intimacy wifh John 
 Stewart, afterward professor of mathematics in Marischal 
 college, and author of a Commentary on Newton's Quad- 
 rature of Curves. His predilection for mathematical 
 pursuits, was confirmed and strengthened by this connec- 
 tion. I have often heard him mention it witli niucli 
 pleasure, while he recollected the ardour with which (hey 
 both prosecuted these fascinating studies, and the lights 
 which they imparted mutually to each other in their first 
 perusal of the Principia, at a time when a knowledge of 
 the Newtonian discoveries was to be acquired only in the 
 writings of their illustrious author. 
 
 • " If 1 have done the public any service, it is due to nothing but indus- 
 trjrand patient thought." 
 
 Sir Isaac Newton's First letter lo Dr. Benlley. 
 
8 ACCOUNT OF THE XITE 
 
 In 1736, Dr. Reid resigned his office of librarian, and 
 accompanied Mr. Stewart on an excursion to England. 
 They visited together London, Oxford, and Cambridge, 
 and were introduced to the acquaintance of many persons 
 of tlie first literary eminence. His relation to Dr. David 
 Gregory procured him a ready.aecess to Martin Folkes, 
 whose house concentrated the most interesting objects 
 which the metropolis had to offer to his curiosity. At 
 Cambridge he saw Dr. Bentley, who delighted him with 
 his learning, and amused him with his vanity; and enjoy- 
 ed repeatedly the conversation of the blind mathematician, 
 Saunderson ; a phenomenon in the history of the human 
 mind, to which he has referred more than once, in his 
 philosophical speculations. 
 
 With the learned and amiable man who was his com- 
 panion on this journey, he maintained an uninterrupted 
 friendship till 1766, when Mr. Stewart died of a malig- 
 nant fever. His death was accompanied with circum- 
 stances deeply afflicting to Dr. Reid's sensibility ,- the 
 same disorder proving fatal to his wife and daughter, 
 both of whom were buried with him in one grave. 
 
 In 1737, Dr. Reid was presented, by the King's col- 
 lege of Aberdeen, (o the living of New Machar in the 
 same county; but the circumstances in which he entered 
 on his preferment were far from auspicious. The intem- 
 perate zeal of one of his predecessors, and an aversion to 
 the law of patronage, had so inflamed the minds of his 
 parishioners against him, that, in the first discharge of 
 his clerical fimctions, he had not only to encounter the 
 most violent opposition, but was exposed to personal dan- 
 ger. His unwearied attention, however, to the duries of 
 his office, the mildness and forbearance of his temper, 
 and the active spirit of his humanity, soon overcame all 
 these prejudices ; and, not many years afterward, when 
 he was called to a different situation, the same persons 
 who had suffered themselves to he so far misled, as to 
 take a share in the outrages against him, followed hiia 
 on his departure, with their blessings aoji tears. 
 
CONTENTS 
 
 TO THE FIEST VOIUMB. 
 
 Sett. '>KC 
 
 PaErA.CE . - - ... V 
 I. Life of the author, by Dagald Stewart From Dr.Heid's birth 
 
 to the date of his latest pablications ... 3 
 
 II. Observations on the spirit and scope of Dr. Reid's Philosophy 25 
 
 III. Conclusion of the Narrative .... . - 70 
 
 Notes to the Life preceding - - - - .87 
 
 BRIEF ACCOUNT OF ARISTOTLE'S LOGIC ; WITH RE- 
 ]MARKS. 
 
 CHAP I, 
 
 OF THE iTRST THREE TKEATISES. 
 
 I. Of the Author ...... 95 
 
 II. Of Porphyry's Introduction - - ... gj 
 
 III. Of the categories - - - - - - 98 
 
 IV. Of the book concerning interpretation • - • 100 
 
 CHAP. II. 
 
 KEMAAKS. 
 
 I. Of the five predicables ..... fog 
 
 II. On the ten categories, and on divisions in general > 106 
 
 III. On distinctions ...... no 
 
 IV. On definitions ...... ng 
 
 V. On the structure of speech - - - . ] 15 
 VI. On propositions ....... . xig 
 
 CHAP. III. 
 
 ACCOUNT OF THE FIRST ANALYTICS. 
 
 I. Of the conversion of propositions . - . ng 
 
 II. Of the figures and modes of pure syllogisms ... 121 
 
 III. Of the invention of a middle term ... 134 
 
 IV. Of the remaining part of the first book - . 125 
 V. Of the second book of the first analytics - - ik. 
 
 A 2 
 
H CONTENTS. 
 
 CHAP. IV. 
 
 B EM ARKS. 
 
 Sect. '"S* 
 
 i. Of the conversion of propositions ■ - l^" 
 
 II. On additions made to Aristotle's theory - 128 
 
 III. On examples used to illusir-ate ttiis'theory - - 130 
 
 IV. On the demonstration of the theory .... 133 
 
 V (Jn this theory, considered as an engine of science - 135 
 
 VI. On modal syllogisms - - - - 139 
 
 VII. On syllogisms that do not belong to figure and mode - 1*1 
 
 CHAP. V. 
 
 ACCOUNT OF THE REMAINING BOOKS OF THE ORGANON. 
 
 I. Of the last analytics ... - - 144 
 
 II. Of the topics ...--- 146 
 
 III. Of the book concerning sophisms 148 
 
 CHAP VI. 
 
 REFLECTIONS ON THE UTILITY OF LOGIC, AND THE MEAKS OF ITS 
 IMPROVEMENT. 
 
 1. Of the utility of Logic ... . 15S 
 
 II. Of the improvement of Logic - - 159 
 
 INQUIRY INTO t^HE HUMAN MIND. 
 CtilP I. 
 
 INTRODUCTION. 
 
 I. The importance of the subject, and the means ofproseouting it 171 
 
 II. The impediments to our knowledge of the mind - - 173 
 III The present state of this part of philosophy. Of Des Cartes, 
 
 IVIalebranche, and i.ocke .... 178 
 
 IV. Apology for those philosophers ..... 181 
 
 V. Of Bishop Berkeley ; the Treatise of Human Nature ; and of 
 
 skepticism ......... 183 
 
 VI. Of the Treatise of Human Nature . - - . 185 
 
 rii. The system of all these authors is the same, and leads to skep. 
 
 ticism - 187 
 
 VIII. We ought not to despair of a better . - 188 
 
 CHAP II. 
 
 OF SMELLING. 
 
 I. The order of proceeding Of the medium and organ of smell 190 
 
 II. The sensation considered abstractly - ^ 191 
 
 III. Sensation and remembrance, natural principles of belief 193 
 IV. Judgment and belief in some cases precede simple apprehen- 
 sion ... .... 195 
 
CONTENTS. Ill 
 
 Sect. Page 
 
 ». Two theories of the nature of belief refuted. Conclusions from 
 
 what hath been said - - - iy6 
 
 Ti. Apology for metaphysical absurdities Sensation witboat a sen- 
 tient, a consequence of the theory of ideas. Consequences 
 of this strange opinion - - - - 199 
 
 vn. The conception and belief of a sentient being or mind, is sug- 
 gested by our constitution. The notion of relations not al- 
 ways got by comparing the related ideas - 205 
 Tin. There is a quality or virtue in bodies, which we cmU their smell. 
 
 How this is connected in the imagination with the sensation 208 
 
 IX. That there is a principle in human nature, from which the no- 
 tion of this, as well as all other natural virtues or causes, is 
 derived - - . . - - . 219 
 
 X. Whether in sensation the mind is active or passive - 214 
 
 CHAP. III. 
 
 Of tasting .... . gig 
 
 CHAP. IV. 
 
 OF HEARING. 
 1. Variety of sounds. Their place and distance learned by cus- 
 tom, without I'easoning ... . ^iqq 
 II. Of natural language - - - 222 
 
 CHAP. V. 
 
 OF TOUCH. 
 
 I. Of heat and cold - - - - 226 
 
 II. Of hardness and softness .... 228 
 
 III. Of natural signs ...... 232 
 
 IV. Of hardness, and other primary qualities - 236 
 
 V. Of K.Ktension - - ... . 237 
 
 VI. Of Extension - ..... . 241 
 
 VII. Of the existence of a material world . 243 
 
 VIII. Of the systems of philosophers concerning the senses - 251 
 
 CHAP. VI. 
 
 OF SEEING. 
 I. The excellence and dignity of this faculty - . 256 
 
 II. Sight discovers almost nothing which Uie blind may not com- 
 prehend. The reason of this - 258 
 III. Of the visible appearance of objects - - 263 
 IT. That colour is a quality of bodies, not a, sensation of the mind 267 
 V. An inference from the preceding - - 270 
 TI. That none of our sensations areresemblancesof any ofthe qual- 
 ities of bodies - - ... 274 
 Tii. Of visible figure and extension .... 280 
 VIII. Some queries concerning visible figure answered 284 
 
}V CONTENTS. 
 
 Seel. Page 
 
 IX. Of the geometry ofvisibles - - - - 291 
 
 X. Of the parallel motion of the eyes ... 302 
 
 XI. Of our seeing objects erect by inverted images - - 306 
 
 XII. The same subject continued .... 313 
 
 XIII. Of seeing objects single Tvith two eyes .... 328 
 
 XIV. Of the laws of vision in brute animals ... - 33C 
 
 XV. Squinting considered hypothetically ... 339 
 
 XVI. Facts relating to squinting - - - 351 
 
 XVII, Of the effect of custom in seeing objects single - - 354 
 
 xviM. Of Dr. Porterfield's account of single and double vision - 362 
 
 XIX. Of Dr. Brigg's theory, and Sir Isaac Newton's conjecture on 
 
 this subject .... 365 
 
 XX. Of perception in general ..... 376 
 
 XXI. Of the process of Nature in perception .... 385 
 
 xxii. Of the signs by which we learn to perceive distance from the 
 
 eye 
 
 390 
 
 xxiii. Of the signs used in other acquired perceptions - 403 
 
 XXIV. Of the analogy between perception, and the credit we give to 
 
 human testimony ... .... 40S 
 
 CHAP. VII. 
 
 CONCLUSION., 
 Containing Reflections upon the opinions of Philosophers on this sub- 
 ject .... . . - 424 
 
PREFACE, 
 
 BY THE AMERICAN EDITORS. 
 
 " If mind," says the author of A Brief Eetrospect of 
 the Eighteenth Century, " be our better part ; if its pow- 
 ers and activity be all important, as every one must ac- 
 knowledge them to be ; and if some correct understand- 
 ing of these powers be intimately connected with our im- 
 provement, comfort, and usefulness | then to despise met- 
 aphysics is to despise one of the noblest objects of hu- 
 man inquiry, and to display a most unworthy ignorance 
 of the comparative worth of those studies which invite 
 our attention." 
 
 The verity of this remark must be admitted, even by 
 those who are not favoured with much metaphysical ac- 
 umen, and we could wish that it might be felt by all 
 who pretiBod to possess some skill in ratiocination. 
 
 The same learned writer considers Dr. Reid as stand- 
 ing at the head of those metaphysical philosophers, who 
 adorned the last century. We accord witli him in this 
 sentiment, because Reid had the sagacity to detect the 
 errors of Locke, and has succeeded in the attempt of 
 developing more clearly than any otiier writer, the pow- 
 ers and operations of the human mind. 
 
 The Essays on the Intellectual potvers of man, were a 
 great acquisition, not only to the literary, but also to the 
 
VI TEEFACE. 
 
 religious world ; for we think wilh the au(hor of the 
 KBTRosPECT, that " while ample justice is done (o Mr. 
 Locke's gejiius ; while the splendid service which he ren- 
 dered to the philosophy of mind is readily acknowledged ; 
 and while his intentions are allowed to have been unex- 
 ceptionably pure; yel iti niag\ b«i doubted, whether his 
 writings have not done more to promote a spirit of skep- 
 ticism than, those ofianyorthaftiitidiyiduHl sineei his liuie. 
 This effect has been produced, not only by some of his 
 doctrinest Iftit a>}&Qi b^y thegeinierajjspiiitj of bis philoso- 
 phy," We add» tb'fit in no cauntry^re (Ije crr>arp of 
 JjW>ii^,M the pres^ut^dayvi more g? npralJy, es^)usied thjin 
 itltAJuerJca; and,w« apjijrehenid.tJie .reason to b^thiti. that 
 the; writing*, of Rcjd andiStewartiare rareJy tq.bei foun^ 
 in tjiiesame libraryi which Gon:UMn$.tbe Mssay ondlte Hur 
 man Understanding.. 
 
 Entertaining a firm persuasion that ^, correot^ edition 
 ofRsin's WoRES> will be of essential, benefit to their 
 country, the Editors have been induced to ftirnislt a copy 
 for the press, which will be introduced by Stewart's Ac- 
 count of the Life and Writings of his venerable father in 
 the philosophy of the human mind. A better preliminary 
 dissertation to the whole work the public oannoti reason- 
 ably desire. This will be followed by »J brief Account of 
 tSristatle's Logic, which was written by Dp. Rcid, at the 
 request of Lord Kaims, and first published in the third 
 volume of his " Sketches' of the history of Man." Ahis- 
 TOTiB, the celebrated philosopher of Stagiea, the in- 
 structor of AxEXANDER the Qrreat, died about 323 years 
 before Christ. He was the founder of that system of 
 Logie which prevailed for two thousand years ,• and from 
 which most of the treatises on this subject have had their 
 
PREFACE. VU 
 
 origin. It must, therefore, gratify the learned to have 
 in connection witli Reid's other works a faithful account 
 of the Stag.> rite's science of reasoning. The exhibition 
 which our author has made will satisfy curiosity, and 
 his labours, in removing the rubbish of antiquity, will 
 present his new temple of Reason to the observer, in all 
 its native magnificence. 
 
 The Inquiry into the Human Mind may be considered 
 as the front view, and the Essays on the Intellectual and 
 tlctive Powers as the principal, internal apartments, of 
 his sublime edifice. 
 
 The text of Reid's works shall be given from the best 
 editions without alterations; but to such parts as they 
 thought needed explanation or correction, the Editors 
 have appended notes. 
 
 The last work of the author will principally engage their 
 attention, for to them, "the Essays on the Active Pow- 
 ers of man have always appeared much inferior to those 
 on the Intellectual Powers. Indeed, in the former there 
 are several doctrines which we must consider as entirely 
 erroneous. But of thus guarding and qualifying one's 
 approbation there is no end. Speaking of Dr. Reid's 
 works in general, they are certainly among the most in- 
 structive and valuable pietaphysical writings of the age."* 
 
 Dr. Miller's Betrospect, Vol. II. p. 1«. 
 
AND WKITING3 OF DB. REID. 9 
 
 Dp. Reid's popularity at New Machar, as I am inform- 
 ed by the respectable clergyman* who now holds that 
 living, increased greatly after his marriage, in 1740, with 
 Elizabeth, daughter of his uncle. Dr. George Reid, phy- 
 sician in London. The accommodating manners of this 
 excellent woman, and her good offices among the sick 
 and necessitous, are still remembered with gratitude, and 
 so endeared the family to the neighbourhood, that its re- 
 moval was regarded as a general misfortune. The sim- 
 ple and affecting language in which some old men ex- 
 pressed themselves on this subject, in conversing with the 
 present minister, deserves to be recorded. " We fought 
 against Dr. Reid, when he came, and would have fought 
 for him \Ahen he went away." 
 
 In some notes relative to the earlier part of his history, 
 which have been kindly communicated to me by the Rev. 
 Mr. Davidson, minister of Rayne, it is mentioned as a 
 proof of his uncommon modesty and diffidence, that long 
 after he became minister of New Machar, he was accus- 
 tomed, from a distrust in his own powers, to preach the 
 sermons of Dr. Tillotson, and of Dr. Evans. I have 
 heard also, through other channels, that, in his youth, he 
 had cultivated the art of composition with less assiduity 
 than might have been expected from his studious habits. 
 The fact is curious, when contrasted with that ease, per- 
 spicuity, and purity of style, wliieh he afterward attained. 
 From some information, however, which has been lately 
 transmitted to me by one of his nearest relations, I have 
 reason to believe, that the number of original discourses 
 which he wrote while a country clergyman, was not in- 
 considerable. 
 
 The satisfaction of his own mind was probably, in this 
 stage of hisv inquiries, a more powerful incentive to his 
 philosophical speculations, than the hope of being able to 
 instruct the world as an author. But whatever his views 
 were, one thing is certain, that during his residence at 
 New Machar^ the greater part of his time was spent in the 
 
 • The Kev. William Stronach. 
 TOl. I. 2 
 
to ACCOUNT OF THE LIFE 
 
 most intense study ; more particularly ia a careful exam- 
 iuatioii of the lav/s of external perceptionj and of the other 
 principles which form the groundwork of human knowl- 
 edge. His chief relaxations were gardening and hotany, 
 to both of which pursuits he retained his attachment even 
 in old age. 
 
 A paper which he published in the Philosophical Trans- 
 actions of tlie Koyal Society of London, for the year 1748 
 affords some light with respect to the progress of his 
 studies at the time when it was written. It is entitled, " An 
 Essay on Quantity, occasioned by reading a Treatise, in 
 which Simple and Compound Ratios are applied to Yir- 
 tue and Merit 5" and shews plainly, by its contents, that, 
 although he had not entirely relinquished the favourite 
 pesearehes of his youth, he was beginning to direct his 
 thoughts to other objects, 
 
 The treatise alluded to in the title of this paper, was 
 maHifestly the " Inquiry into the Origin of our Ideas of 
 Beauty and Virtue," by Dr. Hutcheson of Glasgow. 
 According to this very ingenious writer, the moment of 
 public good produced by an individual, depending partly 
 on his benevolenpe, and partly on his ahility, tlie relation 
 between these dilferent moral ideas may be expressed in 
 fhe technical form of algebraists, by saying, that the first 
 is in the compound proportion of the two others. Hence 
 Dr. Hutclieson infers, that *' the bene-colence of an agent, 
 which in this system is synonymous with Iiis morallmerit, 
 is proportional to a fraction, having the moment of good 
 for the numerator, and the ability of the agent for the 
 denominator." Various other examples of a similar na- 
 ture occur in the same work; and are stated with a grav- 
 ity not altogether worthy of the author. It is probable 
 that they were intended merely as fiZusti-afions of his gen^- 
 eral reasonings, not as media of investigation for the dis- 
 covery of new conclusions J but they appeared to Dr. 
 Beid to be an innovation which it was of importance to 
 resist, on account of the tendency it might have, by con- 
 Ifounding the evidence of different branches of science, to 
 retard the progress of knowledge. The very high repu- 
 
AND WRITINGS OF DB. EEIO, H 
 
 tation which Dr. Hutcheson then possessed in the uni- 
 versities of Scotland, added to the recent attempts of Pit- 
 cairn and Cheyne to apply mathematical reasoning to 
 medicine, would bestow, it is likely, an interest on Dr« 
 Reid's Essay at the time of its publication, which it can 
 scarcely be expected to possess at present. Many of the 
 observations, however, which it contains, are acute and 
 original J and all of them are expressed with that clear- 
 ness and precision, so conspicuous in his subsequent com- 
 positions. The circumstance which renders a subject 
 susceptible of mathematical consideration, is accurately 
 stated ; and the proper province of that science defined 
 in such a manner, as sufficiently to expose the absurdity 
 of those abuses of its technical phraseology which were 
 at that time prevalent. From some passages in it, there 
 is, I think, ground for concluding, that the author's met- 
 aphysical reading had not been very extensive previous to 
 this period. The enumeration, in particular, which he 
 has given of the different kinds o( proper quantity, affords 
 a proof, that he was not acquainted with the refined yet 
 sound disquisitions concerning the nature of number and 
 of proportion, which had appeared almost a century be- 
 fore, in the Mathematical Lectures of Dr. Barrow } nop 
 with the remarks on the same subject introduced by Dr. 
 Clarke in one of bis controversial letters addressed to 
 Leibnitz. 
 
 In the same paper. Dr. Reid takes occasion to ofifer 
 some reflections on the dispute between the Newtonians 
 and Leibnitzians concerning the measure of forces. The 
 fundamental idea on which these reflections proceed, is 
 just and important ; and it leads to the correction of an 
 error, committed very generally by the partisans of both 
 opinions ; that, of mistaking a question concerning the 
 comparative advantages of two deJinitioTis, for a difference 
 of statement with respect to a physical fact. It must, I 
 think, be acknowledged, at the same time, that the whole 
 merits of the controversy are not here exhausted ; and 
 that the honour of placing this very subtle and abstruse 
 
13 ACCOUNT OF THE IIFE 
 
 question id a point of view calculated to reconcile com- 
 pletely the contending parties, was reserved for M. 
 D'Alembert. To have fallen short of the success Avhieh 
 attended the inquiries of that eminent man, on a subject 
 so congenial to his favourite habits of study, will not re- 
 flect any discredit on the powers of Dr. Reid's mind, in 
 the judgment of those who are at all acquainted with the 
 history of this celebrated discussion. 
 
 In 1753, the professors of King's college elected Dr. 
 Reid professor of philosophy, in testimony of the high 
 opinion they had formed of his learning and abilities. Of 
 the particular plan which he followed in his academical 
 lectures, while he held this office, I have not been able to 
 obtain any satisfactory account ; but the department of 
 science which was assigned to him by the general system 
 of education in that university, was abundantly extensive; 
 comprehending mathematics and physics as well as logic 
 and ethics. A similar system was pursued formerly in 
 the other universities of Scotland ; the same professor 
 then conducting his pupils through all those branches of 
 knowledge which are now appropriated to different teach- 
 ers. And where he happened fortunately to possess those 
 various accomplishments which distinguished Dr. Reid in 
 so remarkable a degree, it cannot be doubted that the 
 unity and comprehensiveness of method, of which such 
 academical courses admitted, must necessarily have pos- 
 sessed importantadvantages over that more minute sub- 
 division of literary labour which has since been intro- 
 duced. But as public establishments ought to adapt 
 themselves to what is ordinary, rather than to what is 
 possible, it is not surprising, that experience should have 
 gradually suggested an arrangement more suitable to 
 the narrow limits which commonly circumscribe human 
 genius. 
 
 Soon after Dr. Reid's removal to Aberdeen, he pro- 
 jected, in conjunction with his friend Dr. John Gregory, 
 a literary society, which subsisted for many years, and 
 which seems to have had the happiest efiects in awaken- 
 
AND WRITINGS OF DE. KEID. 13 
 
 ing and directing that spirit of philosophical research, 
 wliieh has since reflected so much lustre on the north of 
 Scotland. The meetings of this society were held weekly; 
 and afforded the members, besides the advantages to be 
 derived from a mutual communication of their sentiments 
 on the common objects of their pursuit, an opportunity 
 of subjecting their intended publications to the test of 
 friendly criticism. The number of valual)le works which 
 issued nearly about the same time, from individuals con- 
 nected with this institution, more particulai'ly the writ- 
 ings of Reid, Gregory, Campbell, Beattie and Gerard, 
 furnish the best panegyric on the enlightened views of 
 those under whose direction it was originally formed. 
 
 Among these works, the most original and profound 
 was unquestionably the Inquiry into the Human Mind, 
 published by Dr. Reid in 176*. The plan appears to 
 have been conceived, and the subject deeply meditated, 
 by the author long before ; but it is doubtful, whether 
 his modesty would have ever permitted him to present to 
 the world the fruits of his solitary studies, without the 
 encouragement which he received from the general acqui- 
 escence of his associates, in the most important conclu- 
 sions to which he had been led. 
 
 From a passage in the dedication, it would seem, that 
 the speculations which tei^minated in these conclusions 
 had commenced as early as the year 1739 ; at which pe- 
 riod the publication of Mr. Hume's Treatise of Human 
 Nature induced him, for the first time, as he himself 
 informs us, " to call in question the principles commonly 
 received with regard to the human understanding." In 
 his Essays on the Intellectual Powers, he acknowledges, 
 that, in his youth, he had, without examination, admitted 
 the established opinions on which Mr. Hume's system of 
 skepticism was raised ; and that it was the consequences 
 which these opinions seemed to involve, which roused his 
 suspicions concerning their truth. " If I may presume," 
 says he, " to speak my own sentiments^ I once believed 
 the doctrine of Ideas so jQrmly, as to embrace the whole 
 
i4 ACCOUNT OF THE MFE 
 
 of Berkeley's system along with it| till, finding other con- 
 sequences to follow from it, which gave me more uneasi- 
 ness than the want of a material world, it came into my 
 mind more than forty years ago, to put the question, 
 "What evidence have I for this doctrine, that all the ob- 
 jects of my knowledge are ideas in my own mind? From 
 that time to the present, I have been candidly and im- 
 partially, as I think, seeking for the evidence of this 
 principle ; but can find none, excepting the authority of 
 philosophers." 
 
 In following the train of Dr. Reid's researches, this 
 last extract merits attention, as it contains an explicit 
 avowal, on his own part, that, at one period of his life, he 
 had been led, by Berkeley's reasonings, to abandon the 
 belief of the existence of matter. The avowal does hon- 
 our to his candour, and the fact reflects no discredit on 
 his sagacity. The truth is, that this article of the Berke- 
 leiaa system, however contrary to the conclusions of a 
 sounder philosophy, was the error of no common mind. 
 Considered in contrast with that theory of materialism, 
 which the excellent author was anxious to supplant, it 
 possessed important advantages, not only in its tendency, 
 but in its scientific consistency ; and it afibrded a proof, 
 wherever it met with a favourable reception, of an under- 
 standing superior to those casual associations, which, in 
 the apprehensions of most men, blend indissolubly the 
 phenomena of thought with the objects of external per- 
 ception. It is recorded as a saying of M. Turgot, whose 
 philosophical opinions in some important points approach- 
 ed very nearly to those of Dr. Reid,* that, " be who had 
 never doubted of the existence of matter, might be assured 
 he bad no turn for metaphysical disquisitions." 
 , As the refutation of Mr. Hume's skeptical theory was 
 the great and professed object of Dr. Reid's Inquiry, he 
 was anxious, before taking the field as a controversial 
 writer, to guard against the danger of misapprehending 
 
 * See, ID particular, the article Existence in the Encyclopedia. 
 
AND WHITINGS OV DR. BEID. IS 
 
 or misrepresenting the meaning of his adversary, by sub- 
 mitting his reasonings to Mr. Hume's private examination. 
 With this view, he availed himself of the good offices of 
 Dr. Blair, with ^yhom both he and Mr. Hume had long 
 lived in habits of friendship. The communications which 
 he at first transmitted, consisted only of detached parts 
 of the work ; and appear evidently, from a correspondence 
 which I have perused, to have conveyed a very imperfect 
 idea of his general system. In one of Mr. Hume's letters 
 to Dr. Blair, he betrays some want of his usual good hu- 
 mour, in looking forward to his new antagonist. " I wish," 
 says he, " that the parsons would confine themselves to 
 their old occupation of worrying one another, and leave 
 philosophers to argue with temper, moderation, and good 
 manners." After Mr. Hume, however, had read the 
 manuscript, he addressed himself directly to the author, 
 in terms so candid and liberal, that it would be unjust to 
 his memory to withhold from the public so pleasing a 
 memorial of his character. 
 
 *< By Dr. Blair's means, I have been favoured with the 
 perusal of your performance, which I have read with great 
 pleasure and attention. It is certainly very rare, that a 
 piece so deeply philosophical is written with so mueh 
 spirit, and affords so much entertainment to the reader ; 
 though I must still regret the disadvantages under which 
 I read it, as I never had the whole performance at once 
 before me, and could not be able fully to compare one 
 part with another. To this reason, chiefly, I ascribe 
 some obscurities, which, in spite of your short analysis 
 or abstract, still seem to hang over your system. For I 
 must do you the justice to own, that when I enter into 
 your ideas, no man appears to express himself with 
 greater perspicuity than you do ; a talent which, above 
 all others, is requisite in that species of literature which 
 you have cultivated. There are some objections which 
 Iwould willingly propose to the [chapter. Of Sight, did 
 I not suspect that they proceed from my not sufficiently 
 understanding it ; and I am the more confirmed in this 
 
16 ACCOUNT or THE IIFB 
 
 suspicion, as Dr. Blair tells me, that the former objec- 
 tions I made had been derived chiefly from that cause, 
 I shall therefore forbear till the whole can be before 
 me, and shall not at present propose any farther difficul- 
 ties to your reasonings. 1 shall only say, that if you 
 have been able to clear up these abstruse and import- 
 ant subjects, instead of being mortified, I shall be so vain 
 as to pretend to a share of the praise j and shall think, 
 that my errors, by having at least some coherence, had 
 led you to make a more strict review of my principles, 
 which were the common ones, and to perceive their fu- 
 tility. 
 
 "As I was desirous to be of some use to you, I kept a 
 watchful eye all along over your style j but it is really so 
 correct, and so good English, that I found not any thing 
 worth the remarking. There is only one passage in this 
 chapter, where you make use of the phrase hinder to do, 
 instead of hinder from doing, which is the English one ; 
 but I could not find the passage when I sought for it. 
 You may judge how unexceptionable the whole appeared 
 to me, when I could remark so small a blemish. I be'g 
 my compliments to my friendly adversaries. Dr. Camp- 
 bell and Dr. Gerard; and also to Dr. Gregory, whom I 
 suspect to be of the same disposition, though he has not 
 openly declared himself such." 
 
 Of the particular doctrines contained in Dr. Reid's In- 
 quiry, I do not think it necessary here to attempt any 
 abstract j nor indeed do his speculations, conducted as 
 they were in strict conformity to the rules of inductive 
 philosophizing, aJSbrd a subject for the same species of 
 rapid outline, which is so useful in facilitating the study 
 of a merely hypothetical theory. Their great object 
 was to record and to classify the phenomena which the 
 operations of the human mind present to those who reflect 
 carefully on the subjects of their consciousness ; and of 
 such a history, it is manifest, that no abridgment could 
 be offered with advantage. Some reflections on the pe- 
 culiar plan adopted by the author, aad on the general 
 
AND WRITINGS OF DB. REID. 17 
 
 scope of his researches in this department of science. Mill 
 afterward find a more convenient place, when I sliall h?»ve 
 finished my account of his subsequent publications. 
 
 The idea of prosecuting the study of the human mind, 
 on a plan analogous to that which had been so success^ 
 fully adopted in physics by the followers of lord Bacon, 
 if not lirst conceived by Dr. Reid, was at least first car- 
 ried successfully into execution in his writings. An at» 
 tempt had long before been announced by Mr. Hume, }n 
 the title page of his Treatise of Human Nature, to intro- 
 duce the experimental method of reasoning into moral 
 subjects ; and some admirable remarks are made in the 
 introduction to that work, on the errors into which his 
 predecessors had been betrayed by the spirit of hypothe» 
 sis ; and yet it is now very generally admitted, that the 
 whole of his own system rests on a principle for which 
 there is no evidence but the authority of philosophers j 
 and it is certain, that in no part of it, has he aimed to in« 
 vestigate by a systematical analysis, those general princi- 
 ples of our constitution which can alone afford a synthet- 
 ical explanation of its complicated phenomena. 
 
 I have often been disposed to think, that Mr. Hume's 
 inattention to those rules of philosophizing which it wan 
 his professed intention to exemplify, was owing in part to 
 some indistinctness in his notions concerning their import. 
 It does not appear, that, in the earlier part of his studies; 
 he had paid much attention to the models of investigatioi) 
 exhibitedinthe writings of Newton and of his successors; 
 and that he was by no means aware of the extraordinary 
 merits of Bacon as a philosopher, nor of the influence 
 which his writings have had on the subsequent progress 
 of physical discovery, is demonstrated by the cold and quaU 
 ified encomium which is bestowed on his genius, in one of 
 the most elaborate passages of the History of England. 
 
 In these respects Dr. Reid possessed important advan- 
 tages ; familiarized, from his early years, to those exper- 
 imental inquiries, which, in the course of the two last 
 centuries, have exalted Xatural Philosophy to the dignity 
 vol. I, 3 
 
18 ACCOUNT OF THE WFE 
 
 of a science J and determined slrongly, by the peculiai' 
 bent of his genius, to connect every step in the progress 
 of discovery with the history of the human mind. The 
 influence of the general views opened in the Novum Or- 
 ganon, may be traced in almost every page of his writ- 
 ings,- and, indeed, the circumstance by whieh these are 
 so strongly and characteristically distinguished, is, that 
 they exhibit the first systematical attempt to exemplify, 
 in the study of human nature, the same plan of investiga- 
 tion which conducted Newton to the properties of light, 
 and to the law of gravitation. It is from a steady adher- 
 ence to this plan, and not from the superiority of his 
 inventive powers, that he claims to himself any merit as 
 a philosopher ; and he seems even willing, with a mod- 
 esty approaching to a fault, to abandon the praise of 
 what is commonly called genius, to the authors of the 
 systems whieh he was anxious to refute. " It is genius,'* 
 he observes in one passage, " and not the want of it, that 
 adulterates philosophy, and fills it with error and false 
 theory. A creative imagination disdains the mean offices 
 of digging for a foundation, of removing rubbish, and 
 carrying materials: leaving these servile employments 
 to the drudges in science, it plans a design, and raises a 
 fabric. Invention supplies materials where they are 
 wanting, and fancy adds colouring, and every befitting 
 ornament. The work pleases the eye, and wants nothing 
 but solidity and a good foundation. It seems even to vie 
 with the works of nature, till some succeeding architect 
 blows it into ruins, and builds as goodly a fabric of his 
 own in its place." 
 
 " Success in an inquiry of this kind," he observes far- 
 ther, " it is not in human power to command ; but per- 
 haps it is possible, by caution and humility, to avoid 
 error and delusion. The labyrinth may be too intricate, 
 and the thread too fine, to be traced through all its wind- 
 ings ; but, if we stop where we can trace it no farther, 
 and secure the ground we have gained, there is no harm 
 done ; a quicker eye may in time trace it farther," 
 
AND WRITINGS OP DR. B£ID. 19 
 
 The unassuming language with which Dr. Reid endeav- 
 ours to remove the prejudices naturally excited by anew 
 attempt to philosophize on so unpromising, and hitherto 
 so ungrateful a subject, recals to our recollection those 
 passages in which lord Bacon, filled as his own imagination 
 was with the future grandeur of the fabric founded by his 
 hand, bespeaks the indulgence of his readers, for an en- 
 terprise apparently so hopeless and presumptuous. The 
 apology he offers for himself, when compared with the 
 height to which the structure of physical knowledge has 
 since attained, may perhaps have some eifeet in attract- 
 ing a more general attention to pursuits still more imme- 
 diately interesting to mankind; and, at any rate, it forms 
 the best comment on the prophetic suggestions in which 
 Dr. Reid occasionally indulges himself concerning the 
 future progress of moral speculation. 
 
 " Si homines per tanta annorum spatia viam veramin- 
 veniendi et colendi scientias tenuissent, nee tamen ulterius 
 progredi potuissent, audax procul dubio et temeraria fo- 
 ret opinio, posse rem in ulterius provehi. Quod si ia via 
 ipsa erratum sit, atque hominum opera in iis consumpta 
 in quibus minime oportebat, sequitur ex eo, nonin rebus 
 ipsis difBcultatem oriri, quss potestatis nostrse non sunt ; 
 sed in intellectu bumano, ejusque usu et applicatione, 
 
 ^use res remedium et medicinam suscipit."* " De 
 
 nobis ipsis silemus : de re autera qua; agitur, petimus ; 
 JJt homines eam non opinionem, sed opus esse cogitent ; 
 ac pro certo habeant, non sectee nos alicujus, aut placiti, 
 sed utililatis et amplitudinis humana; fundameuta moliri. 
 Preeterea, ut bene sperent ; neque Instaurationem nostram 
 ut quiddam infinitum et ultra mortale fingant, et animo 
 concipiant ; quum revera sit infiniti erroris finis et ter- 
 minus legitimus."! 
 
 The impression produced on the minds of speculative 
 men, by the publication of Dr. Reid's Inquiry, was full as 
 great as could be expected from the nature of his under- 
 
 • Nov. Org. 94. flnstanr. Mag. Prsfat. 
 
20 ACCOUNT OF THE HFE 
 
 taking. It was a Work neither addressed to the multitude* 
 tier level to their comprehension ; and the freedom with 
 which it canvassed opinions sanctioned hy the highest au- 
 thorities, was ill calculated to conciliate the favour of the 
 learned. A few, however, habituated, like the author, to 
 the analytical researches of the Newtonian school, soon 
 Jjerceived the extent of his views, and recognised in his 
 pages the genuine spirit and language of inductive investi- 
 gation. Among the membei-s of this university, Mr. Fur- 
 guson was the first to applaud Dr. Reid's success ; warmly 
 feeommending to his pupils a steady prosecution of the 
 same plan, as the only eifectual method of ascertaining the 
 general principles of the human frame: and illustrating 
 happily, by his own profound and eloquent disquisitions, 
 the application of such studies, to the conduct of the un- 
 derstanding, and to the great concerns of life. I recollect, 
 too, when I attended, about the year 1771, the lectures of 
 the late Mr. Russell, to have heard high encomiunis on 
 the Philosophy of Reid, in the course of those compre- 
 hensive discussions concerning the objects and the rules 
 of experimental science, with which he so agreeably 
 diversified the particular doctrines of physics. Nor must 
 t omit this opportunity of paying a tribute to the memory 
 of my old friend Mr. Stevenson, then Professor of Logic j 
 whose candid mind, at the age of seventy, gave a welcome 
 Inception to a system subversive of the theories which he 
 had taught for forty years ; and whose zeal for the ad- 
 vancement of knowledge prompted him, when his career 
 was almost finished, to undertake the laborious task of 
 new modelling that useful compilation of elementary 
 instruction, to whichasingular diffidence of his own pow- 
 ers limited his literary exertions. 
 
 It is with no common feelings of respect and of grati- 
 tude, that I now reeal the names of those to whom I owe 
 Hfiy first attachment to these studies, and the happiness 
 ©fa liberal occupation superior to the more aspiring aims 
 of a servile ambition. 
 
AND WRITIKGS OV DR. REID. 21 
 
 From (he university of Glasgow, Dr. Reid's Inquiry re- 
 ceived a still more substantial testimony of approbation ; 
 the author having been invited, in 1764), by that learned 
 body, to the professorship of Moral Philosophy, then va- 
 cant by the resignation of Mr. Smith. The preferment 
 was in many respects advantageous ; affording an income 
 considerably greater than he enjoyed at Aberdeen ; and 
 enabling him to concentrate to his favourite objects, that 
 attention which had been hitherto distracted by the mis- 
 cellaneous nature of his academical engagements. It was 
 not, however, without reluctance, that he consented to 
 tear himself from a spot where he had so long been fast- 
 ening his roots ; and, much as he loved the society in 
 which he passed the remainder of his days, I am doubt- 
 ful if, in his mind, it compensated the sacrifice of earlier 
 habits and connections. 
 
 Abstracting from the charm of local attachment, the 
 university of Glasgow, at the time when Dr. Reid was 
 adopted as one of its members, presented strong attrac- 
 tions to reconcile him to his change of situation. Rob- 
 ert Simson, the great restorer of ancient geometry, was 
 still alive ; and, although far advanced in years, preserved 
 unimpaired his ardour in study, his relish for social re- 
 laxation, and his amusing singularities of humour. Dr. 
 Moor combined with a gaiety and a levity foreign to this 
 climate, the profound attainments of a scholar and of a 
 mathematician. In Dr. Black, to whose fortunate genius 
 a new world of science had just opened, Reid acknowl- 
 edged an instructor and a guide ; and met a simplicity of 
 manners congenial to bis own. The Wilsons, both father 
 and son, were formed to attach his heart by the similarity 
 of their scientific pursuits, and an entire sympathy with 
 his views and sentiments. Nov was he less delighted with 
 the good humoured opposition which his opinions never 
 failed to encounter in the acuteness of Millar, then in the 
 vigour of youthful genius, and warm from the lessons of 
 a different school. Dr. Leechman, the friend and biog- 
 rapher of Hutcheson, was the official head of the college ; 
 
SS ACCOUNT OF THE IIFE 
 
 and aOded the weight of a venerable name to the reputa- 
 tion of a community, wliich he had once adorned in a 
 more active station.* 
 
 Animated by the zeal of such associates, and by the 
 busy scenes which his new residence presented in every 
 department of useful industry, Dr. Reid entered on his 
 functions at Glasgow, with an ardour not common at the 
 period of life, which he had now attained. His researches 
 concerning the human mind, and the principles of morals, 
 which had occupied hut an inconsiderable space in the 
 wide circle of science, allotted to him by his former ofBce, 
 were extended and methodised in a course which employed 
 five hours every week, during six months of the year: 
 the example of his illustrious predecessor, and the pre- 
 vailing topics of conversation around him, occasionally 
 turned his thoughts to commercial politics, and produced 
 some ingenious essays on different questions connected 
 with trade, which were communicated to a private society 
 of his academical friends : his early passion for the math- 
 ematical sciences was revived by the conversation of 
 Simson, Moor, and the Wilsons ; and, at the age of fifty- 
 five, he attended the lectures of Black, with a juvenile 
 curiosity and enthusiasm. 
 
 As the substance of Dr. Reid's lectures at Glasgow, at 
 least of that part of them which was most important and 
 original, has been since given to the public in a more im- 
 proved form, it is unnecessary for me to enlarge on theplan 
 which he followed in the discharge of his official duties. 
 I shall therefore only observe, that besides his Specula- 
 tions on the Intellectual and Active Powers of Man, and 
 a System of Practical Ethics, his course comprehended 
 some general views with respect to Natural Jurisprudence, 
 and the fundamental principles of Politics. A few lec- 
 tures on Rhetoric, which were read, at a separate hour, 
 to a more advanced class of students, formed a voluntary 
 addition to the appropriate functions of his ofiice, to 
 
 "NoteC. 
 
AND WRITINGS OF DR. EEID. 3S 
 
 which, it is probahle, he was prompted rather by a wish 
 to supply what was then a deficiency in the established 
 course of education, than by any predilection for a branch 
 of study so foreign to his ordinary pursuits. 
 
 The merits of Dr. Reid, as a public teacher, were de- 
 rived chiefly from that rich fund of original and instruct- 
 ive philosophy which is to be found in his writings ; and 
 from his unwearied assiduity in inculcating principles 
 which he conceived to be of essential importance to hu- 
 man happiness. In his elocution and mode of instruction, 
 there was nothing peculiarly attractive. He seldom, if 
 ever, indulged himself in the warmth of extempore dis- 
 course ; nor was his manner of reading calculated to in- 
 crease the effect of what he had committed to writing. 
 Such, however, was the simplicity and perspicuity of his 
 style J such the gravity and authority of his character; 
 and such the general interest of his young hearers in the 
 doctrines which he taught, that by the numerous audi- 
 ences to which his instructions were addressed, he was 
 heard uniformly with the most silent and respectful at- 
 tention. On this subject, I speak from personal knowl- 
 edge ; having had the good fortune, during a considerable 
 part of the winter of 1772, to be one of his pupils. 
 
 It does not appear to me, from what I am now able to 
 recollect of the order which he observed in treating the 
 different parts of his subject, that he had laid much stress 
 on systematical arrangement. It is probable, that he 
 availed himself of whatever materials his private inquiries 
 afforded, for his academical compositions ; without aim- 
 ing at the merit of combining them into a whole, ^j a 
 comprehensive and regular design ; an undertaking, to 
 which, if lam not mistaken, the established forms of his 
 university, consecrated by long custom, would have pre- 
 sented some obstacles. One thing is certain, that neither 
 he nor his immediate predecessor ever published any gen- 
 eral prospectus of their respective plans ; nor any heads 
 or outlines to assist their students in tracing the trains of 
 thought which suggested their various transitions. 
 
34 ACCOUNT or THE IIFE 
 
 The interest, however, excited bj such details as these, 
 even if it were in my power to render them more full and 
 satisfactory, must necessarily be temporary and local ; 
 and I therefore hasten to observations of a more general 
 nature, on the distinguishing characteristics of Dr. Reid's 
 philosophical genius, and on the spirit and scope of those 
 researches Avhich he has bequeathed to posterity, con- 
 cerning the phenomena and laws of the human mind. In 
 mentioning his first performance on this subject, I have 
 already anticipated a few remarks which are equally ap- 
 plicable to his subsequent pnblications ; but the hints then 
 suggested were too slight, to place in so strong a light as 
 I could wish, the peculiarities of that mode of investiga- 
 tion, which it was the great object of his writings to rec- 
 ommend and to exemplify. His own anxiety, to neglect 
 nothing that might contribute to its farther illustration, 
 induced him, while his health and faculties were yet en- 
 tire, to withdraw from his public labours ; and to devote 
 himself wholly to a task of more extensive and permanent 
 utility. It was in the year 1780 that he carried this design 
 into execution, at a period of life (for he was then sev- 
 enty) when the infirmities of age might be supposed to 
 account sufficiently for his retreat ; but when, in fact, 
 neither the vigour of his mind nor of his body seemed to 
 have suffered any injury from time. The works which 
 he published not many years afterward, afibrd a sufficient 
 proof of the assiduity with which he had availed himself 
 of his literary leisure; his Essays on the Intellectual 
 Powers of Man appearing in 1786 ,• and those on the Ac- 
 tive Powers in 1788. 
 
 As these two performances are, both of them, parts of 
 one great work, to which his Inquiry into (he Human 
 Mind may be regarded as the Introduction, I have reserved 
 for this place whatever critical reflections I have to oflfer 
 on his merits as an author ; conceiving that they would 
 be more likely to produce their intended eflfect, when pre- 
 sented at once in a connected form, than if interspersed, 
 according to a chronological order, with the details of a 
 biographical narrative. 
 
AND WRITINGS OF DR. RKID. 
 
 SECTION H, 
 
 OBSERVATIONS ON THE SPIRIT AND SCOPE OIF PR. RBID'S 
 PHILOSOPHY. 
 
 I HAVE already observed, that the distinguishing fea-- 
 ture of Dr. Reid's philosophy, is the systematical stead!-, 
 ness, with which he has adhered in his inquiries, to that 
 plan of investigation which is delineated in the Novum 
 Organon, and which has been so happily exemplified iu 
 physics by Sir Isaac Newton and his followers. To rec- 
 ommend this plan as the only effectual method of enlarg- 
 ing our knowledge of nature, was the favourite aim of all 
 his studies, and a topic on which he thought he could not 
 enlarge too much, in conversing or corresponding with 
 his younger friends. In a letter to Dr. Gregory, which 
 I have perused, he particularly congratulates him, upon 
 his acquaintance with lord Bacon's works ; adding, <^I 
 am very apt to measure a man's understanding, by the 
 opinion he entertains of that author." 
 
 It were perhaps to be wished, thAt he had taken a little 
 more pains to illustrate the fundamental rules of that 
 logic, the value of which he estimated so highly 5 more 
 especially, to point out the modifications with which it 
 is applicable to the science of mind. Many important 
 hints, indeed, connected with this subject, may be collect- 
 ed from different parts of his writings ; but I am inclined 
 to think, that a more ample discussion of it in a prelimi- 
 nary dissertation, might have thrown light on the scope 
 of many of his researches, and obviated some of the most 
 plausible objections which havf; been stated to his coi)? 
 elusions. 
 
 It is not, however, my intention at present, to attempt 
 to supply a desideratum of so great a magnitude ; an un- 
 dertaking which. I trust, will find a more convenient 
 place, in the farther prosecution of those speculations 
 
 TCI. I, ^ 
 
26 ACCOUNT or THE UFE 
 
 with respect to the Intellectual Powers which I have 
 already submitted to the public. 'The detached remarks 
 which follow, are offered merely as a supplement to what I 
 have stated concerning the nature and object of this branch 
 of study, in the introduction to the Philosophy of the Hu- 
 man Mind. 
 
 The influence of Bacon's genius on the subsequent 
 progress of physical discovery, has been seldom fairly 
 appreciated ; by some writers almost entirely overlook- 
 ed ; and by others considered as the sole cause of the ref- 
 ormation in science which has since taken place. Of these 
 two extremes, the latter certainly is the least wide of the 
 truth ; for in the whole history of letters, no other indi- 
 vidual can be mentioned, whose exertions have had so in- 
 disputable an effect in forwarding the intellectual progress 
 of mankind. On the other hand, it must be acknowledged, 
 that before the era when Bacon appeared, various phi- 
 losophers la different parts of Europe had struck into the 
 right path ; and it may perhaps be doubted, whether any 
 one important rule with respect to the true method of in- 
 vestigation be contained in his works, of which no hint 
 can be traced in those of his predecessors. His great 
 merit lay in concentrating their feeble and scattered 
 lights; fixing the attention of philosophers on the distin- 
 guishing characteristics of true and of false science, by a 
 felicity of illustration peculiar to himself, seconded by 
 the commanding powers of a bold and figurative eloquence. 
 The method of investigation which he recommended had 
 been previously followed in every instance, in which any 
 solid discovery had been made with respect to the laws 
 of nature; but it had been followed accidentally, and 
 without any I'cgular preconceived design ; and it was re- 
 served for him to reduce to rule and method what others 
 had effected, either fortuitously, or from some momentary 
 glimpse of the truth. It is justly observed by l>r. Seid, 
 that " the man who first discovered that cold freezes 
 water, and that beat turns it into vapour, proceeded on 
 the same general principle by whieh Newton discovered 
 
AND WKITINGS OF DR. REID. 37 
 
 the law of gravitation and the properties of light. His 
 Itegulse Philosophandi are maxims of common sense, and 
 are practised every day in common life; and he who phi- 
 losophizes by other rules, either concerning the material 
 system or concerning the mind, mistakes his aim." 
 
 These remarks are not intended to detract from the 
 just glory of Bacon ; for they apply to all those, without 
 exception, who have systematized the principles of any of 
 the arts. Indeed, they apply less forcibly to him, than 
 to any other philosopher whose studies have been directed 
 to objects analogous to his ; inasmuch as we know of no 
 art, of whicli the rules have been reduced successfully 
 into a didactic form, when the art itself was as much in 
 infancy as experimental philosophy was when Bacon 
 wrote. Nor must it be supposed, that the utility was 
 small of thus attempting to systematize the accidental 
 processes of unenlightened ingenuity, and to give to the 
 noblest exertions of human reason, the same advantages 
 of scientific method, which have contributed so much to 
 ensure the success of genius in pursuits of inferior im- 
 portance. The very philosophical motto which Reynolds 
 has so happily prefixed to his Academical Discourses, 
 admits, on this occasion, of a still more appropriate ap- 
 plication : " Omnia fere quse prseceptis continentur ab in- 
 gcniosis hominibusiiunt; sed casu quodam magis quam 
 scicntia. Ideoque doctrina et animadversio adhibenda 
 est, ut ea qure interdum sine ratione nobis oceurrunt, 
 semper in nostra potestatc sint; et quoties res postula- 
 verit, a nobis ex prseparalo adhibeantur." 
 
 But although a few superior minds seem to have been 
 in some measure predisposed for that revolution in science, 
 which Bacon contributed so powerfully to accomplish, the 
 case was very different with the great majority of those 
 who were then most distinguished for learning and talents. 
 His views were plainly too advanced for the age in which 
 he lived ; and, that he was sensible of this himself, ap- 
 pears from those remarkable passages, in which he styles 
 himself "the servant of posterity," and "bequeaths his 
 
28 ACCOUNT or THE HFE 
 
 fame to future limes.*' Hobbes, who in his early youth, 
 had enjoyed his friendship, speaks, a considerable time 
 after Bacon's death, of exjierimcntal philosophy, in terms 
 of contempt ; iiiiluenced probably, not a litde, by the ten- 
 dency he perceived in the inductive method of inquiry, to 
 undermine the foundations of that fabric of skepticism 
 which it was the great object of his labours to rear. Nay, 
 even during the course of the last century, it has been 
 less from Bacon's own speculations, than from the exam- 
 ples of sound investigation exhibited by a few eminent 
 men« who professed to follow him as their guide, that the 
 practical spirit of his writings has been caught by the 
 multitude of physical experimentalists over Europe ; 
 truth and good sense descending gradually, in this as in 
 other instances, by the force of imitation and of early 
 habit, from the higher orders of intellect to the lower. In 
 some parts of the continent, more especially, the circula'^ 
 tion of Bacon's philosophical works has been surprisingly 
 slow. It is doubtful whether Des Cartes himself evep 
 perused them ; and as late as the year 1759, if we may 
 credit Montucia, they were Very little known in France. 
 The introductory discourse prefixed by D'Alembert to 
 the Encyclopedic, first recommended them, in that coun- 
 try, to general attention. 
 
 The change which has taken place during the two last 
 centuries, in the plan of physical research, and the suc- 
 cess which has so remarkably attended it, could not fail 
 to suggest an idea, that something analogous might proba- 
 bly be aceomplislied at a future period, with respect to the 
 phenomena of the intellectual world. And accordingly, 
 various hints of this kind may be traced in different au- 
 thors, since the era of Newton's discoveries. A memo- 
 rable instance occurs in tlie prediction with which that 
 great man concludes his Optics ; " That if natural philos- 
 ophy, in all its parts, by pursuing the inductive method, 
 shall at length be perfected, the bounds of moral philos- 
 ophy will also be enlarged." Similar remarks may be 
 founcl in other publications ; particularly in Mr. Hume's* 
 
AND WRITINGS OF DR. HEID. 29 
 
 Treatise of Human Nature, where the subject is enlarged 
 on with much ingenuity. As far, however, as I am able 
 to judge, Dr. Reid was (he first who conceived justly and 
 clearly the analogy between these two diiferent branches 
 of human knowledge ; defining with precision the distinct 
 provinces of observation and of reflection, in furnishing 
 the data of all our reasonings concerning matter and 
 mind; and demonstrating the necessity of a careful sep- 
 aration between the phenomena which they respectively 
 exhibit, while we adhere to the same mode of philoso- 
 phizing in investigating the laws of both. 
 
 That so many philosophers should have thus missed 
 their aim, in prosecuting the study of the human mind, 
 will appear the less surprising, when we consider, in how 
 many difficulties, peculiar to itself, this science is involv- 
 ed. It is sufficient at present to mention those which 
 arise, from the metaphorical origin of all the words which 
 express the intellectual phenomena ; from the subtle and 
 fugitive nature of the objects of our reasonings; from 
 the habits of inattention we acquire, in early life, to the 
 subjects of our consciousness ; and from the prejudices 
 which early impressions and associations create to warp 
 our opinions. It must be remembered, too, that in the 
 science of mind ; so imperfectly are its logical rules as yet 
 understood ! we have not the same checks on the abuses 
 of our reasoning powers, which serve to guard us against 
 error in our other researches. In physics, a speculative 
 mistake is abandoned, when contradicted by facts which 
 strike the senses. In mathematics, an absurd or incon- 
 sistent conclusion is admitted as a demonstrative proof of 
 a faulty hypothesis. But, in those inquiries which relate 
 to the principles of human nature, the absurdities and in- 
 consistencies to which we are led by almost all the sys- 
 tems hitherto proposed, instead of suggesting corrections 
 and improvements on these systems, have too frequently 
 had the eflfect of producing skepticism with respect to all 
 of them alike. How melancholy is the confession of 
 Hume ! " The intense view of these manifold contradic- 
 
so ACCOUNT or THE IIFE 
 
 tions and imperfections in human reason, has so wrouglit 
 upon me, and heated my brain, that I am ready to reject 
 all belief and reasoning, and can look upon no opinion 
 even as more probable or likely than another." 
 
 Under these discouragements to this branch of study, 
 it affords some comfort to reflect on the great number of 
 important facts with respect to the mind, which are scat- 
 tered in tlie writings of philosophers. As the subject of 
 our inquiry here lies within our own breast, a considera- 
 ble mixture of truth may be expected even in those sys- 
 tems which are most erroneous ; not only because a num- 
 ber of men can scarcely be long imposed on by an hypoth- 
 esis wliich is perfectly groundless, concerning the objects 
 of their own consciousness; but because it is generally 
 by an alliance with truth and with the original principles 
 of human nature, that prejudices and associations produce 
 their eifects. Perhaps it may even be affirmed, that our 
 progress in this research depends less on the degree of 
 our industry and invention, than on our sagacity and good 
 sense in separating old discoveries from the errors which 
 have been blended with them | and on that candid and 
 dispassionate temper that may prevent us from being led 
 astray by the love of novelty, or the affectation of singu- 
 larity. In this respect, the science of mind possesses a 
 very important advantage over that wliich relates to the 
 laws of the material world. The former has been cul- 
 tivated with more or less success in all ages and coun- 
 tries : the facts which serve as the basis of the latter 
 have, with a very few exceptions, been collected during the 
 course of the two last centuries. An observation similar 
 to this is applied to systems of Ethics by Mr. Smith, in 
 his account of the theory of Mandeville ; and the illus- 
 tration he gives of it may be extended with equal propri- 
 ety to the science of mind in general. " A system of Nat- 
 ural Philosophy," he remarks, " may appear very plaus- 
 ible, and be, for a long time, very generally received in 
 the world, and yet have no foundation in nature, nor any 
 sort of resemblance to the truth. But it is otherwise with 
 
AND WRITINGS OV DB. HEID. SI 
 
 systems of Moral Philosophy. When a traveller gives an 
 account of some distant country, he may impose upon our 
 credulity the most groundless and absurd fictions as the 
 most certain matters of fact; but when a person pretends 
 to inform us of what passes in our neighbourhood, and of 
 the affairs of the very parish we live in, though here too, 
 if we are so careless as not to examine things with our 
 own eyes, he may deceive us in many respects ; yet the 
 greatest falsehoods which he imposes on us must bear 
 some resemblance to the truth, and must even have a con- 
 siderable mixture of truth in them." 
 
 These considerations demonstrate the essential import- 
 ance, in this branch of study, of forming, at the commence- 
 ment of our inquiries, just notions of the criteria of true 
 and false science, and of the rules of philosophical inves- 
 tigation. They demonstrate, at the same time, that an 
 attention to the rules of philosophizing, as they are exem- 
 plified in the physical researches of Newton and his fol- 
 lowers, although the best of all preparations for an ex- 
 amination of the mental phenomena, is but one of the 
 steps necessary to ensure our success. Oh an accurate 
 comparison of the two subjects, it might probably appear, 
 that after this preliminary step has been gained, the most 
 arduous part of the process still remains. One thing is 
 certain, that it is not from any defect in the power of 
 ratiocination or deduction, that our speculative errors 
 ehiefiy arise ; a fact of which we have a decisive proof in 
 the facility with which most students may be taught the 
 mathematical and physical sciences, when compared with 
 the difficulty of leading their minds to the truth on ques- 
 tions of morals and politics. 
 
 The logical rules which lay the foundation of sound 
 and useful conclusions concerning the laws of this inter- 
 nal world, although not altogether overlooked by lord 
 Bacon, were plainly not the principal object of his work; 
 and what he has written on the subjicct, consists chieflj 
 of detached bints dropped casually in the course of other 
 speculations. A compreheqsive view of the sciences and 
 
32 ACCOUNT or the iifk 
 
 arts dependent on the philosophy of the human mind, ex- 
 hibiting the relations wliieh they bear to each other, and 
 to the general system of human knowledge, would form 
 a natural and useful introduction to the study of these 
 logical principles; but such a view remains still a deside- 
 ratum, after all the advances made toward it by Bacon 
 and D'Alembert. Indeed, in the present improved state 
 of things, much is wanting to complete and perfect that 
 more simple part of their intellectual map which relates 
 to the material universe. Of the inconsiderable progress 
 hitherto made toward a just delineation of the method to 
 be pursued in studying the mental phenomena, no other 
 evidence is necessary than this ; that the sources of error 
 and false judgment so peculiarly connected, in consequence 
 of the association of ideas, with studies in which our best 
 interests are immediately and deeply concerned, have 
 never yet been investigated with such accuracy, as to af- 
 ford effectual aid to the student, in his attempts to coun- 
 teract their influence. One of these sources alone, that 
 which arises from the imperfections of language, furnishes 
 an exception to the general remark. It attracted, for- 
 tunately, the particular notice of Locke, whose observa- 
 tions with respect to it, compose, perhaps, the most val- 
 uable part of his philosophical writings ; and, since the 
 time of Condillac, the subject has been still more deeply 
 analyzed by others. Even on this article, much yet re- 
 mains to be done ; but enough has been already accom- 
 plished to justify the profound aphorism in which Bacon 
 pointed it out to the attention of his followers : " Credunt 
 homines rationem suam verbis imperare ; sed fit etiam ut 
 verba vim suam super rationem rctorqueant."* 
 
 Into these logical discussions concerning the means of 
 advancing the philosophy of human nature, Dr. Reid has 
 seldom entered ; and still more rarely has he indulged 
 
 * This passage of Bacon forms the motto to a very ingenious and philo- 
 sophical dissertation, lately published by M. Prevost of Geneva, entitled, 
 " Des Signes envisages relativeiueat k leur Influence sur la formation de> 
 Mies." Varis, an 8. 
 
AlfD WRITINGS OF DR. llBID. 33 
 
 himself in tracing the numerous relations, by which this 
 philosophy is connected with the practical business of 
 life. But he has done what was still more essential at the 
 time he wrote : he has exemplified, with the happiest 
 success, that method of investigation by which alone any 
 solid progress can be made ; directing his inquiries to a 
 subject which forms a necessary groundwork for the 
 labours of his successors; an analysis of the various 
 powers and principles belonging to our constitution. Of 
 the importance of this undertaking, it is sufficient to 
 observe, that it stands somewhat, although I confess 
 not altogether, in the same relation to the dilTerent 
 branchies of intellectual and moral science, such as gram- 
 mar, rhetoric, logic, ethics, natural theology, and politics, 
 in which the anatomy x)f the human body stands to the 
 different branches of physiology and pathology. And as 
 a course of medical education naturally, or rather neces- 
 sarily, begins with a general survey of man's animal 
 frame ; so, I apprehend, that the proper, or rather the 
 essential preparation of those studies which regard our 
 nobler concerns, is an examination of the principles which 
 belong to man as an intelligent, active, social, and moral 
 being. Nor does the importance of such an analysis rest 
 here; it exerts an influence over all those sciences and 
 arts which are connected with the material world ; and 
 the philosophy of Bacon itself, while it points out the 
 road to physical truth, is but a branch of the philosophy 
 of the human mind. 
 
 The substance of these remarks is admirably expressed 
 by Mr. Hume in the following passage ; allowances being 
 made for a few trifling peculiarities of expression, bor- 
 rowed from the theories which were prevalent at the 
 time when he wrote : " 'Tis evident, that all the sciences 
 have a relation, greater or less, to human nature, and 
 that, however wide any of theih may seem to run from it, 
 they still return back by one passage or another. Even 
 mathematics, natural philosophy, and natural religion, 
 are in some measure dependent on the science of man ; 
 Vox, I. 5 
 
3'i ACCOUNT OF THE IIFE 
 
 since they lie under (he cognisance of men, and are judg- 
 ed of by their powers and faculties. It is impossible to 
 tell what changes and improvements we might make ia 
 these sciences, were we thoroughly acquainted with the 
 extent and force of human understanding, and could ex- 
 plain the nature of the ideas we employ, and of the ope- 
 rations we perform in our reasonings. 
 
 " If, therefore, the sciences of mathematics, natural 
 philosophy, and natural religion, have such a dependence 
 on the knowledge of man, what may be expected in the 
 other sciences, whose connection with human nature is 
 more close and intimate ? The sole end of logic is to ex- 
 plain the principles and operations of our reasoning fac- 
 ulty, and the nature of our ideas : morals and criticism 
 regard our tastes and sentiments : and politics consider 
 men as united in society, and dependent on each other. In 
 these four sciences of logic, morals, criticism and politics, 
 is comprehended almost every thing which it can any way 
 import us to be acquainted with, or which can tend either 
 to the improvement or ornament of the human mind. 
 
 '* Here then, is the only expedient from which we can 
 hope for success in our philosophical researches ; to leave 
 the tedious, lingering method, which we have hitherto 
 followed ; and instead of taking, now and then, a castle 
 or village on the frontier, to march up directly to the cap- 
 ital or centre of these sciences, to human nature itself j 
 which being once masters of, we may every where else 
 hope for an easy victory. From this station, we may ex- 
 tend our conquests over all those sciences which more 
 intimately concern human life, and may afterward pro- 
 ceed at leisure to discover more fully those which are the 
 objects of pure curiosity. There is no question of im- 
 portance, whose decision is not comprised in the science 
 of man ; and there is none which can be decided with any 
 certainty, before we become acquainted with that sci- 
 ence." 
 
 To prepare the way for the accomplishment of the de- 
 sign so forcibly recommeaded in the foregoing quotation, 
 
AND WRITINGS OT DB. REID. Si 
 
 hy exemplifying, in an analysis of our uiost important 
 intellectual and active principles, the only method of 
 carrying it successfully into execution, was the great oh- 
 ject of Dr. Beid, in all his various philosophical publica- 
 tions. Id examining these principles, he liad chiefly in 
 view a vindication of those fundamental laws of belief 
 which form the groundwork of human knowledge, against 
 the attacks made on their authority in some modern sys- 
 tems of skepticism ; leaving to his successors the more 
 agreeable task of applying the philosophy of the mind to 
 its practical uses. On the analysis and classification of 
 our powers, which lie has proposed, much room for im- 
 provement must have been left in so vast an undertaking; 
 but imperfections of this kind do not necessarily affect 
 the justness of his conclusions, even where they may sug- 
 gest to future inquirers the advantages of a simpler ar- 
 rangement, and a more definite phraseology. Nor must 
 it be forgotten, that, in consequence of the plan he has 
 followed, the mistakes which may be detected in particular 
 parts of his works, imply no such weakness in the fabric 
 lie has reared, as might have been justly apprehended, 
 had he presented a connected system founded on gratui- 
 tous hypotheses, or on arbitrary definitions. The detec- 
 tions, on the contrary, of his occasional errors, may be 
 expected, from the invariable consistency and harmony 
 of truth, to throw new lights on those speculations which 
 he has conducted with greater success ; as the correction 
 of a particular mis-statement in an authentic history, is 
 often found, by completing an imperfect link, or recon- 
 ciling a seeming contradiction, to dispel the doubts which 
 hung over the most faithful and accurate details of the 
 narrative. 
 
 In Dr. Eeid's first performance, he confined himself 
 entirely to the five senses, and the principles of our na- 
 ture necessarily connected with them ; reserving the fur- 
 ther prosecution of the subject for a future period. At 
 that time, indeed, he seems to have thought, that a more 
 oompreheusive examination of the mind was an enterprise 
 
36 ACCOITNT OF THE IIFE 
 
 too great for one individual. " The powers," he observes, 
 •' of memory, of imagination, of taste, of reasoning, of 
 moral perception, the will, the passions, the affections, 
 and all the active powers of the soul, present a boundless 
 field of philosophical disquisition, which the author of this 
 Inquiry is far from thinking himself able to explore with 
 accuracy. Many authors of ingenuity, ancient and mod- 
 ern, have made incursions into this vast territory, and 
 have communicated useful observations ; but there is 
 reason to believe, that those who have pretended to give 
 us a map of the whole, have satisfied themselves with a 
 very inaccurate and incomplete survey. If Galileo had at- 
 tempted a complete system of natural philosophy, he had 
 probably done little service to mankind ; but, by confin- 
 ing himself to what was within his comprehension, he 
 laid the foundation of a system of knowledge, which rises 
 by degrees, and docs honour to the human understanding. 
 Newton, building upon this foundation, and in like man- 
 ner, confining his inquiries to the law of gravitation, and 
 the properties of light, performed wonders. If he had 
 attempted a great deal more, he had done a great deal 
 less, and perhaps nothing at all. Ambitious of following 
 such great examples, with unequal steps, alas ! and un- 
 equal force, we have attempted an inquiry into one little 
 corner only, of the human mind ; that corner which seems 
 to be most exposed to vulgar observation, and to be most 
 easily comprehended ; and yet, if we have delineated it 
 justly, it must be acknowledged, that the accounts here- 
 tofore given of it were very lame, and wide of the truth." 
 From these observations, when compared with the mag- 
 nitude of the work which the author lived to execute, 
 there is some ground for supposing, that, in the progress 
 of his researches, he became more and more sensible of 
 the mutual connection and dependence which exists among 
 the conclusions we form concerning the various princi- 
 ples of human nature ; even concerning those which seem, 
 on a superficial view, to have the most remote relation to 
 each other. And it was fortunate for the world, that, in 
 
AND WEITINGS OF DK, REID. 37 
 
 this respect, he was induced to extend his views so far 
 beyond the limits of his original design. His examination, 
 indeed, of the powers of external perception, and of the 
 questions immediately connected with them, bears marks 
 of a still more minute diligence and accuracy than appear 
 in some of his speculations concerning the other parts 
 of our frame I and what he has written on the former 
 subject, in his Inquiry into the Human Mind, is evidently 
 more highly finished both in matter and form, than the 
 volumes which he published in his more advanced years. 
 The value, however, of these is inestimable to future ad- 
 venturers in the same arduous undei-taking ; not only, in 
 consequence of the aids they furnish as a rough draught 
 of the field to be examined, but, by the example (hey 
 exhibit of a method of investigation on such subjects, 
 hitherto very imperfectly understood by philosophers. It , 
 is by the originality of this method, so systematically 
 pursued in all his researches, still more than by the im- 
 portance of his particular conclusions, that he stands so 
 conspicuously distinguished among those who have hith- 
 erto prosecuted analytically the study of man. 
 
 I have heard it sometimes mentioned, as a subject of 
 regret, that the writers who have applied themselves to 
 this branch of knowledge, have, in general, aimed at a 
 great deatmore than it was possible to accomplish ; ex- 
 tending their researches to all the different parts of our 
 constitution, while a long life might be well employed in 
 examining and describing the phenomena connected with 
 any one particular faculty. Dr. Reid, in a passage already 
 quoted from his Inquiry, might have been supposed to 
 give some countenance to this opinion ; if his own subse- 
 quent labours did not so strongly sanction the practice in 
 question. The truth, I apprehend, is, that such detach- 
 ed researches concerning the human mind, can seldom be 
 attempted with much hope of success ; and (hat those 
 who have recommended them, have not attended suffi- 
 ciently to the circumstanceis which so remarkably distin- 
 guish this study, from that which has for its object the 
 
38 ACCOCIirT OF THE IIFE 
 
 philosophy of Ihe material world. A few remarks in 
 illustration of this proposition seem to me lohe necessary, 
 in order to justify the reasonableness of Dr. Reid's under- 
 taking ; and they will he found to apply with still greater 
 force, to the labours of sucli, as may wish to avail them- 
 selves of a similar analj'sis in explaining the varieties of 
 human genius and character, or in developing the latent 
 capacities of the youthful mind. 
 
 One consideration of a more general nature is, in the 
 first place, worlhy of notice ; that in the infancy of every 
 science, the grand and fundamental desideratum is a hold 
 and comprehensive outline ; somewhat for the same rea- 
 son, that, in the cultivation of an extensive country, for- 
 ests must he cleared, and wildernesses reclaimed, before 
 the limits of private property are fixed with accuracy; 
 and long before the period, when the divisions and sub" 
 divisions of separate possessions give rise to the details 
 of a curious and refined husbandry. The speculations of 
 lord Bacon embraced all the objects of human knowledge. 
 Those of Newton and Boyle were confined to physics ; but 
 included an astonishing range of the material universe. 
 The labours of their successors in our own times, have 
 been employed with no less zeal, in pursuing those more 
 particular, but equally abstruse investigations, in which 
 they were unable to engage, for want of a sufficient stock, 
 both of facts and of general principles j and which did 
 not perhaps interest their curiosity in any considerable 
 degree. 
 
 If these observations are allowed to hold to a certain 
 extent with respect to all the sciences, they apply in a 
 more peculiar manner to the subjects treated of in Dr. 
 Beid's writings ; subjects which are all so intimately con- 
 nected, that it may be doubted, if it be possible to inves- 
 tigate any one completely, without some general acquaint- 
 ance, at least, with the rest. Even the theory of the un- 
 derstanding may receive important lights from an exam- 
 ination of the active and the moral powers ; the state of 
 which in the mind of every individual, will be found to 
 
AND WRITINGS OF UB. KBID. 39 
 
 have a powerful influence on his intellectual character : 
 while, on the other hand, an accurate analysis of the fac- 
 ulties of the understanding, would probably go far to ob- 
 viate the skeptical difiiculties which have been start- 
 ed concerning the origin of our moral ideas. It ap- 
 pears to me, therefore, that, whatever be the department 
 of mental science that we propose more particularly to 
 cultivate, it is necessary to begin with a survey of human 
 nature in all its various parts ; studying these parts, how- 
 ever, not so much on their own account, as with a refer- 
 ence to the applications of which our conclusions are sus- 
 ceptible to our favourite purpose. The researches of Dr. 
 Reid, when considered carefully in the relation which 
 they bear to each other, alford numberless illustrations 
 of the truth of this remark. His leading design was evi- 
 dently to overthrow the modern system of skepticism ; 
 and at every successive step of his progress, new and un- 
 expected lights break in on his fundamental principles. 
 
 It is. however, chiefly in their practical application to 
 the conduct of the understanding, and the culture of the 
 heart, that such partial views are likely to be dangerous; 
 for here they tend not only to mislead our theoretical con- 
 clusions, but to counteract our improvement and happiness. 
 Of this I am so fully convinced, that the most faulty 
 theories of hntnan nature, provided only they embrace 
 the whole of it, appear to me less mischievous in their 
 probable efiects, thafi those more accurate and microscop- 
 ical researches which are habitually confined to one par- 
 ticular corner of our constitution. It is easy to conceive, 
 that where the attention is wholly engrossed with the in- 
 tellectual powers, the moral principles will be in danger 
 of running to waste : and it is no less certain, on the other 
 hand, that, by confining our care to the moral constitu- 
 tion alone, we may sufier the understanding to remain 
 under the influence of unhappy prejudices, and destitute 
 of those just and enlightened views, without which the 
 worthiest dispositions are of little use, either to ourselves 
 or society. An exclusive atteption to any oae of the sufo< 
 
40 ACCOUNT or THE IIKE 
 
 ordinate parts of our frame, to the culture of taste, for 
 example, or of the argumentative powers, or even to the 
 refinement of our moral sentiments and feelings, must be 
 attended with a hazard proportionally greater. 
 
 " In forming tlie human character," says Bacon, in a 
 passage which lord Bolingbroke has pronounced to be one 
 of the finest and deepest in his writings, "we must not 
 proceed, as a statuary does in forming a statue, who works 
 sometimes on the face, sometimes on the limbs, sometimes 
 on tlie folds of the drapery; but we must proceed, and 
 it is in our power to proceed, as nature does in forming 
 a flower, or any other of her productions ; she throws out 
 altogether, and at once, the whole system of being, and 
 the rudiments of all the parts. Rudimenta partium om- 
 nium simul purit et producit."* 
 
 Of this passage, so strongly marked with Bacon's ca- 
 pacious intellect, and so richly adorned with his " philo- 
 sophical fancy ,"f I will not weaken the impression by any 
 comment ; and, indeed, to those who do not intuitively 
 perceive its evidence, no comment would be usefuL 
 
 In what I have hitherto said of Dr. Reid's speculations, 
 I have confined myself to such general views of the scope 
 of his researches, and of his mode of philosophizing, as 
 seemed most likely to facilitate the perusal of his works 
 to those readers who have not been much conversant with 
 these abstract disquisitions. A slight review of some of 
 the more important and fundamental objections which 
 have been proposed to his doctrines, may, I hope, be use- 
 ful as a farther preparation for the same course of study. 
 Of these objections, the four following appear to me 
 to be chiefly entitled to attention. 
 
 1. That he has assumed gratuitously in all his reason- 
 ings, that theory concerning the human soul, which the 
 scheme of materialism calls in question. 
 
 * In the foregoing paragraph, I'have borrowed, with a very trifling alter- 
 ation, lord Bolingbroke's words, in a beautiful paraphrase on Bacon's rc" 
 mark. See his Idea of a Patriot King. 
 
 t Am expression applied by Gibbon to the eloquence of Burke. 
 
A»D WRITINGS OF DR. REID. M 
 
 3. That his views tend to damp the ardour of philo- 
 sophical curiosity, by stating as ultimate facts, phenom- 
 ena which may be resolved into principles more simple 
 and general. 
 
 3. That, by an unnecessary multiplication of original 
 or instinctive principles, he has brought the science of 
 mind into a state move perplexed and unsatisfactory, than 
 that in which it was left by Locke and his successors. 
 
 4. That his philosophy, by sanctioning an appeal from 
 the decisions of the learned to the voice of the multitude, 
 is unfavourable to a spirit of free inquiry, and lends ad- 
 ditional stability to popular errors. 
 
 1, With respect to Dr. Reid's supposed assumption of 
 a doubtful hypothesis concerning the nature of the think- 
 ing and sentient principle, it is almost sufiBcient for me to 
 observe, that the charge is directed against that very point 
 of his philosophy in which it is most completely invul- 
 nerable. The circumstance which peculiarly character- 
 izes the inductive science of mind is, that it professes (o 
 abstain from all speculations concerning its nature and 
 essence; confining the attention entirely to phenomena, 
 for which we have the evidence of consciousness, and to 
 the laws by which these phenomena are regulated. In 
 this respect, it differs equally, in its scope, from the pneu- 
 matological discussions of the schools ; and from the no 
 less visionary theories, so loudly vaunted by the physiolog- 
 ical metaphysicians of more modern times. Compared 
 with the first, it differs, as the inquiries of the mechanical 
 philosophers concerning the laws of moving bodies, differ 
 from the discussions of the ancient sophists concerning, 
 the existence and the nature of motion. Compared with 
 the other, the difference is analogous to what exists be- 
 tween the conclusions of Newton concerning the :jaw of 
 gravitation, and his query concerning the invisible ether 
 of which he supposed it might, possibly, be the effect. The 
 facts which this inductive science aims at ascertaining, rest 
 on their own proper evidence ; an evidence unconnected 
 with all these hypotheses, and which would not, in Dw 
 
 vol. I. S 
 
42 ACCOUNT OF THE IirE 
 
 smallest degree, be affected, although the truth of any 
 one of them should be fully established. It is nqt, tht;te- 
 fore, on account of its inconsistency with any favouvit^ 
 opinions of my own, that I would oppose the disquisitions 
 either of scholastic pneumatology, or of physiological 
 metaphysics I but because I consider them as an idle 
 waste of time and genius, on questions where our conclu- 
 sions can neither be verified nor overturned by an appeal 
 to experiment or observation. Sir Isaac Newton's query 
 concerning the cause of gravitation was certainly not i^- 
 consistent with his own discoveries concerning its laws ; 
 but what would have been the consequences to the world, 
 if he had indulged himself in the prosecution of hypothet- 
 ical theories with respect to the former, instead of directing 
 his astonishing powers to an investigation of the latter- 
 That the general spirit of Dr. Reid's philosophy is hos- 
 tile to the conclusions of the materialist, is indeed a fact: 
 not, however, because his system rests on the contrary 
 hypothesis as a fundaniental principle, but because his in- 
 quiries have a powerful tendency to wean the understand- 
 ing gradually from those obstinate associations and preju- 
 dices, to which the common mechanical theories of mind 
 owe all their plausibility. It is, in truth, much more 
 from such examples of sound research concerning the 
 laws of thought, than from any direct metaphysical refu- 
 tation, that a change is to be expected in the opinions of 
 those who have been accustomed to confound together two 
 classes of phenomena, so completely and essentially dif- 
 ferent. But this view of the subject does not belong to 
 the present argument. 
 
 It has been recommended of late, by a medical author 
 of great reputation, to those who wish to study the hu- 
 man mind, to begin with preparing themselves for the 
 task by the study of anatomy. I must confess, I cannot 
 perceive the advantages of this order of investigation ; as 
 the anatomy of the body does not seem to me more likely 
 to throw light on the philosophy of the mind, than an 
 analysis of the mind to throw light on the physiology of 
 the body. To ascertain, indeed, the general laws of their 
 
AND WRITINGS Oil' BR. REID. 43 
 
 (tonnefetion from facts established by observation or ex- 
 periment, is a reasonable and most interesting object of 
 philosophical curiosity ; and in this inquiry, which was 
 long ago proposed and recommended by lord Bacon, a 
 knowledge of the constituiion both of mind and body is 
 indispensably requisite; but even here, if we wish to pro- 
 ceed on firm ground, the two classes of facts must be kept 
 coihpletely distinct,' so that neither of them maybe warp- 
 ed or distorted, in Consequence of theories suggested by 
 their supposed relations or analogies.* Thus, in many 
 of the phenomena, connected with custom and habit, tliere 
 is ample scope for investigating general laws, both with 
 respect to oiir mental and our corporeal frame ; but what 
 light do we derive from Such information concerning this 
 pa^t of our constitution as is contained in the following 
 sentence of Locke? "Habits seem to be but trains of 
 motion in the animal spirits, which, once set a-going, con- 
 tinue in the same steps they have been used to, which by 
 ofteti treading are worn into a smooth path." In like 
 manner, the laws which regulate the connection between 
 the mind and oiir external organs, in the case of percep- 
 lioti, have furnished a very fertile subject of examination 
 to some of the best of our modern philosophers ; but how 
 impotent does the genius of Newton itself appear, when 
 it at tetnpts to shoot the gulf which separates the sensible 
 world, and the sentient principle ? " Is not the sensorium 
 of animals," he asks in one of his queries, " the place 
 where the sentient substance is present, and to which the 
 sensible species of things are brought through the nerves 
 and brain, that they may be perceived by the mind pres- 
 ent in thait place ?" 
 
 It ought to be remembered also, that this inquiry, with 
 respect to the laws regulating the connection between our 
 bodily organization, and the phenomena subjected to our 
 own consciousness, is but one particular department of 
 the phiIos6pIiy of the mind ,- and that there still remains 
 
 * Elements of the Philosophy of the Human Mind, pp. U, 12. 3d. edit. 
 
44 ACCOUNT OF THE IIFE 
 
 a wide and indeed boundless region, whore all our data 
 must be obtained from our own mental operations. In 
 examining, for instance, the powers of judgment and rea- 
 soning, let any person of sound understanding, after pe- 
 rusing the observations of Bacon on the different classes 
 of our prejudices, or those of Locke on the abuse of words, 
 turn his attention to the speculations of some of our con- 
 temporary theorists 5 and he will at once perceive the 
 distinction between the two modes of investigation which 
 I wish at present to contrast. " Beasoning," says one of 
 the most ingenious, and original of these, "is that opera- 
 tion of the sensorium, by which we excite two or many 
 tribes of ideas | and then re-excite the ideas, in which 
 they differ or correspond. If we determine this difference, 
 it is called judgment j if we in vain endeavour to deter- 
 mine it, it is called doubting. If we re-excite the ideas 
 in which they differ, it is called distinguishing j if we re- 
 excite those in which they correspond, it is called com- 
 paring."* In what acceptation the word idea is to be 
 understood in the foregoing passage, may be learned from 
 the following definition of the same author : " The word 
 idea has various meanings in the writers of metaphysic : 
 it is here used simply for those notions of external things, 
 which our organs of sense bring us acquainted with orig- 
 inally ; and is defined, a contraction or motion, or config- 
 uration of the fibres, which constitute the immediate or- 
 gan of sense."! Mr. Hume, who was less of a physiolo- 
 gist than Dr. Darwin, has made use of a language by no 
 means so theoretical and arbitrary ; but still widely re- 
 moved from the simplicity and precision essentially nec- 
 essary in studies, where every thing depends on the cau- 
 tious use of terms. " Belief," according to him, is " a 
 lively idea related to or associated with a present impres- 
 sion ; memory is the faculty by which we repeat our im- 
 pressions, so as that they retain a considerable degree of 
 their first vivacity, and are somewhat intermediate betwixt 
 an idea and an impression." 
 
 * Zoonomia, vol. i. p. 181. 3d edit. t Ibid. vol. i. pp. 11, 13. 
 
AND WRITINGS OF DR. REID. 45 
 
 According to the views of Dr. Reitl, the terms which 
 express the simple powers of the mind, are considered as 
 unsusceptible of definition or explanation ; the words, 
 feeling, fop example, knowledge, will, doubt, belief, being 
 in this respect on the same footing with the words, green 
 or scarlet, sweet or bitter. To the names of these men- 
 tal operations, all men annex some notions, more or less 
 distinct ; and the only way of conveying to them notions 
 more correct, is by teaching them to exercise their own 
 powers of reflection. The definitions quoted from Hume 
 and Darwin, even if they were more unexceptionable iu 
 point of phraseology, would, for these reasons, be unphi- 
 losophical, as attempts to simplify what is incapable of 
 analysis ; but as they are actually stated, they not only 
 envelop truth in mystery, but lay a foundation, at the very 
 outset, for an erroneous theory. It is worth while to add, 
 that of the two theories in question, that of Darwin, how 
 inferior soever, in the estimation of competent judges, as 
 a philosophical work, is by far the best calculated to im- 
 pose on a very wide circle of readers, by the mixture it 
 exhibits of crude and visionary metaphysics, with those 
 important facts and conclusions which might be expected 
 from the talents and experience of such a writer, in the 
 present advanced state of medical and physiological 
 science. The questions which have been hitherto con- 
 fined to a few, prepared for such discussions by habits of 
 philosophical study, are thus submitted to the considera- 
 tion, not only of the cultivated and enlightened minds, 
 which adorn the medical profession, but of tlie half-in- 
 formed multitude who follow the medical trade : nor is 
 it to be doubted, that many of these will give the author 
 credit, upon subjects of which they feel themselves in- 
 competent to judge, for the same ability which he dis- 
 plays within their own professional sphere. The hypothet- 
 ical principles assumed by Hume are intelligible to those 
 only who are familiarized to the language of the schools ; 
 and hisingenuity^nd elegance, captivating as they are 
 to men of taste and refinement}r^ossess slight attractions 
 
46 aCcoun* or TtiB tirfe 
 
 to the majority of such as are most likely to be misled by 
 his conclusions. 
 
 After all, I do not appl-ehend that the physiological 
 theories concerning the mind, which have made so much 
 noise of late, will prodiice a vei"y lasting itnpressidn. The 
 splendour of Dr. Darwin's accomplishments could not fail 
 to bestow a temporary importance on whatever opinions 
 were sanctioned by his name ; as the chemical discoveries 
 which have immortalized that of Priestley, have, for a 
 while, recalled from oblivion the reveries of Hartley. 
 But, abstracting from these accidental instances, in which 
 human reason seems to have held a retrograde course, 
 there has eertaitily been, since the time of Des Cartes, a 
 continual, and, on the whole, a vefy remarkable approach 
 to the inductive plan of studying human nature. We maiy 
 trace this in the writings even of those who profess to 
 consider thought merely as an agitation of the brain ; in 
 the writings more particularly of Hume and of Helvetius j 
 both of whom, although they may have occasionsilly ex- 
 pressed themselves in an unguarded manner concerning 
 the nature of mind, have, in their most useful and prac- 
 tical disquisitions, been prevented, by their own good 
 sense, from blending aiiy theory with respect to the 
 causes of the intellectual phenomena, with the history of 
 facts, or the investigation of general laws. The authors 
 who form the most conspicuous exceptions to this grad- 
 ual progress, consist chiefly of men, whose errors may be 
 easily accounted for, by the prejudices connected with 
 their circumscribed habits of observation and inquiry; of 
 phydologists, accustomed to attend to that part alone of 
 the human frame, which the knife of the anatomist can 
 lay open j or of chemists, who enter on the analysis of 
 thought, fresh from the decompositions of the laborato- 
 ry ; carrying into the theory of mind itself, what Bacon 
 expressively calls, "the smoke and tarnish of the furnace." 
 Of the value of such pursuits, none can think more highly 
 thain myself ; but I must be allowed to observe, that the 
 most distinguished pre-ei&iinence in them does not neces- 
 
AND WRITINGS or DE. BBII). ||^ 
 
 sapily imply a, capacity of cpUecteil an^ abstracteij re-, 
 flection, or an understanding superior to the prejudices 
 of ^arly association, and the illusiona of popular language. 
 I vyill pot go so far as Cicero, when he ascribes to those 
 >vha possess these advantages, a more than o^'di^lary vig- 
 oyr of intellect : " Magni es^t ingenii revocare mentem a, 
 sensibus, et cogitationem a consiietudine al^ducere." I 
 would only claim for them, thp merit of patient and cau- 
 tious research ; aqd would exact from their antagonists 
 the same qualificatioi^s.^ 
 
 In offering these remarks, I hav^ no wish to exalt 
 any one branch of useful knowledge at the expense of 
 ^notlier, but to comliat prejudices equally fatal to the 
 progress of them all. With the same view, I cannot helpi 
 taking notice of a prevailing, tiut very mistaken idea, that 
 tl(e formatioq of a hypothetical system is a stronger 
 proof of inventive genius, than the patient investigation 
 of nature in the way of induction. To form a system, 
 appears to the young and inexperienced understanding, &, 
 species of creation ; to ascend slowly to general conclu- 
 sions, from the observation and comparison of particular 
 facts, is to comment servilely on the works of another* 
 
 No opjni^on, surely, can be more groundless. To fix on 
 a few principles, or even on a single principle, as the 
 foundation of a theory; and by an artful statement of 
 supposed facts, aided bj a dexterous use of language, ta 
 give a pl^ijisible explanation, by meaqs of it, of an im- 
 mense number of phenomena ; is within the peach of most 
 men whose talents have been a little exercised among 
 the subtilties of the schools : whereas, to follow nature 
 through all her varieties with a quiick yet an exact eye; 
 to record fait);ifully what she exhibits, and to record nath.* 
 ing more ; to trace, a,midst the diversity of her opera-' 
 tions, the simple and comprehensive laws by whi<eh they 
 are pegula,<jed, and sometimes to guess at the beneficent 
 purposes to which they are subservient ; may be safety 
 
 * Note D. 
 
48 AccotrNT or the iife 
 
 pronounced to be the highest effort of a created intelli- 
 gence. And, accordingly, the number of ingenious the- 
 orists has, in every age, been great ; that of sound phi- 
 losophers has been wonderfully small,- or rather, they 
 are only beginning now to have a glimpse of their way, in 
 consequence of the combined lights furnished by their 
 predecessors. 
 
 Des Cartes aimed at a complete system of physics, de- 
 duced d priori from the abstract suggestions of his own 
 reason : Newton aspired no higher, than at a faithful 
 "interpretation of nature," in a few of the more general 
 laws which she presents to our notice : and yet the intel- 
 lectual power displayed in the voluminous writings of 
 the former vanishes into nothing, when compared with 
 what we may trace in a single page of the latter. On 
 this occasion a remark of lord Bacon appears singularly 
 apposite ; that " Alexander and Csesar, though they acted 
 without the aid of magic or prodigy, performed exploits 
 that are truly greater than what fable reports of king 
 Arthur or Amadis de Gaul." 
 
 I shall only add farther on this head, that the last ob- 
 servation holds more strictly with respect to the philoso- 
 phy of the human mind, than any other branch of science; 
 for there is no subject whatever, on which it is so easy 
 to form theories calculated to impose on the multitude ; 
 and none, where the discovery of truth is attended with 
 so many difficulties. One great cause of this is, the an- 
 alogical or theoretical terms employed in ordinary lan- 
 guage to express every thing relating either to our intel- 
 lectual or active powers ; in consequence of which, spe- 
 cious explanations of the most mysterious phenomena may 
 be given to superficial inquirers ; while, at the same time» 
 the labour of just investigation is increased to an incal- 
 culable degree. 
 
 3. To allege, that " this circumscription of the field of 
 our inquiries concerning the mind tends to damp the ar- 
 dour of philosophical curiosity," is a charge not less un- 
 founded than the former ; inasmuch as every physical 
 
AND WKITIKGS OF DK. REID. 49 
 
 inquiry concerning the material world is circumscribed 
 hy limits precisely analogous. In all our investigations, 
 whatever their subject maybe, the business of philosophy 
 is confined to a reference of particular facts to other facts 
 more general j and our most successful researches must 
 at length terminate in some law of nature, of which no 
 explanation can be given. In its application to Dr. Reid, 
 this objection has, I think, been more pointedly directed 
 against his reasonings concerning the process of nature in 
 perception; a part of his writings which, as it is offunda^ 
 mental importance in his general system, he has laboured 
 with peculiar care. The result is, indeed, by no means 
 flattering to the pride of those theorists, who profess to 
 explain every thing ; for it amounts to an acknowledg- 
 ment, that, after all the lights which anatomy and physi- 
 ology supply, the information we obtain, by means of our 
 senses, concerning the existence and the qualities of mat- 
 ter, is no less incomprehensible to our faculties, than it 
 appears to the most illiterate peasant ; and that all we 
 hare gained, is a more precise and complete acquaintance 
 with some particulars in our animal economy, highly in- 
 teresting indeed when regarded in their proper light, as 
 accessions to our physical knowledge, but, considered in 
 connection with the philosophy of the mind, affording 
 only a more accurate statement of the astonishing phe- 
 nomena which we would vainly endeavour to explain. 
 This language has been charged, but most unjustly and 
 ignorantly, with mysticism; for the same charge may be 
 brought, with equal fairness, against all the most import- 
 ant discoveries in the sciences. It was in truth, the very 
 objection urged against Newton, when his adversaries 
 contended, that gravity was to be ranked with the occult 
 qualities of the schoolmen, till its mechanical cause should 
 be assigned ; and the answer given to this objection by 
 Sir Isaac Newton's commentator, Mr. Maclaurin, may be 
 literally applied, in the instance before us, to the induc- 
 tive philosophy of the human mind, 
 vol,. I. 7 
 
BO ACCOUXT OF THE IIFE 
 
 "The opponents of Newton, finding nothing to object 
 to his observations and reasonings, pretended to find a 
 resemblance between his doctrines and the exploded ten- 
 ets of the scholastic philosophy. They triumphed might- 
 ily in treating gravity as an occult quality, because he 
 did not pretend to deduce this principle fully from it« 
 cause I know not that ever it was made an ob- 
 jection to the circulation of the blood, that there is no 
 small difficulty in accounting for it mechanically. They* 
 too, who lirst extended gravity to air, vapour, and to all 
 bodies round the earth, had their praise ; though the 
 cause of gravity was as obscure as before ; or rather ap- 
 peared, more mysterious, after they had shewn, that there 
 was no body found near the earth, exempt from gravity, 
 that might be supposed to be its cause. Why, then, were 
 his admirable discoveries, by which this principle was 
 extended over the universe, so ill relished by some phi- 
 losophers ? The truth is, he had, with great evidence, 
 overthrown the boasted schemes by which they pretended 
 to unravel all the mysteries of nature ; and the philoso- 
 phy he introduced, in place of them, carrying with it a 
 sincere confession of our being far from a complete and 
 perfect knowledge of it, could not please those who had 
 been accustomed to imagine themselves possessed of the 
 eternal reasons and primary causes of all things. 
 
 "It was, however, no new thing that this philosophy 
 should meet with opposition. All the useful discoveries 
 that were made in former times, and particularly in the 
 seventeenth century, had to struggle with the prejudices 
 of those who had accustomed themselves, not so much as 
 to think but in a certain systematic way; who could not 
 be prevailed on to abandon their favourite schemes, while 
 they were able to imagine the least pretext for continu- 
 ing the dispute. Every art and talent was displayed to 
 support their falling cause ; no aid seemed foreign to 
 them that could in any manner annoy their adversary; 
 and such often was their obstinacy, that truth was able 
 to make little progress, till they were succeeded by younger 
 
AND WHITINGS OV DR. BEIB. Bi 
 
 persons who had not so strongly imbibed their preju- 
 dices." 
 
 These excellent pbservsilions are not the less applicable 
 to the subject now under consideration, that the part of 
 Dr. Reid's writings which suggested the quotation, leads 
 only to the correction of an inveterate prejudice, not to 
 any new general conclusion. It is probable, indeed, now 
 that the Ideal Theory has in a great measure disappeared 
 from our late metaphysical systems, that those who hare 
 a pleasure in detracting from the merits of their prede- 
 cessors, may be disposed to represent it as an idle waste 
 of labour and ingenuity, to have entered into a serious 
 refutation of an hypothesis at once gratuitous and incon- 
 «eivable. A different judgment, however, will be formed 
 by such, as are acquainted with the extensive influence, 
 which, from the earliest accounts of science, this single 
 prejudice has had in vitiating almost every branch of the 
 philosophy of the mind ; and who, at the same time, 
 reeollect the names of the illustrious men, by whom, in 
 more modern times, it has been adopted as an incontro- 
 vertible principle. It is sufficient for me to mention thpse 
 of Berkeley, Hume, Locke, Clarke and Newton. To the 
 two first of these, it has served as the basis of their skep- 
 tical conclusions, which seem indeed to follow from it as 
 necessary consequences ; while the others repeatedly re- 
 fer to it in their reasonings, as one of those facts concern- 
 ing the mind, of which it would be equally superfluous to 
 attempt a proof or a refutation. 
 
 I have enlarged on this part of Dr. Reid's writings the 
 more fully, as he was himself disposed, on all occasions, 
 to rest upon it his chief merit as an author. Id proof of 
 this, I shall transcribe a few sentences from a letter of 
 his to Dr. Gregory, dated 20th August, 1790. 
 
 " It would be want of candour not to own, that I think 
 
 there is some merit in what you are pleased to call my 
 
 philosophy; but I think it lies chiefly in having called in 
 
 ■ question the common theory of ideas or images of things 
 
 in the miad being the only objects of thought; a theory 
 
52 ACCOUNT OF THE IIFE 
 
 founded on natural prejudices, and so unirergally received 
 as to be interwoven witii the structure of language. Yet 
 Avere I to give you a detail of what led me to call in ques- 
 tion this theory, after I had long held it as self-evident 
 and unquestionable, you would think, as I do, that there 
 was much of chance in the matter. The discovery was 
 the birth of time, not of genius ; and Berkeley andHume 
 did more to bring it to light than the man that hit upon 
 it. I (liink there is hardly any thing that can be called 
 mine in the philosophy of the mind, which does not fol- 
 low with ease from the detection of this prejudice. 
 
 " I must, therefore, beg of you most earnestly, to make 
 no contrast in my favour to the disparagement of my 
 predecessors in the same pursuit. I can truly say of 
 them, and shall always avow, what you are pleased to 
 say of me, tliat but for the assistance I have received 
 from their writings, 1 never could have wrote or thought 
 what I have done." 
 
 3. Somewhat connected with the last objection, are 
 the censures which have been so frequently bestowed on 
 Dr. Reid, for " an unnecessary and unsystematical mul- 
 tiplication of original or instinctive principles." 
 
 In reply to these censures I have little to add to what 
 1 have remarked on the same topic, in the Philosophy of 
 the Human Mind. That the fault which is thus ascrib- 
 ed to Dr. Reid has been really committed by some inge- 
 nious writers in this part of the island, I most readily 
 allow; uor will I take upon me to assert, that he has, in 
 no instance, fallen into it himself. Such instances, how- 
 ever, will be found, on an accurate examination of his 
 works, to be comparatively few, and to bear a very trilling 
 proportion to those, in which he has most successfully 
 and decisively displayed his aeuteness, in exposing the 
 premature and flimsy generalizations of bis predecessors. 
 
 A certain degree of leaning to that extreme to which 
 Dr. Reid seems to have inclined, was, at the time Avhen 
 he wrote, much safer than the opposite bias. From the- 
 earliest ages, the sciences in general^ and more particu- 
 
AND WRITINGS OF DK. REID. 63 
 
 larlj the science of the human mind, have been vitiated 
 by an undue love of simplicity ; and, in the course of the 
 last century, this disposition, after having been long dis- 
 played in subtile theories conceroiag the Active Powers, 
 OP the Principles of Human Conduct, has been directed 
 to similar refinements with respect to the Faculties of 
 the Understanding, and the truths Avith which they are 
 conversant. Mr. Hume himself has coincided so far with 
 the Hartleian^ school, as to represent the " principle of 
 union and cohesion among our simple ideas as a kind of 
 attraction, of as universal application in the mental world 
 as in the natural 5"* and Dr. Hartley, with a still more 
 sanguine imagination, looked forward to an era, " when 
 future generations shall put all kinds of evidences and 
 inquiries into mathematical forms | reducing Aristotle's 
 ten categories, and bishop Wilkin's forty summa genera, 
 to the head of quantity alone, so as to make mathemat- 
 ics and logic, natural history and civil history, natural phi- 
 losophy and philosophy of all other kinds, coincide omni eoe 
 'parte."] 
 
 It is needless to remark the obvious tendency of such 
 premature generalizations to withdraw the attention from 
 the study of particular phenomena j while the effect of 
 Reid's mode of philosophizing, even in those instances 
 where it is carried to an excess, is to detain us, in this 
 preliminary step, a little longer than is absolutely neces- 
 sary. The truth is, that when the phenomena are once 
 ascertained, generalization is here of comparatively little 
 value, and a task of far less difficulty than to observe 
 facts with precision, and to record them with fairness. 
 
 In no part of Dr. Reid's writings, I am inclined to think, 
 could more plausible criticisms be made on this ground, 
 than in his classification of our active principles ; but 
 even there, the facts are always placed fully and distinctly 
 before the reader. That several of the benevolent affec- 
 tions which be has stated as ultimate facts in our consti- 
 
 * Treatise of Human Nature, toI. i. p. 30. f Hartley on Man, 
 
 p. 20r. ito.edit. Loud. 1791. 
 
54 ACCOrWT OF THB IIMB 
 
 tution, might be analyzed into the same general principle 
 differently modified, according to circumstances, there 
 can, in my opinion, be little doubt. This, however, as I 
 have elsewhere observed,* notwithstanding the stress 
 which has been sometimes laid upon it, is chiefly a ques- 
 tion of arrangement. Whether we suppose these affec- 
 tions to be all ultimate facts, or some of them to be re- 
 solvable into other facts more general ; they are equally 
 to be regarded as constituent parts of human nature ; and, 
 upon either supposition, we have equal reason to admire 
 the wisdom with which that nature is adapted to the sit- 
 uation in which it is placed. The laws which regulate 
 the acquired perceptions of sight, are surely as much a 
 part of our frame, as those which regulate any of our 
 original perceptions ; and, although they require, for their 
 development, a certain degree of experience and obser- 
 vation in the individual, the uniformity of the result shews, 
 that there is nothing arbitrary nor accidental in their 
 origin. In this point of view, what can be more philo- 
 sophical, as well as beautiful, than the words of Mr. Fer- 
 guson, that " natural affection springs up in the soul of the 
 mother, as the milk springs in her breast, to furnish nour- 
 ishment to her child !" " The effect is here to the race," 
 as the same author has excellently observed, '' what the 
 vital motion of the heart is to the individual ; too neces- 
 sary to (he preservation of nature's works, to be intrustr 
 ed to the precarious will or intention of those most nearly 
 concerned."! 
 
 The question, indeed, concerning the origin of our dif- 
 ferent affections, leads to some curious analytical disqui- 
 sitions ; but is of very subordinate importance to those 
 inquiries which relate to their laws, and uses, and mutual 
 references. In many ethical systems, however, it seemf 
 to have been considered as the most interesting subject 
 
 • Outlines of Moral Philosophy, pp. 79, 80. 2d edit. Edin. 1801. 
 
 f Principles of Moral and Political Science, Part I. chap. i. sect. 3. Of the 
 principles of society in human nature. The whole discussion unites, in a 
 singular degree, the soundest philosophy with the most eloquent description. 
 
AND WRITIiroS or DR.KEID. 55 
 
 of disqaisitioa which this wonderful part of our frame 
 presents. 
 
 In Dr. Reid's Essays on the Intellectual Powers of 
 Man, and in his Inquiry info the Human Mind, I recol- 
 lect little that can justly incur a similar censure; not- 
 withstanding the ridicule which Dr. Priestley has at- 
 tempted to throw on the last of these performances, in 
 his " Table of Reid's Instinctive Principles."* To ex- 
 amine all the articles enumerated in that table, would 
 require a greater latitude of disquisition than the limits 
 of this memoir allow; and^ therefore, I shall confine my 
 observations to a few instances, where the precipitancy 
 of the general criticism seems to me to admit of little 
 dispute. In this light I cannot help considering it, when 
 applied to those dispositions or determinations of the mind, 
 to which Dr. Reid has given the names of the principle of 
 credulity, and the principle of veracity. How far these 
 titles are happily chosen, is a question of little moment; 
 and on that point I am ready to make every concession. 
 I contend only for what is essentially connected with the 
 •objection which has given rise to these remarks. 
 
 *• That any man," says Dr. Priestley, "should imagine 
 that a peculiar instinctive principle was necessary to ex- 
 plain our giving credit to the relations of others, appears 
 to me> who have been used to see things in a different 
 light, very extraordinary ; and yet this doctrine is ad- 
 vanced by Dp. Reid, -and adopted by Dr. Beat tie. But 
 really," he adds, " what the former says in favour of it, 
 is hardly deserving the slightest notice."! 
 
 The passage quoted by Dr. Priestley, in justificatioa 
 of this very peremptory decision, is as follows : " If cre- 
 dulity were the effect of reasoning and experience, it must 
 grow up and gather strength in the same proportion as 
 reason and experience do. But if it is the gift of nature, 
 it will be the strongest in childhood, and limited and 
 
 * Examination of Reid's liiquiry, &c. Lond. 1774. t 'Examination of 
 
 B«id'9 Inquiry, 8(e. p. 83. 
 
66 Account of thk riiii 
 
 restrained by experience j and the most superficial view 
 of human life shews that this last is the case, and not 
 the first." 
 
 To my own judgment, this argument of Dr. Reid's, 
 when connected with the excellent illustrations which ac- 
 company it, carries complete conviction ; and I am con- 
 firmed in my opinion by finding that Mr. Smith, a writer 
 inferior to none in acuteness, and strongly disposed by the 
 peculiar bent of his genius, to simplify, as far as possible, 
 the philosophy of human nature, has, in the latest edition 
 of his Theory of Moral Sentiments, acquiesced in this 
 very conclusion ; urging in support of it the same reason- 
 ing which Dr. Priestley afiects to estimate so lightly. 
 " There seems to be in young children an instinctive dis- 
 position to believe whatever they are told. Nature seems 
 to have judged it necessary for their preservation, that 
 they should, for some time at least, put implicit confidence 
 in those to whom the care of their childhood, and of the 
 earliest and most necessary part of their education, is in- 
 trusted. Their credulity, accordingly, is excessive, and 
 it requires long and much experience of the falsehood of 
 mankind to reduce them to a reasonable degree of diflii- 
 dence and distrust."* That Mr. Smith's opinion also 
 coincided with Dr. Reid's, in what he has stated coneern- 
 the principle of veracily, appears evidently from the re- 
 marks which immediately follow the passage just quoted. 
 But I must not add to the length of this memoir by un- 
 necessary citations. 
 
 Another instinctive principle mentioned by Reid, is 
 *< our belief of the continuance of the present course of 
 nature." " All our knowledge of nature," he observes, 
 " beyond our original perceptions is got by experience, 
 and consists in the interpretation of natural signs. The 
 appearance of the sign is followed by the belief of the 
 thing signified. Upon this principle of our constitution, 
 not only acquired perception, but also inductive reasoning, 
 
 * Smith's Theory, last edit. Part VII. sect. 4. 
 
AND WHITINGS OF DR.RUID. 57 
 
 and all reasoning from analogy, is grounded ; and, there- 
 fore, for want of a better name, we shall beg leave to call 
 it the inductive principle. It is from the force of this 
 principle that we immediately assent to that axiom, upon 
 which all our knowledge of nature is built, that effects of 
 the same kind must have the same cause. Take away 
 the light of this inductive principle, and experience is as 
 blind as a mole. She may indeed feel what is present, and 
 what immediately touches her, but she sees nothing that 
 is either before or behind, upon the right hand or upon 
 the left, future or past." 
 
 On this doctrine, likewise, the same critic has express- 
 ed himself with much severity ; calling it " a mere quib- 
 ble j" and adding, "Every step ^hat I take among this 
 writer's sophisms, raises my astonishment higher than 
 before." In this, however, as in many other Instances, 
 he has been led to censure Dr. Reid, not because he was 
 able to see farther than his antagonist, but because he did 
 not see quite so far. Turgot, in an article inserted in 
 the French Encyclopedic, and Condorcet, in a discourse 
 prefixed to one of his mathematical publications,^' have, 
 both of them, stated the fact with a true philosophical 
 precision ; and after doing so, have deduced from it an 
 inference, not only the same in substanceVith that of Dr. 
 Reid, but almost expressed in the same form of words. 
 
 In these references, as well as in that already made 
 to Mr. Smith's Theory, I would not be understood to 
 lay any undue stress on authority, in a philosophical 
 argument. I wish only, by contrasting the modesty and 
 caution resulting from habits of profound thought, with 
 that theoretical intrepidity which a blindness to insuper- 
 able difficulties has a tendency to inspire, to invite those 
 whose prejudices against this part of Reid's system rest 
 chiefly on the great names to which they conceive it to 
 be hostile, to re-examine it with a little more attention, 
 before they pronounce finally on its merits. 
 
 * Essai sur I'application de I'analjse k la probability des decisions reii- 
 dues k la plurality des Toix. Paris, 1785. 
 vol. I. 8 
 
&8 ACCOUNT 01' THE WFE 
 
 The prejudices whicli are apt to occur against a modti 
 of piiilosophizing, so mortifying to scholastic arrogance, 
 are encouraged greatly by that natural disposition, to re- 
 fer particular facts to general laws, which is the founda- 
 tion of all scientific arrangement ; a principle of the ut- 
 most importance to our intellectual constitution, but which 
 requires the guidance of a sound and experienced under* 
 standing to accomplish the purposes for which it was des- 
 tined. They are encouraged also, in no inconsiderable 
 degree, by the acknowledged success of mathematicians, 
 in raising, on the basis of a few simple data, the most 
 magnificent, and at the same time the most solid, fabric 
 of science, of which human genius can boast. The absurd 
 references which logicians are accustomed to make to 
 Euclid's Elements of Geometry, as a model which can- 
 not be too studiously copied, both in physics and in mor- 
 als, have contributed, in this as in a variety of other in- 
 stances, to mislead philosophers from the study of facts, 
 into the false refinements of hypothetical theory. 
 
 On these nfiisapplications of mathematical method to 
 sciences which rest ultimately on experiment and obser- 
 vation, I shall take another opportunity of offering some 
 strictures. At present, it is sufficient to remark the pe- 
 culiar nature of the truths about which pure or abstract 
 mathematics are conversant. As these truths have all a 
 necessary connection with each other, all of them resting 
 ultimately on those definitions or hypotheses which are 
 the principles of our reasoning, the beauty of the science 
 cannot fail to increase in proportion to the simplicity of 
 the data, compared with the incalculable variety of con- 
 sequences which they involve : and to the simplifications 
 and generalizations of theory on such a subject, it is per- 
 haps impossible to conceive any limit. How different is 
 the case in those inquiries, where our first principles are 
 not definitions hut facts; and where our business is not 
 to trace necessary connections, but the laws which regu- 
 late the established order of the universe ! 
 
AND WRITINGS OF DR. EEIB. 59 
 
 In various attempts winch have been lately made, more 
 especially on the continent, toward a systematical expo- 
 sition of the elements of physics, tlie effects of (he mis- 
 take I am now censuring are ex(remely remariiable. The 
 happy use of mathematical principles exiiihited in the 
 writings of Newton and his followers, Jiaving rendered 
 an extensive knowledge of them an indispensable prepara- 
 tion for the study of the mechanical philosophy, the early 
 habits of thought acquired in the former piirsnil are nat- 
 urally transferred to the latter. Hence (lie illogical and 
 obscure manner in which its clemen(ary principles have 
 frequently been stated ; an attempt being made to deduce 
 from the smallest (possible number of data, the whole 
 system of truths which it comprehends. The analogy 
 existing among some of the fundamental laws of mechan- 
 ics, bestows, in the opinion of the multitude, an appear- 
 ance of plausibility on such attempts ; and their obvious 
 tendency is to withdraw the attention from that unity of 
 design, which it is the noblest employment of philosophy 
 to illustrate, by disguising it under the semblance of an 
 eternal and necessary order, similar to what the mathe- 
 matician delights to trace among the mutual relations of 
 quantities and figures. 
 
 These slight hints may serve as a reply in part to what 
 Dr. Priestley has suggested with respect to the conse- 
 quences likely to follow, if the spirit of Keid's philosophy 
 should be introduced into physics.* One consequence 
 would unquestionably be, a careful separation between the 
 principles which we learn from experience alone, and 
 those which are fairly resolvable, by mathematical or 
 physical reasoning, into other facts still more general j 
 and, of course, a correction of that false logic, which, 
 while it throws an air of mystery over the plainest and 
 most undeniable facts, levels the study of nature, in point 
 of moral interest, with the investigations of the geometer 
 or of the algebraist. 
 
 * Examination of Reid's Inquiry, p. 110. 
 
60 ACCOUNT OT THE I-IFB 
 
 It must not, however, be supposed, that, in the present 
 state of natural philosophy, a false logic threatens the 
 same dan^a;erous edects as in the philosophy of the mind. It 
 may retard somewhat the progress of the student at his 
 first outset ; or it iisay confound iti his apprehensions, the 
 harmony of systei;iaiical order, witli ihe consistency and 
 mutual dependOscy essential to a series of mathematical 
 theorems : but the fundamental truths of physics are now 
 too well estahllshed, and the checks which it furnishes 
 against sophistry are too numerous and palpable, to ad- 
 mit the possibility of any permanent error in our deduc- 
 tions. In tJie philosophy of the mind, so dilEcuIt is the 
 acquisition of those habits of reflection which can alone 
 lead to a correct knowledge of the intellectual 'phenomena, 
 that a faulty hypothesis, if skilfully fortiiled by the im- 
 posing, though illusory strength of arbitrary definitions 
 and a systeniatical phraseology, may maintain its ground 
 for a succession of ages. 
 
 It will not, ) trust, be inferred from any thing I have 
 here advanced, that I mean to oifei- an apology for those, 
 who, eifhcr in pliysics or morals, Avould presumptuously 
 state their own opinions with respect to the laws of na- 
 ture, as a bar against future attempts to simplify and gen- 
 eralize them still farther. To assert, that none of the 
 mechanical explanations yet given of gravitation are sat- 
 isfactory ; and even to hint, that ingenuity might be more 
 profitably employed than in the search of sueh a theory, 
 is something different from a gratuitous assumption of 
 ultimate facts in physics ; nor does it imply an obstinate 
 determination to resist legitimate evidence, should some 
 fortunate inquirer, contrary to what seems probable at 
 present, succeed where the genius of Newton has failed. 
 If Dr. Reid has gone farther than this in his conclusions 
 concerning the principles which he palls original or in- 
 stinctive, he has departed from that guarded language in 
 which he commonly expresses himself j for all that it 
 was of importance for him to conclude was, that the 
 theories of his predecessors were, in these instances. 
 
AND WRITINGS OF DK.REID. 61 
 
 exceptionable ; and the doubts he may occasionally insin- 
 uate, concerning the success of future adventurers, so far 
 from betraying any overweening confidence in his own 
 understanding, are an indirect tribute to the talents of 
 those, from whose failure he draws an argument against 
 the possibility of their undertaking. 
 
 The same eagerness to simplify and to generalize, which 
 led Priestley to complain of the number of Reid's instinct- 
 ive principles, has carried some later philosophers a step 
 farther. According to them, the very word instinct is 
 unphilosophical ; and every thing either in man or brute, 
 which has been hitherto referred to this mysterious 
 source, may be easily accounted for by experience or im- 
 itation. A few instances in which this doctrine appears 
 to have been successfully verified, have been deemed suf- 
 ficient to establish it without any limitation. 
 
 In a very original work, on which I have already haz- 
 arded some criticisms, much ingenuity has been employed 
 in analyzing the wonderful effects which the human infant 
 is enabled to make for its own preservation, the moment 
 after its introduction to the light. Thus, it is observed, 
 that the fcetus, while still in the uterus, learns to perform 
 the operation of swallowing; and also learns to relieve 
 itself, by a change of posture, from the irksomeness of 
 continued rest : and, therefore, if we admit these propo- 
 sitions, we must conclude, that some of the actions which 
 infants are vulgarly supposed to perform in consequence 
 of instincts coeval with birth, are only a continuation of 
 actions to which they were determined at an earlier period 
 of their being. The remark is ingenious, and it may 
 perhaps be just; but it does not prove that instinct is an 
 unphilosophical term ; nor does it render the operations 
 of the infant less mysterious than they seem to be on the 
 common supposition. How far soever the analysis, in 
 such instances, may be carried, we must at last arrive at 
 some phenomenon no less wonderful than that which we 
 mean to explain : in other words, we must still admit as 
 an ultimate fact, the existence of an original determioa- 
 
62 ACCOUNT OF THE IIPE 
 
 t'lon to a particular mode of aclion salutary or necessary 
 to the animal ,* and all v/e have accomplished is (o connect 
 the origin of (his instinct with an earlier period in the 
 history of ihe human mind. 
 
 The same author has attempted to account, in a man- 
 ner somewhat similar, for the different degrees in which 
 the young of different animals are ahle, at the moment of 
 birth, to exert their bodily powers. Thus, calves and 
 chickens are able to walk almost immediately ; while the 
 human infant, even in the most favourable situations, is six 
 or even twelve months old before he can stand alone. For 
 this. Dr. Darwin assigns two causes. 1. That the young 
 of some animals come into the world in a more complete 
 state than that of others : the colt and Iamb, for example, 
 enjoying, in this respect, a striking advantage over the 
 puppy and the rabbit. 2. That the mode of walking of 
 some animals, coincides more perfectly than that of oth- 
 ers, with (he previous motions of the fmlus in utero. The 
 struggles of all animals, he observes, in the womb, must 
 resemble their manner of swimming, as by this kind of 
 motion, they can best change their attitude in water. But 
 the swimming of the calf and of the chicken resembles 
 their ordinary movements on the ground, which they 
 have thus learned in part to execute, while concealed 
 from our observation ; whereas, the swimming of the hu- 
 man infant differing totally from his manner of walking, 
 he has no opportunity of acquiring the last of these arts 
 till he is exposed to our view. The theory is extremely 
 plausible, and does honour to the author's sagacity ; but 
 it only places in a new light that provident care which 
 nature has taken of all her offspring in the infancy of 
 their existence. 
 
 Another instance may contribute toward a more ample 
 illustration of the same subject. A lamb, not many min- 
 utes after it is dropped, proceeds to search for its nour- 
 ishment in that spot where alone it is to be found ; apply- 
 ing both its limbs and its eyes to their respective oflSees. 
 The peasant observes the fact, and gives the name of 
 
AND WRITINGS OF DK. REIU. 6S 
 
 instinct, or some corresponding term, to the unknown 
 principle by wliich the animal is guided. On a more 
 accurate examination of circumstances, the philosopher 
 finds reason to conclude, that it is by the sense of smell- 
 ing, it is thus directed to its object. In proof of this, 
 among other curious facts, the following has been quot- 
 ed. " On dissecting," says Galen, " a goat great with 
 youngj I found a brisk emhryon, and having detached 
 it from the matrix, and snatching it away before it 
 saw its dam, I brought it into a room where there were 
 many vessels ; some filled with wine, others with oil, some 
 with honey, others wifh milk, or some other liquor,* and 
 in others there were grains and fruits. We first observ- 
 ed the young animal gel upon its feet and walk; then it 
 shook itself, and afterward scratched its side with one of 
 its feet: then we saw it smelling to every one of those 
 things that were set in the room ; and when it had smelt 
 to them all, it drank up the milk.* Admitting this very 
 beautiful story to be true, and, for my own part, I am far 
 from being disposed to question its probability, it only 
 enables us to state the fact with a little more precision, 
 in consequence of our having ascertained, that it is to the 
 sense of smelling, the instinctive determination is attach- 
 ed. The conclusion of the peasant is not here at variance 
 with that of the philosopher. It differs only in this, that 
 he expresses himself in those general terms which are 
 suited to his ignorance of tlie particular process by which 
 nature in this case accomplishes her end; and, if he did 
 otherwise, he would he censurable for pre-judging a 
 question of which he is incompetent to form an accurate 
 opinion. 
 
 The application of these illustrations to some of Dr. 
 Beid's conclusions concerning the instinctive principles of 
 the human mind, is, I flatter myself, sufficiently manifest. 
 They relate, indeed, to a subject which differs, in various 
 respects, from that which has fallen under his more par- 
 ticular consideration ; but the same rules of philosophiz- 
 ing will be found to apply equally to both. 
 
 * DarwiD, vol, i. pp. 19S, 19«. 
 
64 ACCOUNT OF THE XIFE 
 
 4. To examine in detail the criticisms which have been 
 made on what Dr. Reid has written concerning the prin- 
 ciples of common sense, an article of his philosophy which 
 has been supposed " to sanction an appeal from the de- 
 cisions of the learned to the voice of the multitude," 
 would lead me into discussions inconsistent with the lim- 
 its of this memoir : not that the importance of these 
 criticisms demands a long or elaborate refutation ; but 
 . because the subject, according to the view I wish to take 
 of it, involves some other questions of great moment and 
 difficulty, relative to the foundations of human knowledge. 
 Dr. Priestley, the most formidable of Dr. Reid's oppo- 
 nents, has granted as much in favour of this doctrine as 
 it is worth while to contend for, on the present occasion. 
 *' Had these writers," he observes with respect to Dr. 
 Reid and his followers, " assumed, as the elements of 
 their common sense, certain truths which are so plain 
 that no man could doubt of them, without entering into 
 the ground of our assent to them, their conduct would 
 have been liable to very little objection. All that could 
 have been said would have been, that, without any neces- 
 sity, they had made an innovation in the received use of 
 a term. For no person ever denied, that there are self- 
 evident truths, and that these must be assumed as the 
 foundation of all our reasoning. I never met with any 
 person who did not acknowledge this, or heard of any 
 argumentative treatise that did not go upon the supposi- 
 tion of it."* After such an acknowledgment, it is im- 
 possible to forbear asking, with Dr. Campbell, «' What is 
 the great point which Dr. Priestley would controvert ? Is 
 it, whether such self-evident truths shall be denominated 
 principles of common sense, or be distinguished by some 
 other appellation ?"t 
 
 That the doctrine in question has been, in some publi- 
 cations, presented in a very exceptionable form, I most 
 readily allow ; nor would I be understood to subscribe to 
 
 • Examination of Dr. Reid's Inquiry, &c. p. 119. f Philosophy 
 
 of Bhetoric, toI. i. p. 111. See note E. 
 
AND \^RITIIfGa OF liK. KElD. 66 
 
 it implicitly, even as it appears in the works of Dr. Reid. 
 It is but an act of justice to him, however, to request^ 
 that his opinions may be judged of from his own Works 
 alone, not from those of others who may have hap- 
 pened to coincide with him in certain tenets, or in cer- 
 tain modes of expression ; and that, before any ridicule 
 be attempted on his conclusions concerning the authority 
 of common sense, his antagonists would take tlie trouble 
 to examine in what acceptation he has employed that 
 phrase. 
 
 The truths which Dr. Reid seems, in most instances, 
 disposed to refer to the judgment of this tribunal, might, 
 in my opinion, be denominated more unexceptionably, 
 " fundamental laws of human belief." They have been 
 called by a very ingenious foreigner, M. Trembley of 
 Geneva, but certainly with a singular infelicity of lan- 
 guage, Prejnges Legitimes. Of this kind are the follow- 
 ing propositions ; " I am the same person today that I 
 was yesterday ;" " The material world has an existence 
 independent of that of percipient beings ;" " There are 
 other intelligent beings in the universe besides myself;" 
 " The future course of nature will resemble the past." 
 Such truths no man but a philosopher ever thinks of 
 stating to himself in words ; but all our conduct and all 
 our reasonings proceed on the supposition that they are 
 admitted. The belief of them is essential fop the pres- 
 ervation of our animal existence ; and it is«accordingly 
 coeval with the first operations of the intellect. 
 
 One of the first writers who introduced the phrase 
 common sense into the technical or appropriate language 
 of logic, was father Buffier, in a book entitled Traite des 
 Premieres Verites. It has since been adopted by several 
 authors of note in this country ; particularly by Dr. Reid, 
 Dr. Oswald and Dr. Beattie ; by all of whom, however, I 
 am afraid, it must be confessed, it has been occasionally 
 employed without a due attention to precision. The last of 
 
 vol. I. 9 
 
66 ACCOUNT OF THE IIIE 
 
 these writers uses it * to denote that power by which the 
 mind perceives the truth of any intuitive proposition j 
 whether it be an axiom of abstract science ,• or a statement 
 of some fact resting on the immediate information of con- 
 sciousness, of perception, or of memory; or one of those fuij- 
 damentallaws of belief whicli are implied in the application 
 of our faculties to the ordinary business of life. The same 
 extensive use of the word may, I believe, be found in the 
 otherauthors just mentioned. But no authority can justify 
 such a laxity in the employment of language in philosophi- 
 cal discussions ; for, if mathematical axioms be, as they are 
 manifestly and indisputably, a class of propositions essen- 
 tially distinct from the other kinds of intuitive truths now 
 described, why refer them all indiscriminately to the same 
 principle in our constitution? If this phrase, therefore, 
 be at all retained, precision requires, that it should be 
 emplpyed in a more limited acceptation ; and accordingly, 
 in the works under our consideration, it is appropriated- 
 most frequently, though hy no means uniformly, to that 
 class of intuitive truths which I have already called, 
 "fundamental laws of belief."f When thus restricted 
 it conveys a notion, unambiguous at least, and definite j 
 and, consequently, the question about its propriety or 
 impropriety turns entirely on the coincidence of this defi- 
 nition with the meaning of the word as employed in or- 
 dinary discourse. Whatever objections, therefore, may 
 be stated to the expression as now defined, will apply to 
 it with additional force, when used with the latitude which 
 has been already censured. 
 
 I have said, that the question about the propriety of 
 the phrase common sense as employed by philosophers, 
 must be decided by an appeal to general practice : for, 
 although it be allowable and even necessary for a philos- 
 opher, to limit the acceptation of words which are em- 
 
 • Essay on Truth, edition second, p. 40. et seq. also p. 166, et seq. 
 
 t This seems to be nearly the meaning annexed to the phrase, by the 
 learned and acute author of the Philosophy of Rhetoric, vol. i. p. 109, 
 et seq. 
 
AND WRITINGS OF DR. REID. 67 
 
 ployed vaguely in common discourse, it is always danger- 
 ous to give (o a word a scientific meaning essentially dis- 
 tinct from that in wliieh it is usually understood. It has, 
 at least, the effect of misleading those who do not enter 
 deeply into the subject ; and of giving a paradoxical ap- 
 pearance to doctrines, wliich, if expressed in more un- 
 exceptionable terms, would be readily admitted. 
 
 It appears to ine, that tliis has actually happened in 
 the present instance. The phrase common sense, as it is 
 generally understood, is nearly synonymous wiHi molher- 
 wit ; denoting that degree of sagacity, depending partly 
 on original capacity, and partly on personal experience 
 and observation, which qualifies an individual for those 
 simple and essential occupations which all men are called 
 on to exercise habitually by their common nature. In this 
 acceptation, it is opposed to those mental acquirements 
 which are derived from a regular education and from the 
 study of books ; and refers, not to the speculative con- 
 victions of the understanding, but to tliat prudence and 
 discretion which are the foundation of successful conduct. 
 Such is the idea which Pope annexes to the word, when, 
 speaking of good sense, which means only a more than 
 ordinary share of common sense, he calls it 
 
 " the gift of heaven, 
 
 And though no science, fairly worth the seven." 
 
 To speak, accordingly, of appealing from the conclu- 
 sions of philosophy to common sense, had the appearance, 
 to title page readers, of appealing from the verdict of the 
 learned to the voice of the multitude ^ or of attempting 
 to silence free discussion, by a reference to some arbitra- 
 ry and undefinable standard, distinct from any of the 
 intellectual powers, hitherto enumerated by logicians. 
 Whatever coimtenance may be supposed to have been 
 given by some writers to such an interpretation of this 
 mode of expression, I may venture to assert, that none is 
 afforded by the works of Dr. Reid. The standard to 
 which he appeals, is neither the creed of a particular 
 
68 AccouwT or the irKB 
 
 sect, nor the inward light of enthusiastic presumption ^ 
 but that constitution of human nature without which all 
 the business of the world would immediately cease ; and 
 the substance of his doctrine amounts merely to this, that 
 those essential laws of belief, to which skeptics have ob- 
 jected when considered in connection with our scientific 
 reasonings, are implied in every step we take as active 
 beings ; and if called in question by any man in his prac- 
 tical concerns, would expose him universally to the charge 
 of insanity. 
 
 In stating this important argument, it were perhaps to be 
 ivished, that the subject had been treated with somewhat 
 more of analytical accuracy ; and it is certainly to be re- 
 gretted, that a phrase should have been employed, so well 
 calculated by its ambiguity to furnish a convenient handle 
 to misrepresentations; but in the judgment of those who 
 have perused Dr. Reid's writings with an intelligent and 
 candid attention, these misrepresentations must recoil on 
 their authors ; wliile they who are really interested in 
 the progress of useful science, will be disposed rather to 
 lend tlieir aid in supplying what is defective in his views, 
 than to reject hastily a doctrine which aims, by the de- 
 velopment of some logical principles, overlooked in the 
 absurd systems which have been borrowed from the 
 schools, to vindicate the authority of truths intimately 
 and extensively connected with human happiness. 
 
 In the prosecution of my own speculations on the hu- 
 man mind, I shall have occasion to explain myself fully, 
 concerning this as well as various other questions con- 
 nected with the foundations of philosophical evidence. 
 The new doctrines, and new phraseology on that subject, 
 which have lately become fashionable among some meta- 
 physicians in Germany, and which, in my opinion, have 
 contributed not a little to involve it in additional obscurity, 
 are a sutGcient proof, that this essential and fundamental 
 article of logic is not as yet completely exhausted. 
 
AND >fHITlNG8 or DR. REID. 69 
 
 In order to bring the foregoiog remarks within some 
 compass, I have found it necessary to confine myself to 
 such objections as strike at the root of Dr. Reid's philos- 
 ophy, without touching on any of his opinions or partic- 
 ular topics, however important. I have been obliged also 
 to compress what I have stated, within narrower limits 
 than were perhaps consistent with complete perspicuity; 
 and to reject many illustrations which crowded upon me, 
 at almost every step of my progress. 
 
 It may not, perhaps, be superfluous to add, that, sup- 
 posing some of these olyections to possess more force^than 
 I have ascribed to them in my reply, it will not therefore 
 follow, that little advantage is to be derived from a care- 
 ful perusal of the speculations against which they are 
 directed. Even they who dissent the most widely from 
 Dr. Reid's conclusions, can scarcely fail to admit, that as 
 a writer he exhibits a striking contrast to the most suc- 
 cessful of his predecessors, in a logical precision and sim- 
 plicity of language ; his statement of facts being neither 
 vitiated by physiological hypothesis, nor obscured by 
 scholastic mystery. Whoever has reflected on the infinite 
 importance, in such inquiries, of a skilful use of words as 
 the essential instrument of thought, must be aware of the 
 influence which his works are likely to have on the future 
 progress of science ; were they to produce no other effect 
 than a general imitation of his mode of reasoning, and of 
 his guarded phraseology. 
 
 It is not indeed every reader to whom these inquiries 
 are accessible ; for habits of attention in general, and still 
 more habits of attention to the phenomena of thought, 
 require early and careful cultivation : but those who are 
 capable of the exertion, will soon recognise, in Dr. Reid's 
 statements, the faithful history of their own minds, and 
 will find their labours amply rewarded by that satisfac- 
 tion which always accompanies the discovery of useful 
 truth. They may expect, also, to be rewarded by some in- 
 tellectual acquisitions not altogether useless in their other 
 studies. An author well qualified to judge, from his own 
 
70 ACCOUNT OB TUB IIEE 
 
 experience, of whatever conduces to invigorate or to em- 
 bellish the understanding, has beautifullj' remarked, that 
 "by turning the soul inward on itself, its forces are con- 
 centred, and are fitted for stronger and bolder flights of 
 science ; and that, in such pursuits, whether we take, or 
 whether we lose the game, the chace is certainly of ser- 
 vice."* In this respect, the philosophy of the mind, ab- 
 stracting entirely from that pre-eminence which belongs to 
 it in consequence of its practical applications, may claim 
 a distinguished rank among those preparatory disciplines, 
 which another writer of equal talents has happily com- 
 pared to " the crops which are raised, not for the sake of 
 the harvest, but to be ploughed in as a dressing to the 
 land."f 
 
 SECTION lU. 
 
 CONCXrSION OF THE NARRATIVE. 
 
 The three works to which the foregoing remarks re- 
 fer, together with the Essay on Quantity, published in 
 the Philosophical Transactions of the Royal Society of 
 London, and a short but masterly Analysis of Aristotle's 
 Logic, which forms an appendix to the third volume of 
 lord Kaimes's Sketches, comprehend the whole of Dr. 
 Reid's publications. The interval between the dates of 
 the first and last of these amounts to no less than forty 
 years, although he had attained to the age of thirty-eight 
 before he ventured to appear as an author. 
 
 With the Essays on the Active Powers of Man, he 
 closed his literary career ; but he continued, notwithstand- 
 ing, to prosecute his studies with unabated ardour and 
 activity. The more modern improvements in chemistry 
 attracted his particular notice j and he applied himself, 
 
 • Preface to Mr. Burke's Essay od the Sublime and Beautiful. 
 f Bishop Berkeley's Querist. 
 
AND WRITINGSf or DR.KEIO. 71 
 
 with his wonted diligence and success, to the study of its 
 new theories and new nomenclature. He amused him- 
 self also, at times, in preparing for a philosophical so- 
 ciety, of which he was a memher, short essays on partic- 
 ular topics, which happened to interest his curiosity, and 
 on which he thought he might derive useful hints from 
 friendly discussion. The most important of these were, 
 An Examination of Priestley's Opinions concerning Mat- 
 ter and Mind ; Observations on the Utopia of Sir Thomas 
 More ; and Physiological Reflections on Muscular Motion. 
 This last essay appears to have been written in the eighty- 
 sixth year of his age, and was read by the author to his 
 associates, a few months before his death. " His thoughts 
 were led to the speculations it contains," as he himself 
 mentions in the conclusion, " by the experience of some 
 of the effects which old age produces on the muscular 
 motions." " As they were occasioned, therefore," he 
 adds, "by the infirmities of age, they will, I hope, be 
 heard with the greater indulgence." 
 
 Among the various occupations with which he thus en- 
 livened his relirement. the mathematical pursuits of his 
 earlier years held a distinguished place. He delighted 
 to converse about them with his friends ; and often ex- 
 ercised his skill in the investigation of particular prob- 
 lems. His knowledge of ancient geometry bad not prob- 
 ably been, at any time, very extensive ; but he had culti- 
 vated diligently those parts of mathematical science which 
 are subservient to the study of Sir Isaac Newton's Works. 
 He had a predilection, more particularly, for researches 
 requiring the aid of arithmetical calculation, in the prac- 
 tice of which he possessed uncommon expertness and ad- 
 dress. I think, I have sometimes observed in him a slight 
 and amiable vanity connected with this accomplishment. 
 
 The revival, at this period of Dr. Reid's life, of his 
 first scientific propensity, has often recalled to me a re- 
 mark of Mr. Smith's, that of all the amusements of old 
 age, the most grateful and soothing is a renewal of ac- 
 quaintance with the favourite studies, and favourite au- 
 thors of our youth ; a remark which, in his own ease, 
 
72 ACCOUNT 01? THE IIFE 
 
 seemed to be more particularly exemplified, \vbile he was 
 re-perusing, with the enthusiasm of a student, the tragic 
 poets of ancient Greece. I heard him at least, repeat 
 the observation more than once, while Sophocles or Eu- 
 ripides lay open on his table. 
 
 In the case of Dr. Reid, other motives perhaps con- 
 spired with the influence of the agreeable associations, to 
 which Mr. Smith probably alluded. His attention was 
 always fixed on the state ofbis intellectual faculties ; and 
 for counteracting the effects of time on these, mathemat- 
 ical studies seem to be fitted in a peculiar degree. They 
 are fortunately, too, within the reach of many individuals, 
 after a decay of memory disqualifies them for inquiries 
 which involve a multiplicity of details. Such detached 
 problems, more especially, as Dr. Reid commonly selected 
 for his consideration: problems where all the data are 
 brought at once under (he eye, and where a connected 
 train of thinking is not to be carried on from day to day ; 
 will be found, as I have witnessed with pleasure in several 
 instances, by those who are capable of such a recreation, 
 a valuable addition to the scanty resources of a life pro- 
 tracted beyond the ordinary limit. 
 
 While he was thus enjoying an old age, happy in some 
 respects beyond the usual lot of humanity, his domestic 
 comfort suffered a deep and incurable wound by the death 
 of Mrs. Reid. He had had the misfortune, too, of sur- 
 viving, for many years, a numerous family of promising 
 children ; four of whom, two sons and two daughters, died 
 after they attained to maturity. One daughter only was 
 left to him when he lost his wife ; and of her affectionate 
 good offices he could not always avail himself, in conse- 
 quence of the attentions which her own husband's infirm- 
 ities required. Of this lady, who is still alive, the widow 
 of Patrick Carmichael, M. D.* I shall have occasion 
 
 • A learned and -worthy physician, Tvho, after a lonpresidence in Holland, 
 ■where he practised medicine, retired to Glasgow. He was a younger son 
 of Professor Gerschom Carmichael, who published, about the year 1720, an 
 edition of Puffeodorff, De Officio Hominis et Civis, and who is pronounced 
 by Dr.HutchesoD, "by far the best commeutator on that book." 
 
AND IVRITINGS OF DK. EEID. 73 
 
 iigain (o introduce the name, before I conclude this nar- 
 rative. 
 
 A short extract from a letter addressed to myself by 
 Dr. Reid, not many weeks after his wife's death, will, I 
 am persuaded, be acceptable to many, as an interesting 
 relic of the writer. 
 
 " By the loss of my bosom-friend, with whom I lived 
 fifty-two years, I am brought into a kind of new world, at 
 a time of life when old habits are not easily forgot, or 
 new ones acquired. But every world is God's world, and 
 I am thankful for the comforts he has left me. Mrs, 
 Carmichael has now the care of two old deaf men, and 
 does every thing in her power to please them ; and both 
 are very sensible of her goodness. I have more health 
 than at my time of life I had any reason to expect. I walk 
 about ; entertain myself with reading what I soon forget ; 
 can converse with one person, if he articulates distinctly, 
 and is within ten inches of my left ear ; go to church, with- 
 out hearing one word of what is said. You know, I never 
 had any pretensions to vivacity, but I am still free from 
 languor and ennui. 
 
 "If you are weary of this detail, impute it to the anx- 
 iety you express to know the state of my health. I wish 
 you may have no more uneasiness at my age ,• being yours 
 most affectionately." 
 
 About four years after this event, he was prevailed on 
 by his friend and relation. Dr. Gregory, to pass a few 
 weeks, during the summer of 1796, at Edinburgh. He 
 was accompanied by Mrs. Carmichael, who lived with 
 him in Dr. Gregory's house ; a situation which united, 
 under the same roof, every advantage of medical care, of 
 tender attachment, and of philosophical intercourse. As 
 Dr. Gregory's professional engagements, however, nec- 
 essarily interfered much with his attentions to his guest, 
 I enjoyed more of Dr. Reid's society, than might other- 
 wise have fallen to my share. I had the pleasure, ac- 
 cordingly, of spending some hours with him daily, and of 
 vol. I. 10 
 
74 ACCOUNT OF THE IIKB 
 
 attending him in his walking excursions, which frequently 
 extended to the distance of three or four miles. His fac- 
 ulties, excepting his memory which was considerably im- 
 paired, appeared as vigorous as ever j and, although his 
 deatness prevented him from taking any share in general 
 conversation, he was still able to enjoy the company of a 
 friend. Mr. Playfair and myself were both witnesses of 
 the acuteness which he displayed on one occasion, in de- 
 tecting a mistake, by no means obvious, in a manuscript 
 of his kinsman David'Gregory, on the subject of Prime 
 and Ultimate Ratios. Nor had his temper suffered from 
 the hand of time, either in point of gentleness or of gaiety. 
 " Instead of repining at the enjoyments of the young, he 
 delighted in promoting them ; and, after all the losses he 
 had sustained in his own family, he continued to treat 
 children with such condescension and benignity, that some 
 very young ones noticed the peculiar kindness of his eye."* 
 In apparent soundness and activity of body, he resembled 
 more a man of sixty than of eighty-seven. 
 
 He returned to Glasgow in his usual health and spirits ', 
 and continued, for some weeks, to^devote^ as formerly, a 
 regular portion of his time to the exercise both of body 
 and of mind. It appears, from a letter of Dr. Cleghorn'S; 
 to Dr. Gregory, that he was still able to work with his 
 own hands in his garden ; and he was found by Dr. Brown, - 
 occupied in the solution of an algebraical problem of con- 
 siderable difficulty, in which, after the labour of a day or 
 two, he at last succeeded. It was in the course of the 
 same short interval, that he committed to writing those 
 particulars concerning his ancestors, which I have already 
 mentioned. 
 
 This active and useful life was now, however, drawing 
 to a conclusion. A violent disorder attacked him about 
 the end of September ; but does not seem to have occa- 
 
 * I have borrowed this sentence from a just and elegant character of Dr. 
 Reid, which appeared a few days after his death, in one of the Glasgow- 
 Journals. I had occasion frequently to verify the truth of the observation 
 during his last visit to Edinburgh. 
 
AND WRITINGS OF DE. KEID. 75 
 
 «oned much alarm to those about him, till he was visited 
 by Dr. Cleghorn, who soon after communicated his ap- 
 prehensions in a letter to Dr. Gregory. Among other 
 symptoms, lie mentioned particularly, " that alteration of 
 voice and features, which, though not easily described, is 
 so well known to all who have opportunities of seeing life 
 close." Dr. Reid's own opinion of his case was probably 
 the same with that of his physician ; as he expressed to 
 him on his first visit, his hope that he was " soon to get 
 his dismission." After a severe struggle, attended with 
 repeated strokes of palsy, he died on the 7th of October 
 following. Dr. Gregory had the melancholy satisfaction 
 of visiting his venerable friend on his deathbed, and of 
 paying him this unavailing mark of attachment, before 
 his powers of recollection were entirely gone. 
 
 The only surviving descendant of Dr. Reid is Mrs. 
 Carmichael, a daughter worthy in every respect of such 
 a father: long the chief comfort and support of his old 
 age, and his anxious nurse in his last moments.* 
 
 In point of bodily constitution, few men have been more 
 indebted to nature than Dr. Reid. His form was vigor- 
 ous and athletic ; and his muscular force, though he was 
 somewhat under the middle size, uncommonly great | ad- 
 vantages to which his habits of temperance and exercise, 
 and the unclouded serenity of his temper, did ample jus- 
 tice. His countenance was strongly expressive of deep 
 and collected thought; but when brightened up by the 
 face of a friend, what chiefly caught the attention was, a 
 look of good will and of kindness. A picture of him, for 
 which he consented, at the particular request of Dr. 
 Gregory, to sit to Mr. Raeburn, during his last visit to 
 Edinburgh, is generally and justly ranked among the hap- 
 piest performances of that excellent artist. The medal- 
 lion of Tassie, also, for which he sat in the eighty-first 
 year of his age, presents a very perfect resemblance. 
 
 I- have little to add to what the foregoing pages contain 
 with respect to his character. Its most prominent fea- 
 
 * Note F. 
 
76 ACCOUNT OT THE IIFE 
 
 tures were, intrepid and inflexible rectitude ; a pure and 
 devoted atlacliinent to truth; and an entire command, 
 acquired by tlie unwearied exertions of a long life, over 
 all his passions. Hefice, in those parts of his writings 
 where his subject forces him to dispute the conclusions 
 of others, a scrupulous rejection of every expression cal- 
 culated to irritate those whom he was anxious to convince; 
 and a spirit of liberality and good humour toward his op- 
 ponents, from which no asperity on their part could pro- 
 voke him, for a moment to deviate. The progress of 
 useful knowledge, more especially in what relates to hu- 
 man nature and to human life, he believed to be retarded 
 rather than advanced by the intemperance of controversy ; 
 and to be Secured most effectually when intrusted to the 
 slow but irresistible influence of sober reasoning. That 
 the argumentative talents of the disputants might be im- 
 proved by such altercations, he was willing to allow ; but, 
 considered in their connection with the great objects 
 which all classes of writers profess equally to have in 
 view, he was convinced « that they have done more harm 
 to the practice, than they have done service to the theory 
 of morality."* 
 
 In private life, no man ever maintained, more eminently 
 or more uniformly, the dignity of philosophy ; combining 
 with tlje most amiable modesty and gentleness, the noblest 
 spirit of independence. The only preferments which he 
 ever enjoyed, he owed to the unsolicited favour of the two 
 learned bodies who successively adopted him into their 
 number; and the respectable rank which he supported 
 in society, was the well earned reward of his own aca- 
 demical labours. The studies in which he delighted, were 
 little calculated to draw on him the patronage of the great ; 
 and he was unskilled in the art of courting advancement, 
 by " fashioning his doctrines to the varying hour." 
 
 As a philosopher, his genius was more peculiarly char- 
 acterized by a sound, cautious, distinguishing judgment; 
 by a singular patience and perseverance of thought ; and 
 
 * Pceface to Pope's Essay on Man. 
 
AND WRITINGS OF DE.EKID. 77 
 
 l»y habits of the most fixed and concentrated attention to 
 his own mental operations; endowments which, although 
 not the most splendid in the estimation of the multitude, 
 would seem entitled, from the history of science, to rank 
 among the rarest gifts of the mind. 
 
 With these habits and powers, he united, what does 
 not always accompany them, tlie curiosity of a naturalist, 
 and the eye of an observer ; and accordingly, his infor- 
 mation about every thing relating to physical science, and 
 to the useful arts, was extensive and accurate. His mem- 
 ory for historical details was not so remarkable; and he 
 used sometimes to regret the imperfect degree in which 
 he possessed this faculty. I am inclined, however to 
 think, that in doing so, he underrated his natural advan- 
 tages; estimating the strength of memory, as men com- 
 monly do, rather by the recollection of particular facts, 
 than by the possession of those general conclusions, from 
 a subserviency to which, such facts derive their princi- 
 pal value. 
 
 Toward the close of life, indeed, his memory was much 
 less vigorous than the other powers of his intellect ; in 
 none of which, could I ever perceive any symptom of de- 
 cline. His ardour for knowledge, too, remained unex- 
 tinguished to the last ; and, when cherished by the society 
 of the young and inquisitive, seemed even to increase with 
 his years. What is still more remarkable, he retained 
 in extreme old age all the sympathetic tenderness, and 
 all the moral sensibility of youth ; the liveliness of his 
 emotions, wherever the happiness of others was concern- 
 ed, forming an affecting contrast to his own unconquerable 
 firmness under the severest trials. 
 
 Nor was the sensibility which he retained, tlie selfish 
 and steril offspring of taste and indolence. It was alive 
 and active, wherever he could command the means of re- 
 lieving the distresses or of adding to the comforts of oth- 
 ers ; and was often felt in its effects, where he was unseen 
 and unknown. Among the various proofs of this, which 
 have happened to fall under my own knowledge, I cannot 
 
78 ACCOUNT OF THE llIE 
 
 help mentioning particularly, upon the most unquestion- 
 able authority, the secrecy with which he conveyed his 
 occasional benefactions to his former parishoners at New 
 Machar, long after his establishment at Glasgow. One 
 donation, in particular, during the scarcity of 1782, a do- 
 nation which, notwithstanding all his precautions, was dis- 
 tinctly traced to his beneficence, might perhaps have been 
 thought disproportionate to his limited income, had not 
 his own simple and moderate habits multiplied the re- 
 sources of his humanity. 
 
 His opinions on the most important subjects j^re to be 
 found in his works ; and that spirit of piety which ani- 
 mated every part of Iiis conduct, forms the best comment 
 on their practical tendency. In the state in which he 
 found the philosophical world, he believed, that his tal- 
 ents could not be so usefully employed, as in combating 
 the schemes of those who aimed at the complete subver- 
 sion of religion, both natural and revealed ; convinced 
 with Dr. Clarke, that, " as Christianity presupposes the 
 truth of natural religion, whatever tends to discredit the 
 latter, must have a proportionally greater effect in weak- 
 ening the authority of the former."* In his views of 
 both he seems to have coincided nearly with Bishop But- 
 ler ; an author whom he held in the highest estimation, 
 a very careful abstract of the treatise entitled Analogy, 
 drawn up by Dr. Reid, many years ago, for his own use, 
 still exists among his manuscripts ; and the short Disser- 
 tation on Virtue which Butler has annexed to that work, 
 together with the Discourses on Human Nature publish- 
 ed in his volume of Sermons, he used always to recom- 
 mend as the most satisfactory account that has yet ap- 
 peared of the fundamental principles of morals : nor could 
 he conceal his regret, that the profound philosophy which , 
 these discourses contain, should of late have been so gen- 
 erally supplanted in England, by the speculations of some 
 
 * Collection of Papers which passed between Leibnitz and Clarke. See 
 Dr. Clarke's Dedication. 
 
AND WRITINGS OF DR. KBID. 79 
 
 other moralists, who, while they profess to idolize the 
 memory of Loeke, " approve little or nothing in his writ- 
 ings, but his errors."* 
 
 Deeply impressed, however, as he was with his own 
 principles, he possessed the most perfect liberality toward 
 all whom he believed to be honestly and conscientiously 
 devoted to the search of truth. With one very distin- 
 guished character, the late lord Kaimes, he lived in the 
 most cordial and affectionate friendship, notwithstanding 
 the avowed opposition of their sentiments on some moral 
 questions, to which he attached the greatest importance. 
 Both of thenj, however, were the friends of virtue and of 
 mankind ; and both were able to temper the warmth of 
 free discussion, with the forbearance and good humour 
 founded on reciprocal esteem. No two men, certainly, 
 ever exhibited a more striking; contrast in their conver- 
 sation, or in their constitutional tempers : the one, slow 
 and cautious in his decisions, even on those tofties which 
 he had? most diligently studied ; reserved and silent in 
 promiscuous society; and retaining, after alibis literary 
 eminence, the same simple and unassuming manners which 
 he brought from his country residence : the other, lively, 
 rapid, and communicative ; aecustonted', by his profes- 
 sional pursuits, to wield with address the weapons of con- 
 troversy, and not averse to a trial of his powers on ques- 
 tions the most foreign to Ms ordinary habits of inquiry. 
 But these characteristical differences, while to. their com- 
 mon friends they lent an additional charm to the distin- 
 guishing merits of each, served only to enliven their social 
 intercourse, and to cement their mutual attachment. 
 
 I recollect few, if any anecdotes, of Dr. Reid, which 
 appear to me calculated to throw additional light on his 
 character; and I suspect strongly, that many of those 
 which are to be met with in biographical publication?, 
 are more likely to mislead, than to inform. A trifling 
 
 * I have adopted here the words which Dr. Clarke applied to some of 
 Mr. Locke's earlier foUow'ers. They are still more applicable to many 
 ■writers of the present times. See Clarke's first Reply to Leibnitz. 
 
80 iCCorWT OF THE IIFE 
 
 incident, it is true, maly sometimes paint a peculiar fea- 
 ture better than the most elaborate description ; but a 
 selection of incidents really charaeteristicaJ, presupposes, 
 in the observer, a rare capacity to discriminate and to 
 generalize ; and where this capacity is wanting, a biog- 
 rapher, with the most scrupulous attention to the verac- 
 ity of his details, may yet convey a very false conception 
 of the individual he would describe. As, in the present 
 instance, my subject afforded no materials for such a 
 choice, I have attempted, to the best of my abilities, in- 
 stead of retailing detached fragments of conversations, 
 or recording insulated and unmeaning occurrences, to 
 communicate to others the general impressions which Dr. 
 Eeid's character has left on my own mind. In this at- 
 tempt, I am far from being confident I have succeeded ; 
 but, how barren soever I may have thus rendered my 
 pages in the estimation of those who consider biography 
 merely in the light of an amusing tale. I have, at least, 
 the satisfaction to think, that my picture, though faint 
 in the colouring, does not present a distorted resemblance 
 of the original. 
 
 The confidential correspondence of an individual with 
 his friends, affords to the student of human nature, ma- 
 terials of far greater authenticity and importance; more 
 particularly, the correspondence of a man like Dr. Reid, 
 who will not be suspected by those who knew him, of'ac- 
 commodating his letters, as has been alleged of Cicero, 
 to the humours and principles of those whom he address- 
 ed. T am far. at the same time, from thinking, that the 
 correspondence of Dr. Reid would be generally Interest- 
 ing ; or even that he excelled in this species of writing : 
 but few men, I sincerely believe, who have written so 
 much, have left behind them such unblemished memori- 
 als of their virtue. 
 
 At present, I shall only transcribe two letters, which I 
 select from a considerable number now lying before me, 
 as they seem to accord, more than the others, with the 
 general design of this memoir. The first, which is dated 
 
AND WRITINGS OF DR. RUID. 81 
 
 January 15, 1779, is addressed to the Rev. William Greg- 
 ory, now rector of St. Andrew's, Canterbury, then an 
 undergraduate in Baliol college, Oxford. It relates to 
 a remarkable peculiarity in Dr. Reid's physical tempera- 
 ment, connected with a subject of dreaming j and is far- 
 ther interesting as a genuine record of some particulars 
 in his early habits, in which it is easy to perceive the 
 openings of a superior mind. 
 
 " The fact which your brother the Doctor desires to 
 be informed of, was as you mention it. As far as I re- 
 member the circumstances, they are as follow : 
 
 " About the age of fourteen, I was, almost every night, 
 unliappy in my sleep from frightful dreams. Sometimes 
 hanging over a dreadful precipice, and just ready to drop 
 down 5 sometimes pursued for my life, and stopped by a 
 wall, oPj by a sudden loss of all strength; sometimes 
 ready to be devoured by a wild beast. How long I was 
 plagued with such dreams, I do not now recollect. I be- 
 lieve it was for a year or two at least ', and I think they 
 had quite left me before I was fifteen. In those days, I 
 was much given to what Mr. Addison, in one of his Spec- 
 tators, calls castle-building; and in my evening solitary 
 walk, which was generally all the exercise I took, my 
 thoughts would hurry me into some active scene, where 
 I generally acquitted myself much to my own satisfaction j 
 and in these scenes of imagination I performed many a 
 gallant exploit. At the same time, in my dreams I fbund 
 myself the most arrant coward that ever was. Not only 
 my courage, but my strength, failed me in every danger ; 
 and I often rose from my bed in the morning in such a 
 panic, that it took some time to get the better of it. J 
 wished very much to get free of these uneasy dreams, 
 which not only made me unhappy in sleep, but often left 
 a disagreeable impression in my mind for some part of 
 the following d^y. I thought it was worth trying, wheth- 
 er it was possible to recollect that it was all a dream, and 
 that I was in no real danger. I often went to sleep with 
 my mind as strongly impressed as I could with this thought, 
 
 vol. I. 11 
 
82 ACCOUNT OP THE IIEE 
 
 that I never in my life time was in any real danger, and 
 that every fright I had was a dream. After many fruit- 
 less endeavours to reeoMect this when the danger appear- 
 ed, I effected it at last, and have often, when I was slid- 
 ing over a precipice into the abyss, recollected that it was 
 all a dream, and boldly jumped down. The efiect of this 
 commonly was, that I immediately awoke. But I awoke 
 calm and intrepid, which I thought a great acquisition. 
 After this, my dreams were never very nneasy; and, in 
 a short time, I dreamed not at all. 
 
 " During all this time I was in perfect health ; but 
 whether my ceasing to dream was the effect of the recol- 
 lection above mentioned, or of any change in the habit of 
 my body, which is usual about that period of life, I can- 
 not tell. I think it may more probably be imputed to the 
 last. However, the fact was, that, for at least forty 
 years after, I dreamed none, to the best of my remem- 
 brance : and finding, from the testimony of others, that 
 this is somewhat uncommon. I have often, as soon as I 
 awoke, endeavoured to recollect, without being able to 
 recollect, any thing that passed in my sleep. For some 
 years past, I can sometimes recollect some kind of dream- 
 ing thoughts, but so incoherent that I can make nothing 
 of them. 
 
 " The only distinct dreaii I ever had since I was about 
 sixteen, as far as T remember, was about two years ago. 
 I had got my head blistered for a fall. A plaster which 
 was put upon it after the blister, pained me excessively 
 for a whole night. In the morning; I slept a little, and 
 dreamed very distinctly, that I had fallen into the hands 
 of a party of Indians, and was scalped. 
 
 " I am apt to think, that as there is a state of sleep, and 
 a state wherein we are awake, so there is an intermediate 
 state, which partakes of the other two. If a man per- 
 emptorily resolves to rise at an early hour for some 
 interesting purpose, he will of himself awake at that 
 hour. A sick-nurse gets the habit of sleeping in such a 
 manner that she hears the least whisper of the sick per- 
 
AND WRITINGS or DII.BEID. 83 
 
 «on, and yet is refreshed by this kind of half sleep. The 
 same is the case of a nurse who sleeps with a child in her 
 arms. I have slept on horseback, but so as to preserve 
 my balance j and if the horse stumbled, I could make the 
 exertion necessary for saving me from a fall, as if 1 was 
 awake. 
 
 , "I hope the sciences at your^ood university are not 
 in this state. Yet, from so many learned men, so much 
 at their ease, one would expect something more than we 
 hear of." 
 
 Fop the other letter, I am indebted to one of Dr. Reid's 
 most intimate friends, to whom it was addressed, in the 
 year 1784, on occasion of the melancholy event to which 
 it alludes. 
 
 ** I sympathize with you ve^-y sincerely in the loss of 
 a most amiable wife. I judge of your feelings by the 
 impression she made upon my own heart, on a very short 
 acquaintance. But all the blessings of this world ar.e 
 transient and uncertain ; and it would be but a melan- 
 chply scene, if there were no prospect of another. 
 
 " I have often had occasion to admire the resignation 
 and fortitude of young persons, even of the weaker sex, 
 in the views of death, when their imagination is filled 
 with all the gay prospects wbich the world presents at 
 that period. I have been witness to instances of this 
 
 kind, which I thought truly heroic, and I hear Mrs. G 
 
 gave a remarkable one. 
 
 '* To see the soul increase in vigour and wisdom, and 
 in every amiable quality, when health and strength and 
 animal spirits decay; when it is to be torn by violence 
 from all that filled the imagination, and flattered hope, is 
 a spectacle truly grand, and instructive to the surviving. 
 ,Tq thiqk, that the soul perishes in that fatal moment, 
 wjien it is purified by this fiery trial, and fitted for the 
 noblest exertions in another state, is an opinion which I 
 cannot help looking down upon with contempt and dis- 
 dain. 
 
si ACCOriTT or THE IITE 
 
 « In old people, there is no more merit in leaving this 
 world with perfect acquiescence, than in rising from a 
 feast after one is fall. When I hate before me the pros- 
 pect of the infirmities, the distresses and the peevishness 
 of old age, and when I have already received more than 
 my share of the good things of this life, it would be ridic- 
 ulous indeed to be anxious about prolonging it; but when 
 1 was four and twenty, to have had no anxiety for its con- 
 tinuance, would, I think, have required a noble effort. 
 Such efforts in those that are called to make them, surely 
 shall not lose their reward." 
 
 *jfr ^ •» j& 
 "W "A* If tf 
 
 I HAVE now finished all that the limits of my plan per- 
 mit me to offer here, as a tribute to the memory of this 
 excellent person. In the details which I have stated, 
 both with respect to his private life and his scientific pur- 
 suits, I have dwelt chiefly on such circumstances as ap- 
 peared to me most likely to interest the readers of his 
 Works, by illustrating his character as a man, and his 
 Views as an aiithor. Of his merits as an instructor of 
 youth, I have said but little ; partly from a wish to avoid 
 unnecessary diffuseness ; but chiefly from my anxiety to 
 enlarge on those still more impdrtant labours, of which 
 he has beqneathed the fruits to future ages. And yet 
 hard he left no such monument to perpetuate his name, 
 the fidelity and zeal with which he discharged, during so 
 Jotig a period, the obscure but momentous duties of his 
 official station, woiild, in the judgment of the wise arid 
 good, have ranked him in the first order Of useful citizens. 
 " Nee enim is solus reipublicse prodest,'qui eandidatos ex- 
 trahit, et tuetur reos, et de pace belloque censet ; sed qui ju- 
 ventutem fexhortatur; qui,intantabonorumpr8eeeptorum 
 inopia, virtute instruit animos; qui, iad pecuniam luxuHam- 
 que eursu ruentes prensat ac retrahit, et, si nihil alind, 
 eerte moratur : In private, 'publicum negotium agit."* 
 
 * Seneea, De Tranquil!. An. Cap. 3. 
 
AND WRITINGS OV DR. REID. 85 
 
 In concluding this memoir, I trust I shall be pardoned, 
 if, for once, I give way to a personal feeling, while I ex- 
 press the satisfaction with which I now close finally, my 
 attempts as a biographer. Those which I have already 
 made, were imposed on me by the irresistible calls of 
 duty and attachment ; and, feeble as they are, when com- 
 pared with the magnitude of subjects, so splendid and so 
 various, they have encroached deeply on that small por- 
 tion of literary leisure which indispensable engagements 
 allow me to command. I cannot, at the same time, be 
 insensible to the gratification of having endeavoured to 
 associate, in some degree, my name with three of the 
 greatest whicli have adorned this age ; happy, if without 
 deviating intentionally from truth, I may have succeeded, 
 however imperfectly, in my wish, to gratify, at once, the 
 curiosity of the public, and to sooth the recollections of 
 surviving friends. But I, too, Iiave designs and enter- 
 prises of my own ; and the execution of these, which 
 alas ! swell in magnitude, as the time fop their accom- 
 plishment hastens to a period, claims at length, an undi- 
 vided attention. Yet I should not look back on the past 
 with regret, if I could indulge the hope, that the facts 
 which it has been my province to record, by displaying 
 those fair rewards of extensive usefulness, and of perma- 
 nent fame, which talents and industry, when worthily di- 
 rected, cannot fail to secure, may contribute, in one sin- 
 gle instance, to foster the proud and virtuous independ- 
 ence of genius ; or, amidst the gloom of poverty and sol- 
 itude, to gild the distant prospect of the unfriended schol- 
 ar, wHpse laurels are now slowly ripening in the unnoticed 
 privacy of bumble life. 
 
NOTES 
 
 TO THE LIFE PRECEDING. 
 
 NOTE A, PAGE S. 
 
 An the account, given in the text, of Dr. Eeid's ancestors, 
 I have followed scrupulously the information contained 
 in his own memorandunis. I have some suspicion, how- 
 ever, that he has committed a mistake with respect to 
 the name of the translator of Buchanan's History; which 
 would appear, from the MS. in Glasgow college, to have 
 been, not Adam, but John. At the same time, as this 
 last statement rests on an authority altogether unknown, 
 being written in a hand different from the rest of the MS. 
 there is a possibility that Dr. Reid's account may be cor- 
 rect ; and, therefore, I have thought it advisable, in a 
 matter of so very trifling consequence, to adhere to it in 
 preference to the other. 
 
 The following particulars with respect to Thomas 
 Reid may, perhaps, be acceptable to some of my readers. 
 They are copied from Dempster, a contemporary writer; 
 whose details concerning his countrymen, it must, how- 
 ever, be confessed, are not always to be implicitly relied 
 on. 
 
 " Thomas Reidus Aberdonensis, pueritiee mese et in- 
 fantilis otii sub Thoma Cargillo collega, Lovanii literas 
 in schola Lipsii serio didicit, quas magno nomine in Ger- 
 mania docuit, earns Frincipibus. Londini din in comita- 
 tu humanissimi ac clarissimi viri, Fulconis Grevilli, Re- 
 git Consiliarii Interioris et Anglise Proqusestoris, egit : 
 turn ad amieitiam Regis, eodem Fulcone deducente, 
 evectus> inter Palatinos admissus, a Uteris Latinis Regi 
 
88 ACCOUNT OF THE IIFK 
 
 fuit. Seripsit multa, ut est magna indole et varia eru- 
 ditione," &c. «' Ex aula se, nemine conscio, nuper pro- 
 ripuit, dum illi omnia festinati honoris augmenta singuli 
 ominarentur, nee quid deinde egerit aut quo loeorum se 
 contulerit qui squam indicare potuit. Multi suspicaban- 
 tur, teedio aulaj affectum, monasticse quieti seipsum tra- 
 didisse, sub annum 1618. Rumor postea fuit in aulam 
 rediisse, et meritissimis honoribus redditum, sed nunquam 
 id eonsequetur quod virtus promeretur." Hist. Ecclesi- 
 astiea Gentis Seotorum, lib. xvi. p. 676. 
 
 What was the judgment of Thomas Reid's own times 
 with respect to his genius, and what their hopes of his 
 posthumous fame, may be collected from an elegy on his 
 death by his learned countryman Robert Aytoun. Al- 
 ready, before the lapse of two hundred years, some apol- 
 ogy, alas ! may be thought necessary for an attempt to 
 rescue his name from total oblivion. 
 
 Aytoun's elegy on Reid is referred to in terms very 
 flattering both to its author and to its subject, by the ed- 
 itor of the collection, entitled. "Poetarum Seotorum 
 Musse Sacrffi." « In obitum Thomse Rheidi epicedium 
 extat elegantissimum Roberti Aytoni, viri literis ac dig- 
 nitate clarissimi, in Deliciis Poetarum Seotorum, ubi et 
 ipsius quoque poemata, paucula quidem ilia, sed venusta, 
 sed elegantia, eomparent." 
 
 The only works of Alexander Reid of which T have 
 heard, are Chirurgical Lectures on Tumors and Ulcers, 
 London, 1635 ; and a Treatise of the First Part of Chi- 
 rurgerie, London, 1638. He appears to have been the 
 physician and friend of the celebrated mathematician 
 Thomas Harriot, of whose interesting history so little 
 was known, till the recent discovery of his manuscripts, 
 by Mr. Zaeh of Saxe-Gotha. 
 
 A remarkable instance of the careless or capricious 
 orthography formerly so common in writing proper names, 
 occurs in the different individuals to whom this note re- 
 fers. Sometimes the family name is written, Reid j on 
 other occasions, Riede, Read, Rhead, or Rhaid. 
 
AND WRITINGS or OR. KEID. 89 
 
 NOTE B, PAGE 6. 
 
 t)r. TumbuU's work on Moral Philosophy was publish* 
 ed in London, in 1740. As I have only turned over a 
 few pages, I cannot say any thing with respect to its 
 merits. The mottos on the title pagfc are curious, when 
 considered in connection with those inquiries which his 
 pupil afterward prosecuted with so much success j and 
 may, perhaps without his perceiving it, have had some 
 effect in suggesting to him that plan of philosophizing 
 which he so systematically and so happily pursued. 
 
 " If natural philosophy, in all its parts, by pursuing 
 this method, shall at length be perfected, the bounds of 
 moral philosophy \^ill also be enlarged." 
 
 Newton's Optics. 
 
 "Account for moral as for tiatural things." Pope. 
 
 Fop the opinion of a very competent judge with respect 
 to the merits of the Treatise on Ancient Painting, vide 
 Hogarth's print, entitled, Beer-Lane. 
 
 NOTE C, PAGE 32i 
 
 " Dr. Moop combined," &c.] James Moor, LL.D. au- 
 thor of a very ingenious fragment on Greek grammar, 
 and of other philological essays. He was also distinguish'- 
 ed by a profound acquaintance with ancient geometry. 
 Dr. Simson, an excellent judge of his merits both in lit- 
 erature and science, has somewhere honoured him with 
 the following encomium : " Turn in Mathesi, turn in Gras- 
 cis Uteris multum et feliciter versatus." 
 
 " The Wilsons, both father and son," &c.l Alexander 
 Wilson, M.D. and Patrick Wilson, Esq. well known over 
 Europe by their Observations on the Solar Spots ,• and 
 many other valuable memoirs. 
 
 NOTE D, PAGE 47< 
 
 A writer of great talents, after having reproached Dr. 
 Reid with " a gross ignorance, disgraceful to the univer-' 
 sity of which he was a member," boasts of the trifling 
 expense of time and thought which it had cost himself to 
 
 vol,. I. 12 
 
90 ACCOUNT OF THE IIPE 
 
 avertunt his philosophy. " Dr. Oswald is pleased to pay 
 me a compliment in saying, that " I might employ myself 
 to more advantage to the public, by pursuing other 
 branches of science, than by deciding rashly on a subject 
 which he sees I have not studied." In return to this com- 
 pliment, I shall not affront him, by telling him how very 
 little of my time this business has hitherto taken up. If 
 he alludes to my experiments, I can assure him, that I 
 have lost no time at all ; for having been intent upon such 
 as require the use of a burning lens, I believe I have not 
 lost one hour of sunshine on this account. And the public 
 may perhaps be informed, some time or other, of what I 
 have been doing in the sun, as well as in the shade." 
 Examination of Reid's Inquiry, &c. p. 357. See also pp. 
 101, 102. of the same work. 
 
 NOTE E, PAGE 64. 
 
 The following strictures on Dr. Priestley's Examina- 
 tion, &c. are copied from a very judicious note in Dr. 
 Campbell's Philosophy of Rhetoric, vol. i. p. 111. 
 
 "I shall only subjoin two remarks on this book. The 
 first is, that the author, through the whole, confounds 
 two things totally distinct, certain associations of ideas, 
 and certain judgments implying belief, which, though in 
 some, are not in all cases, and therefore not necessarily 
 connected with association. And if so, merely to account 
 for the association, is in no case to account for the belief 
 with which it is attended. Nay, admitting his plea, p. 86, 
 that by the principle of association, not only the ideas, but 
 the concomitant belief may be accounted for, even this 
 does not invalidate the doctrine he impugns. Far, let it 
 be observed, that it is one thing to assign a cause, which, 
 from the mechanism of our nature, has given rise to a 
 particular tenet of belief, and another thing to produce a 
 reason by which the understanding has been convinced. 
 Now, unless this be done as to the principles in question, 
 they must be considered as primary truths in respect of 
 the understanding, which never deduced them from other 
 
AND WHITINGS OF DR. KEIl). 91 
 
 truths, and which is under a necessity, in all her moral 
 reasonings, of founding upon them. In fact, to give any 
 other account of our conviction of them, is to confirm, in- 
 stead of confuting the doctrine, that in all argumentation 
 they must be regarded as primary truths, or truths wliich 
 reason never inferred through any medium, from other 
 truths previously perceived. My second remark is, that 
 though this examiner has, from Dr. lieid, given us a cata- 
 logue of first principles, which he deems unworthy of the 
 honourable place assigned them, he has no where thought 
 proper to give us a list of those self-evident truths, which^ 
 by his own account, and in his own express words, ' must 
 be assumed as the foundation of all our reasoning.' How 
 much light might have been thrown upon the subject by 
 the contrast ! Perhaps we should have been enabled, on 
 the eomparison, to discover some distinctive characters 
 in his genuine axioms, which would have preserved us 
 from the danger of confounding them with their spurious 
 ones. [Nothing is more evident than that, in whatever 
 regards matter of fact, the mathematical axioms will not 
 answer. These are purely fitted for evolving the abstract 
 relations of quantity. This he in effect owns himself, p. 
 39. It would have been obliging, then, and would have 
 greatly contributed to shorten the controversy, if he had 
 given us, at least, a specimen of those self-evident prin- 
 ciples, which, in his estimation, are the non plus ultra of 
 moral reasoning." 
 
 NOTE F, PAGE 75. 
 
 Dr. Reid's father, the Reverend Lewis Reid, married, 
 for his second wife, i Janet, daughter of Mr. Fraser of 
 Phopachy, in the county of Inverness, A daughter of 
 this marriage is still alive ; the wife of the Reverehd Al- 
 exaniler Leslie, and the mother of the Reverend James 
 Leslie, ministers of Fordoun. To the latter of these gen- 
 tlemen, I am indebted for the greater part of the infor- 
 mation I have been able to collect with respect to Dr. 
 Beid, previous to his removal to Glasgow ; Mr. Leslie's 
 
93 ACCOUNT OF THE IIFB 
 
 regard for the memory of his uncle having prompted him, 
 not only to transmit to me such particulars as had fallen 
 under his own knowledge, hut some valuable letters on 
 the same subject, which he procured from his relations 
 and friends in the north. 
 
 For all the members of this most respectable family. 
 Dr. Reid entertained the strongest sentiments of affection 
 and regard. During several years before his death a 
 daughter of Mrs. Leslie's, was a constant inmate of his 
 house, and added much to the happiness of his small do- 
 mestic circle. 
 
 Another daughter of Mr. Lewis Reid was married to 
 the Reverend John Rose, minister of Udny. She died in 
 1793. In this connection, Dr. Reid was no less fortunate 
 than in the former ; and to Mr. Rose I am indebted for 
 favours of tlie same kind with those which I have already 
 acknowledged from Mr. Leslie. 
 
 The widow of Mr. Lewis Reid died in 1798, in the 
 eighty-sevent h year of her age ; having survived hec step- 
 son, Dr. Reid, more than a year. 
 
 The limits within which I was obliged to confine my 
 biographical details, prevented me from availing myself 
 of many interesting circumstances which were communi- 
 cated to me through the authentic channels which I have 
 now mentioned. But I cannot omit this opportunity of 
 yeturning to my different correspondents, my warmest 
 acknowledgments for the pleasure and instruction which 
 I received from their letters. 
 
 Mr. Jardine, also, the learned professor of logic in the 
 university of Glasgow, a gentleman, who, for many years,' 
 lived in habits of tlie most confidential intimacy with Dr. 
 Reid and his family, is entitled to my best thanks for his 
 obliging attention to various queries, which I took the 
 liberty to propose to him, concerning the history of our 
 common friend. 
 
BRIEF ACCOUNT 
 
 AMSTOTIiE'S X.OC-IC, 
 
 REMARKS, 
 
 THOMAS REIB, D.D. F.R.S. 
 
/ fOr>' : 1 
 
 I ..•/lacKf a'.K:j-it>':rai:r 
 
 ;■. ■•.v,*'.av\- 
 
A 
 
 BRIEF ACCOUNT 
 
 OP 
 
 ARISTOTLE'S LOGIC 
 
 AVITH REMARKS. 
 
 CHAPTER I. 
 
 OF THE FIRST THREE TREATISES. 
 SECT. I OF THE AUTHOK. 
 
 Aristotle had very uncommon advantages : born in 
 an age when the philosophical spirit in Greece had long 
 ilourished, and was in its greatest vigour; brought up in 
 the court of Macedon, where his father was the king's 
 physician ; twenty years a favourite scholar of PlatOj and 
 tutor to Alexander the Great ; who both honoured him 
 with bis friendship, and supplied him with every thing 
 necessary for the prosecution of his inquiries. 
 
 These advantages he improved by indefatigable study, 
 and immense reading. He was the first we know, says 
 Strabo, who composed a library. And in this the Egyp- 
 tian and Pergamenian kings, copied his example. As to 
 his genius, it would be disrespectful to mankind, not to 
 allow an uncommon share to a man who governed the 
 opinions of the most enlightened part of the species near 
 two thousand years. 
 
 If his talents had been laid out solely for the discovery 
 of truth, and the good of mankind, bis laurels would have 
 remained for ever fresh; but he seems to have had a 
 
96 A BHIEF ACCOUNT OF 
 
 greater passion for fame than for truth, and to have want- 
 ed rather to be admired as the prince of philosophers, 
 than to be useful : so that it is dubious >¥hether there be 
 in his character most of the philosopher, or of the soph- 
 ist. The opinion of lord Bacon is not without probabil- 
 ity, that his ambition was as boundless as that of his 
 royal pupil, the one aspiring at universal monarchy over 
 the bodies, and fortunes of men, the other over their opin- 
 ions. If this was the case, it cannot be said, that the 
 philosopher pursued his aim with less industry, less abil- 
 ity, or less success, than the hero. 
 
 His writings carry too evident marks of that philo- 
 sophical pride, vanity, and envy, which have often sullied 
 the character of the learned. He determines boldly things 
 above all human knowledge ; and enters upon the most 
 difficult questions, as his pupil entered on a battle, with 
 full assurance of success. He delivers his decisions 
 oracularly, and without any fear of mistake. Rather 
 than confess his ignorance, he hides it under hard words 
 and ambiguous expressions, of which his interpreters can 
 make what pleases them. There is even reason to sus- 
 pect, that he wrote often with affected obscurity, either 
 that the air of mystery might procure greater veneration, 
 or that his books might be understood only by the adepts 
 who had been initiated in his philosophy. 
 
 His conduct toward the writers that went before him 
 has been much censured. After the manner of the Ot- 
 toman princes, says lord Verulam, he thought his throne 
 could not be secure unless he killed all his brethren. Lu- 
 dovicus Vives charges him with detracting from all phi- 
 losophers, that he might derive that glory to himself, of 
 'which he robbed them. He rarely quotes an author but 
 with a view to censure, and is not very fair in represent- 
 ing the opinions which he censures. 
 
 The faults we have mentioned, are such as might be 
 expected in a man, who had the daring ambition to be 
 transmitted to all future ages, as the prince of philoso- 
 phers, as one who had carried every branch of human 
 
abistotlb's xoqto» 97 
 
 knowledge to its utmost limit ; and who was not very 
 scrupulous about (he means he took to obtain his end. 
 
 We ought, however, to do him the justice to observe, 
 that although the pride and vanity of the sophist appear 
 too much in his writings in abstract philosopliy, yet in 
 natural history the fidelity of his narration seems to he 
 equal to his industry ; and he always distinguishes be- 
 tween what he knew and what he had by report. And 
 even in abstract philosophy, it would be unfair to impute 
 to Aristotle all the faults, all the obscurities, and all the 
 contradictions that are to be found in his wntings. The 
 greatest part, and perhaps the best part of his writings is 
 lost. There is reason to doubt whether some of those 
 we ascribe to him be really his; and whether what are 
 his be not much vitiated and interpolated. These sus- 
 picions are justilied by the fate of Aristotle's writings, 
 which is judiciously related, from the best authorities, in 
 Bayle's Dictionary, under the article Tyraiinion, to which 
 I refer. 
 
 His books in logic which remain, are, 1. One book of 
 the Categories. 2. One of Interpretation. 3. First An- 
 alytics, two books. 4. Last Analytics, two books. 5. 
 Topics, eight books. 6. Of Sophisms, one book. Diog- 
 enes Laertius mentions many others that are lost. Those 
 I have mentioned have commonly been published together, 
 under the name. Aristotle's Organon. or hisy. Logic; and 
 for many ages. Porphyry's Introduction to the Categories 
 has been prefixed to them. 
 
 SECTION II. 
 OF PORPHTRT's INTRODtrCTIOTr* I 
 
 In this Introduction, which is addressed to Chrysoari- 
 us, the author observes, that in order to understand Ar- 
 istotle's doctrine concerning the categories, it is neces- 
 sary to know what a. genus isj what a species, what sf£< 
 
 TOIi. I. 13 
 
98 A BRIEF ACCOUNT OF 
 
 cific difference, what a property, and wbat an accident ; 
 that the knowledge of these is also very useful in defi- 
 nition, in division, and even in demonstration : therefore 
 he proposes, in this little tract, to deliver shortly and 
 simply the doctrines of the ancients, and chiefly of the 
 Peripatetics, concerning these five predicahles; avoiding 
 the more intricate questions concerning them ; such as, 
 whether genera and species do really exist in nature ? or, 
 whether they are only conceptions of the human mind ? 
 If they exist in nature, whether they are corporeal or in- 
 corporeal ? and whether they are inherent in the objects 
 of sense, or disjointed from them ? These, he says, are 
 very difficult questions, and require accurate discussion ; 
 but that he is not to meddle with them. 
 
 After this preface, he explains very minutely each of 
 the five words above mentioned, divides and subdivides 
 each of them, and then pursues all the agreements and 
 differences between one and another through sixteen 
 chapters. 
 
 SECTION III. 
 OF THE CATEGORIES. 
 
 The book begins with an explication of what is meant 
 by univocaU words, what by equivocal, and what by de- 
 nominative. Then it is observed, that what we say is 
 either simple, without composition or structure, as man, 
 horse; or it has composition and structure, as a manjights, 
 the horse runs. Next comes a distinction between a sub- 
 ject of predication ; that is, a subject of which any thing 
 is affirmed or denied, and a subject of inhesion. These 
 things are said to be inherent in a subject, which although 
 they are not part of a subject, cannot possibly exist 
 ■without it, as figure in the thing figured. Of things that 
 are, says Aristotle, some may be predicated of a subject^ 
 but are in no subject ; as man may be predicated of James 
 or John, but it is not in any subject. Some agaia are in 
 
AKISTOTXE'g lOGIC. 99 
 
 a subject, but can be predicated of no subject. Thus, my 
 knowledge in grammar is in me as its subject, but it can 
 be predicated of no subject ; because it is an individual 
 thing. Some are both in a subject, and may be predi- 
 cated of a subject, as science ; which is in the mind as its 
 subject, and may be predicated of geometry. Lastly, 
 some things can neither be in a subject, nor be predicated 
 of any subject. Such are all individual substances, which 
 cannot be predicated, because they are individuals j and 
 cannot be in a subject, because they are substances. Af- 
 ter some other subtilties about predicates and subjects, ! 
 we come to the categories themselves ; the things above 
 mentioned being called by the schoolmen the anteprcedi- 
 camenta. It may be observed, however, that notwith- 
 standing the distinction now explained, the being in a sub- 
 ject, and the being predicated truly of a subject, are in the 
 Analytics used as synonymous phrases ; and this varia- 
 tion of style has led some persons to think that the Cat- 
 egories were not written by Aristotle. 
 
 Things which may be expressed without composition 
 OP structure, are, says the author, reducible to the follow- 
 ing heads. They are either substance, or quantity, or 
 quality, or relqfives, or place, or time, or having, or doing, 
 or suffering. These are the predicaments or categories. 
 The first four are largely treated of in four chapters ; the 
 others are slightly passed over, as sufficiently clear of 
 themselves. As a specimen, I shall give a summary of 
 what he says on the category of substance. 
 
 Substances are either primary, to wit, individual sub- 
 stances, or secondary, to wit, the genera and species of 
 substances. Primary substances neither are in a sub- 
 ject, nor can be predicated of a subject ; but all other 
 things that exist, either in primary substances, or may 
 be predicated of them. For whatever can be predicated 
 of that which is in a subject, may also be predicated of 
 the subject itself. Primary substances are more sub- 
 stances than the secondary ; and of the secondary, the 
 »peeies is more a substance than the genus. If there 
 were no primary, there could be no secondary substances. 
 
iOd A BRIEI' ACCOUNT OF 
 
 The properties of substance are these : 1. No substance 
 is (■ ipiibli orinfenlion or remission. 2. No substance can 
 be in anv other thing as ils subject of inhesion. 3. No 
 sub'iiance has a contrary : for one substance cannot be 
 contrary toanodier: nor can there be contrariety between 
 a subslance. avid that which is no substance. 4. The 
 most remarkable property of subslance, is. that one and 
 the same substance may, by some change in itself, become 
 the subject of things that are contrary. I'hus, the same 
 body may be a( one time hot, at anolher cold. 
 
 Let (liis serve as a specimen of Aristotle's manner of 
 treating ilie categories. Af(er ttiem, we liave some chap- 
 ters, which the schoolmen call postprwdicamenta ; where- 
 in, iirsi, (he four kinds of opposition of terms are explain- 
 ed ; to v/U, relative, privative, oT contrariety, and ot'contra- 
 diction. This is repeated of all systems of logic. Last of 
 all we have dit^tineiions of the four Greek words which 
 answer to the Latin ones, prius, simul, motus, and habere, 
 
 SECTION IV. 
 or THE BOOK CONCBEJVING IXTERPRETATIOKT. 
 
 We are to consider, says Aristotle, what a noun is, 
 vhat a verb, what affirmation, what negation, what speech, 
 "Words are the signs of what passeth in the mind; writ- 
 ing is the sign of words. The signs both of writing and 
 of words are different in difTerent nations, but the opera- 
 tions of mind signified bj them are the same. There aro 
 some operations of thought which are neither true nor 
 false. These are expressed by nouns or verbs singly, 
 and without composition. 
 
 A noun is a sound which by compact signifies some- 
 thing without respect to time, and of which no j)art has 
 signification by itself. The cries of beasts may have a 
 natural signification, but they are not nouns. We giv© 
 that name only to sounds which hctve their signification 
 
101 
 
 by compact. The cases of a noun, as the genitive, da- 
 tive, are not nouns. J^on homo is not a noun, but, for 
 distinction's sake, may be called a nomen injinitum, 
 
 A verb signifies something by conijiact with relation to 
 time. Thus, valet is a verb ; but valetudo is a noun, be- 
 cause its signiRculion has no relation to time, li ib only 
 the present tense of the indicative that is properlj called 
 a verb; tlie other tenses and mouds are variations of the 
 verb. JVon valet juay be called a ver'onm injinitum. 
 
 Speech is sound sigiiifu^ant b^ compact, of which some 
 part is also significant. And it is eidier enunciative, or 
 not enunciative. Enunciative speech is that which affirms 
 or denies. As to speedi which is not enunciative, such 
 as a prayer or wish, the consideradon of it belongs to 
 oratory or poetry. Every enunciative speech must have 
 a verb, or some variation of a verb. Affirmation is the 
 enunciation of one thing concerning another. Negatiou 
 is the enunciation of one thing from another. Contra- 
 diction is an affirmation and negation that are opposite. 
 This is a summary of the first six chapters. 
 
 The seventh and eighth treat of the various kinds of 
 enunciations or propositions, universal, particular, indef- 
 inite, and singular ; and of the various kinds of opposition 
 in propositions, and the axioms concerning them. These 
 things are repeated in every system of logic. In the ninth 
 chapter he endeavours to prove, by a long metaphysical 
 reasoning, that propositions respecting future contingen- 
 cies are not, dcterminately, eidier true or false ; and that 
 if they were, it would follow, that all things happen nec- 
 essarily, and could not have been otherwise than they are. 
 The remaining chapters contain many minute observations 
 coneeiaiing the equipollency of propositions both pure and 
 piodal. 
 
102 A BRIEF ACCOUNT OF 
 
 CHAPTER II. 
 
 REMARKS. 
 
 SECTION I. 
 OF THK FIVE PREDICABIES. 
 
 The writers on logic have borrowed their materials 
 almost enfirelj' from Aristotle's Organon, and Porphyry's 
 Introdticfion. The Organon however was not written by 
 Aristotle as one work. It comprehends various tracts, 
 written without the view of making them parts of one 
 whole, and afterward thrown together by his editors un- 
 der one name on account of their aiSnity. Many of his 
 books that are lost would have made a part of the Orga- 
 non, if they had been saved. 
 
 The three treatises of which we have given a brief ac- 
 count, are unconnected with each other, and with those 
 that follow. And although the iirst was undoubtedly 
 compiled by Porphyry, and the two last probably by Ar- 
 istotle, yet I consider them as the venerable remains of a 
 philosophy more ancient than Aristotle. Archytas of 
 Tarentum, an eminent mathematician and philosopher of 
 the Pythagorean school, is said to have writtea>upon the 
 ten categories. And the five predicables probably had their 
 origin in the same school. Aristotle, though abundantly 
 careful to do justice to himself, does not claim the inven- 
 tion of either. And Porphyry, without ascribing the lat- 
 ter to Aristotle, professes only to deliver the doctrine of 
 the ancients, and chiefly of the Peripatetics, concerning 
 them. 
 
 The writers on logic have divided that science into 
 three parts; the first treating of simple apprehension, 
 and of terms ; the second, of judgment, and of proposi- 
 tions ; and the third, of reasoning, and of syllogisms. 
 The materials of the first part are taken from Porphyry's 
 
akistotie's xogic, 103 
 
 Introduction, and the Categories : and those of the second 
 from the hook of Interpretation. 
 
 A predicable, according to the grammatical form of 
 the word, might seem to signify, whatever may be pred- 
 icated, that is, affirmed or denied, of some subject. And 
 in this sense every predicate would be a predicable. But 
 the logicians give a different meaning to the word. They 
 divide propositions into certain classes, according to tlie 
 relation which the predicate of the proposition bears to 
 the subject. The first class is that wherein the predi- 
 cate is the genus of the subject ; as when we say, this is 
 a triangle, Jupiter is a planet. In the second class, the 
 predicate is a species of the subject j as when we say, 
 this triangle is right-angled. A third class is when the 
 predicate is the specific difference of the subject ; as when 
 we say, every triangle has three sides and three angles. A 
 fourth when the predicate is a property of the subject ; 
 as when we say, the angles of evei'y triangle are equal to 
 two right angles. And a fifth class is when the predicate 
 is something accidental to the subject ; as when we say, 
 this triangle is neatly drawn. 
 
 Each of these classes comprehends a great variety of 
 propositions having different subjects, and different pred- 
 icates ; but in each class the relation between the predi- 
 cate and the subject is the same. Now it is to this rela- 
 tion that logicians have given the name of a predicable. 
 Hence it is, that although the number of predicates be 
 infinite, yet the number of predicables can be no greater 
 than that of the different relations wbich may be in prop- 
 ositions between the predicate and the subject. And if 
 all propositions belong to one or other of tbe five classes 
 above mentioned, there can be but five predicables, to 
 wit, genus, species, differentia, projmum, and accidens. 
 These might, with more propriety perhaps, have beea 
 called the Jtve classes of predicates; but use has deter- 
 Oiined them to be called the Jive predicables. / 
 
 It may also be observed, that as some objects of thought 
 are individuals, such as, Jtiiius Ctesar, the city Rome; 
 
104 A BHIEP ACCOUNT Ot 
 
 »o others are cotnino!! to many individuals, as gooA, great) 
 virtuous, vicions. Of (his lasl liiud are all tilings ex- 
 pressed by adjectives. Things commoii to many individ- 
 uals were by tine ancients called imiversals. All prcdi- 
 ca)es are univei-saK, ibr they aii have the nature of ad- 
 jectives; and, 1 the oilier hand, all universals may be 
 predicates. On this aecoun! universals may he divided 
 into the same classes as pi'cdir-ales.and as the five classes 
 of !»i e'licates above mentioned have been called tlie five 
 predicables, so by the same kind of phraseology they have 
 beea called the five unwevsals ; although they may more 
 propei'ly be culled thejirc classes irf uninersals. 
 
 The doctrine of the five universals or predicables makes 
 an essen<ial part of every system of logic, and has been 
 handed down without any change to this day. The very 
 name oY predicaldes shews, that (he author of this division, 
 •whoever he was, intended it as a complete enumeration 
 of all the kinds of things that can be affirmed of any sub- 
 ject ; and so it has always been understood. So that it 
 is implied in this division, that all that can be affirmed 
 of any thing whatsoever, is either the genus of the thing, 
 or its species, or its specific difference, or some property 
 or accident belonging to it. 
 
 Burgersdick, a very acute writer in logic, seems to have 
 been aware, that strong objections might be made to the 
 five predicables, considered as a complete enumeration; 
 but unwilling to allow any imperfection in this'ancient 
 division, he endeavours to restrain the meaning of the 
 word predicaUe, so as to obviate objections. Those things 
 only, says he, are to be accounted predicables, which may 
 be affirmed of many individuals, truly, properly, and im- 
 mediately. The consequence of putting such limitations 
 upon the word predicahle is. that in many propositions, 
 perhaps in most, the predicate is not a predicahle. But 
 admitting all his limitations, the enumeration will still 
 be very incomplete ; for of many things we may affirm, 
 truly, properly, and immediately, their existence, their 
 end, their cause, their effect, and various relations whieb 
 
ARISTOTIE'S KOGIC. 105 
 
 they bear to other things. These, and perhaps many 
 more, are predicables in the strict sense of the word, no 
 less than the five which have been so long famous. 
 
 Although Porphyry, and all subsequent writers, make 
 the predicables to be, in number, five ; yet Aristotle him- 
 self, in the beginning of the Topics, reduces them to four 5 
 and demonstrates, that they can be no more. We shall 
 give his demonstration when we come to the Topics; and 
 shall only here observe, that as Burgersdick justifies the 
 fivefold division, by restraining the meaning of the word 
 predicable; so Aristotle justifies the foiir-Pold division, by 
 enlarging the meaning of the words property and accident. 
 
 After all, I apprehend, that this ancient division of 
 predicables, with all its imperfections, will bear a com- 
 parison with those which have been sul)stituted in its stead 
 by the most celebrated modern philosopiiers. 
 
 Locke, in his Essay on the Human Understanding, 
 having laid it down as a principle, tiiat all our knowledge 
 consists in perceiving certain agreements and disagree- 
 ments between our ideas, reduces these agreements and 
 disagreements to four heads : to wit, 1. Identity and Di- 
 versity ; 2. Relation ; 3. Coexistence ; 4. Real Existence.* 
 Here are four predicables given as a complete enumera- 
 tion, and yet not one of the ancient predicables is includ* 
 ed iti the number. 
 
 The author of the Treatise of Human Nature, proceed- 
 ing on the same principle, that all our knowledge is only 
 a perception of the relations of our ideas, says, " that it 
 may perhaps be esteemed an endless task, to enumerate 
 all those qualities which admit of comparison, and by 
 which the ideas of philosophical relation are produced ; 
 but if we diligently consider them, we shall find, that 
 without diflSculty they may be comprised under seven 
 general heads: 1. Resemblance | 3. Identity; 3. Relations 
 of Space and Time; 4. Relations of Quantity and Num- 
 ber ; 5. Degrees of Quality ; 6. Contrariety ; 7. Causa- 
 tion."t Here again are seven predicables given as a com- 
 
 • Book IT. chap. 1. f Vol. i. p. 33, and 125. 
 
 TOX. I. 14 
 
lOS A, BRIEF ACCOUNT OF 
 
 pletc enumeration, wherein all the predieables of the ad- 
 cients, as well as two of Locke's, are left out. 
 
 The ancients in their division attended only to categor- 
 ical propositions which have one subject and one predicate ; 
 and of these, only to such as have a general term for their 
 subject. The moderns, by their definition of knowledge, 
 have been led to attend only to relative propositions, which 
 express a relation between two subjects, and those sub- 
 jects they suppose to be always ideas. 
 
 SECTION II. 
 
 ON THE TEN CATEGORIES, AND ON DIVISIONS IN 
 GENERAL 
 
 The intention of the. categories or predicaments is, to 
 muster every object of human apprehension under ten 
 heads : for the categories are given as a complete enu- 
 meration of every thing which can be expressed without 
 composition and structure; that is, of every thing which 
 can be either the subject or the predicate of a proposition. 
 So that as every soldier belongs to some company, and 
 every company to some regiment ; in like manner every 
 thing that can be the object of human thought, has its 
 place in one or other of the ten categories ; and by 
 dividing and subdividing properly the several categories, 
 all the notions that enter into the human mind maybe 
 mustered in rank and file, like an army in the day of 
 battle. 
 
 The perfection of the division of categories into ten 
 heads, has been strenuously defended by the followers of 
 Aristotle, as well as that of the five predieables. They 
 are indeed of kin to each other. They breathe the same 
 spirit, and probably had the same origin. By the one we 
 are taught to marshal every term that can enter into a 
 proposition, either as subject or predicate ; and by the 
 other, we are taught all the possible relations which the 
 
aristotie's xogic. 107 
 
 subject can have to the predicate. Thus, the whole fur- 
 niture of the human mind is presented to us at one view, 
 and contracted as it were, into a nutshell. To attempt, 
 in so early a period, a methodical delineation of the vast 
 region of human knowledge, actual and possible, and to 
 point out the limits of every district, was indeed magnan- 
 imous in a high degree, and deserves our admiration, 
 while we lament that the human powers are unequal to 
 so bold a flight. 
 
 A regular distribution of things under proper classes 
 or heads, is without doubt a great help both to memory 
 and judgment. And as the philosopher's province in- 
 cludes all things human and divine that can be objects of 
 inquiry, he is naturally led to attempt some general di- 
 vision, like that of the categories. And the invention of 
 a division of this kind, which the specul£|tive part of man- 
 kind acquiesced in for two thousand years, marks a supe- 
 riority of genius in the inventor, whoever he was. Nor 
 does it appear, that the general divisions which, since the 
 decline of the Peripatetic philosophy, have been substi- 
 tuted in place of the ten categories, are more perfect. 
 
 Locke has reduced all things to three categories j to 
 wit, substances, modes, and relations. In this division, 
 time, space, and number, three great objects of human 
 tliought, are omitted. 
 
 The author of the Treatise of Human Nature has re- 
 duced sfll things to two categories ; to wit, ideas, and im- 
 pressions : a division which is very well adapted to his 
 system ; and which puts me in mind of another made by 
 an excellent mathematician in a printed thesis I have seen. 
 In it the author, after a severe censure of the ten cate- 
 gories of the Peripatetics, maintains, that there neither 
 are nor can be more than two categories of things ; to 
 wit, data, and qucesita. 
 
 There are two ends that may be proposed by such di- 
 visions. The first is, to methodise or digest in order what 
 a man actually knows. This is neither unimportant nor 
 impracticable j and in proportion to the solidity and 
 
108 A BRIEF ACCOUNT 01' 
 
 accuracy of a inaii'sjuclgment, his divisions of things which 
 he knows, will be elegant and useful. The same subject 
 may admit, and even require, various divisions, according 
 to the differenf points of view from which we contemplate 
 it: nor does it follow, that because one division is good, 
 therefore another is naught. To be acquainted with the 
 divisions of the logicians and metaphysicians, without a 
 superstiiious attachment to them, maybe of use in divid- 
 ing the same subjects, or even those of a different nature. 
 Tiius, Quintilian borrows from the ten categories his di- 
 vision of the topics of rhetorical argumentation Of all 
 methods of arrangement the most antiphilosophical seems 
 to be the invention of this age ; I mean, the arranging 
 the arts and sciences by the letters of the alphabet, in 
 dictionaries and encyclopedies. With these authors the 
 categories are, A, B, C, &c. 
 
 Another end commonly proposed by such divisions, but 
 very rarely attained, is, to exhaust the subject divided; 
 so that nothing that belongs to it shall be omitted. It is 
 one of the generalrulesof division in all systems of logic, 
 that the division should be adequate to the subject divid- 
 ed : a good rule, without doubt ; but very often beyond 
 the reach of human power. To make a perfect division, 
 a man must have a perfect comprehension of the whole 
 subject at one view. When our knowledge of the subject 
 is imperfect, any division we can make of it, must be like 
 the first sketch of a painter, to he extended, eonfracted, 
 or mended, as the subject shall be found to require. Yet 
 nothing is more common, not only among the ancient, but 
 even among modern philosophers, than to draw from 
 their incomplete divisions, conclusions which suppose 
 them to be perfect. 
 
 A division is a repository which the philosopher frames 
 for holding his ware in convenient order. The philoso- 
 pher maintains, that such or such a thing is not good ware, 
 because there is no place in his ware room that fits it. 
 "We are apt to yield to this argument in philosophy, but 
 it would appear ridiculous in any other traffic. 
 
akistotie's logic. 109 
 
 Peter Ramus, who had the spirit of a reformer in phi- 
 losophy, and who bad a force of genius sufBcientto shalie 
 the Aristotelian fabric in many parts, but insufficient to 
 erect any thing more solid in its place, tried to remedy 
 the imperfection of philosophical divisions, by introducing 
 a new manner of dividing. His divisions always consisted 
 of two members, one of which was contradictory of the 
 other ; as if one should divide England into Middlesex and 
 what is not Middlesex. It is evident that these two mem- 
 bers comprehend all England : for the logicians observe, 
 that a term, along with its contradictory, comprehend 
 all things. In the same manner we may divide what is 
 not Middlesex into Kent, and what is not Kent. Thus 
 one may go on by divisions and subdivisions that are ab- 
 solutely complete. This example may serve to give an 
 idea of the spirit of Bamean divisions, which were in no 
 small reputation about two hundred years ago. 
 
 Aristotle was not ignorant of this kind of division. But 
 he used it only as a touchstone to prove by induction the 
 perfection of some other division, whieh indeed is the best 
 use that can be made of it ; when applied to the common 
 purpose of division, it is both inelegant, and burdensome to 
 the memory ; and, after it has put one out of breatli by 
 endless subdivisions, there is still a negative term left be- 
 hind, whieh shows that you are no nearer the end of your 
 journey than when you began. 
 
 Until some more effectual remedy be found for the im- 
 perfection of divisions, I beg leave to propose one more 
 simple than that of Ramus. It is this : when you meet 
 with a division of any subject imperfectly comprehended,; 
 add to the last member an etccetera. That this et cwteraf, 
 makes the division complete, is undeniable ; and thereford 
 it ought to hold its place as a member, and to be alway^. 
 understood, whether expressed or not, until clear and 
 positive proof be brought that the division is complete 
 without it. And this same et ccetera shall be the reposi-, 
 tory of all members that shall in any future time shew a 
 good and valid right to a property in the subject. 
 
lie X BRIEF ACCOUNT OF 
 
 SECTION iir. 
 
 OW DTSTINCTIOWS. 
 
 Having said so muehof logical divisions, we shall next 
 make some remarks upon distinctions. 
 
 Since the philosophy of Aristotle fell into disrepute, it 
 has been a common topic of wit and raillery, to inveigh 
 against metaphysical distinctions. Indeed the abuse of 
 them in the scholastic ages, seems to justify a general 
 prejudice against them : and shallow thinkers and writ- 
 ers have good reason to be jealous of distinctions, because 
 they make sad work when applied to their flimsy compo- 
 sitions. But every man of true judgment, while he con- 
 demns distinctions that have no foundation in the nature 
 of things, must perceive, that indiscriminately to decry 
 distinctions, is, to renounce all pretensions to just reason- 
 ing; for as false reasoning commonly proceeds from con- 
 founding things that are different, so without distinguish- 
 ing such things, it is impossible to avoid error, or detect 
 sophistry. The authority of Aquinas, or Suarez, or even 
 of Aristotle, can neither stamp a real value upon distinc- 
 tions of base metal, nor ought it to hinder the currency of 
 those that have intrinsic value. 
 
 Some distinctions are verbal, others are real. The first 
 kind distinguish the various meanings of a word ; some 
 of which may be proper, others metaphorical. Distinc- 
 tions of this kind make a part of the grammar of a lan- 
 guage, and are often absurd when translated into another 
 language. Real distinctions are equally good in all lan- 
 guages, and suffer no hurt by translation. They distin- 
 guish the different species contained under some general 
 notion, or the different parts contained in one whole. 
 
 Many of Aristotle's distinctions are verbal merely j 
 and therefore more proper materials for a dictionary of 
 the Greek language than for a philosophical treatise. At 
 least they ought never to have been translated into other 
 
AKISTOTIE's lOGIC. Ill 
 
 languages, when the idiom of the language will not jus- 
 tify them: for this is to adulterate the language, to in" 
 troduce foreign idioms into it without necessity or use, 
 and to make it ambiguous where it was not. The dis- 
 tinctions in the end of categories of the four words, yriMS^ 
 Sitnul, motus, and habere, are all verbal. 
 
 The modes or species of pn'us, according to Aristotle, 
 are five. One thing may be prior to another ; first, ia 
 point of time ; secondly, in point of dignity ; thirdly, in 
 point of order ; and so forth. The modes of simul are 
 only three. It seems this word was not used in the Greek 
 with so great latitude as the other, although they are rel- 
 ative terms. 
 
 The modes or species of motion he makes to be six, t6 
 wit, generation, corruption, increase, decrease, alteration, 
 and change of place. 
 
 The modes or species of having are eight. 1. Having^ 
 a quality or habit, as having wisdom. 2. Having quan- 
 tity or magnitude. 3. Having things adjacent, as having 
 a sword. 4. Having things as parts, as having hands or 
 feet. 5. Having in a part or on a part, as having a ring 
 on one's finger. 6. Containing, as a cask is said to have 
 wine. 7. Possessing, as having lands or houses. 8. Hav- 
 ing a wife. 
 
 Another distinction of this kind is Aristotle's distinc- 
 tion of causes ; of which he makes four kinds, efficient, 
 material, formal, and final. These distinctions may de- 
 serve a place in a dictionary of the Greek language ; but 
 in English or Latin they adulterate the language. Yet 
 so fond were the schoolmen of distinctions of this kind, 
 that they added to Aristotle's enumeratiotj, an impulsive 
 cause, an exemplary cause, and I do not know how many 
 more. We seem to have adopted into English a final 
 cause ; but it is merely a term of art, borrowed from the 
 Peripatetic philosophy, without necessity or use ; for the 
 English word end is as good Asjinal cause, though not so 
 long uor so learned. 
 
lis A. BBIET ACCOUNT OF 
 
 SECTION IV. 
 ON DEFINITIONS. 
 
 It remains that we make some remarks on Aristotle's 
 definitions, which have exposed him to much censure and 
 ridicule. Yet I think it must be allowed, that in things 
 which need definition, and admit of it, his definitions are 
 commonly judicious and accurate; and had he attempted 
 to define such things only, his enemies 1iad wanted great 
 matter of triumph. I believe it may likewise be said in 
 his favour, that until Locke's essay was written, there 
 was nothing of importance delivered by philosophers with 
 regard to definition, beyond what Aristotle has said upon 
 that subject. 
 
 He considers a definition as a speech declaring what a 
 thing is. Every thing essential to the thing defined, and 
 nothing more, must be contained in the definition. Now 
 the essence of a thing consists of these two parts: first, 
 what is common to it with other things of the same kind ; 
 and, secondly, what distinguishes it from other things of 
 the same kind. The first is called the genus of the thing, 
 the second its specijic difference. The definition there- 
 fore consists of these two parts. And for finding them, 
 we must have recourse to the ten ealegories ; in one or 
 other of which every thing in nature is to be found. Each 
 category is a geniis, and is divided into so many species, 
 which are distinguished by their specific diffei-enees. Each 
 of these species is again subdivided into so many species, 
 with regard to which it is a genus. This division and 
 subdivision continues until we come to the lowest species, 
 which can only be divided into individuals, distinguished 
 from one another, not by any specific difference, but by 
 accidental differences of time, place, and other circum- 
 stances. 
 
 The category itself being the highest genus, is in no 
 respect a species, and the lowest species is in no respeet 
 a genus ; but every iatermediate order is a genus com- 
 
AEISTOTIiE'S iogic. 113 
 
 pat*ed with those that are below it, and a species com- 
 pared with those above it. To find the definition of any 
 thing, therefore, you must take the genus which is im- 
 mediately above its place in the category, and the specific 
 difference, by which it is distinguished from other species 
 of the same genusi These two make a perfect definitioUi 
 This I take to be the substance of Aristotle's system j 
 and probably the system of the Pythagorean school be-» 
 fore Aristotle, concerning definition. 
 
 But notwithstanding the specious appearance of this 
 system, it has its defects. Not to repeat what was before 
 said, of the imperfection of the division of things into ten 
 categories, the subdivisions of each category are no less 
 imperfect. Aristotle has given some subdivisions of a 
 few of them ; and as far as he goes, his followers pretty 
 unanimously take the same road. But when they attempt 
 to go farther, they take very different roads. It is evi- 
 dent, that if the series of each category could be com- 
 pleted, and the division of things into categories could be 
 made perfect, still the highest genus in each category 
 could not be defined, because it is not a species ; nor 
 could individuals be defined, because they have no spe- 
 cific difference. There are also many species of things, 
 whose specific difierence cannot be expressed in language,' 
 even when it is evident to sense, or to the understanding. 
 Thus, green, red, and blue, are very distinct species of 
 colour ; but who can express in words wherein green dif- 
 fers from red or blue ? 
 
 Without borrowing light from the ancient system, we 
 may perceive, that every definition must consist of words 
 that need no definition ; and that to define the common 
 words of a language that have no ambiguity, is trifling, 
 if it could be done ; the only use of a definition being to 
 give a clear and adequate conception of the meaning of 
 a word. 
 
 The logicians indeed distinguish between the definition 
 of a word, and the definition of a thing ; considering tha 
 
 vol. I. 15 
 
114- A BRIEF ACCOVNT OF 
 
 former as the mean office of a lexicographer, but the lasC 
 as the grand work of a philosopher. But what they have 
 said about the definition of a thing, if it has a meaning, 
 is bejond my comprehension. All the rules of definition 
 agree to the definition of a word : and if they mean by 
 the definition of a thing, the giving an adequate concep- 
 tion of the nature and essence of any thing that exists; 
 this is impossible, and is the vain boast of men uncon- 
 scious of the weakness of human understanding. 
 
 The works of God are all imperfectly known by us. 
 We see their outside, or perhaps we discover some of 
 their qualities and relations, by observation and experi- 
 ment, assisted by reasoning ; but we can give no defini- 
 tion of the meanest of them which comprehends its real 
 essence. It is justly observed by Locke, that nominal 
 essences only, which are the creatures of our own minds, 
 are perfectly comprehended by us, or can be properly de- 
 fined ; and even of these there are many too simple in 
 their nature to admit of definition. When we cannot give 
 precision to our notions by a definition, we must endeav- 
 our to do it by attentive reflection upon them, by observ- 
 ing minutely their agreements and differences, and espec- 
 ially by a right understanding of the powers of our own 
 minds by which such notions are formed. 
 
 The principles laid down by Locke with regard to defi- 
 nition, and with regard to the abuse of words, carry con- 
 viction along with them ; and I take them to be one of 
 the most important improvements made in logic since 
 the days of Aristotle; not so much because they enlarge 
 our knowledge, as because they make us sensible of our 
 ignorance, and shew that a great part of what speculative 
 men have admired as profound philosophy, is only a dark- 
 ening of knowledge by words without understanding. 
 
 If Aristotle had understood those principles, many of 
 his definitions, which furnish matter of triumph to his 
 enemies, had never seen the light : let us impute them to 
 the times rather than to the man. The sublime Plato, 
 it is said, thought it necessary to have the definition of 
 
Hi 
 
 a man, and could find none belter than Animal implutne 
 hipes; upon which Diogenes sent to his school a cock with 
 his feathers plucked off, desiring to know whether it 
 was a man or not. 
 
 SECTION V. 
 ON THE STKUCTURE OF SPEECH. 
 
 The few hints contained in the beginning of the book 
 concerning Interpretation, relating to the structure of 
 speech, have been left out on trealtises of logic, as belong- 
 ing rather to grammar ; yet I apprehend this is a rich 
 field of philosophical speculation. Language being the 
 express image of human thought, the analysis of the one 
 must correspond to that of the other. Nouns adjective 
 and substantive, verbs active and passive, with their va- 
 rious moods, tenses, and persons, must be expressive of 
 a like variety in the modes of thought. Things which 
 are distinguished in all languages, such as substance and 
 quality, action and passion, cause and effect, must be dis- 
 tinguished by the natural powers of the human mind. 
 The philosophy of grammar, and that of the human un- 
 derstanding, are more nearly allied than is commonly 
 imagined. 
 
 The structure of language was pursued to a consider- 
 able extent, by the ancient commentators upon this book 
 of Aristotle. Their speculations upon this subject, which 
 are neither the least ingenious nor the least useful part 
 of the Peripatetic philosophy, were neglected for many 
 ages, and lay buried in ancient manuscripts, or in books 
 little known, till they were lately brought to light by the 
 learned Mr. Harris in his Hermes. 
 
 The definitions given by Aristotle, of a noun, of a verb, 
 and of a speech, will hardly bear examination. It is easy 
 in practice to distinguish the various parts of speech ; but 
 very difficult, if at all possible, to give accurate defini- 
 tions of them. 
 
116 A BRIEF ACCOUNT OF 
 
 He observes justly, that besides that kind of speech 
 called a proposition, which is always either true or false, 
 there are other kinds which are neither true nor false ; 
 such as, a prayer, or wish ; to which we may add, a ques- 
 tion, a command, a promise, a contract, and many others. 
 These Aristotle pronounces to have nothing to do with 
 his subject, and remits them to oratory, or poetry; and 
 so they have remained banished from the regions of phi- 
 losophy to this day : yet I apprehend, that an analysis 
 of such speeches, and of the operations of mind which 
 they express, would be of real use, and perhaps would 
 discover how imperfect an enumeration the logicians have 
 given of the powers of human understanding when they 
 reduce them to simple apprehension, judgment, and rea- 
 soning. 
 
 SECTION YI. 
 ON PROPOSITIONS. 
 
 Mathematicians use the word proposition in a larger 
 sense than logicians. A problem is called a proposition 
 in mathematics, but in logic it is not a proposition : it is 
 one of those speeches which are not enunciative, and 
 which Aristotle remits to oratory or poetry. 
 
 A proposition, according to Aristotle, is a speech 
 wherein one thing is affirmed or denied of another. Hence 
 it is easy to distinguish the thing affirmed or denied, 
 which is called the predicate, from the thing of which it 
 is affirmed or denied, which is called the subject; and 
 these two are called the terms of the proposition. Hence 
 likewise it appears, that propositions are either affirma- 
 tive or negative ; and this is called their quality. All 
 affirmative propositions have the same quality, so likewise 
 have all the negative ; but an affirmative and a negative 
 are contrary in their quality. 
 
 When the subject of a proposition is a general term, 
 the predicate is affirmed or denied, either of the whole, 
 
aristotie's iogic. 117 
 
 or of a part. Hence propositions are distinguished into 
 universal and particular. Ml men are mortal, is an uni- 
 versal proposition ; Some men are learned, is a particular, 
 and this is called the quaniity of the proposition. All 
 universal propositions agree in quantity, as also all par- 
 ticular : while an universal and a particular are said to 
 differ in quantity. A proposition is called indejinite, wlien 
 there is no mark either of universality or particularity 
 annexed to the subject : thus, Man is of few days, is an 
 indefinite proposition ; but it must be understood either 
 as universal or as particular, and therefore is not a third 
 species, but by interpretation is brought under one of the 
 other two. 
 
 There are also singular propositions, which have not 
 a general term but an individual for their subject ; as, 
 tSlexander was a great conqueror. These are considered 
 by logicians as universal, because, the subject being in- 
 divisible, the predicate is affirmed or denied of the whole, 
 and not of a part only. Thus all propositions, with re- 
 gard to quality, are either affirmative or negative ; and 
 •with regard to quantity, are universal or particular; and 
 taking in both quantity and quality, they are universal 
 affirmatives, or universal negatives, or particular affirma- 
 tives, or particular negatives. These four kinds, after 
 the days of Aristotle, came to be named by the names of 
 the four first vowels, A, E, I, O, according to the follow- 
 ing distich : 
 
 Asserit A, negat E, sed univeraaliter ambse ; 
 Asserit I, negat O, sed particulariter ambo. 
 
 When the young logician is thus far instructed in the 
 nature of propositions, he is apt to think there is no diffi- 
 culty in analyzing any proposition, and shewing its sub- 
 ject and predicate, its quantity and quality | and indeed, 
 unless he can do this, he will 'be unable to apply the 
 pultes of logic to use. Yet he will find, there are some 
 difficulties in this analysis, which are overlooked by Aris- 
 totle altogether J and although they are sometimes touch- 
 
118 A BRIEF ACCOUNT OF 
 
 ed, they are not removed by his followers. For, 1. Tliere 
 are propositions in which it is difficult to find a subject 
 and a predicate; as in these, It rains, it snows, 2. In 
 some propositions either term may be made a subject 
 or the predicate as you like bestj as in this. Virtue 
 is the road to happiness. 3. The same example may 
 serve to shew, that it is sometimes difficult to say, 
 •whether a proposition be universal or particular, i. The 
 quality of some propositions is so dubious, that logic- 
 ians have never been able to agree whether they be 
 affirmative or negative,* as in this proposition. Whatever 
 is insentient is not an animal. 5. As there is one class 
 of propositions which have only two terms, to wit, one 
 subject and one predicate, which are called categorical 
 propositions; so there are many classes that have more 
 than two terms. What Aristotle delivers in this book is 
 applicable only to categorical propositions ; and to them 
 only the rules concerning the conversion of propositions, 
 and concerning the figures and modes of syllogisms, are 
 accommodated. The subsequent writers of logic have 
 taken notice of some of the many classes of complex 
 propositions, and have given rules adapted to them ; but 
 finding this work endless, they have left us to manage 
 the rest by the rules of common sense. 
 
aristotie's toQie. 119 
 
 CHAPTER III. 
 
 ACCOXJNT OF THE FJRST ANALYTICS. 
 
 SECTION I. 
 
 OF THE CONVERSION OE PROPOSITIONS. 
 
 In attempting to give sotne account of the Analytics 
 and the Topics of Aristotle, ingenuity requires me to con- 
 fess, that though 1 have often purposed to read the whole 
 with care, and to understand what is intelligible, yet my 
 courage and patience always failed before I had done. 
 Why should I throw away so much time and painful at- 
 tention upon a thing of so little real use ? If I had lived 
 in those ages when the knowledge of Aristotle's Organon 
 entitled a man to the highest rank in philosophy, ambi- 
 tion might have induced me to employ upon it some years 
 painful study ; and less, I conceive, would not be sufficient.^ 
 Such reflections as these, always got the better of my 
 resolution, when the first ardour began to cool. All I caa 
 say is, that I have read some parts of the different books 
 with care, some slightly, and some perhaps not at all. I 
 have glanced over the whole ofien, and when any thing 
 attracted my attention, have dipped into it till my appe- 
 tite was satisfied. Of all reading it is the most dry and 
 the most painful, employing an infinite labour of demon- 
 stration, about things of the most abstract nature, deliv- 
 ered in a laconic style, and often, I think, with affected 
 obscurity ; and all to prove general propositions, which 
 when applied to particular instances appear self-evident. 
 
 There is probably but little in the Categories, or in 
 the book of Interpretation, which Aristotle could claim 
 as his own invention : but the whole theory of syllogisms 
 he claims as his own, and as the fruit of much time and 
 labour. And indeed it is a stately fabric, a monument of 
 ft great gejiius> which we QOiJd wish to have been more 
 
120 A BRIEF ACCOUNT 01? 
 
 usefully employed. There must be somettiing howeivei' 
 adapted to please the human understanding, or to flatter 
 human pride, in a work which occupied men of speculation 
 for more than a thousand years. These books are called 
 Analytics, because the intention of them is to resolve all 
 reasoning into its simple ingredients. 
 
 The first book of the First Analytics, consisting of 
 forty-six chapters, maybe divided into four parts; the 
 first treating of the conversion of propositions ; the second, 
 of the structure of syllogisms in all the different figures 
 and modes ; the third, of the invention of a middle term ; 
 and the last, of the resolution of syllogisms. We shall 
 give a brief account of each. 
 
 To convert a proposition, is to infer from it another 
 proposition, whose subject is the predicate of the first, 
 and whose predicate is the subject of the first. This is 
 reduced by Aristotle to three rules. 1. An universal 
 negative may be converted into an universal negative: 
 thus, no man is a quadruped; therefore, no quadruped is 
 a man. 2. An universal afiirraative can be converted 
 only into a particular afiirmative : thus, all men are mor- 
 tal ; thercforej some mortal beings are men. 3. A par- 
 ticular affirmative may be converted into a particular af- 
 firmative ; as, some men are just ; therefore, some just 
 persons are men. When a proposition may be converted 
 without changing its quantity, this is called simple conver- 
 sion; but when the quantity is diminished, as in the uni- 
 versal affirmative, it is called conversion per accidens. 
 
 There is another kind of conversion, omitted in this 
 place by Aristotle, but supplied by his followers, called 
 convei'sion hy contraposition, in which the term which is 
 contradictory to the predicate is put for the subject, and 
 the quality of the proposition is changed ; as, all animals 
 are sentient ; therefore, what is insentient is not an ani- 
 mal. A fourth rule of conversion therefore is, that an 
 universal affirmative, and a particular negative, may be 
 converted by contraposition. 
 
ARISTOTIiE's lOGIC. 121 
 
 SECTION U. 
 OF THE riGrRBS AND MODES OF PTJHE STXX06ISMS. 
 
 A SYULOGisM is an argument, or reasoning, conaisling 
 of three propositions, the last of which, called the conclu- 
 sion, is inferred from the two preceding, which are called 
 the premises. The conclusion having two terms, a sub- 
 ject and a predicate, its predicate is called the major term, 
 and its subject the minor term. In order to prove the 
 conclusion, each of its terms is in the premises compar- 
 ed with a third term, called the middle term. By tiiis 
 means one of the premises will have for its two terms 
 the major term and the middle term ; and this premise 
 is called the major premise, or the major proposition of 
 the s^'llogisra. The other premise must have for its two 
 terms the minor term and the middle term, and it is call- 
 ed the minor proposition. Thus the syllogism consists 
 of three propositions, distinguished by the names of the 
 major, the minor, and the conclusion ; and although each 
 of these has two terms, a subject and a predicate, yet 
 there are only three different terms in all. The major 
 term is always the predicate of the conclusion, and is 
 also either the subject or predicate of the major proposi- 
 tion. The minor term is always the subject of the con- 
 clusion, and is also either the subject or predicate of the 
 minor proposition. The middle term never enters into 
 the conclusion, but stands in both premises, either in the 
 position of subject or of predicate. 
 
 According to the various positions which the middle 
 term may have in the premises, syllogisms are said to 
 be of various figures. Now all the possible positions of 
 the middle term are only four : for, first, it may be the 
 subject of the major proposition, and the predicate of the 
 minor, and then the syllogism is of the first figure : or it 
 may be the predicate of both premises, and then the syllo- 
 gism is of the second figure ; or it may be the subject of 
 both, which makes a syllogism of the third figure } or it 
 
 Toil. I. 16 
 
122 A BEIEF ACCOUNT OF 
 
 may be the predicate of the major proposition, and the 
 subject of the minor, which makes the fourth figure. Ar- 
 istotle takes no notice of the fourth figure. It was added 
 by the famous Galen, and is often called the Galenical 
 figure. 
 
 There is another division of syllogisms according to 
 their modes. The mode of a syllogism is determined by 
 the quality and quantity of the propositions of which it 
 consists. Each of the three propositions must be either 
 an universal aflirmative, or an universal negative, or a 
 particular affirmative, or a particular negative. These 
 four kinds of propositions, as was before observed, have 
 been named by the four vowels, A, E, I, O, by which mean» 
 the mode of a syllogism is marked by any three of those 
 four vowels. Thus A, A, A, denotes that mode in which 
 the major, minor, and conclusion, are all universal af- 
 firmatives ; E, A, E, denotes that mode in which the ma- 
 jor and conclusion are universal negatives, and the minop 
 is an universal affirmative. 
 
 To know all the possible modes of syllogism, we must 
 find how many different combinations may be made of 
 three out of the four vowels, and from the art of combi- 
 nation the number is found to be sixty-four. So many 
 possible modes there are in every figure, consequently in 
 the three figures of Aristotle there are one hundred and 
 ninety-two, and in all the four figures two hundred and 
 sixty-six. ' -.-- *,-, ,■ 
 
 Now the theory of syllogism requires, that we shew 
 what are the particular modes in each figure, which do, 
 or do not, form a just and conclusive syllogism, that so 
 the legitimate may be adopted, and the spurious rejected. 
 This Aristotle has shewn in the first three figures, ex- 
 amining all the modes one by one, and passing sentence 
 upon each ; and from this examination he collects some 
 rules which may aid the memory in distinguishing the 
 false from the true, and point out the properties of eaeb 
 figure. 
 
ABISTOTIE'S lOGIC, 12S 
 
 The first figure has only four legitimate modes. The 
 major proposition in this figure must he universal, and 
 the minor affirmative | and it has this property, that it 
 yields conclusions of all kinds, affirmative and negative, 
 universal and particular. 
 
 The second figure has also four legitimate modes. Its 
 major proposition must be universal, and one of the prem- 
 ises must be negative. It yields conclusions both uni- 
 versal and particular, but all negative. 
 
 The third figure has six legitimate modes. Its minor 
 must always be affirmative; and it yields conclusions both 
 affirmative and negative, but all particular. 
 
 Besides the rules that are proper to each figure, Aris- 
 totle has given some that are common to all, by which 
 the legitimacy of syllogisms may be tried. These may, 
 I think, be reduced to five. i. There must be only three 
 terms in a syllogism. As each term occurs in two of the 
 propositions, it must be precisely the same in both.: if it 
 be not, the syllogism is said to have four terms, which 
 makes a vicious syllogism. 3. The middlie term must be 
 taken universally in one of the premises. 3. Both 
 premises must not be particular propositions, nor both 
 negative. 4. The conclusion must be particular, if either 
 of the premises be particular ; and negative, if either of 
 the premises be negative. 6. No term can be taken uni- 
 versally in the conclusion, if it be not taken universally 
 in the premises. 
 
 For understanding the second and fifth of these rules, 
 it is necessary to observe, that a terra is said to be taken 
 universally, not only when it is the subject of an univer- 
 sal proposition, but when it is the predicate of a negative 
 proposition ; on the other hand, a term is said to be taken 
 particularly, when it is either the subject of a particular, 
 or the predicate of an affirmative proposition. 
 
124 A BRIEF ACCOUNT 01 
 
 SECTION III. 
 OF THE INVENTION OF A MIDDIE TERM, 
 
 The third part of this book contains rules general and 
 special for the invention of a middle term ; and this the 
 author conceives to be of great utility. The general rules 
 amount to this, that you are to consider well both terms 
 of the proposition to be proved ; their definition, their 
 properties, the things which may be affirmed or denied of 
 them, and those of which they may be affirmed or denied : 
 those things collected together, are the materials from 
 which your middle term is to be taken. 
 
 The special rules require you to consider the quantity 
 and quality of the proposition to be proved, that you may 
 discover in what mode and figure of syllogism the proof is to 
 proceed. Then from the materials before collected, you 
 must seek a middle term which has that relation to the sub- 
 ject and predicate of the proposition to be proved, which the 
 nature of the syllogism requires. Thus, suppose the prop- 
 osition I would prove is an universal affirmative, I know 
 by the rules of syllogisms, that there is only one legiti- 
 mate mode ill which an universal affirmative proposition 
 can be proved ; and that is the first mode of the first fig- 
 ure. I know likewise, that in this mode both the prem- 
 ises must be universal affirmatives ,* and that the middle 
 term must be the subject of the major, and the predicate 
 of the minor. Therefore of the terms collected accord- 
 ing to the general rule, I seek out one or more which 
 have these two properties : first, that the predicate of the 
 proposition to be proved can be universally affirmed of it ; 
 and, secondly, that it can be universally affirmed of the 
 subject of the proposition to be proved. Every term you 
 can find which has those two properties, will serve you 
 as a middle term, but no other. In this way, the author 
 gives special rules for all the various kinds of propositions 
 to be proved ; points out the various modes in which Uiey 
 
aristotib's xooig. 12S 
 
 may be proved, and the properties which the middle term 
 must have to make it fit for answering that end. And 
 the rules are illustrated, or rather, in my opinion, pur- 
 posely darkened, by putting letters of the alphabet for 
 the several terms. 
 
 SECTION IV. 
 or THE REMAINING PART OF THE FIRST BOOK. 
 
 The resolution of syllogisms requires no other princi- 
 ples, but those before laid down for constructing them. 
 However it is treated of largely, and rules laid down for 
 reducing reasoning to syllogisms, by supplying one of the 
 premises when it is understood, by rectifying inversiotts 
 and putting the propositions in the proper order. 
 
 Here he speaks also of hypothetical syllogisms ; which 
 he acknowledges, cannot he resolved into any of the fig- 
 ures, although there be many kinds of them which ought 
 diligently to be observed ; and which he promises to han- 
 dle afterward. But this promise is not fulfilled, as far 
 as I know, in any of his works that are extant. 
 
 SECTION V. 
 OF THE SECOND BOOK OF THE FIRST ANAiTTICS. 
 
 The second book treats of the powers of syllogisms, 
 and shows, in twenty-seven chapters, how we may perform 
 many feats by them, and what figures and modes are 
 adapted to each. Thus, in some syllogisms several dis- 
 tinct conclusions may be drawn from the same premises : 
 in some, true conclusions may be drawn from false prem- 
 ises : in some, by assuming the conclusion and one pre- 
 mise, you may prove the other ; you may turn a direct 
 syllogism into one leading to an absurdity. 
 
126 A BRIEF ACCOirSTT 01 
 
 We have likewise precepts given in tliis book, both to 
 the assailant in a syllogistical dispute, how to carry on his 
 attack witli art, so as to obtain the victory ; and to the 
 defendant, how to keep the enemy at such a distance as 
 that he shall never be obliged to yield. ■ From which we 
 learn, that Aristotle introduced in his own school, the 
 practice of disputing syllogistieally, instead of the rhetor- 
 ical disputations which the sophists were wont to use in 
 more ancient times. 
 
 CHAPTER IV. 
 REMARKS. 
 
 SECTION I. 
 OF THE CONVERSION OF PROPOSITIONS. 
 
 We have given a summary view of the theory of pure 
 syllogisms as delivered by Aristotle, a theory of which he 
 claims the sole invention. And I believe it will be diflS- 
 eult, in any science, to find so large a system of truths of 
 so very abstract and so general a nature, all fortified by 
 demonstration, and all invented and perfected by one man. 
 It shows a force of genius, and labour of investigation, 
 equal to the most arduous attempts. I shall now make 
 some remarks upon it. 
 
 As to the conversion of propositions, the writers on 
 logic commonly satisfy themselves with illustrating each 
 of the rules by an example, conceiving them to be self- 
 evident when applied to particular cases. But Aristotle 
 has given demonstrations of the rules he mentions. As a 
 specimen. I shall give his demonstration of the first rule. 
 " Let A 6 be an universal negative proposition ; I say, 
 that if A is in no B, it will follow that B is in no A. If you 
 deny this consequence, let B be in some A, for example, 
 in C ; then the first supposition will aot be true, for C is 
 
abistotie's lOOIC. 127 
 
 oftbeB's." In this demonstration, if I understand it» 
 the third rule of conversion is assumed, that if B is in 
 some A, then A must be in some B, which indeed is con- 
 trary to the first supposition. If the third rule be as- 
 sumed for proof of the first, the proof of all the three goes 
 round in a circle, for the second and third rules are proved 
 by the tirst. This is a fault in reasoning which Aristotle 
 condemns, and which I should be very unwilling to charge 
 him with, if I could find any better meaning in bis dem- 
 onstration. But it is indeed a fault very difficult to be 
 avoided, when men attempt to prove things that are self- 
 evident. 
 
 The rules of conversion cannot be applied to all propo- 
 sitions, but only to those that are categorical ; and we 
 are left to the direction of common sense in the conver- 
 sion of other propositions. To give an example : Alex- 
 ander was (he son of Philip ; therefore Philip was the 
 father of Alexander : A is greater than B| therefore B 
 is less than A. These are conversions which, as far as 
 I know, do not fall within any rule in logie i nor do we 
 find any loss for want of a rule in such cases. 
 
 Even in the conversion of categorical propositions, it is 
 not enough to transpose the subject and predicate. Both 
 must undergo some change, in order to fit them for their 
 new station : for in every proposition the subject must be 
 a substantive, or hare the force of a substantive; and the 
 predicate must be an adjective, or have the force of aa 
 adjective. Hence it follows, that when the subject is, ast 
 individual, the proposition admits not of conversion. How 
 for instance, shall we convert this proposition, God is 
 omniscient ? 
 
 These observations show, that the doctrine of the con* 
 version of propositions is not so complete as it appears. 
 The rules are laid down without any limitation j yet they 
 are fitted only to one class of propositions, to wit, the; 
 categorical ; and of these only to such as have a geaecal 
 term foi: their sut^ect^ .. 
 
128 A BRIEI' ACCOUNT OIT 
 
 SECTION II. 
 ON ADDITIONS MADB TO AEISTOTXE's THEORY. 
 
 AiTHouGH the logicians have enlarged the first antf 
 second parts of logic, by explaining some technical words 
 and distinctions which Aristotle had omitted, and by giv- 
 ing names to some kinds of propositions which he over- 
 looks; yet in what concerns the theory of categorical 
 syllogisms, he is more full, more minute and particular, 
 than any of them ; so that they seem to have thought this 
 capital part of the Organon rather redundant than de- 
 ficient. 
 
 It is true, that Galen added a fourth figure to the three 
 mentioned by Aristotle. But there is reason to think 
 that Aristotle omitted the fourth figure, not through ig- 
 norance or inattention, but of design, as containing only 
 some indirect modes, which, when properly expressed, 
 fall into the first figure. 
 
 It is true also, that Peter Kamus, a professed enemy 
 of Aristotle, introduced some new modes that are adapt- 
 ed to singular propositions ; and that AristoMe takes no 
 notice of singular propositions, either in his rules of con- 
 version, or in the modes of syllogism. But the friends 
 of Aristotle have shewn, that this improvement of Ra- 
 mus is more specious than useful. Singular propositions 
 have the force of universal propositions, and are subject 
 to the same rules. The definition given by Aristotle of 
 an universal proposition applies to them; and therefore 
 he might think, that there was no occasion to multiply 
 the modes of syllogism upon their account. 
 
 These attempts, therefore, show rather inclination than 
 power, to discover any material defect in Aristotle's 
 theory. 
 
 The most valuable addition made to the theory of cat- 
 egorical syllogisms, seems to be the iqveution of those 
 
AHISTOTIE'S rOGIC. 129 
 
 technical names given to the legitimate modes, by which 
 they may be easily remembered, and which have been 
 comprised in these barbarous verses. 
 
 Barbara, Celarent, Darii, Ferio, dato primse ; 
 Cesare, Camenris, Festino, Buroco, secumlie ; 
 Tenia grande sunans rccitat Darapti, Felapton ; 
 Adjungens Disamia, Datisi, Bocardo, Ferison. 
 
 In these verses, every legitimate mode belonging to the 
 three figures has a name given to it, by which it may be 
 distinguished and remembered. And this name is so 
 contrived as to denote its nature : for the name has three 
 vowels, which denote the kind of each of its propositions. 
 
 Thus, a syllogism in Bocardo must be made up of the 
 propositions denoted by the three vowels, O, A, O ; that 
 is, its major and conclusion must be particular negative 
 propositions, and its minor an universal affirmative ; and 
 being in the third figure, the middle tei-m must be the 
 subject of both premises. 
 
 This is the mystery contained in the vowels of those 
 barbarous words. But there are other mysteries contain- 
 ed in their consonants : for by their means, a child may 
 be taught to reduce any syllogism of the second or third 
 figure to one of the first. So that the four modes of the 
 first figure being directly proved to be conclusive, all the 
 modes of the other two are proved at the same time, by 
 means of this operation of reduction. For the rules and 
 manner of this reduction; and the difiTerent species of it, 
 called ostensive and •per impossible, I refer to the logieiana« 
 that I may not disclose all their mysteries. 
 
 The invention contained in these verses is so ingenious, 
 and so great an adminicle to the dexterous management 
 of syllogisms, that I think it very probable that Aristotle 
 had some contrivance of this kind, which was kept as 
 one of the secret doctrines of his school, and handed 
 down by tradition, until some body brought it to light. 
 This is ofiered only as a conjecture, leaving it to those 
 who are better acquainted with the most ancient commen- 
 tators on the Analytics, either to refute or to confirm it. 
 
 TOIr. I. 17 
 
ISO A BRIEF ACCOUNT OF 
 
 SECTION III. 
 OSr EXAMPIES USED TO IllUSTKATE THIS THEORY, 
 
 We may observe, that Aristotle hardly ever gives ex- 
 amples of real syllogisms to illustrate his rules. In 
 demonstrating the legitimate modes, he takes A, B, C, 
 for the terms of the syllogism. Thus, the first mode of 
 the first figure is demonstrated by him in this manner. 
 " For," says he, " if A is attributed to every B, and B to 
 every C, it follows necessarily, that A may be attributed 
 to every C." Fop disproving the illegitimate modes, he 
 uses the same manner ; with this difierenee, that he com- 
 monly for an example gives three real terms, such as 60- 
 num, liuhitus, prudentia ; of which three terms you are 
 to make up a syllogism of the figure and mode in ques- 
 tion, which will appear to be inconclusive. 
 
 The commentators, and systematical AVriters in logic, 
 have supplied this defect ; and given us real examples of 
 every legitimate mode in all the figures. This we must 
 acknowledge to be charitably done, to assist the imagin- 
 ation in the conception of matters so very abstract ; but 
 whether it was prudently done for the honour of the art, 
 may be doubted. I am afraid this was to uncover the 
 nakedness of the theory ; and has contributed much to 
 bring it into contempt : for when one considers the silly 
 and uninstructive reasonings that have been brought forth 
 by this grand organ of science, he can hardly forbear cry- 
 ing out, Parturiunt montes, et nascitur ridiculus mus. 
 Many of the writers of logic are acute and ingenious, and 
 much practised in the syllogistical art j and there must 
 be some reason why the examples they have given of syl- 
 logisms are so lean. 
 
 We shall speak of the reason afterward ; and shall now 
 give a syllogism in each figure as an example. 
 
 No work of God is bad j 
 
akistotie's xoGie. 131 
 
 The natural passions and appetites of men are the 
 work of God ,• 
 
 Therefore none of them is bad. 
 In this syllogism, the middle term, work of God, is the 
 subject of the major and the predicate of the minor; so 
 that the syllogism is of the first figure. The mode is 
 that called Celarent; the major and conclusion being 
 both universal negatives, and the minor an universal af- 
 firmative. It agrees to the rules of the figure, as the 
 major is universal, and the minor afiSritiative ; it is also 
 agreeable to all the general rules ; so that it maintains 
 its character in every trial. And to show of what duc- 
 tile materials syllogisms are made, we may, by converting 
 simply the major proposition, reduce it to a good syllo- 
 gism of the second figure, and of the mode Casare, thus: 
 
 Whatevf r is bad is not the worii of God ; 
 
 All the natural passions and appetites of men are the 
 work of God ; 
 
 Therefore they are not bad. 
 
 Another example : 
 
 Every thing virtuous is praise-worthy ; 
 Some pleasures are not praise-worthy ; 
 Therefore some pleasures are not virtuous. 
 
 Here the middle term praise-worthy being the predi- 
 cate of both premises, the syllogism is of the second fig- 
 ure ; and seeing il is made up of the propositions. A, O, O, 
 the mode is Baroco. It will be found to agree both with 
 the general and special rules : and it maybe reduced into 
 a good syllogism of the first figure upon converting the 
 major by contraposition, thus : 
 
 What IS not praise-worthy is not virtuous : 
 Some pleasures are not praise- worthy; 
 Therefore some pleasures are not virtuous. 
 
 That this syllogism is conclusive, common sense pro- 
 nounces, and all logicians must allow ; but it is somewhat 
 unpliable to rules, and requires a little straining to make 
 it tally with them. 
 
 That it is of the first figure is beyond dispute ; but to 
 what mode of that figure shall we refer it ? This is a 
 
132 A BRIEF ACCOUNT? OF 
 
 question of some diiBcuIty. Fop, in the first place, the 
 premises seem to be both negative, which contradicts the 
 tbirni general rule ; and moreover, it is contrary to a 
 special rule of the first figure, that the minor should be 
 negative. These are the difiiculties to be removed. 
 
 Some logicians think tliat the two negative particles in 
 the major are equivalent to an affirmative ; and that 
 therefore the major proposition, What is not praise-wor- 
 thy, is not virtuous, is to be accounted an affirmative prop- 
 osition. This if granted, solves one difiiculty ; but the 
 other remains. The most ingenious solution, therefore, 
 is this : let the middle term be not praise-worthy. Thus 
 making the negative particle a part of the middle term, 
 the syllogism stands thus : 
 
 Whatever is not praise-worthy is not virtuous j 
 Some pleasures are not praise-worthy; 
 Therefore some pleasures are not virtuous. 
 By this analysis, the major becomes an universal nega- 
 tive, the minor a particular afiirmative, and the conclu- 
 sion a particular negative, and so we have a just syllo- 
 gism in Ferio. 
 
 We see, by this example, that the quality of proposi- 
 tions is not so invariable, but that, when occasion re- 
 quires, an affirmative may be degraded into a negative, 
 or a negative exalted to an affirmative. Another ex- 
 ample : 
 
 All Africans are black 5 
 
 All Africans are men ; 
 
 Therefore some men are black. 
 This is of a third figure, and of the mode IJarapti; and 
 it may be reduced to Barii in the first figure, by convert- 
 ing the minor. 
 
 All Africans are black ; 
 
 Some men are Africans ; 
 
 Therefore some men are black. 
 By this time I apprehend the reader has got as many ex- 
 amples of syllogisms as will stay his appetite for that 
 kind of entertaiument. 
 
aristotxe's lOGie. 138 
 
 SECTION IV. 
 ON THE DEMONSTRATION OF THE THEORY. 
 
 Aristotxe and his followers have thought it neces- 
 sary, in order to bring this theory of categorical syllo- 
 gisms to a science, to demonstrate, both that the four- 
 teen authorized modes conclude justly, and that none of 
 the rest do. Let us now see how this has been executed. 
 
 As to the legitimate modes, Aristotle, and those who 
 follow him the most closely, demonstrate the four modes 
 of the first figure directly from an axiom called the Dictum 
 de omni et nulla. The amount of the axiom is, that what 
 is afiirmed of a whole genus, may be affirmed of all the 
 species and individuals belonging to the genus; and that 
 what is denied of the whole genus, may be denied of 
 its species and individuals. The four modes of the 
 first figure are evidently included in this axiom. And 
 as to the legitimate modes of the other figures, they 
 are proved by reducing them to some mode of the first. 
 Nor is there any other principle assumed in these re- 
 ductions but the axioms concerning the conversion of 
 propositions, and in some cases the axioms concerning 
 the opposition of propositions. 
 
 As to the illegitimate modes, Aristotle has taken the 
 labour to try and condemn them one by one in all the 
 three figures : but this is done in such a manner that it is 
 very painful to follow him. To give a specimen. In order 
 to prove, that those modes of the first figure in which 
 the major is particular, do not conclude, be proceeds 
 thus : " If A is or is not in some B, and B in every C, 
 no conclusion follows. Take for the terms in the affirm- 
 ative case, good, habit, prudence, in the negative, good, 
 habit, ignorance." This laconic style, the use of symbols 
 not familiar, and in place of giving an example, his leav- 
 ing us to form one from three assigned terms, give such 
 embarrassment to a reader, that he is like one reading a 
 book of riddles. 
 
1S4 A BRIEF ACCOUNT O* 
 
 Having thus ascertained the true and false modes of a 
 figure, he subjoins the particular rules of that figure, 
 which seem (o be reduced from the particular cases be- 
 fore determined. Tlie general rules come last of all, as 
 a general corollary from what goes before. 
 
 I know not whether it is from a diffidence of Aristotle's 
 demonstrations, or from an apprehension of their obscu- 
 rity, or from a desire of improving upon his method, that 
 almost all the writers in logic I have met with, have in- 
 verted his order, beginning where he ends, and ending 
 where he begins. They first demonstrate the general 
 rules, which belong to all the figures, from three axioms,* 
 then from the general rules and the nature of each fig- 
 ure, they demonstrate the special rules of each figure. 
 When this is done, nothing remains but to apply these 
 general and special rules, and to reject every mode which 
 contradicts them. 
 
 This method has a very scientific appearance; and 
 when we consider, that by a few rules once demonstrated, 
 an hundred and seventy-eight false modes are destroyed 
 at one blow, which Aristotle had the trouble to put to 
 death one by one, it seems to be a great improvement. 
 I have only one objection to the three axioms. 
 
 The three axioms are these : 1. Things which agree 
 with the same third, agree with one another. 2. When 
 one agrees with the third, and the other does not, they 
 do not agree with one another. 3. When neither agrees 
 with the third, you cannot thence conclude, either that 
 they do, or do not agree with one another. If these ax? 
 ioms are applied to mathematical quantities, to which 
 they seem to relate when taken literally, they have all 
 the evidence which an axiom ought to have ; but the lo- 
 gicians apply them in an analogical sense to things of an- 
 other nature. In order, therefore, to judge whether they 
 are truly axioms, we ought to strip them of their figura- 
 tive dress, and to set them down in plain English, as the 
 logicians understand them. They amount therefore to 
 this. 1. If two things be affirmed of a third, or the third 
 be affirmed of them j or if one be affirmed of the third, 
 
aristotie's loGie. 135 
 
 and the third affirmed of the other ; then they may be 
 affirmed one of the other. 2. If one is affirmed of the 
 third, or the third of it, and the other denied of the third, 
 or the third of it, they may be denied one of the other. 
 3. If both are denied of the third, or the third of them ; 
 or if one is denied of the third, and the third denied of 
 the other ; nothing can be inferred. 
 
 When the three axioms are thus put in plain English, 
 they seem not to have that degree of evidence, which ax- 
 ioms ought to have ; and if there is any defect of evidence 
 in the axioms, this defect will be communicated to the 
 whole edifice raised upon them. 
 
 It may even be suspected, that an attempt, by any 
 method, to demonstrate, that a syllogism is conclusive, is 
 an impropriety somewhat like that of attempting to de- 
 monstrate an axiom. In a just syllogism, the connection 
 between the premises and the conclusion is not only real, 
 but immediate; so that no proposition can come between 
 them to make their connection more apparent. The very 
 intention of a syllogism is, to leave nothing to be supplied 
 that is necessary to a complete demonstration. There- 
 fore a man of common understanding, who has a perfect 
 comprehension of the premises, finds himself under a ne- 
 cessity of admitting the conclusion, supposing the prem- 
 ises to be true; and the conclusion is connected with the 
 premises with all the force of intuitive evidence. In a 
 word, an immediate conclusion seen in the premises, by 
 the light of common sense ; and where that is wanting, 
 no kind of reasoning will supply its place. 
 
 SECTION V. 
 
 ON THIS THEORY, CONSIDERED AS AN ENGINE OF 
 SCIENCE. 
 
 The slow progress of useful knowledge, during the 
 raany ages in which the syllogistic art was most highly 
 
i36 A BSIE* ACCOUNT OS 
 
 cultivated as the only guide to science, and its quick 
 progress since that art was disused, suggest a presump- 
 tion against it ; and this presumption is strengthened by 
 the puerility of the examples which have always been 
 brought to illustrate its rules. 
 
 The ancients seem to have had too high notions, both 
 of the force of the reasoning power in man, and of the 
 art of syllogism as its guide. Mere reasoning can carry 
 us but a very little way in most subjects. By observa- 
 tion, and experiments properly conducted, tlie stock of 
 human knowledge may be enlarged without end ; but the 
 power of reasoning alone, applied with vigour through a 
 long life, would only carry a man round, like a horse in a 
 mill, who labours hard, but makes no progress. There 
 is indeed an exception to this observation in the mathe- 
 matical sciences. The relations of quantity are so vari- 
 ous, and so susceptible of exact mensuration, that long 
 trains of accurate reasoning on that subject may be form- 
 ed, and conclusions drawn very remote from the first 
 principles. It is in this science, and those which depend 
 upon it, that the power of reasoning triumphs : in other 
 matters its trophies are inconsiderable. If any man 
 doubt this, let him produce, in any subject unconnected 
 with mathematics, a train of reasoning of some length, 
 leading to a conclusion, which without this train of rea- 
 soning would never have been brought within human 
 sight. Every man acquainted with mathematics can 
 produce thousands of such trains of reasoning. I do not 
 say, that none such can he produced in other sciences ; 
 but I believe they are few, and not easily found ; and that 
 if they are found, it will not be in subjects that can he ex- 
 pressed by categorical propositions, to which alone the 
 theory of figure and mode extends. 
 
 In matters to which that theory extends, a man of good 
 sense, who can distinguish things that differ, and avoid 
 the snares of ambiguous words, and is moderately prac- 
 tised in such matters, sees at once all that can be inferred 
 from his premises ; or finds; that there is but a very short 
 step to the conclusioD. 
 
ARISTOTrE'S XOGIC. 137 
 
 W^hen the power of reasoning is so feeble by nature, 
 especially in subjects to which this theory can be applied, 
 it would be unreasonable to expect great effects from it. 
 And hence we see the reason why the examples brought 
 to illustrate it by the most ingenious logicians, have rather 
 tended to bring it into contempt. 
 
 If it should be thought, that the syllogistic art may be 
 an useful engine in mathematics, in which pure reasoning 
 has ample scope : first, it maybe observed, (hat facts are 
 unfavourable to this opinion : for it does not appear, that 
 Euclid, or Apollonius, or Archimedes, or Hugens, or 
 Newton, ever made the least use of this art ; and I am 
 even of opinion, that no use can be made of it in mathe- 
 matics. I would not wish to advance this rashly, since 
 Aristotle has said, that mathematicians reason, for the 
 most part in the first figure. What led him to think so 
 was, that the first figure only yields conclusions that are 
 universal and affirmative, and the conclusions of mathe- 
 matics are commonly of that kind. But it is to be ob- 
 served, that the propositions of mathematics are not cat- 
 egorical propositions, consisting of one subject and one 
 predicate. They express some relation which one quan- 
 tity bears to another, and on that account must have three 
 terms. The quantities compared make two, and the re- 
 lation between them is a third. Now to such proposi- 
 tions we can neither apply the rules concerning the con- 
 version of propositions, nor can they enter into a syllogism 
 of any of the figures or modes. We observed before, that 
 this conversion. A is greater than B, therefore B is less 
 than A, does not fall within the rules of conversion givea 
 by Aristotle or the logicians ; and we now add, that this 
 simple reasoning, JL is equal to B, and Bto C; therefore 
 •9 is equal to C, cannot be brought into any syllogism ia 
 figure and mode. There are indeed syllogisms into 
 which mathematical propositions may enter, and of such 
 we shall afterwai-d speak : but they have nothing to do 
 with the system of figure and mode. 
 
 TOI. I. 18 
 
138 A BKIEr ACCOUNT OF 
 
 When we go without the circle of the mathematical 
 sciences. I know nothing in which there seems to be so 
 miH'.h demonstpation as in that part of logic which treats 
 of the figures and modes of syllogism; but the few re- 
 marks we have made, shew, that it has some weak 
 places : and besides, this system cannot be used as an en- 
 gine to rear itself. 
 
 The compass of the syllogistic system as an engine of 
 science, may be discerned by a compendious and general 
 view of the conclusion drawn, and the argument used to 
 prove it, in each of the three figures. 
 
 In the first figure, the conclusion affirms or denies 
 something, of a certain species or individual ; and the ar- 
 gument to prove this conclusion is, that the same thing 
 may be affirmed or denied of the whole genus to which 
 that species or individual belongs* 
 
 In the second figure, the conclusion is, that some spe- 
 cies or individual does not belong to such a genus ; and 
 the argument is, that some attribute common to the whole 
 genus does not belong to that species or individual. 
 
 In the third figure, the conclusion is, that sneh an at- 
 tribute beloni»s to part of a genus ; and the argument \s, 
 that 'be attribute in question belongs to a species or indi- 
 vidual which is part of that genns. 
 
 T aonrehend. that, in this short view, every conclusion 
 that falls within the compass of the three figures, as well 
 as the mean of proof, is comprehended. The rules of all 
 the figures might be easily deduced from it ; and it ap- 
 pears, that there is only one principle of reasoning in all 
 tlie tbree; so that it is not strange, that a syllogism of 
 one figure should be redueed to one of another figure. 
 
 The general principle in which the whole terminates, 
 and of which every categorical syllogism is only a par- 
 ticular application, is this, that what is affirmed or denied 
 of the whole genus, may be afiirmed or denied of every 
 species and individual belonging to it. This is a princi- 
 ple of undoubted certainty indeed, but of no great depth. 
 Aristotle and all the logicians assume it as an axiom os 
 
amstotie's xogic. 139 
 
 first principle, from which the syllogistic system, as it 
 ■were, takes its departure : and after a tedious voyage, and 
 great expense of demonstrations, it lands at las) in this 
 principle as its ultimate conclusion. Ocuras Iwminum ! 
 O quantum est in rebus inane ! 
 
 SECTION VI. 
 OK MODAI, STUOGISMS. 
 
 Gategorical propositions, besides their quantity and 
 quality, have another affection, by which they are divided 
 into pure and modal. In a pure proposition, the predicate 
 is barely affirmed or denied of the subject ; but in a modal 
 proposition, the affirmation or negation is modified, by 
 being declared to be necessary or contingent, or possible 
 or impossible. These are the four modes observed by 
 Aristotle, from which he denominates a proposition mO' 
 dal. His genuine disciples maintain, that these are all 
 the modes that can affect an affirmation or negation, and 
 that the enumeration is couiplete. Others maintain, that 
 this enumeration is incomplete ; and that when an affirm- 
 ation or negation is said to be certain or uncertain, 
 probable or improbable, this makes a modal proposition, 
 no less than tVie four modes of Aristotle. We shall not 
 enter into this dispute; but proceed to observe, that the 
 epithets of fure and modal are applied to syllogisms as 
 well as to propositions. A pure syllogism is that in which 
 both premises are pure propositions. A modal syllogism 
 is that in which either of the premises is a modal propo- 
 sition. 
 
 The syllogisms of which we have already said so much, 
 are those only which are pure as well as categorical. But 
 when we consider, that through all the figures and modes, 
 a syllogism may have one premise modal of any of the 
 four modes, while the other is pure, or it may have both 
 premises modal, and that they may be either of the same 
 
140 A BEIEr ACCOUNT OB 
 
 mode or of different modes ; what prodigious variety 
 arises from aii these couibinatiuns ! Now it is the busi- 
 ness of a logician, to shew how the conclusion is affected 
 in all this variety of cases. Aristotle has done this in 
 his First Analytics, with immense labour; and it will 
 not be thought strange, that when he had employed only 
 four chapters in discussing one hundred and ninety-two 
 modes, true and false, of pure syllogisms, he should em- 
 ploy fifieen upon modal syllogisms. 
 
 I am very willing to excuse myself from entering upon 
 this great branch of logic, by the judgment and example 
 of those who cannot be charged either with want of re- 
 spect to Aristotle, or with a low esteem of the syllogistic 
 art. 
 
 Keckerman, a famous Dantzican professor, who spent 
 bis life in teaching and writing logic, in his huge folio 
 system of that science, published ann. 1600, calls the 
 doctrine of the modals the crux logicorwm. With regard 
 to the scholastic doctors, among whom this was a prov- 
 erb, J)e modalibus non giistabit asinus, he thinks it very 
 dubious, whether they tortured most the modal syl- 
 logisms, or were most tortured by them. But those 
 crabbed geniuses, says he, made this doctrine so very 
 thorny, that it is fitter to tear a man's wits in pieces than 
 to give them solidity. He desires it to be observed, that 
 the doctrine of modals is adapted to the Greek language. 
 The modal terms were frequently used by the Greeks in 
 their disputations ; and, on that account, are so fully 
 bandied by Aristotle : but in the Latin tongue you shall 
 bardly ever meet with them. Nor do I remember in all 
 my experience, says he, to have observed any man in 
 danger of being foiled in a dispute, through his ignorance 
 of the modals. 
 
 This author, however, out of respect to Aristotle, 
 treats pretty fully of modal propositions, shewing how to 
 distinguish their subject and predicate, their quantity 
 and quality. But the modal syllogisms he passes ovev 
 altogether. 
 
akistotie's xogic. 141 
 
 Ludovicus Yives, whom I mention, not as a devotee of 
 Aristotle, but on account of his own judgment and learn- 
 ing, thinks that the doctrine of modals ought to be ban- 
 ished out of logic, and remitted to grainixiar; and that if 
 the grammar of the Greek tongue had been brought to a 
 system in the time of Aristotle, that most acute philoso- 
 pher would have saved the great labour he has bestowed 
 on this subject. 
 
 Burgersdick, after enumerating five classes of modal 
 B^'llogisms, observes, that they require many rules and 
 cautions, which Aristotle hath handled diligently ; but 
 as the use of them is not great, and their rules are very 
 difficult, he thinks it not worth while to enter into the 
 discussion of them; recommending to those who would 
 understand them, the most learned paraphrase of Joan- 
 nes Monlorius, upon the first book of the First Analyt- 
 ics. 
 
 All the writers of logic for two hundred years back 
 that have fallen into my hands, have passed over the rules 
 of modal syllogisms Avith as little ceremony. So that this 
 great branch of the doctrine of syllogism, so diligently 
 handled by Aristotle, fell into neglect, if not contempt, 
 even while the doctrine of pure syllogisms continued in 
 the highest esteem. Moved by these authorities, I shall 
 let this doctrine rest in peace, without giving the least 
 disturbance to its ashes. 
 
 SECTION vn. 
 
 Olf SYXI.06ISMS THAT DO NOT BEIONG TO FIGUHE AKD 
 
 MODE. 
 
 Aristotie gives some observations upon imperfect 
 syllogisms : such as, the Enthiniema, in which one of the 
 premises is not expressed but understood : induction, 
 wherein we collect an universal from a full enumeration 
 
142 A BRIEF ACCOtTNT OT 
 
 of particulars : and examples, which are an imperfect in- 
 duction. The logicians have copied Aristotle upon these 
 kinds of reasoning, without any considerable improve- 
 ment. But to compensate (he modal sjllngisms, which 
 they have laid aside, they liave given rules for several 
 kinds of syllogism, of vthich Arisiotle takes no notice. 
 These may be reduced to two classes. 
 
 The first class comprehends the syllogisms into which 
 any exclusive, restrictive, exceptive, or reduplicative 
 proposition enters. Such propositions are by some called 
 exponibk, by others imperfectly modal. The rules given 
 with regard lo these are obvious, from a just interpreta- 
 tion of the propositions. 
 
 The second class is that of hypothetical syllogisms^ 
 which take that denomination from having a hypotheti- 
 cal proposition for one or both premises. Most logicians 
 give the name of hypothetical to all complex propositions 
 which have more terms than one subject and one predi- 
 cate. I use the word in this large sense ; and mean by 
 hypothetical syllogisms, all those in which either of the 
 premises consists of more terms than two. How many 
 various kinds there may be of such syllogisms, has never 
 been ascertained. The logicians have given names to 
 some ; such as, the copulative, the conditional, by some 
 called hypothetical, and the disjunctive. 
 
 Such syllogisms cannot be tried by (he rules of figure 
 and mode. Every kind would require rules peculiar to 
 it. Logicians have given rules for some kinds j but 
 there are many that have not so much as a name. 
 
 The Dilemma is considered by most logicians as a 
 species of the disjunctive syllogism. A remarkable prop- 
 erty of this kind is, (hat it may sometimes be happily 
 retorted: it is, it seems, like a hand grenade which, by 
 dexterous management, may be thrown back, so as to 
 spend its force upon the assailant. We shall conclude 
 this tedious account of syllogisms, with a dilemma men- 
 tioned by A. Gellius, and from him by many logicians, as 
 insoluble in any other way. 
 
aeistotib's xogic. 143 
 
 <' Euathlus, a rich young man, desirous of learning the 
 art of pleading, applied to Protagoras, a celebrated soph- 
 ist, to instruct bini, promising a great sum of money as 
 his reward; one half of whicli was paid down; the 
 other half he bound himself to pay as soon as he should 
 plead a cause before the judges, and gain it. Protagoras 
 found him a very apt scholar ; but, after he had made 
 good progress, he was in no haste to plead causes. The 
 master, conceiving that he intended by this means to 
 shift off his second payment, took, as he thought, a sure 
 method to get the better of his delay. He sued Euathlus 
 before the judges; and, having opened his cause at the 
 bar, lie pleaded to this purpose. O most foolish young 
 man, do you not see that in any event, I must gain my 
 point ? for if the judges give sentence for me, you must 
 pay by their sentence; if against me, the condition of our 
 bargain is fulfilled, and you have no plea left for your 
 delay, after having pleaded and gained a cause. To which 
 Euathlus answered. O most wise master, I have avoid- 
 ed the force of your argument, by not pleading my own 
 cause. But, giving up this advantage, do you not see, 
 that whatever sentence the judges pass, I am safe? If 
 they give sentence for me, I am acquitted by their sen- 
 tence ; if against me, the condition of our bargain is not 
 fuiniled, by my pleading a cause and losing it. The 
 judges, thinking the arguments unanswerable on both 
 sides, put off the cause to a long day." 
 
14i) A BHIET ACCOUSTT OE 
 
 CHAPTER V. 
 
 ACCOUNT OF THE REMAINING BOOKS OF THE 
 ORGANON. 
 
 SECTION 1. 
 OF THE LAST ANAITTICS. 
 
 In the First Analytics, syllogisms are considered ir» 
 respect of their form ; they are now to be considered in 
 respect of their matter. The form lies in the necessary 
 connection between the premises and the conclusion ; and 
 where such a connection is wanting, they are said to be 
 informal, or vicious in point of form. 
 
 But where there is no fault in the form, there may be 
 in the matter ; that is, in the propositions of which they 
 are composed, which may be true or false, probable or 
 improbable. 
 
 When the premises are certain, and the conclusion 
 drawn from them in due form, this is demonstration, and 
 produces sciences. Such syllogisms are called apodic- 
 tieal ; and are handled in the two books of the Last Ana- 
 lytics. When the premises are not certain, but probable 
 only, such syllogisms are called dialectical ; and of them 
 he treats in the eight books of the Topics. But there are 
 some syllogisms which seem to be perfect both in matter 
 and form, when they are not really so : as, a face may 
 seem beautiful which is but painted. These being apt 
 to deceive, and produce a false opinion, are called sophist- 
 ical ; and they are the subject of the book concerning 
 Sophisms. 
 
 To return to the Last Analytics, which treat of dem- 
 onstration and of science : we shall not pretend to abridge 
 those books; for Aristotle's writings do not admit of 
 abridgment : no man can say what he says in fewer words ; 
 and he is not often guilty of repetition. We shall only give 
 some of his capital couclusious^ omitting his long reason- 
 
ARISTOTIE'S lOGIG. 145 
 
 ings and nice distinctions, of which his genius was won- 
 derfully productive^ 
 
 All demonstration must be built upon principles al- 
 ready known ; and these upon others of the same kind ; 
 until we come at last to first principles, which neither 
 can be demonstrated, nor need to be, being evident of 
 themselves. 
 
 We cannot demonstrate things in a circle, supporting 
 the conclusion by the premises, and the premises again 
 by the conclusion. Nor can there be an infinite number 
 of middle terms between the first principle and the con- 
 clusion. 
 
 In all demonstration, the first principles, the conclu- 
 eion, and all the intermediate propositions, must be nec- 
 essary, general, and eternal truths ; for of things fortui- 
 tous, contingent, or mutable, or of individual things, there 
 is no demnnstration> 
 
 Some demon^rations prove only, that the thing is thus 
 afiected ; others prove, why it is thus afiected. The for- 
 mer may be drawn from a remote cause, or from an ef- 
 fect : but the latter must be drawn from an immediate 
 cause ; and are the most perfect. 
 
 The first figure is best adapted to demonstration, be- 
 cause it afibrds conclusions universally affirmative ; and 
 this figure is commonly used by the mathematicians. 
 
 The demonstration of an afi'irmative proposition is 
 preferable to that of a negative ; the demonstration of 
 an universal to that of a particular; and direct demon- 
 stration to that ad dbsurdum. 
 
 The principles are more certain than the conclusion. 
 
 There cannot be opinion and science of the same thing 
 at the same time. 
 
 In the second book we are taught, that the questions 
 that may be put, with regard to any thing, are four : 
 1. Whether the thing be thus afiected. 3. Why it is thus 
 aflTected. 3. Whether it exists. 4. AVhat it is. 
 
 The last of these questions Aristotle, in good Greek, 
 calls the What is it of a thing. The sehoolaien> in very 
 
 TOL. z. 19 
 
146 A BKIEF ACCOUNT OK 
 
 barbarous Latin, called this, the quiddity of a thing. This 
 quiddity, he proves by many arguments, cannot be de- 
 monstrated, but must be fixedby adefiaition. This gives 
 occasion to treat of deKuition, and how a right deiiaitiea 
 should be formed. As an example be gives a definition 
 of the number three, and defines it to be the first odd 
 number. 
 
 In this book he treats also of the four kinds of causes,* 
 efficient, material, formal and final. 
 
 Another thing treated of in this book is, the manner in 
 Trfaicb we acquire first principles, which are the foundation 
 of all demonstration. These are not innate, because we 
 may be for a great part of life ignorant of them : nor can 
 they be deduced demonstratively from any antecedent 
 knowledge, otherwise they would not be first principles. 
 Therefore he concludes, that first principles are got by 
 induction, from the informations of sense. The senses 
 give us informations of individual things, and from these 
 by induction we draw general conclusions : for it is a 
 maxim with Aristotle, that there is nothing in the under, 
 standing which was not before in some sense. 
 
 The knowledge of first principles, as it is not acqure- 
 ed by demonstration, ought not to be called science j and 
 therefore he calls it intelligence. 
 
 SECTION II. 
 or THE TOPICS. 
 
 The professed design of the Topics, is, to shew a 
 method by which a man may be able to reason with 
 probability and consistency upon every question that 
 may occur. 
 
 Ev.j-y question is either about the genus of the subject, 
 or its specific difierence, or some tiling proper to it, or 
 something accidental. 
 
AKISTOTIB'S XOGliC. 147 
 
 To prove that this division is complete, Aristotle rea- 
 sons thus : whatever is attributed to subject, it must 
 either be, that Ihe subject can be reciproeallj' attributed 
 to it, or that it cannot. If the subject and attrihute can 
 be reciprocated, the attribute either declares what the 
 subject is, and then il is a definition ; or it does not de- 
 clare what the subject is, and then it is a property. If 
 the attribute cannot be reciprocated, it must be some- 
 thing contained in the definition of the subject, it must 
 be the g^nus of the subject, or its specific difference; 
 fov the i^finition consists of these two. If it is not 
 contained in the definition of the subject, it must be an 
 accident. 
 
 The furniture proper to fit a man for arguing dialec- 
 tieally may be reduced to these four heads : 1. Probable 
 propositions of all sorts, which may on occasion be as- 
 sumed in an argument. 2. Distinctions of words which 
 are nearly of the same signification. 3. Distinctions of 
 things which are not so far asunder but that they may be 
 taken for one and the same. 4. Similitudes. 
 
 The second and the five following books are taken up 
 in enumerating the topics or heads of argument that may 
 be used in questions about the genus, the definition, the 
 properties, and the accidents of a thing ; and occasionally 
 he introduces the topics for proving things to be the same, 
 or different ; and the topics for proving one thing to be 
 better or worse than another. 
 
 In this enumeration of topics, Aristotle has shewn more 
 the fertility of his genius, than the accuracy of method. 
 The writers of logic seem to be of this opinion : for I 
 know none of them that has followed him closely upon 
 this subject. They have considered the topic of argu- 
 mentation as reducible to certain axioms. For iastance> 
 when the question is about the genus and species ; when 
 it is about definition, it must be determined by some ax- 
 iom relating to definition, and things defined : and so of 
 other questions. They have therefore reduced the doc- 
 
148 A BRIEF ACCOVNT OF 
 
 trine of the topics to certain axioms or canons, and dis- 
 posed these axioms in order under certain heads. 
 
 This method seems to be more commodious and ele- 
 gant than that of Aristotle. Yet it must be acknowl- 
 edged, that Aristotle has furnished the materials from 
 which all the logicians have borrowed their doctrine of 
 topics: and even Cicero, Quintilian and other rhetor- 
 ical Avriters, have been much indebted to the topics of 
 Aristotle. 
 
 He was the first, as far as 1 know, who made an at- 
 tempt of this kind : and in this he acted up to the mag- 
 nanimity of his own genius, and that of ancient philoso- 
 phy. Every subject of human thought had been reduced 
 to ten categories ; every thing that can be attributed to 
 any subject, to five predicables : he attempted to reduce 
 all the forms of reasoning to fixed rules of figure and mode, 
 and to reduce all the topics of argumentation under cer- 
 tain heads ; and by that means to collect as it were into 
 one store all that can be said on one side or the other 
 of every question, and provide a grand arsenal, from 
 which all future combatants might be furnished with 
 arms offensive and defensive in every cause, so as to leave 
 no room to future generations to invent any thing new. 
 
 The last book of the topics is a code of the laws, ac- 
 cording to which a syllogistical disputation ought to be 
 managed botli on the part of the assailant and defendant. 
 From which it is evident, that this philosopher trained 
 his disciples to contend, not for the truth merely, but for 
 Tjctory. 
 
 SECTION III. 
 OF THE BOOK CONCBENIBTG SOPHISMS. 
 
 A STLioGisM which leads to a false conclusion, must 
 be vicious either in matter or form : for from true prin- 
 ciples nothing bat truth can be justly deduced. If the 
 
AKISTOTIB'S X061C. 149 
 
 matter be faulty, that is, if either of the premises be false, 
 that premise must be denied by the defendant. If the 
 form be faulty, some rule of syllogism is transgressed ; 
 and it is the part of the defendant to shew, what general 
 or special rule it is that is transgressed. So that, if he 
 is an able logician, he will be impregnable in the defence 
 of truth, and may resist all the attacks of the sophist. 
 But as there are syllogisms which may seem to be per- 
 fect both in matter and form, when they are not really 
 so, as a piece of money may seem to be good coin, when 
 it is adulterate j such fallacious syllogisms are considered 
 in this treatise, in order to make a defendant more expert 
 in the use of his defensive weapons. 
 
 And here the author, with his usual magnanimity, at- 
 tempts to bring all the fallacies that can enter into a syl- 
 logism under thirteen heads ; of which six lie in the dic- 
 tion on language, and seven not in the diction. 
 
 The fallacies in diction are, 1. when an ambiguous 
 word is taken at one time in one sense, and at another 
 time in another. 2. when an ambiguous phrase is taken 
 in the same manner. 3. and 4. are ambiguities in syn- 
 tax; when words are conjoined in syntax that ought to 
 be disjoined ; or disjoined when they ought to be con- 
 joined. 5. is an ambiguity in prosody, accent or pro- 
 nunciation. 6. an ambiguity arising from some figure 
 of speech. 
 
 When a sophism of any of these kinds is translated 
 into another language, or even rendered into unambig- 
 uous expressions in the same language, the fallacy is evi- 
 dent, and the syllogism appears to have four terms. 
 
 The seven fallacies which are said not to be in the dic- 
 tion, but in the thing, have their proper names in Greek 
 and in Latin, by which they are distinguished. Without 
 minding their names, we shall give a brief account of 
 their nature. 
 
 1. The Arst is, taking an accidental conjunction of 
 things for a natural or necessary connection : as, when 
 from aa accident we infer a property } when from an 
 
150 A BRIEF ACCOtTNT OF 
 
 example we infer a rule j when fnoni a single act we io- 
 £er a habit. 
 
 2. Taking that absolutely which ought to be taken 
 comparatively, or with a certain limitation. The con- 
 struction of language often leads into (his fallacy ; for in 
 all languages it is common to use absolute terms, to sig- 
 nify things which carry in them some secret comparison; 
 OP to use some unlimited terms, to signify what from its 
 nature must be limited. 
 
 3. Taking- that for the cause of a thing which was only 
 an oceasion, or concomitant. 
 
 4. Begging the question. This is done when the thing 
 to be proved, or something equivalent, is assumed in the. 
 premises. 
 
 5. Mistaking the question. When the conclusion of 
 the syllogism is not tlie thing that ought to be proved,, 
 but something else that is mistaken for it. 
 
 6. When that which is not a consequence is mistaken 
 for a consequence ; as if, because all Africans are black, 
 it were taken for granted that all the blacks are Africans. 
 
 7. The last fallacy lies in propositions that are complex, 
 and imply two afBrmations, whereof one maybe true, and 
 the other false ; so that whether you grant the proposi- 
 tion, or deny it, you are entangled : as when it is atBrra- 
 ed that such a man has left off playing the fool. If it 
 be granted, it implies, that he did play the fool formerly. 
 If it be denied, it implies, or seems to imply, that he plays 
 the fool still. 
 
 In this enumeration, we ought, in justice to Aristotle, 
 to expect only the fallacies incident to categorical syllo- 
 gisms. And I do not find, that the logicians have made 
 any additions to it when taken in this view ; although 
 they have given some otiier fallacies that are incident to 
 syllogisms of the hypothetical kind, particularly the fal- 
 lacy of an incomplete enumeration in disjunctive syllo- 
 gisms and dilemmas. 
 
 The di0erent species of sophisms above mentioned are 
 not so precisely defined by Aristotle, or by subsequent 
 
abistotie's xogxc. IBI 
 
 logicians, but that tbey allow of great latitude in the ap- 
 plication } and it is often dubious under what particular 
 species a sopkistical syllogism ought to be «las3ed. We 
 even find the same example brought under one species by 
 one author, and under another species by another. Nay, 
 what is more strange, Aristotle himiself employs a long 
 chapter in proving by a particular inductinn, that all the 
 seven may be brought under that which we have called 
 mistaking the que^i&n, and which is commonly called ig- 
 noratio elencM. And indeed the proof of this is easy, 
 without tliat laborious detail which Aristotle uses for the 
 purpose : for if you lop off from the conclusion of a so- 
 phistical syllogism all that is not supported by the prem- 
 ises, the conclusion, in that case, will always be found 
 different from that which ought to have been proved j 
 and so it falls under the ignoratio elenchi. 
 
 It was probably Aristotle's aim, to reduce all the pos- 
 sible variety of sophisms, as he had attempted to do of 
 just syllogisms, to certain definite species : but he seems 
 to be sensible that he had fallen short in this last attempt. 
 When a genus is properly divided into its species, the 
 species should not only, when taken together, exhaust the 
 whole genus ; but every species should have its own pre- 
 cinct so accurately defined, that one shall not encroach 
 upon another. And when an individual can be said to 
 belong to two or three different species, the division is im- 
 perfect ; yet this is the case of Aristotle's division of the 
 sophisms, by his own acknowledgment. It ought not 
 therefore to be taken for a division strictly logical. It 
 may rather be compared to the several species or forms 
 of action invented in law for the redress of wrongs. F©r 
 every wrong there is a remedy in law by one action or 
 another: but sometimes -a man may take his choice 
 among several different actions. So every sophistical 
 syllogism, may, by a little art, be brought under one or 
 other of the species mentioned by Aristotle, and very 
 often you may take your choice of two or three. 
 
162 A BRIEF ACCOUNT OF 
 
 Besides the enumeration of the various kinds of sopfa' 
 isms, there are many other things in this treatise con- 
 cerning the art of managing a syllogistical dispute with 
 an antagonist. And indeed, if the passion fop this kind 
 of litigation, which reigned for so many ages, should ever 
 again lift up its head, we may predict, that the Organon 
 of Aristotle will then become a fashionable study : for 
 it contains such admirable materials and documents for 
 this art, that it may be said to have brought it to a sci- 
 ence. 
 
 The conclusion of this treatise ought not to be over- 
 looked : it manifestly relates, not to the present treatise 
 ■only, but also to the whole analytics and topics of the au- 
 thor. I shall therefore give the substance of it. 
 
 " Of those who may be called inventers, some have 
 made important additions to things long beforie beguOf 
 and carried on through a course of ages ; others have 
 given a small beginning to things which, in succeeding 
 times, will be brought lo greater perfection. The be- 
 ginning of a thing, though small, is the chief part of it, 
 and requires the greatest degree of invention ; for it is 
 easy to make additions to inventions once begun. Now 
 with regard to the dialectical art, there was not some- 
 thing done, and something remaining to be done. There 
 was absolutely nothing done : for those who professed the 
 art of disputation, had only a set of orations composed, 
 and of arguments, and of captious questions, which might 
 suit many occasions. These their scholars soon learned, 
 and fitted to the occasions. This was not to teach you 
 the art, but to furnish you with the materials produced 
 by the art : as if a man professing to teach you the art 
 of making shoes, should bring you a parcel of shoes of 
 various sizes and shapes, from which you may provide 
 those who want. This may have its use ; but it is not 
 to teach the art of making shoes. And indeed, witli re- 
 gard to rhetorical declamation, there are many precepts 
 handed down from ancient times : but with regard to the 
 construction of syllogisms; not one. 
 
ARISTOTLE'S LOGIC, 153 
 
 " We have therefore employed much lime and labour 
 upon this subject ; and if our system appears to you not 
 to be in the number of those things, Avhich, being before 
 carried a certain length, were left to be perfected ; we hope 
 for your favourable acceptance of what is done, and youp 
 indulgence in what is left imperfect," 
 
 CHAPTER VI, 
 REFLECTIONS ON THE UTILITY OF LOGIC, 
 
 AND THE MEANS OF ITS IMPROVEMENT, 
 
 SECTION I. 
 
 OP THE UTILITY OF LOGIC, 
 
 Men rarely leave one extreme without running into 
 the contrary. It is no wonder, therefore, that the exces- 
 sive admiration of Aristotle, which continued for so many 
 ages, should end in an undue contempt ; and that the 
 high esteem of logic as the grand engine of science, should 
 at last make way for too unfavourable an opinion, which 
 seems now prevalent of its being unworthy of a place la 
 a liberal education. Those who think, according to the 
 fashion, as the greatest part of men do, will be as prone 
 to go into this extreme, as their grandfathers were to go 
 into the contrary, 
 
 Laying aside.prejudice, whether fashionable or un- 
 fashionable, let us consider whether logic is, or may be 
 made subservient to apy good purpose. Its professed end 
 is, to teach men to think, to judge, and to reason, with 
 precision and accuracy. No man will say that this is a 
 matter of no importance ; the only thing therefore that 
 admits of doubt, is, whether it can be taught. 
 
 To resolve this doubt, it may be observed, that our 
 rational faculty is the gift of God, given to men in very 
 different measure. Some have a larger portion, some a 
 
 TOX, I. 20 
 
154l A BRIEF ACCOUNT OF 
 
 less; and where there is a remarkable defect of the nat- 
 ural power, it cannot be supplied by any culture whatso- 
 ever. But this natural power, even where it is strongest, 
 may lie dead for want of the means of improvement; and 
 a savage may have been born with as good faculties as a 
 Bacon or a Newton. The amazing difference that appears 
 in advanced life, is owing to this, that the talent of one 
 was buried, being never put to use, while that of the 
 other was cultivated to the best advantage. 
 
 It may likewise be observed, that the chief mean of 
 improving our rational power, is the vigorous exercise of 
 it, in various ways, and in different subjects, by which 
 the habit is acquired of exercising it properly. Without 
 such exercise, and good sense over and above, a man who 
 has studied logic all liis life may. after all, be only a pet- 
 ulant wrangler, without true judgment, or skill of rea- 
 soning, in any science. 
 
 I take this to be Locke's meaning, when, in his Thoughts 
 on Education, he says, "If you would have your son to 
 reason well, let him read Chillingworth." The state of 
 things is much altered since Locke wrote. Logic has 
 been much improved, chiefly by his writings ; and yet 
 inuch less stress is laid upon it, and less time consumed 
 in it. His counsel, therefore, was judicious, and season- 
 able; to wit, that the improvement of our reasoning 
 power is to be expected much more from an intimate ac- 
 quaintance with the authors- who reason best, than from 
 studying voluminous systems of logic. But if he had 
 meant, that the study of logic was of no use. nor deserv- 
 ed any attention, he surely would not have taken the pains 
 to have made so considerable an addition to it, by his 
 Essay on the Human Understanding and by his Thoughts 
 on the Conduct of the Understanding. Nor would he 
 Iiave remitted his pupil to Chillingworth, the acutest lo- 
 gician, as well as the best reasoner, of bis a^e ; and one 
 who, in innumerable places of his excellent book, without 
 pedantry even in that pedantic age, makes the happiest 
 application of the rules of logic, for uuravelliog the so- 
 phistical reasouing of his aotagonist. 
 
ABISTOTIE'S I.06IC. 155 
 
 Our reasoning power makes no appearance in in&ncy ; 
 but as we grow up, it unfolds itself by degrees like the 
 bud of a tree. When a child first draws an inference* or 
 perceives the force of an inference drawn by another per- 
 son, we may call this tile birth of his reason : but it is yet 
 like a new-born babe, weak and tender ; it must be cher- 
 ished, and carried in arms, aud have food of easy diges- 
 tion, till it gathers strength. 
 
 I believe no man remembers this birth of his reason ; 
 but it is probable that his decisions will at first be weak 
 and waving ; and, compared with that steady conviction 
 which he acquires in ripe years, will be like the dawn of 
 the morning compared with noon-day. We see that (he 
 reason of children yields to authority, as a reed to the 
 wind ; nay, that it clings to it, and leans upon it, as if 
 conscious of its own weakness. 
 
 When reason acquires such strength as to stand on its 
 own bottom, without the aid of authority, or even in op- 
 position to authority, this may be called its manly agd 
 But in most men, it hardly ever arrives at this periods 
 Many, by their situation in life, have not the oppoi'tunity 
 of cultivating their rational powers. Many from (h^ 
 babit they have acquired, of submitting their opinions to 
 the authority of others, or from some other principle 
 which operates more powerfully than the love of truth, 
 suffer their judgment to be carried along to the end of 
 their days* either by the authority of a leader, or of a 
 party, or of the multitude, or by their own passions. 
 Such persons, however learned, however acute, may be 
 said to be all their days children in understanding. They 
 reason, they dispute, and perhaps write ; but it is not 
 that they may find the truth ; but that they may defend 
 opinions which have descended to them by inheritance, or 
 into which they have fallen by accident, or been led by 
 affection. 
 
 I agree with Mr. Locke, that there is no study better 
 fitted to exercise and strengthen the reasoning powers, 
 than that of the mathematical sciences ; for two reasons; 
 
156 A BEIEF ACCOtJNT OF 
 
 first, because there is no otlier branch of science which 
 gives such scope to long and accurate trains of reason- 
 ing; and secondly, because in mathematics there is no 
 room for authority, or for prejudice of any kind, which 
 may give a false bias to the judgment. 
 
 When a youth of moderate parts begins to study Eu- 
 clid, every thing at first is new to him. His apprehen- 
 sion is unsteady ; his judgment is feeble : and rests partly 
 upon the evidence of tlie thing, and partly upon the 
 authority of his teacher. But every time he goes over 
 the definitions, the axioms, the elementary propositions, 
 more light breaks in upon him ; the language becomes 
 familiar, and conveys clear and steady conceptions ; the 
 judgment is confirmed ; he begins to see M'hat demonstra- 
 tion is ; and it is impossible to see it without being charm- 
 ed with it. He perceives it to be a kind of evidence 
 which has no need of authority to strengthen it. He 
 finds himself emancipated from that bondage, and exults so 
 much in this new state of independence, that he spurns at 
 authority, and would have demonstration for every thing; 
 until experience teaelies him, that this is a kind of evi- 
 dence which cannot be had in most things ; and that in 
 his most important concerns, he must rest contented with 
 probability. 
 
 As he goes on in mathematics, the road of demonstra- 
 tions becomes smooth and easy ; he can walk in it firmly, 
 and take wider steps : and, at last, he acquires tlie habit, 
 not only of understanding a demons( ration, but of discov- 
 ering and demonstrating mathematical trutlis. 
 
 Thus, a man without rules of logic, may acquire the 
 habit of reasoning justly in matliematics j and I believe^ 
 he may, by like means, acquire the habit of reasoning 
 justly in mechanics, in jurisprudence, in politics, or in 
 any other science. Good sense, good examples, and as- 
 siduous exercise, may bring a man to reason justly and 
 acutely in his own profession, without rules. 
 
 But if any man think, that from this concession he 
 may infer the inutility of logic, he betrays a great want 
 
aristotxe's loeic. 157 
 
 of that art by this inference : for it is no better reason- 
 ing than this, that because a man may go from Edin- 
 burgh to London by the way of Paris, therefore any other 
 road is useless. 
 
 There is perhaps no practical art which may not be 
 acquired, in a very considerable degree, by example and 
 practice, without reducing il to rules. But practice, join- 
 ed with rules, may carry a man on in his art farther and 
 more quickly, than practice without rules. Every in- 
 genious artist knows the utility of having his art reduced 
 to rules, and by that means made a science. He is there- 
 by enlightened in his practice, and works with more as- 
 surance. By rules, he sometimes corrects his own er- 
 rors, and often detects the errors of others : he finds 
 them of great use to confirm his judgment, to justify 
 what is right, and to condemn what is wrong. 
 
 Is it of no use in reasoning, to be well acquainted with 
 the various powers of the human understanding, by which 
 we reason ? Is it of no use to resolve the various kinds of 
 reasoning into their simple elements; and to discover, as 
 far as we are able, the rules by which those elements are 
 combined in judging and in reasoning? Is it of no use, to 
 mark the various fallacies in reasoning, by which even 
 the most ingenious men have been led into error? It must 
 surely betray great want of understanding, to think these 
 things useless or unimportant. These are the things 
 which logicians have attempted ; and which they have 
 executed ; not indeed so completely as to leave no room 
 for improvements, but in such a manner as to give very 
 considerable aid to our reasoning powers. That the prin- 
 ciples laid down with regard to definition and division, 
 with regard to the conversion and opposition of proposi- 
 tions and the general rules of reasoning, are not with- 
 out use, is sufficiently apparent from the blunders com- 
 mitted by those who disdain any acquaintance with them. 
 
 Although the art of categorical syllogism is better fit- 
 ted for scholastic litigation, than for real improvement 
 in knowledge^ it is a venerable piece of antiquity, and a 
 
158 A BRIEF ACCOUNT OF 
 
 great eflfbrt of human genius. We admire the pyramids 
 of Egypt, and tlie wall of China, though useless burdens 
 upon the earth. We can bear the most minute descrip- 
 tion of them, and travel hundreds of leagues to see them. 
 If any person should, with sacrilegious hands, destroy or 
 deface them, his memory would be had in abhorrence. 
 The predicaments and prcdicables, the rules of syllogism, 
 and the topics, have a like title to our veneration as antiq- 
 uities: they are uncommon efforts, not of human power, 
 but of human genius; and they make a remarkable pe- 
 riod in the progress of human reason. 
 
 The prejudice against logic has probably been strength- 
 ened by its being taught too early in life. Boys are often 
 taught logic as they are taughttheir creed, when it isan ex- 
 ercise of memory only, without understanding. One may 
 as well expect to understand grammar before he can speak, 
 as to understand logic before he can reason. It must even 
 be acknowledged, than commonly we are capable of rea- 
 soning in mathematics more early than in logic. The ob- 
 jects presented to the mind in this science, are of a very 
 abstract nature, and can be distinctly conceived only when 
 we are capable of attentive reflection upon the operations 
 of our own understanding, and after we have been accus- 
 tomed to reason. There may be an elementary logic, 
 level to the capacity of those who have been but little 
 exercised in reasoning ; but the most important parts of 
 this science require a ripe understanding, capable of re- 
 flecting upon its own operations. Therefore to make 
 logic the first branch of science that is to be taught, is 
 an old error that ought to be corrected. 
 
abistotlb's iogic. 159 
 
 section u. 
 of the improvement of x06ic. 
 
 Iir compositions of human thought expressed by speech 
 OP by writing, whatever is excelient and whatever is 
 faulty, fall within the province, either of grammar, or of 
 rhetoric, op of logic. Propriety of expression is the prov- 
 ince of grammar ; grace, elegance, and force, in thought 
 and in expression, are the province of rhetoric; justness 
 and accuracy of thought are the province of logic. 
 
 The faults in composition, therefore, which fall under 
 the censure of logic, are obscure and indistinct concep- 
 tions, false Judgment, inconclusive reasoning, and all im- 
 proprieties in distinctions, definitions, division, or method. 
 To aid. our rational powers, in avoiding these faults, and 
 in attaining the opposite excellencies, is the end of logiej 
 and whatever there is in it that has no tendency to pro- 
 mote this end, ought to be thrown out. 
 
 The rules of logic being of a very abstract nature, ought 
 to be illustrated by a variety of real and striking exam- 
 ples taken from the writings of good authors. It is both 
 instructive and entertaining, to observe the virtues of ac- 
 curate composition in writers of fame. We cannot see 
 them, without being drawn to the imitation of them, in a 
 more powerful manner than we can be by dry rules. Nor 
 are the faults of such writers less instructive or less pow- 
 erful monitors. A wreck, left upon a shoal or upon a rock, 
 is not more useful to the sailor, than the faults of good 
 writers, when set up to view, are to those who come after 
 them. It was a happy thought in a late ingenious writ- 
 er on English grammar, to collect under the several rules, 
 examples of bad English found in the most approved au- 
 thors. It were to be wished that the rules of I(^ic were 
 illustrated in the same manner. By this means, a sys- 
 tem of logic would become a repository ; wherein what- 
 ever is most acute in judging and ia reasoning, whatever 
 
169 . A BRIET ACCOPNT OF 
 
 is most accurate in dividing, distinguishing, and defining, 
 should be laid up and disposed in order for our imitation ; 
 and wherein the false steps of eminent authors should be 
 recorded for our admonition. 
 
 After men had laboured in the search of truth near 
 two thousand years, by the help of syllogisms, lord Ba- 
 con proposed the method of induction, as a more eiiectual 
 engine for that purpose. His Novum Organum gave anew 
 turn to the thoughts and labours of the inquisitive, more 
 remarkable, and more useful, than that which the Orga- 
 num of Aristotle had given before ; and may be consid- 
 ered as a second grand era in the progress of human 
 reason. 
 
 The art of syllogism produced numberless disputes, 
 and numberless sects, who fought against each other with 
 much animosity, without gaining or losing ground ; but 
 did nothing considerable for the benefit of human life. 
 The art of induction, first delineated by lord fiacon, pro- 
 duced numberless laboratories and observatories, in which 
 nature has been put to the question by thousands of ex- 
 periments, and forced to confess many of her secrets, 
 ■which before were hid from mortals. And by these, 
 arts have been improved, and human knowledge wonder- 
 fully increased. 
 
 In reasoning by syllogism, from general principles we 
 descend to a conclusion virtually contained in them. The 
 process of induction is more arduous ; being an ascent 
 from particular premises to a general conclusion. The 
 evidence of such general conclusions is not demonstrative, 
 but probable : but when the induction is sufficiently co- 
 pious, and carried on according to the rules of art, it 
 forces conviction no less than demonstration itself does. 
 
 The greatest part of human knowledge rests upon evi- 
 dence of this kind. Indeed we can have no other for 
 general truths which are contingent in their nature, and 
 depend upon the will and ordination of the Maker of the 
 world. He governs the world he has made, by general 
 
AMSTOTIiE'a ro6ic.< 161 
 
 laws. The effects of these laws in particular phenomena 
 are open to our observation j and by observing a train of 
 uniform effects with due caution, we may at least deey- 
 pher the law of nature by which they are regulated. 
 
 Lord Sacon has displayed no less force of genius in re- 
 ducing to rules this method of reasoning, than Aristotle 
 did in the method of syllogism. His Novum Organum 
 ought therefore to be held as a most important addition 
 to the ancient logic. Those who understand it, and entei" 
 into the spirit of it, will be able to distinguish the chaff 
 from the wheat in philosophical disquisitions into the 
 works of God. They will learn to hold in due contempt 
 all hypotheses and theories, the creatures of human im- 
 agination, and to respect nothing but facts sufficiently 
 vouched, or conclusions drawn from them by a fair and 
 chaste interpretation of nature. 
 
 Most arts have been reduced to rules, after they had 
 been brought to a considerable degree of perfection by 
 the natural sagacity of artists ; and the rules have been 
 drawn from the best examples of the art that had been 
 before exhibited : but the art of philosophical induction 
 was delineated by lord Bacon in a very ample manner, 
 before the world had seen any tolerable example of iU 
 This, although it adds greatly to the merit of the author, 
 must have produced some obscurity in the work, and a 
 defect of proper examples for illustration. This defect 
 may now be easily supplied, from those authors who, in 
 their philosophical disquisitions, have most strictly pur- 
 sued the path pointed out in the Novum Organum. 
 Among these Sir Isaac Newton seems to hold the first 
 rank, having, in the third book of his Principiaj and in 
 his Optics, had the rules of the Novum Organum con- 
 stantly in his eye. 
 
 I think lord Bacon was also the first who endeavoured 
 to reduce to a system the prejudices or biases of the 
 mind, which are the causes of false judgment, and which 
 he calls, the idols of the human understanding. Some 
 late w niters of logic have very properly introduced thjn 
 
 yoi, I. 21 
 
162 A BRIES ACCOUNT A* 
 
 into their system ; but it deserves to be more copiously 
 handled, and to be illustrated by real examples. 
 
 It is of great consequence to accurate reasoning, to 
 distinguish first principles which are to be taken for 
 granted.^from propositions which require proof. All the 
 real knowledge of mankind may be divided into two parts : 
 the first consisting of self-evident propositions; the sec- 
 ond, of those which are deduced by just reasoning from 
 self-evident propositions. The line which divides these 
 two parts ought to be marked as distinctly as possible, 
 and the principles that are self-evident reduced, as f^ras 
 can be done, to general axioms. This has been done in 
 mathematics from the beginning, and has tended greatly 
 to the emolument of that science. It has lately been done 
 in natural philosophy : and by this means that science 
 has advanced more in an hundred and fifty years, than it 
 had done before in two thousand. Every science is in an 
 unformed state until its first principles are ascertained : 
 after that is done, it advances regularly, and secures the 
 ground it has gained. 
 
 Although first principles do not admit of direct proof, 
 yet there must be certain marks and characfers, by which 
 those that are truly such may be distinguished from coun- 
 terfeits. These marks ought to be described, and applied, 
 to distinguish the genuine from the spurious. 
 
 In the ancient philosophy there is a redundance, rather 
 than a defect, of first principles. Many things were as- 
 sumed under that character without a just title : that 
 nature abhors a vacuum; that bodies do not gravitate in 
 their proper place ; that the heavenly bodies undergo no 
 change ; that they move in perfect circles, and with an 
 equable motion. Such principles as these were assumed 
 in the Peripatetic philosophy, without proof, as if they 
 were self-evident. 
 
 Des Cartes, sensible of this weakness in the ancient 
 philosophy, and desirous to guard against it in his own 
 system, resolved to admit nothing until his assent was 
 forced by irresistible evidence. The first thing which 
 
16S 
 
 he found to be certain and evident was< th&t he thought, 
 and reasoned, and doubted. He found himself under a 
 necessity of believing the existence of those operations 
 of mind of which he was conscious : and having thus 
 found sure footing in this one principle of eonsciousties^, 
 he rested satisfied trith it> hoping to be able to build th6 
 whole fabric of his knowledge upon it ^ like Archimedds> 
 who wanted but one fixed point to move the whole earth. 
 Bat the foundation was too narrow ; and in liis prog- 
 ress he unawares assumes many things less evidetit than 
 those which he attempts to prove. Although be was not 
 able to suspect the testimony of consciousness, yet he 
 thought the testimony of sense, of memory, and of 
 every Other faculty, might be suspected, and ought not to 
 be received until procf was broti^ht that they are tftft 
 &llaci6us. Therefore he applies these faculti^, whose 
 ehartotei? is y^t in question, to prove, that there is an ib'- 
 finitely perfect Being who made hiiii, and who made his 
 senses, his memory, his reason, and all his faculties ^ fhslt 
 this Beibg is no deceiver, and tberefwe could not give 
 him iaoultieS (bat are fallacidus ; and that on tlnaiecMM 
 tbey dieserve credits 
 
 It is strange that tbis pbilosophei*, Who found hitHSi^lf 
 atider a necessity of yieldiitg t& the testimony of cOM- 
 «eiousnes9, did not find th^ saftie necessity Of yielding t6 
 the testimony of his senses, his memory, and his utlde^" 
 stdndiflg : and tfafat while he wstscertaintbathe doubted* 
 And reasoned, he Mas uncertain Whether two and three 
 rabde five, and whether he was dreamiffg or aW^ke. It 
 ia moi^ strange, that so acate a rcasoner shouM not pet^ 
 eeive, that his whole train of reasoning to prove that hU 
 faculties were not fallacious, was mere sophistry : for if 
 his faculties were fallacious, they might deceive him in 
 this train of reasoning | and so the conclusion, that they 
 were not fallacious, was only the testimony of his facul- 
 ties in their own favour, and might be a fallacy. 
 
 It is difficult to give any reason for distrusting oui^ 
 other faculties^ that will not reach consciousness itself. 
 
464 A HUtat ACCOUNT, &C. 
 
 And he who distrusts those faculties of judging and rea- 
 soning which God hath given him, must even rest in his 
 skepticism till he come to a sound mind, or until God 
 give him new faculties to sit in judgment upon the old. 
 If it be not a first principle, that our faculties are noi 
 fallacious, we must be absolute skeptics : for this princi' 
 pie is incapable of proof; and if it is not certain, nothing 
 else can be certain. 
 
 Since the time of Bes Cartes, it has been fashionable 
 with those who dealt in abstract philosophy, to em- 
 ploy their invention in finding philosophical arguments, 
 either to prove those truths which ought to be received 
 &8 first principles, or to overturn them : and it is not easy 
 to say, whether the authority of first principles is more 
 hurt by the first of these attempts, or by the last ; for 
 such principles can stand secure only upon their own 
 bottom ; and to place them upon any other foundation 
 than that of their intrinsic evidence, is in efiect to over- 
 turn them. 
 
 I have lately met with a vety sensible and judicioui 
 treatise, written by father Bu£Ser about fifty years ago, 
 concerning first principles, and the source of human 
 judgments, which, with great propriety, he prefixed to 
 his treatise of logic. And indeed I apprehend it is a sub- 
 ject of such consequence, that if inquisitive men can be 
 brought to the same unanimity in the first principles of 
 the other sciences, as in those of mathematics and natu- 
 ral philosophy | and why should we despair of a general 
 agreem^ent in things that are self-evident ? this might be 
 jDonsidered as a third gtand era in the progress of human 
 f-eason. 
 
AN 
 
 INQUIRY 
 
 INTO THE 
 
 PRINCIPLES OF COMMON SENSE, 
 
 THOMAS REID, D.D. F.R.S. 
 
 The Inspli^ujon of the Abnighty giveth them understondingiiK Ji>^. 
 
/.:?M^Z ViCmiAO'.y ■} "■' RK JIIC /;,* 51^ 
 
 /.l.\f.4.V-v,'.' 
 
 ■; ,: 1,^ ^iiiaJ...;'. .-j '■ '^-^ 
 
THE RIGHT HONOXIRABLE 
 
 JAMES, EARL OFFINDLATER AND SEAFIELD, 
 
 CHANCELLOR OF THE UNIVEKSITT OF OLD ABERDEEN. 
 MY LORD, 
 
 Though I appreh';nd that there are things new, and of some 
 importance, in the iollowing Inquiry, it is not without timidity 
 that I have consented to the publication of it. The subject has 
 been canvassed by msn of very great penetration and genius : 
 for who does not acknowledge Des Cartes, Malebranche, Locke, 
 Berkeley, and Hume, to be such ? A view of the human under- 
 standing, so different from that which they have exhibited, will, 
 no doubt, be condemned by many without examination, as pror 
 ceeding from temerity and vanity. 
 
 But I hope the candid and discerning few, who are capable Of 
 attending to the operations of their own minds, will weigh delib. 
 erately what is here advanced, before they pass sentence upon it. 
 To such I appeal, as the only competent judges^ If they dis- 
 approve, I am probably in, the wrong, and shall be ready to 
 change my opinion upon conviction. If they approve, the many 
 will at last yield to their authority, as they always do. 
 
 However contrary my notions are to those of the writers I 
 have mentioned, their speculations have been of great use to me, 
 and seem even to point out the road which I have taken ;, and 
 your lordship knows, that the merit of useful discoveries is some- 
 times not more justly due to those that have hit upon them, than 
 to others who have ripened them, and brought them to the birth. 
 
 I acknowledge, my lord, that I never thought of calling in ques- 
 tion the principles commonly received with regard to the human 
 understanding, until the Treatise of Human Nature vi'as pub- 
 lished, in the year 1739. The ingenious author of that treatise, 
 upon the principles of Locke, who was no skeptic, hath built a 
 system of skepticism, which leaves no. ground to believe any one 
 thing rather than its contrary. His reasoning appeared to me 
 to be just : there was therefore a necessity to call in questfon 
 
168 DEDICATION. 
 
 the principles upon which it was founded, or to admit the con- 
 clusion. 
 
 But can any ingenious mind admit this skeptical system with- 
 out reluctance ? I truly could not, my lord : for I am persuaded, 
 that absolute skepticism is not more destructive of the faith of a 
 Christian, than of the science of a philosopher, and of the pru- 
 dence of a man of common understanding. I am persuaded, 
 that the unjust live by faith as well as \hejust ; that, if all belief 
 could be laid aside, piety, patriotism, friendship, parental affec' 
 tion, and private virtue, would appear as ridiculous as knight-er- 
 rantry ; and that the pursuits of pleasure, of ambition, and of 
 avarice, must be grounded upon belief, as well as those that are 
 honourable or virtuous. 
 
 The day-labourer toils at his work, in the belief that he shall 
 receive his wages at night ; and if he had not this belief, he 
 would not toil. We may venture to say, that even the- author 
 of this skeptical system, wrote it in the belief that it should be 
 read and regarded. I hope he wrote it in the belief also, that it 
 would be useful to mankind : and perhaps it may prove so at 
 last. For I conceive the skeptical writers to be a set of men, 
 whose business it is, to pick holes in the fabric of knowledge 
 wherever it is weak and faulty ; and when these places are prop- 
 erly repaired, the whole building becomes more firm and solid 
 than it was formerly. 
 
 For my own satisfaction, I entered into a serious examination 
 of the principles upon which this skeptical system is built : and 
 was not a little surprised to find, that it leans with its whole 
 weight upon a hypothesis, which is ancient indeed, and hath 
 been very generally received by philosophers, but of which I 
 could find no solid proof The hypothesis I mean is, that noth- 
 ing is perceived but what is in the mind which perceives it : that 
 we do not really perceive things that are external, but only cer- 
 tain images and pictures of them imprinted upon the mind, 
 which are called imfiressions and ideas. 
 
 If this be true ; supposing certain impressions and ideas to ex- 
 ist in my mind, I cannot, from their existence, infer the existence 
 of any thing else ; my impressions and ideas are the only exist- 
 ences of which I can have any knowledge or conception ; and they 
 are such fleeting and transitory beings, that they can have no ex- 
 istence at all any longer than I am conscious of thein. So that, 
 
DEDICATION. 169 
 
 Upon this hypothesis, the whole universe about me, bodies and 
 spirits, sun, moon, stars, and earth, friends and relations, all 
 things without exception, which I imagined to have a permanent 
 existence, whether I thought of them or not, vanish at once ; 
 
 And, like the baseless fabric of a vision. 
 Leave not a track behind. 
 
 I thought it unreasonable, my lord, upon the authority of phi- 
 losophers, to admit a hypothesis, which, in my opinion, overturns 
 all philosophy, all religion and virtue, and all common sense : 
 and finding that all the systems concerning the human under- ( 
 standing which I was acquainted with, were built upon this hy- ' 
 pothesis, I resolved to inquire into this subject anew, without 
 regard to any hypothesis. 
 
 What I now humbly present to your lordship, is the fruit of 
 this inquiry, so far only as it regards the five senses ; in which 
 I claim no other merit, than that of having given great attention 
 to the operations of my own mind, and of having expressed with 
 all the perspicuity I was able, what I conceive every man, who 
 gives the same attention, will feel and perceive. The produc- 
 tions of imagination, require a genius which soars above the 
 common rank ; but the treasures of knowledge are commonly 
 buried deep, and may be reached by those drudges M'ho can dig 
 with labour and patience, though they have ndt wings to Hy. 
 The experiments that were to be made in this investigation suit- 
 ed me, as th^y required no other expense, but that of time and 
 attention, which I could bestow. The leisure of an academical 
 life, disengaged from the pursuits of interest and ambition ; the 
 duty of my profession, which obliged me to give prelections 
 on these subjects to the youth ; and an early inclination to spec- 
 ulations of this kind, have enabled me, as I flatter myself, to give 
 a more minute attention to the subject of this Inquiry, than has 
 been given before. % 
 
 My thoughts upon this subject were, a good many years ago, 
 put together in another form, for the use of my pupils ; and af- 
 terward were submitted to the judgment of a private philosoph- 
 ical society, of which I have the honour to be a member. A 
 great part of this Inquiry was honoured even by your lordship's 
 perusal. And the encouragement which you, my lord, and oth- 
 ers, whose friendship is my boast, and whose judgment I rever- 
 
 Tox. I. 22 
 
170 BBDICATIOW. 
 
 ence, were pleased to give me, counterbalanced my timidity and 
 diffidence, and determined me to offer it to the public. 
 
 If it appears to your lordship to justify the common sense and 
 reason of mankind, against the skeptical subtilties which, m this 
 age, have endeavoured to put them out of countenance ; if it 
 appears to throw any new light upon one of the noblest parts 
 of the divine workmanship ; your lordship's respect for the arts 
 and sciences, and your attention to every thing which tends to 
 the improvement of them, as well as to every thing else that con- 
 tribuies to the felicity of your country, leave me no room to 
 doubt of your favourable acceptance of this essay, as the fruit of 
 my industry in a profession wherein I was accountable to your 
 lordship ; and as a testimony of the great esteem and respecf 
 wherewith I have the honour to be, 
 My Lord, 
 
 Your Lordship's 
 most obliged, and 
 most devoted servant, 
 
 THOiVIAS REID, 
 
INQUIRY INTO THE HUMAN MIND. 
 
 CHAP. I. 
 INTRODUCTION. 
 
 SECTION I. 
 
 THE IMPORTANCE OF THE SUBJECT, AND THE MEANS 
 OF PROSECUTING IT, 
 
 The fabric oFthe fiuman mind is curious and wonder- 
 ful, as well as ihat of ihe human body. TLe faculties of 
 the one are with no less wisdom adapted to their several 
 ends, than the organs of the otiier. Nay, it is reasonable 
 to think, that as the mind is a nobler work, and of a higher 
 order than the body, even more of (he wisdom and skill 
 of the Divine Architect hath been employed in its struc- 
 ture, it is therefore a subject highly worthy of inquiry on 
 its own account, but still more worthy on account of the 
 extensive influence which the knowledge of it bath over 
 every other branch of science. 
 
 In the arts and sciences which have least connection 
 with the mind, its faculties are the engines which we 
 must employ ; and (he better we understand (heir nature 
 and use, their defects and disorders, the more skilfully 
 Me shall apply them, and with the greater success. But 
 in the noblest arts, tlie mind is also the subject upon 
 which we operate. The painter, the poet, the actor, (he 
 orator^ the moralist^ and the statesman^ attempt to ope« 
 
172 OF THE HUMAIf MIND. 
 
 rate upon the mind in different ways, and for different 
 ends ; and they succeed, according as they touch proper- 
 ly the strings of the human frame. Nor can their sev- 
 eral arts ever stand on a solid foundation, or rise to the 
 dignity of science, until they are built on the principles of 
 the human constitution. 
 
 Wise men now agree, or ought to agree in this, that 
 tliere is but one way to the knowledge of nature's works j 
 the way of observation and experiment. By our consti- 
 tution, we have a strong propensity to trace particular 
 facts and observations to general rules, and to apply such 
 general rules to account for other effects, or to direct us 
 in the production of them. This procedure of the under- 
 standing is familiar to every human creature in the com- 
 mon affairs of life, and it is the only one by which any 
 real discovery in philosophy can be made. 
 
 The man who first discovered tliat cold freezes water, 
 and that heat turns it into vapour, proceeded on the same 
 general principles, and in the same method, by which 
 Newton discovered the law of gravitation, and the prop- 
 erties of light. His regulce philosophandi are maxims of 
 common sense, and are practised every day in common 
 life J and he who philosophizes by other rules, either con- 
 cerning tlie material system, or concerning the mind, mis- 
 takes his aim. 
 
 Conjectures and theories are the creatures of men, and 
 will always be found very unlike the creatures of God. If 
 we would know the works of God, we must consult them- 
 selves with attention and humility, without daring to add 
 any thing of ours to what they declare. A just interpre- 
 tation of nature is the only sound and orthodox philoso- 
 phy : whatever we add of our own, is apocryphal, and of 
 no authority. 
 
 All our curious theories of the formation of the earth, 
 of the generation of animals, of the origin of natural and 
 moral evil, so far as they go beyond a just induction from 
 facts, are vanity and folly, no less than the vortices of 
 Des Cartes, or the Archseus of Paracelsus. Perhaps the 
 
INTHODTrCTlON. 178 
 
 pfailosopliy of the mind has been no less adulterated by 
 theories than that of the material system. The theory 
 of ideas is indeed very ancient, and hath been very uni- 
 versally received ; but as neither of these titles can give 
 it authenticity, they ought not to screen it from a free 
 and candid examination ; especially in this age, when it 
 hath produced a system of skepticism, that seems to tri- 
 umph over all science, and even over the dictates of com- 
 mon sense. 
 
 All that we know of the body, is owing to anatomical 
 dissection and observation, and it must be by anatomy of 
 the mind that we can discover its powers and principles. 
 
 SECTION II. 
 tWE IMPEDIMENTS TO OUR KNOWLEDGE OF THE MIT^D. 
 
 But it must be acknowledged, that this kind of anat- 
 omy is niucii more diflicult than the other ; and therefore 
 it needs not seem strange, that mankind have made less 
 progress in it. To attend accurately to the operation of 
 our minds, and make them an object of thought, is no 
 easy matter even to the contemplative, and to the bulk 
 of mankind is next to impossible. 
 
 An anatomist who hath happy opportunities, may have 
 access to examine with !iis own eyes, and with equal ac- 
 curacy, bodies of all different ages, sexes, and conditions ; 
 so that what is defective, obscure, or preternatural in 
 ot»e. may be discerned clearly, and in its most perfect 
 state, in another. But the anatomist of the mind cannot 
 have the same advantage. It is his own mind only that 
 he can examine, with any degree of accuracy and distinct- 
 ness. This is the only subject he can look into. He 
 may, from outward signs, collect the operations of other 
 minds ; but these signs are for the most part ambiguous, 
 and must be interpreted by what he perceives within him- 
 self. '■ 
 
±7i or THE HUMAN MIWD. 
 
 So ihai if a philosoplier could delineale to us, distinctly 
 and nielliodically. all the operations of the (hinkin,s; prin- 
 ciple Mitliin him, which no man was ever able to do, this 
 Would be only the anatomy of one particular subject ; 
 which would be both deficient and erroneous, if applied 
 to human nature in .s;eneral. For a little reflection niay 
 saliitfy us, that the difference of minds is greater than 
 that of any other beings which we consider as of Ibe same 
 species. 
 
 Of the various powers and faculties we possess, there 
 are some which nature seems both to have planted and 
 reared, so as to have left nothing to human industry. 
 Sucli are the powers which we have in common with the 
 brutes, and which are necessary to the preservation of 
 the individual, or the continuance of the kind. There 
 are other powers, of which nature hath only planted the 
 seeds in our minds, but hath left the rearing of them to 
 human culture. It is by the proper culture of these that 
 we are capable of all those improvements in intellectuals, 
 in taste, and in morals, which exalt and dignify human 
 nature; while, on the other band, the neglect or perver- 
 sion of them makes its degeneracy and corruption. 
 
 The two legged animal that eats of nature's dainties, 
 what his taste or appetite craves, and satisfies his thirst 
 at the crystal fountain, who propagates his kind as oc- 
 casion and lust prompt, repels injuries, and takes alter- 
 nate labour and repose, is, like a tree in the forest, purely 
 of nature's growth. But this same savage hath within 
 hini the seeds of the logician, the man of taste and breed- 
 ing, the orator, the statesman, the man of virtue, and the 
 saint; which seeds, though planted in his mind by na- 
 ture, yet, through want of culture and exercise, must lie 
 for ever buried, and be hardly perceivable by himself op 
 by others.* 
 
 • Man, in his most savage state, is born with such a constitution of soul, that 
 he is capable of becoming, ihrougb the aid of human learning, and ihr influ- 
 ence of refined society, a logician, an orator, a statesman, a roan of taste and 
 breeding. By a virluous education he may be made to possess what la GOBfa- 
 
INTBODtTCTIOW. 175 
 
 The lowest degree of social life will bring to light some 
 of (hose principles which la.v liifl in (he savage stale : and 
 according (o his training, and company, and nianner of 
 life, some of (hem. ei(hor by iheir native vigour, or by 
 the force of culture, will (hrive and grow up to great 
 peifeclion ; odiers will be strangely perverted from their 
 natural, form ; and o(hers checked, or perhaps qui(e 
 eradicated. 
 
 This makes human nature so various and multiform 
 in the individuals (hat partake of i(, tha(. in point of mor- 
 als, and in(elleciual endowmen(s. it fills up all that gap 
 which we conceive to be be(ween bru(es and devils below, 
 and the celesdal orders above ; and such a prodigious di- 
 vepsi(y of minds must make i( extremely difficult to dis- 
 cover (he common principles of (he species. 
 
 The language of philosophers, with regard to the orig- 
 inal faculties of the mind, is so adapted to (he prevailing 
 
 monly called virtue ; and by the communication of spiritual influence from 
 heaven, without the creation of any new natural faculties, he may become 
 a saint (d no other sense has the savage within him the seeds of a smnt. 
 By receiving human knowledge, he obtains power in the human sciences j 
 and by receiving spiritual knowledge from Him who alone can give it, he 
 obtains power to perform the actions of a spiritual man. Teach any one 
 the principles of mathematics, and he will have the power of solving math- 
 ematical problems Let any one be taught, divinely, to know God and .lesus 
 Christ, and he will then have power to become a saint Neither in common 
 concerns of life, nor in spiritual things, can any one know what he has no 
 meand of knowing. How, then, could any person have faith and hope, with- 
 out the spiritual perception of gospel truth to be accredited, and of those 
 good things which are the objects of hope. How should he have evangeli- 
 cal perceptions, without power lo perceive, and the exhibition of the object 
 to be perceived. President Kdwards, in his " Treatise concerning Kelig- 
 ious Alfebtions," observes, *'that those gracious influences which the saints 
 are subjects of, and the eifects of God's Spirit which they experience, are 
 entirely above nature, altogether of a different kind from »ny thing that 
 men find within themselves by nature, or only in the exercise of naturat 
 principles ; and are things which no improvement of those qualifications, 
 or principles that are natural, no advancing or exalting them to higher de- 
 grees, and no kind of composition of them, will ever bring men to ; because 
 they not only differ from what is natural, and from every thing that natural 
 ^en experience, in degree and circumstMnces, but also in kind ; and are of 
 a nature vastly more excellent." This statemeut accords no less with sound 
 philosophy than with the Holy Scriptures. AittEiiicAN Eb. 
 
4^6 »T THE HUMAN MIND. 
 
 system, that it cannot fit any other ; like a coat that fits 
 the man for whom it was made, and shows him to ad- 
 vantage, which yet will set very awkward upon one of a 
 different make, although perhaps as handsome and as well 
 proportioned. It is hardly possible to make any innova- 
 tion in our philosophy concerning the mind and its ope- 
 rations, without using new words and phrases, or giving 
 a different meaning to those that are received ; a liberty 
 which, even when necessary, creates prejudice and mis- 
 construction, and which must wait the sanction of time 
 to authorize if. For innovations in language, like those 
 in religion and government, are always suspected and 
 disliked by the many, till use has made them familiar, 
 and prescription hath given them a title. 
 
 If the original perceptions and notions of the mind 
 were to make their appearance single and unmixed, as 
 we first received them from the hand of nature, one ac- 
 customed to reflection would have less difficulty in trac- 
 ing them ; hut hefore we are capable of reflection, they 
 are so mixed, compounded and decompounded, by habits, 
 associations and abstractions, that it is hard to know what 
 they were originally. The mind may in this respect be 
 compared to an apothecary or a chymist, whose materials 
 indeed are furnished by nature; but for the purposes of 
 his art, he mixes, compounds, dissolves, evaporates, and 
 sublimes them, till they put on a quite different appear* 
 ance ; so that it is very difiicult to know what they were 
 at first, and much more to bring them back to their orig- 
 inal and natural form. And this work of the mind is not 
 carried on by deliberate acts of mature reason, which we 
 might recollect, but by means of instincts, habits, asso- 
 ciations, and other principles, which operate before we 
 come to the use of reason ; so that it is extremely difficult 
 for the mind to return upon its own footsteps, and trace 
 back those operations which have employed it since it 
 first began to think and to act. 
 
 Could we obtain a distinct and full history of all that 
 hath passed in the mind of a child, from the beginning of 
 
INTRODUCTIOir. 177 
 
 life and sensation, till it grows up to the use of reason; 
 how its infant faculties began to work, and how they 
 brought forth and ripened all the various notions, opin- 
 ions, and sentiments, which we iind in ourselves when we 
 come to be capable of reflection : this would he a treasure 
 of natural history, wiiich would probably give more light 
 into the human faculties, than all the systems of philoso- 
 phers about them since the beginning of the world. But 
 it is in vain to wish for what nature has not put within 
 the reach of our power. ReBeetion, the only instrument 
 by which we can discern the powers of the mind, comes 
 too late to observe the progress of nature, in raising them 
 from their infancy to perfection. 
 
 It must therefore require great caution, and great ap. 
 plication of mind, for a man that is grown up in all the 
 prejudices of education, fashion, and philosophy, to un^ 
 ravel his notions and opinions, till he finds out the simple 
 and original principles of his constitution, of which no 
 account can be given but the will of our Maker. This 
 may be truly called an analysis of the human faculties ; 
 and till this is performed, it is in vain we expect any just 
 system of (he. mind ; that is, an enumeration of the orig- 
 inal powers and laws of our constitution , and an explica- 
 tion from them of the various phenomena of human na' 
 ture. 
 
 Success in an inquiry of this kind, it is not in human 
 power to command ; but perhaps it is possible, by caution 
 and humility, to avoid error and delusion. The labyrinth 
 may be too intricate, and the thread too fine, (o be traced 
 through all its windings ; but if we stop where we can 
 trace it no further, and secure the ground we have gained, 
 there is no harm done ; a quicker eye may in time trace 
 it further. 
 
 It is genius, and not the want of it, that adulterates, 
 philosophy, and fills it with error and false theory. A{ 
 creative imagination disdains the mean offices of digging 
 for a foundation, of removing rubbish, and carrying ma. 
 terials : leaving these servile employments to the drud,^s 
 
 YOU I, 38 
 
178 or THE HUMAN MINU. 
 
 ia science, it plans a design, and raises a fabric. Inven- 
 tion supplies materials where they are wanting, and fancy 
 adds colouring, and every befitiing ornament. The work 
 pleases the eye, and wants nothing but solidity and a good 
 foundation. It seems even to vie with the works of na- 
 ture; till some succeeding architect blows it into rubbish, 
 and builds as goodly a fabric of his own in its place. Hap- 
 pily for the present age, the castle builders employ them- 
 selves more in romance than in philosophy. That is un- 
 doubtedly their province, and in those regions 4he off- 
 spring of fancy is legitimate ; but in philosophy it is all 
 spurious. 
 
 SECTION in. 
 
 THE PRESENT STATE OE THIS PAKT OE PHIIOSOPHT. 
 OF DES CARTES, MAIEBKANCHE, AND I,OCKE. 
 
 That our philosophy concerning the mind and its fac- 
 ulties, is but in a very low state, may be reasonably con- 
 jectured, even by those who never have narrowly exam- 
 ined it. Are there any principles with regard to the 
 mind, settled with that perspicuity and evidence, which at- 
 tends the principles of mechanics, astronomy, and optics? 
 These are really sciences built upon laws of nature which 
 universally obtain. What is discovered in them, is no 
 longer matter of dispute : future ages may add to it, but 
 till the course of nature be changed, what is already es- 
 tablished can never be overturned. But when we turn 
 our attention inward,' and consider the phenomena of hu- 
 man thoughts, opinions, and perceptions, and endeavour 
 to trace them to the general laws and the first principles 
 of our constitution, we are immediately involved in dark- 
 ness and perplexity. And if common sense, or the prin- 
 ciples of education, happen not to be stubborn, it is odds 
 but we end in absolute skepticism. 
 
 Des Cartes finding nothing established in this part of 
 philosophy, in order to lay the foundation of it deep, re- 
 
INTRODrCTIOWi 179 
 
 solved not to believe iiis own existence till he should be 
 able to give a good reason for it. Be was, perhaps, the 
 first that took up such a resolution ; .but if he could in, 
 deed have effected his purpose, and really become diffi. 
 dent of his existence, his case would have been deplorable, 
 and without any remedy from reason or philosophy. A 
 man that disbelieves his own existence, is surely as unfit 
 to be reasoned with, as a man Ihat believes he is made of 
 glass. There may be disorders in the human frame that 
 may produce such extravagancies ; but (hey Avill never be 
 cured by reasoning. Des Cartes indeed would make us 
 believe that he got out of this delirium by this logical 
 argument, Cogito, ergo sum. But it is evident he was in 
 his senses all the time, and never seriously doubted of his 
 existence. For he takes it for granted in this argument^ 
 and proves nothing at all. I am thinking, says be, there- 
 fore I am : and is it not as good reasoning to say, I am 
 sleeping, therefore I am ? or, I aih doing nothing, there- 
 fore I am ? If a body moves, it must exist> no doubt ; but 
 if it is at rest, it must exist likewise. 
 
 Perhaps Des Cartes meant not to assume bis own ex- 
 istence in this enthymeme, but the existence of thought | 
 and to infer from that (he existence of a mind, or subject 
 of thought. But why did he not prove the existence of his 
 thought? Consciousness, it may be said, vouches that. 
 But who is voucher for consciousness ? can any man prove 
 (hat his consciousness may not deceive him ? No man can : 
 nor can we give a better reason for trusting to it, than that 
 every man, while his mind is sound, is determined, by the 
 constitution of his nature, to give implicit belief to it, and 
 to laugh at, or pity, the man who doubts its testimony. 
 And is not every man, in his wits, as much determined to 
 take his existence upon trust as his consciousness 7 
 
 The other proposition assumed in this argument, that 
 thought cannot be without a mind or subtjeot, is liable to 
 the same objection : not that it wants evidence ; but that 
 its evidence is no clearer, nor more immediate, than that 
 «f the proposittoa to be proved by it. And taking all 
 
180 61F THE HUMAN MIUD. 
 
 these propositions together. I think, I am conscious, evet^ 
 thing that thinks, exists, I exist j would not every sober man 
 form the same opinion of the man who seriously doubted 
 any one of them ? And if be was his friend, would he not 
 hope for his cure from physio and good regimen, rather 
 than from metaphysic and logic ? 
 
 But supposing it proved, that my thought and my con- 
 sciousness must have a subject, and consequently that I 
 exist, bow do I know that all that train and succession of 
 thoughts whicli I remember belong to one subject, and 
 that the I of this moment, is the very individual I of yes- 
 terday, and of times past ? 
 
 Des Cartes did not think proper to start this doubt : but 
 Locke has done it ; and, in order to resolve it, gravely 
 determines, that personal identity consists in conscious- 
 ness ; that is, if you are conscious that you did such a thing 
 a twelvemonth ago, this consciousness makes you to be the 
 very person that did it. Now, consciousness of what is 
 past, can signify nothing else but the remembrance that 
 I did it. So that Locke's principle must be, that identity 
 consists in remembrance ; and consequently a man must 
 lose his personal identity with regard to every thing he 
 forgets. 
 
 Nor are these the only instances whereby our philos- 
 ophy concerning the mind appears to be very fruitful in 
 creating doubts, but very unhappy in resolving them. 
 
 Des Cartes, Malebranche, and Locke, have all employ- 
 ed their genius and skill, to prove the existence of a ma- 
 terial world ; and with very bad success. Poor untaught 
 mortals believe undoubtedly, that there is a sun, moon, 
 and stars ; an earth, which we inhabit; country, friends, 
 and relations, which we enjoy ; land, houses and move- 
 ables, which we possess. But philosophers, pitying the 
 the. credulity of the vulgar, resolve to have no faith but 
 what is founded upon reason. They apply to philosophy 
 to furnish them with reasons for the belief of those things, 
 which all mankind have believed without being able to 
 igive any reason for it. And surely one would expect, 
 
INTRODUCTION. 181 
 
 thai, in matters of such importance, the proof would not 
 be difficult: but it is the must difficult thing in the worlds 
 For these three great men, with the best goodwill, have 
 not been able, from all the treasures of philosophy, to 
 draw one argument, that is lit to convince a man that can 
 reason, of the existence of any one thing without himj 
 Admired Philosophy! daughter of light! parent of wis- 
 dom and knowledge ! if thou art she ! surely thou hast 
 not yet arisen upon the human mind, nor blessed us with 
 more of thy rays, than are sufficient to shed a "darkness 
 visible" upon the human faculties, and to disturb that re- 
 pose and security which happier mortals enjoy, who never 
 approached thine altar, nor felt thine influence ! But if 
 indeed thou hast not power to dispel those clouds and 
 phantoms which thou hast discovered or created, with- 
 draw this penurious and malignant ray : f despise philos- 
 ophy, and renounce its guidance ; let my soul dwell with 
 ciommon sense. 
 
 SECTION IV. 
 APOIOGT FOR THOSE PHILOSOPHKES. 
 
 But instead of despising the dawn of light, we ought 
 rather to hope for its increase : instead of blaming the 
 philosophers I have mentioned, for the defects and blem- 
 ishes of their system, we ought rather to honour their 
 memories, as the first discoverers of a region in philos- 
 ophy formerly unknown I and, however lame and imper- 
 fect the system may be, they have opened the way to fu- 
 ture discoveries, and are justly entitled to a great share 
 in the merit of them. They have removed an infinite 
 deal of rust and rubbish, collected in the ages of scholas- 
 tic sophistry, which had obstructed the way. They have 
 put us in the right road, that of experience and accurate 
 reflection. They have taught us to avoid the snares of 
 ambiguous and ill-defined words, and have spoken and 
 thought upon this subject with a distinctness and perspi- 
 
188 or THE HUMAN MIND. 
 
 cuity formerly unknown. They made many openings that 
 may lead to the discovery of truths which they did not 
 reach, or to the detection of errors in which they were 
 involuntarily entangled. 
 
 It may be observed, that the defects and blemishes in 
 the received philosophy concerning the mind, which have 
 most exposed it to the contempt and ridicule of sensible 
 men, have chiefly been owing (o this ; that the votaries 
 of this philosophy, from a natural prejudice in her favour, 
 have endeavoured to extend her jurisdiction beyond its 
 just limiU, and to call to her bar the dictates of common 
 sense. But these decline this jurisdiction j they disdain 
 the trial of reasoning, and disown its authority ; they 
 neither claim its aid, nor dread its attacks. 
 
 In this unequal contest betwixt common sense and phi- 
 losophy, the latter will always come oflTboth with dishon- 
 our and loss; nor can she ever thrive till this rivalship 
 is dropped, these encroachments given up, and a cordial 
 friendship restored : for, in reality, common sense holds 
 nothing of philosophy, nor needs her aid. But, on the 
 other hand, philosophy, if I may be permitted to change 
 the metaphor, has no other root but the principles of com- 
 mon sense ; it grows out of them, and draws its nourish- 
 ment from them : severed from this root, its honours 
 wither, its sap is dried up, it dies and rots. 
 
 The philosophers of the last age ^vhom I have mention- 
 ed, did not attend to the preserving this union and sub- 
 ordination so carefully as the honour and interest of phi- 
 losophy required : but those of the present have waged 
 open war with common sense, and hope to make a com- 
 plete conquest of it by the subtilties of philosophy ; an 
 attempt no less audacious and vain, than that of the giants 
 to dethrone almighty Jove. 
 
INTRODUCTIOW. IgS 
 
 SECTION II. 
 
 OF BISHOP bekkbiet; the treatise of human ka- 
 
 TUKEJ AND OF SKEPTICISM. 
 
 The present age, I apprehend, has not produced i\to 
 more acute or more practised in this part of philosophy 
 than the Bishop of Cloyne, and the author of the Treatise 
 of Human Nature. The first was no friend to skepti- 
 cism, but had that warm coucera for religious and moral 
 principles which became his order: yet the result of his 
 inquiry was a serious conviction, that there is no such 
 thing as a material world ; nothing in nature but spirits 
 and ideas ; and that the belief of material substances, and 
 of abstract ideas, are the chief causes of all our errors in 
 philosophy, and of all infidelity and heresy in religion. 
 His arguments are founded upon the principles which 
 were formerly laid down by Des Cartes, Malebranche, 
 and Locke, and which have been very generally receivedij' 
 
 And the opinion of the ablest judges seems to be, that 
 they neither have been, nor can be confuted ; and that 
 he hath proved, by unanswerable arguments, what no man 
 in his senses can believe. 
 
 The second proceeds upon the same principles, but 
 carries them to their full length ; and as the Bishop un- 
 did the whole material world, this author upon the same 
 grounds, undoes the world of spirits, and leaves nothing 
 in nature but ideas and impressions, without any subject 
 on which tliey may be impressed. 
 
 It seems to be a peculiar strain of humour in this author, 
 to set out in his introduction, by promising with a grave 
 face, no less than a complete system of the sciences, upon 
 a foundation entirely new, to wit, that of human nature ; 
 when the intention of the whole work is to shew, that 
 there is neither human nature nor science in the world. 
 It may perhaps be unreasonable to complain of this con- 
 duct in an author, who neither believes his own existence, 
 nor that of bis reader | and therefore could not mean to 
 
1S4 OF THE HtMAN MIND. 
 
 disappoint him, or to laugh at his credulity. Yet I can- 
 not imagine, that the author of the Treatise of Human 
 Nature is so skeptical as to plead this apology. He be- 
 lieved, against his principles, that he should be read, and 
 that he should retain his personal identity, till he reaped 
 the honour and reputation justly due to his metaphysical 
 acumen. Indeed he ingeniously acknowledges, that it 
 ■was only in solitude and retirement that he could yield 
 any assent to his own philosophy ; society, like daylight, 
 dispelled (he darkness and fogs of skepJicism, and made 
 him yield to the dominion of common sense. Nor did I 
 ever hear him charged with doing any thing, even in sol- 
 itude, that argued such a degree of skepticism, as his prin- 
 ciples maintain. Surely if his friends apprehended this, 
 they would have the charity never to leave him alone. 
 
 Pyrrho the Elean,the father of this philosophy, seems 
 to have carried it to greater perfection than any of his 
 successors ; for if we may believe Antigonus the Carystian, 
 quoted by Diogenes Laertius, his life corresponded to his 
 doctrine. And therefore, if a cart run against him, or 
 a dog attacked him, or if he came upon a precipice, he 
 would not stir a foot to avoid the danger, giving no 
 credit to his senses. But his attendants, who, happily 
 for him, were not so great skeptics, took care to keep him 
 out of harm's way; so that he lived till he was ninety 
 years of age. Nor is it to be doubted, but this author's 
 friends would have been equally careful to keep him from 
 harm, if ever his principles had taken too strong ahold 
 of him. 
 
 It is probable the Treatise of Human Nature was not 
 written in company ; yet it contains manifest indications, 
 that the author every now and then relapsed into the 
 faith of the vulgar, and eonld hardly, for half a dozen 
 pages, keep up the skeptical character. 
 
 In like manner, the great Pyrrho himself forgot his 
 •principles on some occasions ; and is said once to have 
 been in such a passion with his cook, who probably had not 
 roasted his dinner to his mind, that with the spit in his 
 
INTRODUCTION. 185 
 
 hand, and the meat upoa it, he pursued him even into 
 the market-place. 
 
 It is a bold philosophy that rejects, without ceremony, 
 principles which ii-resistibly govern the belief and the 
 conduct of all mankind in the common concerns of life; 
 and to which the philosopher himself must yield, after 
 he imagines he hath confuted them. Such principles are 
 older, and of more authority, than philosophy : she rests 
 upon them as her basis, no( they upon her. If she could^ 
 overturn them, she must be buried in their ruins ; but all 
 the engines of philosophical subliliy are too weak for this 
 purpose ; and the attempt is no less ridiculous, than if a 
 mechanic should contrive an axis in peritroehio to remove 
 the earth out of its place; or if a mathematician should 
 pretend to demons! rate, that things equal to the same 
 thing, are not equal to one another. 
 
 Zeno endeavoured to demonstrate the impossibility of 
 motion ; Hobbes, that there was no difference between 
 right and wrong; and this author, that no credit is to be 
 given to our senses, to our memory, or even to demon- 
 stration. Such philosophy is justly ridiculous, even to 
 those who cannot detect the fallacy of it. It can have 
 no other tendency, than to shew the acuteness of the soph- 
 ist, at the expense of disgracing reason and human na> 
 ture, and making mankind Yahoos. 
 
 SECTION VI. 
 OF THE TREATISE OT HUMAN NATURE. 
 
 There are other prejudices against this system of hu- 
 man nature, which, even upon a general view, may make 
 one diffident of it. 
 
 Des Cartes, Hobbes, and this author, have each of them 
 given us a system of human nature; all undertaking 
 too vast for any one man, how great soever his genius 
 and abilities may be. There must surely be reasoa 
 
 Tox. I. 24i 
 
186 OF THE HUMAN MIND. 
 
 to apprehend, that many parts of human nature never 
 came under their observation ; and (hat others have been 
 stretched and distorted, to fill up blanks, and complete 
 the system. Christopher Columbus, or Sebastian Cabot 
 might almost as reasonably have undertaken to give us a 
 complete map of America. 
 
 There is a certain character and style in nature's works, 
 which is never attained in the most perfect imitation of 
 them. This seems to be wanting in the systems of hu- 
 man nature Ihave mentioned, and particularly in thelast. 
 One may see a puppet make a variety of motions and ges- 
 ticulations, which strike much at first view ; but when it 
 is accurately observed, and taken to pieces, our admira- 
 tion ceases ; we comprehend tlie whole art of the maker. 
 How unlike is it to that which it represents ; what a poop 
 piece of work compared with the body of a man. whose 
 structure the more we know, the more wonders we dis- 
 cover in it. and tlie more sensible we are of our ignorance ! 
 Is the mechanism of the mind so easily comprehended, 
 when that of the body is so difficult ? Yet by this system, 
 .ithree laws of association, joined to a few original feelings, 
 explain the whole mechanism of sense, imagination, mem- 
 ory, belief, and of all the actions and passions of the mind. 
 Is this the man that nature made ? I suspect it is not so 
 easy to look behind the scenes in nature's work. This is 
 a puppet surely, contrived by too bold an apprentice of 
 nature, to mimic her work. It shews tolerably by candle 
 lights but brought into clear day, and taken to pieces, it 
 will appear to be a man made with mortar and a trowel. 
 The more we know of other parts of nature, the more 
 we like and approve theuj. The little I know of the 
 planetary system ; of the earth which we inhabit ; of 
 minerals, vegetables, and animals ; of my own body, and of 
 the laws which obtain in these parts of nature; opens to 
 my mind grand and beautiful scenes, and contributes 
 equally to my happiness and power. But when I look 
 within, and consider the mind itself which makes me ca- 
 pable of all these prospects and enjoyments j if it is in- 
 
INTKODUCTION. 187 
 
 deed what the Treatise of Human Nature makes it, I find 
 I have been only in an enchanted caslKi, imposed upon by 
 spectres and apparitions. I blush inwardly to think how I 
 have been deluded ; I am ashamed of my frame, and can 
 hardly forbear expostulaiing with my destiny : Is this 
 thy pastime, O Nature, to put such tricks upon a silly 
 creature, and then to take off tlie mask, and shew him 
 how he hath been befooled ? If this is the philosophy of 
 human nature, my soul enter thou not into her secrets. 
 Jt is surely the forbidden tree of knowledge ; I no sooner 
 taste of it, than I perceive myself naked, and stripped of 
 all things, yea, even of my very self. I see myself, and 
 the whole frame of nature, shrink into fleeting ideas, 
 which, like Epicurus's atoms, dance about in emptiness. 
 
 SECTION VII. 
 
 THE SYSTEM OF AXl THESE AUTHORS IS THE SAME, 
 AND rEADS TO SKEPTICISM. 
 
 But what if these profound disquisitions into the first 
 principles of human nature, do naturally and necessai-ily 
 plunge a man into this abyss of skepticism ? May we not 
 reasonably judge so from what hath happened ?,/bes Cartes 
 no sooner began to dig in this mine, than skepticism was 
 ready to break in upon him. He did what he could to 
 shut it out. Malebranche and Locke, who dug deeper, 
 found the difficulty of keeping out this enemy still to in- 
 crease; but they laboured honestly in the design. Then 
 Berkeley, who carried on the work, despairing of secur-; 
 ing all. bethought himself of an expedient : by giving up 
 the material world, which he thought might be spared; 
 without loss, and even with advantage, he hoped, by 
 an impregnable partition, to secure the world of spirits. 
 But, alas ! the Treatise of Human Nature wantonly sap-\ 
 ped the foundation of this partition, and drowned all in' 
 one universal deluge. 
 
188 eF THE HUMAN MINB. 
 
 These facts, which are undeniable, do indeed give rea-* 
 son to apprehend, ihat Des Cartes's system of the human 
 understanding, which I shall beg leave to call the ideal 
 system, and which, with some improvements made by later 
 writers, is now generally received, hath some original de- 
 fect; that this skepticism is inlaid in it, and. reared along 
 with it; and, therefore, that we must lay it open to the 
 foundation, and examine the materials, before we can ex^ 
 pect to raise any solid and useful fabric of knowledge on 
 this subject. 
 
 SECTION VIII. 
 WE OUGHT NOT TO DESPAIR 01 A BETTEH, 
 
 But is this to be despaired of, because Des Cartes and 
 his followers have failed ? By no means. This pusilla- 
 nimity would be injurious to ourselves, and injurious to 
 truth. Useful discoveries are sometimes indeed the effect 
 of superior genius, but more frequently they are the birth 
 of time and of accidents. A traveller of good judgment 
 may mistake his way, and be unawares led into a wrong 
 track ; and while the road is fair before him, he may go 
 on without suspicion and be followed by others ; but when 
 it ends in a coal-pit, it requires no great judgment to 
 know that he hath gone wrong, nor perhaps to find out 
 >vhat had misled him. 
 
 In the mean time, the unprosperous state of this part 
 of philosophy hath produced an effect, somewhat discour- 
 aging indeed to any attempt of this nature, but an effect 
 which might be expected, and which time only and better 
 success can remedy. Sensible men, who never will be 
 skeptics in matters of common life, are apt to treat with 
 sovereign contempt every thing that hath been said, or is 
 to be said, upon (his subject. It is metaphysic, say they : 
 who minds it ? Let scholastic sophisters entangle them- 
 selves in their own cobwebs ; I am resolved to take my 
 
INTRODFCTIOJf. 189 
 
 own existence, and the existence of other things, upon 
 trust; and to believe thai snow is cold, and honey sweet, 
 •whatever they may say to the contrary. He must either 
 be a fool, or want to make a fool of me, that would rea- 
 son me out of my reason and senses. 
 
 I confess I know not what a skeptic can answer to this,| 
 nor by what good argument lie can plead even for a hear-| 
 ing; for either his rea'.oning is sophistry, and so deserves^ 
 contempt; orihcreisno (puth in the'human faculties,| 
 and then why should we reason ? * 
 
 If therefoi-e a man find himself entangled in these met- 
 aphysical toils, and can find no other way to escape, let 
 him bravely cut the knot which he cannot loose, curse 
 metaphysic, and dissuade every man from meddling with 
 it. For if I have been led into bogs and quagmires by 
 following an ignis futuus, what can I do better, than to '\ 
 warn others to beware of it ? If philoso|)by contradicts ; 
 herself, befools her votaries, and deprives them of every j 
 object worthy to be pursued or enjoyed, let her be sent 
 back to the infernal regions from which she must have 
 had her original. 
 
 But is it absolutely certain that this fair lady is of the 
 party? Is it not possible she may have been misrepre- 
 sented ? Have not men of genius in former ages often 
 made their own dreams to pass for her oracles ? Ought 
 she then to be condemned without any further hearing ? 
 This would be unreasonable. I have found her in all 
 other matters an agreeable companion, a faithful coun- 
 sellor, a friend to common sense, and to the happiness of 
 mankind. This justly entitles her to my correspondence 
 ^nd confidence, till I find infallible proofs of her infidelity. 
 
 "TC . 
 
190 or THE HUMAN MIND. 
 
 CHAP. II. 
 
 OF SMELLING 
 
 SECTION I. 
 
 THE ORDER OP PROCEEDING. OP THE MEDIUM AND 
 ORGAN OF SMEII. 
 
 It is SO difficult to unravel the operations of the human 
 understanding, and to reduee them to their first princi- 
 ples, that we cannot expect to succeed in tlie attempt, but 
 by beginning with the simplest and proceeding by very 
 cautious steps to the more complex. The five external 
 senses may, for this reason, claim to be first considered in 
 an analysis of the human faculties. And the same rea- 
 son ought to determine us to make a choice even among 
 the senses, and to give the precedence, not to the noblest, 
 or most useful, but to the simplest, and that whose ob- 
 jects are least in danger of being mistaken for other 
 things. 
 
 In this view, an analysis of our sensations may be carried 
 on, perhaps with most ease and distinctness, by taking 
 them in this order : smelling, tasting, hearing, touch, 
 and, last of all, seeing. 
 
 Natural philosophy informs us, that all animal and 
 vegetable bodies, and probably all or most other bodies, 
 while exposed to the air, are continually sending forth 
 effluvia of vast subtilty, not only in their state of life and 
 growth, but in the states of fermentation and putrefaction. 
 These volatile particles do probably repel each other, and 
 so scatter themselves in the air, until they meet with 
 other bodies to which they have some ehymical affinity, 
 and with which they unite and form new concretes. All 
 the smell of plants, and of other bodies, is caused by these 
 volatile parts, and is smelled wherever they are scattered 
 
SMEILING. 191 
 
 in the air ; and the acuteness of smell in some animals, 
 shews us, that these efi9uvia spread far, and must be in- 
 coaceivably subtile. 
 
 Whether, as some chymists conceive, every species of 
 bodies hath a spiritus rectm;a kind of soul, which causes 
 the smell, and all the specific virtues of that body, and 
 which, being extremely volatile, flies about in the air in 
 quest of a proper receptacle, I do not inquire. This, 
 like most other theories, is perhaps rather the product 
 of imagination than of just induction. But that all bodies 
 are smelled by means of effluvia which they emit and 
 which are drawn into the nostrils along with the air, 
 there is no reason to doubt. So that there is manifest 
 appearance of desij>;n in placing the organ of smell in the 
 inside of that canal, through wliieh the air is continually 
 passing in inspiration and expiration. 
 
 Anatomy informs us, that the memhrana pituifana, and 
 the olfactory nerves, which are distributed to the villous 
 parts of this membrane, are the organs destined by the 
 wisdom of nature to this sense ; so that when a body 
 emits no effluvia, or when they do not enter into the nose, 
 or when the pituitary membrane or olfactory nerves are 
 rendered unlit to perform their office, it cannot be smelled. 
 
 Yet notwithstanding tliis, it is evident that neither the 
 organ of smell, nor the medium, nor any motions we can 
 conceive excited in the membrane above mentioned, or in 
 the nerve or animal spirits, do in the least resemble the 
 sensation of smelling; nor could that sensation of itself 
 ever have led us to think of nerves, animal spirits, and 
 effluvia. 
 
 SECTION II. 
 THE SENSATION CONSIDERED ABSTKACTIT. 
 
 Having premised these things, with regard to the 
 medium and organ of this sense, let us now attend care- 
 fully to what the mind is conscious of when we smell a 
 rose or a.lily i and since our language affords no other 
 
192 OF TUB HTTMAS" MIND. 
 
 name for this sensalion. we shall call it a smell or odour, 
 carefully excluding from the meaning of those names 
 every thing but the sensation itself, at least till we have 
 examined it. 
 
 Suppose a person who never had (his sense before, to 
 receive it all at once, and to smell a rose ; can he per- 
 ceive any similitude or agreement between the smell and 
 the rose ? or indeed between it and any other object what- 
 soever? Certainly he cannot. He finds himself affected 
 in a new way, he knows not why or from what cause. 
 Like a man (hat feels some pain or pleasure formerly un- 
 known to him. he is conscious that he is not the cause of 
 it himself; but cannot, from the nature of the thing, de- 
 termine whether it is caused by body or spirit, by some- 
 thing near, or by something at a distance. It has no simil- 
 itude to any thing else, so as to admit of a eomparison; 
 and therefore he can conclude nothing from it, unless 
 perhaps tliat there must be some unknown cause of it. 
 
 It is evidently ridiculous, to ascribe to it figure, colour, 
 extension, or any other quality of bodies. He cannot 
 give it a place, any more than he can give a place to mel- 
 ancholy or joy : nor can he cont-eive i( to have any exist- 
 ence, but when it is smelled. So that if appears to be a 
 simple and original affection or feeling of the mind, alto- 
 gether inexplicable and unaccountable. It is indeed im- 
 possible that it can be in any body : it is a sensation j and 
 a sensation can only be in a sentient thing. 
 
 The various odours have each (heir different degrees 
 of strength or weakness. Most of them are agreeable or 
 disagreeable; and frequently those that are agreeable 
 when weak are disagreeable when stronger. When we 
 compare different smells together, we can perceive very 
 few resemblances or contrarieties, or indeed relations of 
 any kind between them. They are all so simple in them- 
 selves, and so diffei-ent from each other, that i( is hardly 
 possible to divide them into s^enera and .species. Most of 
 the names we give them are particular ; as the smell of 
 a rose, of a jasmine, and the like. Yet there are some 
 general aames; as sweet, stinking, musty, putrid, cadav- 
 
erpus, aromatic. Some of tJiem seem to refresli and ani- 
 mate the mind, others to deaden and depress it. 
 
 SECTION III. 
 
 SBNSATIOlf AND REMEMBRANCE, NATURAI PRINCIPXES 
 OE BEIilEE. 
 
 So far we liave considered this sensation abstractly* 
 Let us next compare it with olher (liings to which il bears 
 some relation. And first I shall compare this sensation 
 wilh the remembrance, and the imagination of it. 
 
 I can think of (he smell of a rose when I do not smell 
 it ; and it is possible that when I think of it, there is nei- 
 ther rose nor smell any where existing. But when I 
 smell it, I am necessarily determined to believe (hat the 
 sensation really exists. This is common to all sensations, 
 that as they cannot exist but in being perceived, so they 
 cannot be perceived but they must exist. I could as 
 easily doubt of my own existence, as of the existence of 
 iny sensations. Even those profound philosophers who 
 have endeavoured to disprove their own existence, have 
 yet left their sensations to stand upon their own bottom, 
 stripped of a subject, rather than call in question the re- 
 ality of their existence. 
 
 Here then a sensation, a smell for instance., may be 
 presented to the mind three different ways: it maybe 
 smelled, it may be remembered, it may be imagined or 
 thought of. In the first case, it is necessf.rily accompa< 
 nied with a belief of its present existence. ; in the second, 
 it is necessarily accompanied with a be'iief of its past ex- 
 istence ; and in the last, it is not acco'aipanied with belief 
 at all, but is wha,t the logicians call a. sim.'ple apprehension. 
 
 Why sensation should compel ov.v belief of the present 
 existence of the thing, memory a belief of its past exist- 
 ence, and imagination no belief a.t all, I believe no philos- 
 opher can give a shadow of reason, but that such is the 
 
 vol,. I. 35 
 
19 i OF THE HDMAN MIWD. 
 
 nature of these operations. They are all simple and orig- 
 inal, and therefore inexplicable acts of the mind. 
 
 Suppose that once, and only once, I smelled a tuberose 
 in a certain room M'here it grew in a pot, and gave a very 
 grateful perfume. Next day I relate what I saw and 
 smelled. When I attend as carefully as I can to what 
 passes in my mind in this case, }t appears evident, that 
 the very thing I saw yesterday, and the fragrance I smell- 
 ed, are now the immediate objects of my mind when I re- 
 member it. Further, 1 can imagine this pot and flower 
 transported to the room where I now sit, and yiejdingthe 
 same perfume. Here likewise it appears, that the indi- 
 vidual thing which I saw and smelled, is the object of my 
 imagination. 
 
 Philosophers indeed tell me, that the immediate object 
 of my memory and imagination in this case, is not the 
 past sensation, but an idea of it, an image, phantasm, or 
 species of the odour I smelled : that this idea now exists 
 in my mind, or in my sensorium ; and the mind contem- 
 plating this pleasant idea, finds it a representation of what 
 is past, or of what may exist ; and accordingly calls it 
 memory, or imagination. This is the doctrine of the 
 ideal philosophy ; which we shall not now examine, that 
 we may not interrupt the thread of the present investiga- 
 tion. Upon the strictest attention, memory appears to 
 me to have things that are past, and not present ideas, 
 for its object. We shall afterward examine this system 
 of ideas, anfl endeavour to make it appear, that no solid 
 proof has ever been advanced of the existence of ideas; 
 that they are a mere fiction and hypothesis contrived to 
 solve the phenomena of the human understanding; that 
 they do not at all answer this end ; and that this hypoth- 
 esis of ideas or images of things in the mind, or in the 
 sensorium, is the parent of those many paradoxes so 
 shocking to common sense, and of that skepticism, which 
 disgrace our philosophy of the mind, and have brought 
 upon it the ridicule and contempt of sensible men. 
 
SMEllING. 195 
 
 In the mean time, I beg leave to think wi(h the vulgar, 
 that when 1 remember the smell of the tuberose, that 
 very sensation which I had yesterday, and which has now 
 no more any existence, is the immediate object of my 
 memory; and when I imagine it present, the sensation 
 itself, and not any idea of it, is the object of my imagin- 
 ation. But though the object of my sensation, memory, ^ 
 and imagination, be in this ease the same, yet these acts 
 or operations of llie mind as are different, and as easily 
 distinguishable, as smell, taste, and sound. I am conscious 
 of a difference in kind between sensation and memory 
 and between both and imagination. I find this also, tha 
 the sensation compels my belief of the present existence 
 of the smell, and memory my belief of its past existence. 
 There is a smell, is the immediate testimony of sense j 
 there was a smell, is the immediate testimony of memory. 
 If you ask me, why I believe that the smell exists ? I can 
 give no other reason, nor shall ever be able to give any 
 other, than that I smell it. If you ask, why I believe 
 that it existed yesterday ; I can give no other reason but 
 that I remember it. 
 
 Sensation and memory therefore are simple, original, 
 and perfectly distinct operations of the mind, and both of 
 them are original principles of belief. Imagination is 
 distinct from both, but is no principle of belief. Sensa- 
 tion implies the present existence of its object ; memory 
 its past existence ; but imagination views its object naked, 
 and without any belief of its existence or non-existence, 
 and is therefore what the schools call simple apprehension. 
 
 SECTION IV. 
 
 JUDGMENT AND BEXIE7 IN SOME CASES PRECEDE SIM- 
 PIB APPREHENSION. 
 
 But here again the ideal system comes in our way ; it 
 teaches us, that the first operation of the mind about its 
 ideas, is simple apprehension ; that is, the bare coucep- 
 
196 OP THE HtlMAN MIND, 
 
 lion of a thing without any belief about it ; and that after 
 V/e have got simple apprehensions, hy comparing them 
 together, we perceive agreements or disagreements be- 
 tv^een (hem; and that this perception of the agreement or 
 disagreement of ideas, is all that we call belief, judgment, 
 or knowledge. Kow, this appears to me to he all fiction, 
 without any foundation in nature : for it is acknowledged 
 by all, that sensation must go before memory and imag- 
 ination ; and hence it necessarily follows, that apprehen- 
 sion accompanied with belief and knowledge, must go be- 
 fore simple apprehension, at least in the matters we are 
 now speaking of. So that here, instead of saying, that 
 the belief or knowledge is got by putting together and 
 comparing the simple apprehensions, we ought rather to 
 say, that the simple apprehension is performed by resolv- 
 ing and analyzing a natural and original judgment. And 
 it is with the operations of the mind, in this case, as with 
 natural bodies, which are indeed compounded of simple 
 principles or elements. Nature does not exhibit these 
 elements separate, to be compounded by us ; she exhibits 
 them mixed and compounded in concrete bodies, and it is 
 only by art and chymical analysis that they can be sepa- 
 rated. 
 
 SECTION V. 
 
 TWO THEORIES OF THE NATUEE OF BEXlIEF REFUTED. 
 CONCIUSIONS FROM WHAT IIATH BEEN SAID. 
 
 But what is this belief or knowledge which accompa- 
 nies sensation and memory ? Every man knows what it is, 
 but no man can define it. Does any man pretend to de- 
 fine sensation, or to define consciousness? it is happy in- 
 deed (bat no man does. And if no philosopher had at- 
 tempted to define and explain belief, some paradoxes in 
 philosophy, more incredible than ever were brought forth 
 by the most abject superstition, or the most frantic en- 
 thusiasm, had never seen the light. Of this kind surely 
 
sMEXiixe. 107 
 
 is that modern discovery of the ideal philosophy, that 
 sensation, memory, belief and imagination, when they 
 have the same object, are only different degrees of strength 
 and vivacity in the idea. Suppose the idea to be that of 
 a future state after death ; one man believes it firmly ; 
 this means no more than that he bath a strong and lively 
 idea of it. Another neitlier believes nor disbelieves ; that 
 is, he has a weak and faint idea. Suppose now a third 
 person believes firmly that there is no such thing ; I am 
 at a loss to know whether his idea be faint or lively : if 
 it is faint, then there may be a firm belief where the idea 
 is faint ; if the idea is lively, then the belief of a future 
 state, and the belief of no future state must be one and 
 the same. The same arguments that are used to prove 
 that belief implies only a stronger idea of the object than 
 simple apprehension, might as well be used to prove that 
 love implies only a stronger idea of the object than indif* 
 ference. And then what shall we say of hatred, which 
 must upon this hypothesis be a degree of love, or a de- 
 gree of indifference ? If it should be said, that in love 
 there is something more than an idea, to wit, an affection 
 of the mind j may it not be said with equal reason, that 
 in belief there is something more than an idea, to wit, an 
 assent or persuasion of the mind. 
 
 But perhaps it may be thought as ridiculous to argue 
 against this strange opinion, as to maintain it. Indeed, 
 if a man should maintain, that a circle, a square, and a 
 triangle, differ only in magnitude, and not in figure, I be- 
 lieve he would find no body disposed either to believe him 
 or to argue against him ; and yet I do not think it less 
 shocking to common sense, to maintain, that sensation, 
 memory, and imagination, differ only in degree, and not 
 in kind. I know it is said, that in a delirium, or in dream- 
 ing, men are apt to mistake one for the otber. But does 
 it follow from this, that men who are neither dreaming, 
 nor in a delirium, cannot distinguish them? But how 
 floes a man know that he is not in a delirium ; I cannot 
 tell : neither can I tell how a man knows that he exists. 
 
198 OF THE HUMAN- MIND. 
 
 But if any man seriously doubts whether he is in a deliri- 
 um, I think it highly probable that he is, and that it is 
 time to seek for a cure, which I am persuaded he will 
 not find in the whole system of logic. 
 
 I mentioned before Locke's notion of belief or knowl- 
 edge : he holds that it consists in a perception of the 
 agreement or disagreement of ideas; and this he values 
 himself upon as a very important discovery. 
 
 We shall have occasion afterward to examine more 
 particularly this grand principle of Locke's philosophy, 
 and to shew that it is one of the main pillars of modern 
 skepticism, although he had no intention to make that 
 use of it. At present let us only consider how it agrees 
 with the instances of belief now under consideration ; and 
 whether it gives any light to them. I believe that the 
 sensation I have, exists : and that the sensation I remem- 
 ber, does not now exist, but did exist yesterday. Here, 
 according to Locke's system, I compare the idea of a 
 sensation with the ideas of past and present existence : 
 at one time that this idea agrees with that of present 
 existence, but disagrees with that of past existence ; 
 but at another time it agrees with the idea of past ex- 
 istence, and disagrees with that of present existence. 
 Truly these ideas seem to be very capricious in their 
 agreements and disagreements. Besides, I cannot for 
 my heart conceive what is meant by either. I say a 
 sensation exists, and I think I understand clearly what 
 I mean. But you v^ant to make the thing clearer, and 
 for that end tell me, that there is an agreement be- 
 tween the idea of that sensation and the idea of existence. 
 To speak freely, this conveys to me no light, but darkness, 
 I can conceive no otherwise of it, than as an odd and ob- 
 scure circumlocution. I conclude, then, that the belief 
 which accompanies sensation and memory, is a simple at 
 of the mind, which cannot be defined. It is in this re- 
 ject like seeing and hearing, which can never be so defin- 
 ed as to be understood by those who have not these fac^ 
 ulties : and to such as have them, no definition can make 
 
SMElllNG. 199 
 
 these operations more clear than they are already; In 
 like manner, every man that has any belief, and he must 
 be a curiosity that has none, knows perfectly what belief 
 is, but can never define or explain it. I conclude also, 
 that sensation, memory, and imagination, even where they 
 have the same object, are operations of a quite different 
 nature, and perfectly distinguishable by those who are 
 sound and sober. A man that is in danger of confound- 
 ing them, is indeed to be pitied ; but whatever relief he 
 may find from another ail, lie. can find none from logic 
 or mefapfiysic. I conclude further, that it is no less a 
 part of the liumnn constitution, to believe the present ex- 
 istence of our sensations, and to believe the past existence 
 of what we remember, than it is to believe that twice 
 two make four. The evidence of sense, the evidence of 
 memory, and tiie evidence of the necessary relations of 
 things, are all distinct and original kinds of evidence, 
 equally grounded on our constitution : none of them de- 
 pends upon, or can be resolved into anotlier. To reason 
 against any of these kinds of evidence, is absurd ; nay. to 
 reason for them, is absurd. They are first principles; 
 and such fall not within the province of reason, but of 
 common sense. 
 
 SECTION VI. 
 
 APC OGY FOR METAPHYSICAL ABSURDITIES. SENSATION ■WTTHOUT A 
 SENTIENT, A CONSEqUENCE OF THE THEORY OF IDEAS. CONSE- 
 QUENCES OF THIS STRANGE OPINION. 
 
 Having considered the relation which the sensation of 
 smelling bears to the remembrance and imagination of 
 it, I proceed to consider, what relation it bears to a mind, 
 or sentient principle. It is certain, no man can conceive 
 or believe smelling to exist of itself, without a mind, or 
 something that has the power of smelling, of which it is 
 called a sensation, an operation or feeling. Yet if any 
 man should demand a proof, that sensation cannot be with- 
 out a mind or sentient being, I confess that I can give 
 
200 or THE HUMAN MIND. 
 
 none ; and that to pretend to prove it, seems to me almost 
 as absurd as to deny it. 
 
 This might have been said without any apology before 
 the Treatise of Human Nature appeared in the Avorld. 
 Fop till that time, no man, as far as I know, ever thought 
 either of calling iti question that principle, or of giving a 
 reason for his belief of it. Whether thinking beings 
 Were of an ethereal or igneous nature, whether material 
 or immaterial, was variously disputed ; but that thinking 
 is an operation of some kind of being or other, was always 
 taken for granted, as a principle that could not possibly 
 admit of doubt. 
 
 However, since the author above mentioned, who is 
 undoubtedly one of the most acute metaphysicians that 
 this or any age hath produced, hath treated it as a vulgar 
 prejudice, and maintained, that the mind is only a suc- 
 cession of ideas and impressions without any subject; his 
 opinion, however contrary to the common apprehensions 
 of mankind, deserves respect. I beg therefore, once for 
 all, that no offence may be taken at charging this or other 
 metaphysical notions with absurdity, or with being con- 
 trary to the common sense of mankind. No disparage- 
 ment is meant to the understandings of the authors or 
 maintainers of such opinions. Indeed, they commonly 
 proceed not from defect of understanding, but from an 
 excess of refinement : the reasoning that leads to them, 
 often gives new light to the subject, and shews real genius 
 and deep penetration in the author, and the premises do 
 more than atone for the conclusion. 
 
 If there are certain principles, as I think there are, 
 which the constitution of our nature leads us to believe, 
 and which we are under a necessity to take for granted' 
 in the common concerns of life, without being able to give 
 a reason for them ; these are what we call the principles 
 of common sense; and what is manifestly contrary to 
 them, is what we call absurd. 
 
 Indeed, if it is true, and to be received as a principle 
 of philosophy, that seusatioa and thought may be without 
 
SMElllXG. 201 
 
 a thinking being ; it must be acknowledged to be the 
 most wonderful discovei^v tliat this or an^ oiher age hath 
 produced. The received doctrine of ideas is the principle 
 from which it is deduced, and of wliich indeed it seems 
 to be a just and natural consequence. And it is probable 
 that it would not liave been so late a discovery, but that 
 it is so shocking and repugnant to the common apprehen- 
 sions of mankind, thai it required an uncommon degree 
 of philosophical intrepidity to usher it into the world. It 
 is a fundamental principle of the ideal system, that every 
 object of thought must be an impression, or an idea, that is, 
 a faint copy of some preceding impression. This is a prin- 
 ciple so commonly received, that the author above men- 
 tioned, although his whole system is built u[M)n it, never 
 offers the least proof of it. It is upon this principle, as a 
 fixed point, that he erects his metafthysical engines, to 
 overturn heaven and earth, body and spirit. And indeed* 
 in my apprehension, it is altogether sufficient for the pur- 
 pose. For if impressions and ideas are the only objects 
 of thought, then heaven and earth, and body and spirit) 
 and every thing you please, must signify only impressions 
 and ideas, or they must be words without any meaning. 
 It seems, therefore, that this notion*: however strange, is 
 closely connected with the received doctrine of ideas, and 
 we must either admit the conclusion, or call in question 
 the premises. 
 
 Ideas seem to have something in their nature unfriendly 
 to other existences. They were first introduced into phi- 
 losophy, in the humble character of images or represen- 
 tatives of things ; and in this character they seemed not 
 only to be inoffensive, but to serve admirably well for ex- 
 plaining the operation of the human understanding. But 
 since men began to reason clearly and distinctly about 
 them, they have by degrees supplanted their constituents, 
 and undermined the existence of every thing but them- 
 selves. First, they discarded all secondary qualities of 
 bodies ; and it was found out by their means, that tire is 
 not hot, nor snow cold, nor hopey sweet; and^ in a \vord> 
 
 Toi. I. 36 
 
S03 OF THE HUMAN MIND. 
 
 that heat and cold, sound, colour, taste, and smell, arc 
 nothing hut ideas or impressions. Bishop Berkeley ad- 
 vanced them a step higher, and found out, by just reason- 
 ing, from the same principles, that extension, solidity, 
 space, figure, and body, are ideas, and that there is noth- 
 ing in nature but ideas and spirits. But the triumph of 
 ideas was completed by the Treatise of Human Nature, 
 'which discards spirits also, and leaves ideas and impres- 
 sions as the sole existences in the universe. What if at 
 last, having nothing else to contend with, they should 
 fall foul of one another, and leave no existence in nature 
 at-all? This would surely bring philosopliy into danger; 
 for what should we have left to talk or to dispute about? 
 However, hitherto these philosophers acknowledge the 
 existence of impressions and ideas ; they acknowledge 
 certain laws of attraction, or rules of precedence, accord- 
 ing to which ideas and impressions range themselves in 
 various forms, and succeed one another : but that they 
 should belong to a mind, as its proper goods and chattels, 
 this they have found to be a vulgar error. These ideas 
 are as free and independent as the birds of the air, or as 
 Epicurus's atoms when they pursued their journey in the 
 vast inane. Shall we conceive them like the films of 
 things in the Epicurean system ? 
 
 Principio hoc dico, rerurn simulacra vagari, 
 
 Multa modis multis, in cunctas undique parteis 
 
 Tennia quse facile inter se jungunter in auris, 
 
 Obvia cum veniunt. Lucr. 
 
 Or do they rather resemble Aristotle's intelligible spe- 
 cies after they are shot forth from the object, and before 
 they have yet struck upon the passive intellect ? but why 
 should we seek to compare them with any thing, since 
 there is nothing in nature but themselves? They make 
 the whole furniture of the universe; starting into exist- 
 ence, or out of it, without any cause; combining into par- 
 cels which the vulgar call minds; and succeeding one 
 another by fixed laws, without time, place, or author of 
 those laws. 
 
SMELLING. 20S 
 
 Yet, after all, these self-existent and independent ideas 
 look pitifully naked and destitute, when left thus alone 
 in the universe, and seem, upon the whole, to he in a 
 worse condition than they were hefore. Des Cartes, 
 Malebranche, and Locke, as they made much use of ideas^ 
 treated them handsomely, and provided them in decent 
 accommodation j lodging them either in tlie pineal gland, 
 or in the pure intellect, or even in the Divine Mind. They 
 moreover clothed them with a commission, and made them 
 representatives of things, which gave them some dignity 
 and character. But the Treatise of Human Nature, 
 though no less indebted to them, seems to have made but 
 a had return, by bestowing upon them this independent 
 existence ,• since thereby they are turned out of house and 
 home, and set adrift in the world, without friend or con- 
 nection, without a rag to cover their nakedness ; and who 
 knows but the whole system of ideas may perish by the 
 indiscreet zeal of their friends to exalt them? 
 
 However this may be, it is certainly a roost amazing 
 discovery that thought and ideas may be without any 
 thinking being : a discovery big vi'ith consequences which 
 cannot easily be traced by those deluded mortals who 
 think and reason in the common track. We were always 
 apt to imagine, that thought supposed a thinker, and love 
 a lover, and treason a traitor : but this, it seems, was all 
 a mistake ; and it is found out, that there may be treason 
 without a traitor, and love without a lover, laws without 
 a legislator, and punishment without a sufferer, succes- 
 sion without time, and motion without any thing moved, or 
 space in which it may move : or if, in these cases, ideas are 
 the lover, the sufferer, the traitor, it were to be wished that 
 the author of this discovery had farther condescended to 
 acquaint us, whether ideas *an converse together, and be 
 under obligations of duty or gratitude to each other; 
 whether they can make promises, and enter into leagues 
 and covenants, and fulfil or break them, and be punished for 
 the breach ? If one set of ideas makes a covenaitt, another 
 
204 OF THE HUMAN MIND. 
 
 breaks it, and a ihird is punished for it, there is reasoH 
 to tliiiik thai justice is no natural virtue in this system. 
 
 It seemed very natural lo think, that the Treatise of 
 Human Nature required an author, and a very ingenious 
 one too; but now we learn, that it is only a set of ideas 
 which came together, and arranged themselves by cer- 
 tain assui-iatiuns and attractions. 
 
 After all, this curious system appears not to be fitted 
 to the present state of human nature. How far it may 
 suit some choice spirits, who are refined from the dregs 
 of common sense, 1 cannot say. It is acknowledged. I 
 think, that even these can enter into this system only in 
 their most speculative hours, when they soar so high in 
 pursuit of those self-existent ideas, as to lose sight of all 
 other things. But when they condescend to mingle again 
 with the human race, and to converse with a friend, a 
 compauion, or a fellow citizen, the ideal system vanishes; 
 common sense, like an irresistible torrent, carries them 
 along ; and, in spite of all their reasoning and philosophy, 
 they believe their own existence, and the existence of 
 other things. 
 
 Indeed, it is happy they do so ; for if they should carry 
 their closet belief into the world, the rest of mankind 
 would consider them as diseased, and send them to an in- 
 firmary. Therefore, as Plato required certain previous 
 qualifications of those who entered his school, I think it 
 would be prudent for the doctors of this ideal philosophy 
 to do the satne, and to refuse admittance to every man 
 who is so weak, as to imagine that he ought to have the 
 same belief in solitude and in company, or that his prin- 
 ciples ought to have any inlluence upon his practice : for 
 this philosophy is like a hobby-horse, which a man in bad 
 health mayridein his closed without hurting his reputa- 
 tion; but if he should take him abroad with him to 
 church, or to the exchange, or to the play house, his heir 
 ^ould immediately call a jury, and seize his estate. 
 
SMEXXINQ. WB 
 
 SECTION VII. 
 
 THE CONCEPTION AND BELIEF OF A SENTIENT BEING OR MIND IS SUG. 
 
 GESTED BY OUR CONSTITUTION. THE NOTION OF RELATIONS NOT 
 
 ALWAYS GOT BY COMPARING THE RELATED IDEAS. 
 
 Leaving this philosophy, therefore, to those who have 
 occasioa for it, and can uae it discreetly as a chamber 
 exercise, we may still inquire, how tlie rest of mankind, 
 and even the adepts themselves, except in some solitary 
 moments, liave got so strong and irresistible a belief, that 
 thought must have a subject, and be the act of some 
 thinking being: how every man believes himself to be 
 something distinct from his ideas and impressions; some- 
 thing which continues the same identical self when all 
 his ideas and impressions are clianged. It is impossible 
 to trace the origin of this opinion in history : for all lan- 
 guages have it inierwoven in their original construction. 
 All nations have always believed it. The constitutiooof 
 all laws and governments, as well as the common trans- 
 actions of life, suppose it. 
 
 It is no less impossible for any man to recollect when 
 be himself came by this notion ; for as far back as we can 
 remember, we were already in possession of it, and as 
 fully persuaded of our own existence, and the existence 
 of other things, as that one and one make two. It seems, 
 therefore, that this opinion preceded all reasoning, and 
 experience, and instruction ; and this is the more prob- 
 able, because we could not get it by any of these means. 
 It appears then to be an undeniable fact, that from thought 
 or sensation, all mankind, constantly and invariably, from 
 the first dawning of reflection, do infer a power or fac- 
 ulty of thinking, and a permanent being or mind to which 
 that faculty belongs ; and that we as invariably ascribe 
 all the various kinds of sensation and thought we are 
 conscious of, to one individual mind or self. 
 
 But by what rules of logic we make these inferences, 
 H is impossible to show, nay, it is impossible to show how 
 
a06 or THE HUMAN MIND. 
 
 our sensations ant] thoughts can give us the vefy notion and 
 conception either of a mind orof a faculty. The faculty of 
 smelling is something very different from the actual sensa- 
 tion of smelling ; for the faculty may remain when we have 
 no sensation. And the mind is no less different from the 
 faculty; for it continues the same individual being when 
 that faculty is lost. Yet this sensation suggests to us 
 both a faculty and a mind ; and not only suggests the 
 notion of them, hut creates a heiief of their existence; 
 although it is impossible to discover, by reason, any tie or 
 connection between one and the other. 
 
 What shall we say then ? Either those inferences which 
 we draw from our sensations, namely, the existence of a 
 luind, and of powers or faculties belonging to it, are 
 prejudices of philosophy or education, mere fictions of the 
 mind, which a wise man should throw off as he does the 
 belief of fairies ; or they are judgments of nature, judg- 
 ments n«t got by comparing ideas, and perceiving agree- 
 ments and disagreements, but immediately inspired by 
 our constitution. 
 
 If this last is the case, as I apprehend it is, it will be 
 
 impossible to shake off those opinions, and we must yield 
 
 to them at last, though we struggle hard to get rid of 
 
 them. And if we could, by a determined obstinacy, shake 
 
 off the principles of our nature, this is not to act the phi- 
 
 llosopher, but the fool or the madman. It is incumbent 
 
 upon those who think that these are not natural prinei- 
 
 jples, to show, in the first place, how we can otherwise 
 
 jget the notion of a mind and its faculties, and then to 
 
 shew, how we come to deceive ourselves into the opinion 
 
 that sensation cannot be without a sentient being. 
 
 It is the received doctrine of philosophers, that our 
 notions of relations can only be got by comparing the re- 
 lated ideas ; but in the present case there seems to be an 
 instance to the contrary. It is not by having first the 
 notions of mind and sensation, and then comparing Ihem 
 together, that we perceive the one to have the relation of 
 a subject or substratum, and the other that of an act or 
 
SMELIIXG. sat 
 
 operation : on the contrary, one of the related things, to 
 wit, sensation, suggests to us both the correlate and the 
 relation. lA 
 
 I beg leave to make use of the word suggestion, because 
 I know not one more proper, to express a power of the' 
 mipd, which seems entirely to have escaped the notice of 
 phi^sophers, and to which we owe many of our simple 
 notions which are neither impressions nor ideas, as well 
 as many original principles of belief. I shall endeavour 
 to ilhistrate, by an example, what I understand by this 
 word. We all know, that a certain kind of sound sug- 
 gests ijpmediately to the mind, a coach passing in the 
 street ; and not only produces the imagination, but the 
 belief, tha.t a eoaeh is passing. Yet there is here no com- 
 paring of ideas, no perception of agreements or disagree- 
 ments, to produce this belief: nor is there the least simil- 
 itude between the sound we hear, and the coach we im- 
 agine and belie,ye to be passing. 
 
 It is true ("hat this suggestion is not natural and orig- 
 inal ; it is the result of experience and habit. But I think 
 it appears, from what hath been said, that there are nat- 
 ural suggestions,- particularly, that sensation suggests 
 the notion of present existence, and the belief that what 
 we perceive or feel, does now exist ; that memory sug- 
 gests the notion of past existence, and the belief that what 
 we remember did exist in time past ; and that our sensa- 
 tions and thoughts do also suggest the notion of a mind, 
 and the belief of its existence, and of its relation to our 
 thoughts. By a like natural principle it is, that a begin- 
 ning of existence, or any change in nature, suggests to 
 us the notion of a cause, and compels our belief of its ex- 
 istence. And in like manner, as shall be shewn when wo 
 come to the sense of touch, certain sensations of touch, by 
 the constitution of our nature, suggest to us extension, so- 
 lidity, and motion, which are nowise like to sensations, 
 although they hare been hitherto confounded with them. 
 
20S on THE HUMAN MIND. 
 
 SECTION VIII. 
 
 THERE IS A CtUALITV OR VIRTUE IN BODIES, WHICH WE CALL '^IeIK 
 SMEIX. HOW THIS IS CONNECTED IN THE IMAGINATION WlTlj 
 THE SENSATION. 
 
 We have considered smell as signifying a sensai||on, 
 feeling, or impression upon the mind, and in this seiRe, it 
 can onlj be in a mind, or sentienl being : but it is eviaea^ 
 that mankind give the name of smell much more fre- 
 quently to something which they conceive to be^CUgrnal, 
 and to be a quality of body ; they understan^'''soriie|png 
 by it wliich does not at all infer a mind, and haVe not the 
 least difliculty in conceiving the air perfi|itied with aro- 
 matic odours in the deserts of Arabia, or in 9i>me unin- 
 habited island where the human foot never trod. Every 
 sensible day-labourer hath as clear a ntifton' pf this, and 
 as full a conviction of the possibility of it, asMie hath of 
 his own existence ; and can no more ^o^fet'^of the one 
 than of the other. 
 
 Suppose that such a man meets with a modern philos- 
 opher, and wants to be informed, what smell in plants is. 
 The philosopher tells him, that there is no smell in plants^ 
 nor in any thing but in the mind: that it is impossible 
 there can be smell but in a mind ; and that all this hath 
 been demonstrated by modern philosophy. The plain 
 man will, no doubt, be apt to think him merry : but if he 
 finds that he is serious, his next conclusion will be, that 
 he is mad ; or that philosophy, like magic, puts men into 
 a new world, and gives them different faculties fi-om com- 
 mon men. And thus philosophy and common sense are 
 set at variance. But who is to blame for it ? Jn my opin- 
 ion the philosopher is to blame. For if he means by smell 
 what the rest of mankind most commonly mean, he is 
 certainly mad. But if he puts a different meaning upon 
 the word, without observing it himself, or giving warning 
 to others, he abuses language, and disgraces philosophy, 
 without doing any service to truth: as if a man should 
 exchange the meaning of the words daughter and cow, 
 
SMELIING. 209 
 
 and then endeavour to prove to his plain neighhour, that 
 his cow is his daughter, and his daughter his cow. 
 
 I believe there is not much more wisdom in many of 
 those paradoxes of the ideal philosophy, which to plain 
 sensible men appear to be palpable absurdities, hut with 
 the adepts pass for profound discoveries. I resolve, for ^ 
 my own part, always to pay a great regard to the dictates i 
 of common sense, and not to depart from them without 
 absolute necessity; and therefore I am apt to think, that 
 there is really something in tlie rose or lily, which is by 
 the vulgar called nmeU. and which continues to exist when 
 it is not smelted xand shall proceed to inquire what this ^ 
 is; how we come by the notion of it ; and what relation 
 this quality or virtue of smell hath to the sensation, which 
 vie have been obliged to call by the same name, for want 
 of another. 
 
 Let us therefore suppose, as before, a person to exer- 
 cise the sense of smelling: a little expeiience will dis- 
 cover to him, that (he nose is the organ of this sense, and 
 that the air, or something in the air, is a medium of it. 
 And finding by fuither experience, that when a rose is 
 near, he has a certain sensation ; when it is removed, the 
 sensation is gone; he finds a connection in nature betwixt 
 the rose and this sensation. The rose is considered as a 
 cause, occasion, or antecedent, of the sensation ; the sensa- 
 tion as an efTecl or consequent of the presence of the rose : 
 they are associated in the mind, and constantly found con- 
 joined in the imagination. 
 
 But here it deserves our notice, that although the sen- 
 sation may seem more closely related to the mind its sub- 
 ject, or to the nose its organ ; yet neither of these con-j/ 
 neclions operale^so powerfully upon the imagination, as 
 its connection with (he rose iis concomitant. The rea- 
 son of this seems to be, that its connection with the mind 
 is more general, and no way dislinguisheth it from other 
 smells, or even from tastes, sounds, and other kinds of 
 sensations. The relation it hath to the organ, is likewise 
 general, and doth aot distinguish it from other smells : 
 VOL. I. %7 
 
210 OT THE HUMAW MINI). 
 
 but the connection it hath with the rose is special^ and 
 eoDstant : bj which means they become almost insepa- 
 rable in the imagination ; in like manner as thunder and 
 lightning, freezing and cold. 
 
 SECTION IX. 
 
 THAT THERE IS A PRINCIPLE IN HUMAN NATURE, FROM WHICH THE 
 
 NOTION OF THIS, AS WELL AS ALL OTHER NATURAL VIRTUES OR 
 
 CAUSES, IS DERIVED. 
 
 In order to illustrate further how we come to conceive 
 a quality or virtue in the rose which we call smell, and 
 what this smell is, it is proper to observe, that the mind 
 begins very early to thirst after principles, which may 
 direct it in the exertion of its powers. The smell of a 
 rose is a certain affection or feeling of the mind j and as 
 it is not constant, but comes and goes, we want to know 
 when and where we may expect it, and are uneasy till we 
 find something, which being present, brings this feeling 
 .along with it, and being removed, removes it. This, when 
 found, we call the cause of it ,• not in a strict and philosoph- 
 ical sense, as if the feeling were really eff. cted or produced 
 by that cause, but in a popular sense : foi- the mind is 
 satisfied, if there is a constant conjunction between them; 
 and such causes are in reality nothing else but laws of 
 nature. Having found the smell thus constantly conjoin- 
 ed with the rose, the mind is at rest, without inquiring 
 whether this conjunction is owing to a real efficiency or 
 not ; (hat being a philosophical inquiry, which does not 
 concern human life. But every discovery of such a con- 
 stant conjunction is of real importance in life, and makes 
 a strong impression upon the mind. 
 
 So ardently do we desire to find every thing that hap- 
 pens within our observation, thus connected with some- 
 thing else, as its cause or occasion, that we are apt to 
 fancy connections upon the slightest grounds; and this, 
 weakness is most remarkable in the ignorant, who know 
 *east of the real connections established in nature. A man 
 
SMELIING. 3ii 
 
 meels with an unlucky accident on a certain day of the 
 year, and knowing no other cause of his misfortune, he is 
 apt to conceive sometliing unlnckyin that day of the cal- 
 endar ; and if he finds the same connection hold a second 
 time, is strongly confirmed in his superstition. I remem- 
 ber many years ago, a white ox was brought into this 
 country, of so enormous a size, that people came ntany 
 miles to see him. There happened some months after, 
 an uncommon fatality among women in child-bearing. 
 Two such uncommon events following one another, gave 
 a suspicion of their connection, and occasioned a common 
 opinion among the country people, that the white ox was 
 the cause of this fatality. 
 
 However silly and ridiculous this opinion was, it sprung 
 from the same root in human nature, on which all nat- 
 ural philosophy grows ; namely, an eager desire to find 
 out connections in things, and a natural, original, and un- 
 accountable propensity to believe, that the connections 
 which we have observed in times past, will continue in 
 time to come. Omens, portents, good and bad luck,< 
 palmistary, astrology, all the numerous arts of divination, 
 and of interpreting dreams, false hypotheses and systems, 
 and true principles in the philosophy of nature, are all 
 built upon the same foundation in the human constitu- 
 tion ; and are distinguished only according as we conclude 
 rashly from too few instances, or cautiously from a suf- 
 ficient induction. 
 
 As it is experience only that discovers these connec- 
 tions between natural Causes and their efiects ; without 
 inquiring further, we attribute to the cause some vague 
 and indistinct notion of power or virtue to produce the 
 effect. And in many cases, the purposes of life do not 
 make it necessary to give distinct names to the cause and 
 the effect. Whence it happens, that being closely con- 
 nected in the imagination, although very unlike to each 
 other, one name serves for both ; and, in common dis-^; 
 . course, is most frequently applied to that which, of the 
 two, is most the object of our attention. This occasions 
 
212 «¥ THE HrMASi MlIfD. 
 
 an ambiguity in many wbrds, which having fhe same 
 causes in all languages, is common to ali< and is apt to 
 be overlooked even by philosophers. Some instances will 
 serve both to illustrate and confirm what we have said. 
 
 Magnetism signifies both the tendency of the iron toward 
 the magnet, and the power of the magnet to produce that 
 tendency j and if it was asked, whether it is a quality of 
 the iron or of the magnet ? one would perhaps be puz- 
 zled at first ; but a little attention would discover, that 
 •we conceive a power or virtue in the magnet as the cause, 
 and a motion in the iron as the effect ; and although these 
 are things quite unlike, they are so united in the imag- 
 ination, that we give the common name of magnetism to 
 both. The same thing may be said of gravitation, which 
 sometimes signifies the tendency of bodies toward the 
 earth, sometimes the attractive power of the earth, which 
 we conceive as the cause of that tendency. We may ob- 
 serve the same ambiguity in some of Sir Isaac Newton's 
 definitions ; and that even in words of his own making. 
 In three of his definitions, he explains very distinctly what 
 he understands to be the absolute quantity, and what by 
 the acceierafiwe quantity, and w hat by the motive quantity, 
 of a centripetal force. In the first of these three defini- 
 tions, centripetal force is put for the cause, which we 
 conceive to be some power or virtue in the centre or cen- 
 tral body : in the two last, the same word is put for the 
 effect of this cause, in producing velocity, or in producing 
 motion to\>ard that centre. 
 
 Heat signifies a sensation, and colrl a contrary one. But 
 heat likewise signifies a quality or state of bodies, which 
 hath no contrary, but difierent degrees. When a man 
 feels the same water hot to one hand, and cold to the 
 other, this gives him occasion to distinguish between the 
 feeling, and the heat of the body ; and although he knows 
 that the sensations are contrary, he does not imagine that 
 the body can have contrary qualities at the same time. 
 And when he finds a different taste in the same body in 
 sickness and in health, he is easily conviooed, that the 
 
SMELXINe. 213 
 
 quality in the body called taste is tlie same as before, al- 
 though (he sensations he has from it are perhaps opposite. 
 
 The vulgar are cuminonly charged by philosophers with 
 the absurdity of imagining ilie smell in the rose, to be 
 something like to the sensation of smelling: but. I think, 
 unjustly; for they neither give the same epithets to both, 
 nor do they reason in tiie same manner from them. What 
 IS smell in the rose? It is a quality or virtue of the rose, 
 or of something proceeding from it. which we perceive 
 by the sense of smelling; and (his is all we know of the 
 matter. But what is smelling? It is an act of the mind, 
 but is never imagined to be a quality of the mind. Again, 
 the sensation of smelling is conceived to infer necessarily 
 a mind or sentient being; but smell in the rose infers no 
 such thing. We say, this body smells sweet, that stinks; 
 but we do not say, (his mind smells sweet, and that stinks. 
 Therefore, smell in the rose, and the sensation which it 
 causes, are not conceived, even by the vulgar, to be things 
 of the same kind, although they have the same name. 
 
 From what hath been said, we may learn, that the 
 smell of a rose signifies two things. First, A sensation, 
 which can have no existence but when it is perceived, 
 and can only be in a sentient being or mind. Secondly, 
 It signifies some power, quality or virtue, in the rose, op 
 in eflBuvia proceeding from it, which haih a permanent 
 existence, independent of the mind, and which by the 
 constitution of nature, produces the sensation in us. By 
 ,the original constitution of our nature, we are both led 
 to believe, that there is a permanent cause of (he sensa- 
 tion, and prompted to seek after it ; and experience de- 
 termines us to place it in the rose. The names of all 
 smells, tastes, sounds, as well as heat and cold, have a 
 like ambiguity in all languages ; but it deserves our at- 
 tention, that these names are but rarely, in common lan- 
 guage, used to signify the sensations ; for the most part, 
 they signify the external qualities which are indicated by 
 the sensations. The cause of which phenomenon I take 
 to be this : our sensations have very different degrees of 
 strength. Some «f them are 40 quick and lively; as to 
 
214 OF THE HTTMAKT MIND. 
 
 give US a great ileal either of pleasure or of uneasiness. 
 When this is the ease, we are compelled to attend to the 
 sensation itself, and to make it an object of thought and 
 discourse ; we give it a name, which signifies nothing but 
 the sensation ; and in this case we readily acknowledge, 
 that the thing meant by that name is in the mind only, 
 and not in any thing external. Such are the various kinds 
 of pain, sickness, and the sensations of hunger and other 
 appetites. But where the sensation is not so interesting 
 as to require to be made an object of thought, our con- 
 stitution leads us to consider it as a sign of something 
 external, which hath a constant conjunction with it; and 
 having found what it indicates, we give a name to that: 
 the sensation, having no proper name, falls in as an ac- 
 cessory to the thing signified by it, and is confounded un- 
 der the same name. So that the name may indeed be 
 applied to the sensation, but most properly and commonly 
 is applied to the thing indicated by that sensation. The 
 sensations of smell, taste, sound, and colour, are of infi- 
 nitely more importance as signs or indications, than they 
 are upon their own account ; like the words of a language, 
 wherein we do not attend to the sound, but to the sense. 
 
 SECTrON X. 
 
 WHETHER ISr SENSATION THE MIND IS ACTIVE OK 
 PASSIVE ? 
 
 There is one inquiry remains, Whether in smelling, 
 and in other sensations, the mind is active or passive ? 
 This possibly may seem to be a question about words, or 
 at least of very small importance ; however, if it lead us 
 to attend more accurately to.the operations of our minds, 
 than we are accustomed to do, it is upon that very ac- 
 count not altogether unprofitable. I think the opinion of 
 modern philosophers is, that in sensation the mind is al- 
 together passive. And this undoubtedly is so far true, 
 that we cannot raise any sensation in our minds by will* 
 
ing it; and, on the other hand, it seems hardly possible 
 to avoid having the sensation, when tlie object is present- 
 ed. Yet it seems likewise to be true, that in proportion 
 as the attention is more or less turned to a sensation, or 
 diverted from it, that sensation is more or less perceived 
 and remembered. Every one linows, that very intense 
 pain may be diverted by a surprise, or by any thing that 
 entirely occupies the mind. When we are engaged in 
 earnest conversation, the clock may strike by us without 
 being heard; at lea«t we remember not the next moment 
 that we did hear it. The noise and tumult of a great 
 trading city, is not heard by them who have lived in it 
 all their days; but it stuns those strangers who have 
 lived in the peaceful retirement of the country. Whether 
 therefore there can be any sensation where the mind is 
 purely passive, I will not say; but I think we are con- 
 scious of having given some attention to every sensation 
 which we remember, though ever so recent. 
 
 No doubt, where the impulse is strong and uncommon, 
 it is as diffifMiIt to withhold attention, as it is to forbear 
 crying ont in racking pain, or starting in a sudden, fright : 
 but how far both might be attained by strong resolution 
 and practice, is not easy to determine. So that although 
 the Peripatetics had no good reason to suppose an active 
 and a passiveintelleet. since attention may he well enough 
 accounted an act of the will ; yet T think they came nearer 
 to the truth, in holding the mind to be in sensation partly 
 passive and partlv active, than the moderns, in affirming 
 it to be purely passive. Sensation, imagination, memory, 
 and judgment, have, by thevnlerar, in all ages, been con- 
 sidered as acts of the mind. The manner in which they 
 are expressed, in all languages, shews this. "When the 
 mind is much employed in them, we say it is very active; 
 whereas, if they were impressions only, as the ideal phi- 
 losophy would lead us to conceive, we ought in such a 
 case rather to say. that the mind is very passive; for I 
 suppose no man would attribute great activity to th» 
 paper I write upon, because it receives variety of charao- 
 ters. 
 
SIS or THE HUMASr MIND. 
 
 The relation which (he sensation of smell bears to the 
 memory and imagination of it. and to a mind or subject, is 
 common to all our sensations, and indeed lo all the opera- 
 tions i^f the mind . the relation it bears to the will is com- 
 mon to it with all the powers of undeistanding: and the 
 relation it bears to (hat quality or virtue of bodies which 
 it indicates, is common to it with the sensations of taste, 
 hearing, colour, heat, and cold: so that what hath been said 
 of this sense may easily be applied to several of our 
 senses, and toother operations of the mind; and this> I 
 hope, will apologize for our insisting so long upon k. 
 
 CHAP. III. 
 
 OF TASTING. 
 
 A GREAT part of what hath been said of the sense of 
 smelling is so easily applied to those of tasting and hear- 
 ing, that we shall leave the application entirely to the 
 reader's judgment, and save ourselves the trouble of a 
 tedious repetition. 
 
 It is probable that every thing that affects the taste is 
 in some degree soluble in the saliva. It is not conceiv- 
 able how any thing should enter readily, and of its own 
 accord, as it were, into the pores of the tongue, palate, 
 aui\ fauces, unless if had some chymical affinity to that 
 liquor with which these pores are always replete. It is 
 therefore an admirable contrivance of nature, that the 
 organs of taste should always We moist with a liquor which 
 is so universal a menstriiu>'), and which deserves to be 
 examined more than it hath been hitherto, both in that 
 capacity, and as a medical unguent. Nature teaches dogs, 
 and other animals, to use it in this last way; and its sub- 
 serviency both to taste and digestion, shews its efficacy 
 in the former. 
 
 It is with manifest design and propriety, that the or- 
 gao of this sense guards the entrance of the alimentary 
 
TASTING. 217 
 
 canal, as that of smell, the entrance of the canal for res- 
 piration. And from tliese organic being placed in such man- 
 ner, that every thing that enters into the stomach must 
 undergo the scrutiny of hoth senses, it is plain, that they 
 tvere intended by nature to distinguish wholesome food 
 from that \thich is noxious. The brutes have no other 
 means of choosing their food ; nor would mankind, in the 
 savage state. And it is very probable, that the smell and 
 ta'ite, no way vitiated by luxury or bad habits, would 
 rarely, if ever, lead us to a wrong choice of food among 
 the productions of nature ; although the artificial com- 
 positions of a refined and luxurious cookery, or of chym- 
 istry and pharmacy, may often impose upon both, and 
 produce things agreeable to the taste and smell, which 
 are noxious to health. And it is probable, that both snicU 
 and taste are vitiated, and rendered less fit to perform 
 their natural offices, by the unnatural kind of life men 
 commonly lead in society. 
 
 These senses are likewise of great use to distinguish 
 bodies that cannot be distinguished by our other sen»ies, 
 and to discern the changes which the same body under- 
 goes, which in many cases are sooner perceived by taste 
 and smell than by any other means. How many things 
 are there in tlie market, the eaiing house, and the tavern, 
 as well as in the apothecary and chymist's shops, which 
 are known to be what they are given ont to be. and are 
 perceived to be good or bad in their kind, only by taste 
 or smell ? And how far our judgment of things, by means 
 of our senses might be improved by accurate attention to 
 the small differences of taste and smeil, and other sensible 
 qualities, is not easy to' determine. Sir Isaac Newton, 
 by a noble effort of his great genius, attempted from the 
 colour of opaque bodies, to discover the magnitude of the 
 minute pellucid parts, of which they are compounded : 
 and who knows what new lights natural philosophy may 
 yet receive from other secondary qualities duly examined ? 
 
 Some tastes and smells stimulate the nerves, and raise 
 the spirits ; but such an artificial elevation of the spirits 
 
 vox. i- 28 
 
218 OF TIG HUMAN MIND. 
 
 is, by the laws of nature, folIo>¥ed by a depression, which 
 can only be relieved by time, or by the repeated use of 
 the like stimulus. By the use of such things we create 
 an appetite for them, which very much resembles, and 
 hath all tlie force of a natural one. It is in this manner 
 that men acquire an appetite for snufif, tobacco, strong 
 liquors, laudanum, and the like. 
 
 Nature indeed seems studiously to have set bounds to 
 the pleasures and pains we have by these two senses, and 
 to have confined them within very narrow limits, that we 
 might not place any part of our happiness in them ; there 
 being hardly any smell or taste so disagreeable that use 
 will not make it tolerable, and at last perhaps agreeable; 
 nor any so agreeahle as not to lose its relisti by constant 
 use. Neither is there any pleasure or pain of these senses 
 which is not introduced, or followed, by some degree of 
 its contrary, which nearly balances it. So that we may 
 here apply the beautiful allegory of the divine Socrates j 
 that although pleasure and pain are contrary in their 
 nature, and their faces look different ways, yet Jupiter 
 hath tied them so together, that he that lays hold of the 
 one, draws the other along with it. 
 
 As there is a great variety of smells seemingly simple 
 and uncompounded, not only altogether unlike, but some 
 of them contrary to others; and as the same thing may 
 be said of tastes ; it would seem that one taste is not less 
 different from another than it is from a smell : and there- 
 fore it may be a question, how all smells come to be con- 
 sidered as one genus, and all tastes as another I What is 
 the generieal distinction ? Is it only that the nose is the 
 organ of the one, and the palate of the other ? or, ab- 
 stracting from the organ, is there not in the sensations 
 themselves something common to smells, and something 
 else common to tastes, whereby the one is distinguished 
 from the other? It seems most probable that the latter 
 is the case ; and that under the appearance of the great- 
 est simplicity, there is still in these seusations somethmg 
 of composition. 
 
TASTING. 219 
 
 If one considers the matter abstractly, it would seem, 
 that a number of sensations, or indeed of any other indi- 
 vidual things, which are perfectly simple and uncom- 
 pounded, are incapable of being reduced into genera and 
 species; because individuals which belong to a species, 
 must have something peculiar to each, by which they arc 
 distinguished, and something common to the whole spe- 
 cies. And the same maybe said of species which belong 
 to one genus. And whether this does not imply some 
 kind of composition, we shall leave to metaphysicians to 
 determine. 
 
 ThC'Sensations both of smell and taste do undoubtedly 
 admit of an immense variety of modifications, which no 
 language can express. If a man was to examine five hun- 
 dred different wines, he would hardly find two of them 
 that had precisely the same taste : the same thing holds 
 in cheese, and in many other things. Yet of five hundred 
 difierent tastes in cheese or wine, we can hardly describe 
 twenty, so as to give a distinct notion of them to one who 
 had not tasted them. 
 
 Dr.Nchemiah Grew, a most judicious and laborious nat- 
 uralist, in a discourse read before the Royal Society, anno 
 1675, ha<h endeavoured to show that tliere are at least 
 sixteen different simple tastes, which he enumerates. How 
 many compound ones may be made out of all the various 
 combinations of two, three, four, or more of these simple 
 ones, they who are acquainted with the theory of com- 
 binations will easily perceive. All these have various 
 degrees of inlcnseness and weakness. Many of them have 
 other varieties : in some the taste is more quickly per- 
 ceived upon the application of the sapid body, in others 
 more slowly; in some the sensation is more permanent, 
 in others more transient ; in some it seems to undulate, 
 OP return after certain intervals, in others it is constant : 
 the various parts of the organ, as the lips, the root of the 
 tongue, the fauces, the uvula, and the throat, are some of 
 them chiefly affected by one sapid body, and others by 
 
220 OF THE HUMAN MIND. 
 
 another. All these, and other varieties of tastes, that 
 accurate writer illustrates by a number of examples. Nor 
 is it to be doubted, but smells, if examined with the same 
 accuracy, would appear to have as great variety. 
 
 CHAP. IV. 
 
 OF HEARING. 
 
 SECTION I. 
 
 VARIETT OF SOUNDS. THEIR PLACE AND DISTANCE LEARNED BY CUS- 
 TOM, WI'l'HGUr REASONING. 
 
 Sounds have probably no less variety of modifications, 
 than either tastes or odours. For, first, sounds differ in 
 tone. The ear is capable of perceiving four or five hun- 
 dred variations of tone in sound, and probably as many 
 different degrees of strength; by combining these, we 
 have above twenty thousand simple sounds that differ 
 either in tone or strength, supposing every tone to be 
 perfect. But it is to be observed, that to make a perfect 
 tone, a great many undulations of elastic air are required, 
 which must all be of equal duration and extent; and fol- 
 low one another with perfect regularily ; and each undu- 
 lation rauiit be made up of the advance and recoil of in- 
 numerable particles of elastic air, whose motions are all 
 utiiform in direction, force, and time. Hence we may 
 easily conceive a prodigious variety in the same tone, 
 arising from irregularities of it, occasioned by the con- 
 stitution, figure, situation, or manner of striking the so- 
 norous body : from the constitution of the elastic medium, 
 or its being disturbed by other motions ; and from the 
 constitution of the ear itself upon which the impression 
 is made. 
 
 A flute, a violin, a hautboy, and a French horn, may 
 sail sound the same tone, and be easily distinguishable. 
 
HEABTNO. 2Si 
 
 Nay, if twenty human voices sound the same note, and 
 with equal strength, there will be some difference. The 
 same voice, while it retains its proper distinctions, may 
 yet be varied many ways, by sickness or health, youth or 
 age. leanness or fatness, good or bad humour. The same 
 words spoken by foreigners and natives, nay, by persons 
 of different provinces of the same nation, may be dis- 
 tinguished. 
 
 Such an immense variety of sensations of smell, taste, 
 and sound, surely was not given us in vain. They are 
 signs, by which we know and distinguish things without 
 us ; and it was tit that the variety of ihe signs should in 
 some degree correspond with the variety of things signi- 
 fied by them. 
 
 It seems to be by custom, that we learn to distinguish 
 both the place of things, and their nature, by means of 
 their sound. That such a noise is in the street, such an- 
 other in the room above ine ; that this is a knock at my 
 door, that, a person walking up stairs, is probably leaint 
 by experience. I remember, that once lying abed, and 
 having been put into a fright. I heard my own heart beat ; 
 but I look it to be one knocking at the door, and arose 
 and opened the door oftener than once, before I discov- 
 ered that the sound was in my own brea>t. Il is prob- 
 able, that previous to all experience, we should as little 
 know, whether a sound came from the right or left, from 
 above or below, from a great or a small distance, as we 
 should know whether it was the sound of a drum, or a 
 bell, or a cart. Nature is frugal in her operations, and 
 will not he at the expense of a particular instinct to give 
 us that knowledge which experience will soon produce, 
 by means of a general principle of human nature. 
 
 For a little experience, by the constilulion of human 
 nature, ties together, not only in our imaginalion. but in 
 our belief, those things which were in their nature un- 
 connected. When 1 hear a certain sound. T conclude im- 
 mediately, without reasoning, that a coach passes by. 
 There are no premises from which this couclusiou is ia- 
 
323 OF THE HUMAN MIND. 
 
 ferred by any rules of logic. It is the effect of a princi' 
 pie of our nature, common to us with the brutes. 
 
 Although it is by hearing, that we are capable of the 
 perceptions of harmony and melody, and of all charms of 
 music ; yet it would seem, that these require a higher fac- 
 ulty, which we call a musical ear. This seems to be in 
 very different degrees, in those who have the bare faculty 
 of hearing equally perfect ,• and therefore ought not to be 
 classed with the external senses, but in a higher order. 
 
 SECTION II. 
 or NATURAI lANGUAGB. 
 
 One of the noblest purposes of sound undoubtedly is 
 language j without which mankind would hardly be able 
 to attain any degree of improvement above the brutes. 
 Language is commonly considered as purely an invention 
 of men, who by nature are no less mute than the brutes, 
 but having a superior degree of invention and reason, 
 have been able to contrive artificial signs of their thoughts 
 and purposes, and to establish them by common consent. 
 But the origin of language deserves to be more carefully 
 inquired into, not only as this inquiry may be of import- 
 ance for the improvement of language, but as it is related 
 to the present subject, and tends to lay open some of the 
 first principles of human nature. I shall therefore offer 
 some thoughts upon this subject. 
 
 By language, I understand all those signs which man- 
 kind use in order to communicate to others their thoughts 
 and intentions, their purposes and desires. And such 
 signs may be conceived to be of two kinds: first, such as 
 have no meaning, but what is affixed to them by compact 
 or agreement among those who use them ; these are ar- 
 tificial signs : secondly, such as, previous to all compact 
 or agreement, have a meaning which every man under- 
 stands by the principles of his nature. Language, so far 
 
HEABINe. 2^3 
 
 as it consists of artificial signs, may be called artificial; 
 so far as it consists of natural signs, I call it natural. 
 
 Having premised these definitions, I think it is demon- 
 strable, that if mankind had not a natural language, they 
 could never have invented an artificial one by their rea- 
 son and ingenuity. For all artificial language supposes 
 some compact or agreement to afiix a certain meaning to 
 certain signs ; therefore there must be compacts or agree- 
 ments before the use of artificial signs ; but there can be 
 no compact or agreement without signs, nor without lan- 
 guage; and therefore there must be a natural language 
 before any artificial language can be invented : which was 
 to be demonstrated. 
 
 Had language in general been a human invention, as 
 much as writing or printing, we should find whole nations 
 as mute as the brutes. Indeed the brutes have some nat- 
 nral signs by which they express their own thoughts, af- 
 fections and desires, and understand those of others. A 
 chick, as soon as hatched, understands the difi'erent sounds 
 whereby its dam calls it to food, or gives the alarm of 
 danger. A dog or ahorse understands, by nature, when 
 the human voice caresses, and when it threatens him. But 
 brutes, as far as we know, have no notion of contracts or 
 covenants, or of moral obligation to nerform them. If 
 nature had given them these notions, she would probably 
 have given them natural signs to express them. And 
 where nature has denied these notions, it is as impossible 
 to acquire them by art, as it is for a blind man to acquire 
 the notion of colours. Some brutes are sensible of hon- 
 our or disgrace; they have resentment and gratitude; 
 but none of them, as far as we know, can make a prom- 
 ise, or plight their faith, having no such notions from their 
 constitution. And if mankind had not these notions by 
 nature, and natural signs to express them by, with all 
 their wit and ingenuity they could never have invented 
 language. 
 
 The elements of this natural language of mankind, op 
 the signs thai are naturally expressive of our thoughts^. 
 
224 eF THE HUMAN MIND. 
 
 may, T think, be reduced to tliese three kinds ; modula* 
 tiofis of the voice, gestures, and features. By means of 
 these, two savages who have no common artificial lan- 
 guage, can converse together, can communicate their 
 thoughts in some tolerable manner ; can ask and refuse, 
 affirm and deny, threaten and supplicate ; can traffic, en- 
 ter into covenants, and plight their faith. This might be 
 confirmed by historical facts of undoubted credit, if it 
 were necessary. 
 
 Mankind having thus a common language by nature, 
 though a scanty one, adapted only to the necessities of 
 nature, there is no great ingenuity required in improv- 
 ing it by the addition of artificial signs, to supply the de- 
 ficiency of the natural. These artificial signs must mnlti- 
 ply with the arts of life, and the improvements of knowl- 
 edge. The articulations of the voice, seem to be, of all 
 signs, the most proper for artificial language; and as 
 mankind have universally used them for that purpose, we 
 may reasonably judge that nature intended them for it. 
 But nature probably does not intend that we should lay 
 aside the use of the natural signs: it is enough (hat we 
 supply their defects by artificial ones. A man that rides 
 always in a chariot, by degrees loses the u«ie of his Tegs; 
 and one who uses artificial signs only, loses both the 
 knowledge and use of the natural. Dumb ??eople retain 
 much more of the natural language than others, because 
 necessity obliges them to use it. And for the same rea- 
 son, savages have much more of if than civilized nations. 
 It is by natural signs chiefly thai we give force and en- 
 ergy to language: and the less language has of them, it 
 is the less expressive and persuasive. Thus, writing is 
 less expressive than reading, and reading less expressive 
 than speaking without book : speaking without the prop- 
 er and natural modulations, force, and variations of the 
 Toice. is a frigid and dead language, compared with that 
 which is attended with them : it is still more expressive 
 when we add the language of the eyes and features; and 
 is theu onljr ia its perfect and natural state; and attended 
 
HEAlllNG. 225 
 
 witli its proper energy, wLen to all these we superadd the 
 force of action. 
 
 Where speech is natural, it will be an exercise, not of 
 the voice and lungs only, but of all the muscles of the 
 body ; like that of dumb people and savages, whose lan- 
 guage, as it has more of nature, is more expressive, and 
 is more easily learned. 
 
 Is it not pity that the refinements of a civilized life, in- 
 stead of supplying the defects of natural language, should 
 root it out, and plant in its stead dull and lifeless articu- 
 lations of unmeaning sounds, or the scrawling of insignifi- 
 cant characters ? The perfection of language is common- 
 ly thought to be, to express human thoughts and senti- 
 ments distinctly by these dull signs ; but if this is the 
 perfection of artificial language, it is surely the corrup- 
 tion of the natural. 
 
 Artificial signs signify, but they do not express j they 
 speak to the understanding, as algebraical characters 
 may do, but the passion, the affections, and the will, hear 
 them not : these continue dormant and inactive, till we 
 speak to them in the language of nature, to which they 
 are all attention and obedience. 
 
 It were easy to shew that the fine arts of thenfusician, 
 the painter, the actor, and the orator, are natural so far 
 as they are expressive j although the knowledge of them 
 requires in us a delicate taste, a nice judgment, and much 
 study and practice ; yet they are nothing else but the lan- 
 guage of nature, which we brought into (he world with 
 us, but have unlearned by disuse, and so find the greatest^ 
 difiieulty in recovering it. 
 
 Abolish the use of articulate sounds and writing among 
 mankind for a century, and every man would be a painter, 
 an actor, and an orator. We mean not to affirm that 
 such an expedient is practicable | or, if it were, that the 
 advantage would counterbalance the loss; but that, as 
 men are led by nature and necessity to converse together, 
 they will use every mean in their power to make them- 
 
 Toi. 1. 39 
 
226 OF THE HUMAN MIND. 
 
 selves understood ; and where they cannot do this by 
 artificial signs, they will do it, as far as possible, by nat- 
 ural ones : and he that understands perfectly the use of 
 natural signs, must be the best judge in all the expressive 
 arts. 
 
 CHAP.V. 
 
 OF TOUCH. 
 
 SECTION I. 
 or HEAT AND COLD. 
 
 The senses which we have hitherto considered, are 
 very simple and uniform, each of them exhibiting only 
 one kind of sensation, and thereby indicating only one 
 quality of bodies. By the ear we perceive sounds, and 
 nothing else ; by the palate, tastes ; and by the nose, 
 odours. These qualities are all likewise of one order, 
 being all secondary qualities : whereas by touch we per- 
 ceive not one quality only, but many, and those of very 
 different kinds. The chief of them are heat and cold, 
 hardness and softnes.s, roughness and smoothness, figure, 
 solidity, motion, and extension. We shall consider these 
 in order. 
 
 As to heat and cold, it will easily be allowed that they 
 are secondary qualities, of the same order with smell, 
 taste, and sound. And, therefore, what hath been already 
 said of smell, is easily applicable to tliem ; that is, that 
 the words heat and cold have each of them two significa- 
 tions ; they sometimes signify certain sensations of the 
 mind, which can have no existence when they are not 
 felt, nor can exist any where but in a mind or sentient 
 being; but more frequently they signify a quality in bod- 
 ies, which, by the laws of nature, occasions the sensations 
 of heat and cold in us : a quality which, though connect- 
 
TOUCH. 227 
 
 ed by eustom so closely with the seusation, that we can- 
 not without difficulty separate them ; yet hath not the 
 least resemblance to it, and may continue to exist when 
 there is no sensation at all. 
 
 The sensations of heat and cold are perfectly known ; 
 for they neither are, nor can be. any thing else than what 
 we feel them to be ; but the qualities in bodies which we 
 call heat and cold, are unknown. They are only conceiv- 
 ed by us, as unknown causes or occasions of the sensa- 
 tions to which we give the same names. But though 
 common sense says nothing of tlie nature of these quali- 
 ties, it plainly dictates the existeijce of (hem ; and to deny 
 that there can be heat and cold when they are not felt, is 
 an absurdity too gross to merit confutation. For what 
 could be more absurd, than to say, that the thermometer 
 cannot rise or fall, unless some person be present, or that 
 the coast of Guinea would be as cold as IVova Zerobla, if 
 it ha^ ^o inhabitants. 
 
 It is the business of philosophers to investigate, by 
 proper experiments and induction, what heat and cold are 
 in bodies. And whether they make heat a particular el- 
 ement diffused through nature, and accumulated in the 
 heated body, or whether they make it a certain vibration 
 of the parts of the heated body ; whether they determine 
 that heat and cold are contrary qualities, as the sensa- 
 tions undoubtedly are contrary, or that heat only is a 
 quality, and cold its privation : these questions are within 
 the province of philosophy ; for common sense says noth- 
 ing on the one side or the other. 
 
 But whatever be the nature of that quality in bodies 
 which we call heat, we certainly know Jhis, that it can- 
 not in the least resemble the sensation of heat. It is no 
 less absurd to suppose a likeness between the sensation 
 and the quality, than it would be to suppose, that the 
 pain of the gout resembles a square or a triangle. The 
 simplest man that hath common sense, does not imagine 
 the sensation of heat, or any thing that resembles that 
 sensation, to be in the fire. He only imagines, that there 
 
328 OF THE HUMAW MIND. 
 
 is something in the fire, which makes him and other sen- 
 tient beings feel heat. Yet as the name of heat, in com- 
 mon language, more frequently and more properly signi- 
 fies this unknown something in the fire, than the sensa- 
 tion occasioned by it, he justly laughs at the philosopher 
 who denies that there is any heat in the fire, and think; 
 that he speaks contrary to common sense. 
 
 SECTION II. 
 
 4 
 
 OF HARDNESS AND SOFTNESS. 
 
 Let us next consider hardness and softness j by which 
 words we always understand real properties or qualities 
 of bodies of which we have a distinct conception. 
 
 When the parts of a body adhere so firmly that it can- 
 not easily be made to change its figure, we call it hard ; 
 when its parts are easily displaced, we call it soft. This 
 is the notion which all mankind have of hardness and 
 softness : they are neither sensations, nor like any sensa- 
 tion ,• they were real qualities before they were perceived 
 by touch, and continue to be so when they are not perceiv- 
 ed : for if any man will affirm, that diamonds were not 
 hard till they were handled, who would reason with him ? 
 
 There is no doubt a sensation by which we perceive a 
 body to be hard or soft. This sensation of hardness may 
 easily be had, by jiressing one's hand against the table, 
 and attending to the feeling that ensues, setting aside, as 
 much as possible, all thought of the table and its quali- 
 ties, or of any external thing. But it is one thing to have 
 the sensation, and another to attend to it, and make it a 
 distinct object of reflection. The first is very easy ; the 
 last, in most cases, extremely difficult. 
 
 We are so accustomed to use the sensation as a sign, 
 and to pass immediately to the hardness signified, that, 
 as far as appears, it was never made an object of thought, 
 either by the vulgar or by philosophers } nor has it a name 
 
TdUCH. 229 
 
 in any language. There is no sensation more distinct, 
 or more frequent ; yet it is neyer attended to, but passes 
 through the inind instantaneously, and serves only to 
 introducej that quality in bodies, which, by a law of our 
 constitution, it suggests. 
 
 There are indeed some cases wherein it is no difficult 
 matter to attend to the sensation occasioned by the hard- 
 ness of a body ; for instance, when it is so violent as to 
 occasion considerable pain : then nature calls upon us to 
 attend to it, and then we acknowledge that it is a mere 
 sensation, and can only be a sentient being. If a man 
 runs his head with violence against a pillar, I appeal to 
 him, whether the pain he feels resembles the hardness of 
 the stone j or if he can conceive any thing like what he 
 feels to be in an inanimate piece of matter. 
 
 The attention of the mind is here entirely turned to- 
 ward the painful feeling; and, to speak in the common 
 language of mankind, he feels nothing in the stone, but 
 feels a violent pain in his head. It is quite otherwise 
 when he leans his head gently against the pillar; for then 
 be will tell you that he feels nothing in his head, but feels 
 hardness in the stone. Hath he not a sensation in this 
 case as well as in the other 7 Undoubtedly he hath ; but 
 it is a sensation which nature intended only as a sign of 
 something in the stone ,* and, accordingly, he instantly 
 fixes his attention upon the thing signified ; and cannot, 
 without great difficulty, attend so much to the sensation, 
 as to be persuaded that there is any such thing distinct 
 from the hardness it signifies. 
 
 But however difficult it may be to attend to this fugi- 
 tive sensation, to stop its rapid progress, and to disjoin it 
 from the external quality of hardness, in whose shadow 
 it is apt immediately to hide itself; this is what a phi- 
 losopher by pains and practice must attain, otherwise it 
 will be impossible for him to reason justly upon this sub- 
 ject, or even to understand what is here advanced. For 
 the last appeal, in subjects of this nature, must be to what 
 a man feels aqd perceives in his own mind. 
 
330 OB THE HUMAX MIND. 
 
 It is indeed strange, that a sensation which we have 
 every time we feel a body Ijard, and which consequently, 
 ■we can command as often, and continue as long as we 
 please, a sensation as distinct and determinate as any other, 
 should yet be so much unknown, as never to have been 
 made an object of thought and reflection, not to have been 
 honoured with a name in any language ; that philosophers, 
 as well as the vulgar, should have entirely overlooked i(, 
 or confounded it with tiiat quality of bodies which we call 
 hardness, to which it hath not the least similitude. May 
 we not hence conclude, that the knowledge of the human 
 faculties is but in its infancy ? That we liave not yet learn- 
 ed to attend to those operations of the mind, of which we 
 are conscious every hour of our lives ? that there are 
 habits of inattention acquired very early, which are as 
 hard to be overcome as other habits ? For I think it is 
 probable, that the novelty of this sensation will procure 
 some attention to it in children at first ; but being in no- 
 wise interesdng in itself, as soon as it becomes familiar, 
 it is overlooked, and the attention turned solely to that 
 which it signifies. Thus, when one is learning a lan- 
 guage, he attends to the sounds ; but when he is master 
 of it, he attends only to the sense of what he would ex- 
 press. If this is the case, we must become as little chil- 
 dren again, if we will be philosophers : we must overcome 
 this habit of inattention which has been gathering strength 
 ever since we began to think ; a habit, the usefulness of 
 which, in common life, atones for the difiiculty it creates 
 to the philosopher, in discovering the first principles of 
 the human mind. 
 
 The firm cohesion of the parts of a body, is no more 
 like that sensation by which I perceive it to be hard, than 
 the vibration of a sonorous body is like the sound I hear : 
 nor can I possibly perceive, by my reason, any connection 
 between the one and the other. No man can give a rea- 
 son, why the vibration of a body might not have given 
 the sensation of smelling, and the effluvia of bodies af- 
 fected our hearing, if it had so pleased our Maker. In 
 
TOUCH. 231 
 
 like manner, no man can give a reason, wby tlie sensa- 
 tions of smell, or taste, on sound, might not have indicat- 
 ed hardness, as well as that sensation, which, by our con- 
 stitution, does indicate it. Indeed no man can conceive 
 any sensation to resemble any known quality of bodies. 
 Nor can any man shew, by any good argument, that all 
 our sensations might not have been as they are, though 
 no body, nor quality of body, had ever existed. 
 
 Here, then, is a phenomenon of human nature, which 
 comes to be resolved. Hardness of bodies is a thing that 
 we conceive as distinctly, and believe as firmly, as any 
 thing in nature. We have no way of coming at this con- 
 ception and belief, but by means of a certain sensation of 
 touch, to which hardness hath not the least similitude | 
 nor can we, by any rules of reasoning, infer the one from 
 the other. The question is, how we come by this con- 
 ception and belief? 
 
 First, as to the conception : shall we call it an idea of 
 sensation, or of reflection ? The last will not be affirmed ; 
 and as little can the first, unless we will call that an idea 
 of sensation, which hath no resemblance to any sensation. 
 So that the origin of this idea of hardness, one of the 
 most common and most distinct we have, is not to be 
 found in all our systems of the mind : not even in those 
 which have so copiously endeavoured to deduce all our 
 notions from sensations and reflection. 
 
 But, secondly, supposing we have got the conception of 
 hardness, how come we by the belief of it ? Is it self-evi- 
 dent, from comparing the ideas, that such a sensation 
 could not be felt, unless such a quality of bodies existed ? 
 No. Can it be proved by probable or certain arguments ? 
 No, it cannot. Have we got this belief, then, by tradi- 
 tion, by education, or by experience ? No, it is not got in 
 any of these ways. Shall we then throw off this belief, 
 as having no foundation in reason ? Alas ! it is not in our 
 power ; it triumphs over reason, and laughs at all the ar- 
 guments of a philosopher. Even the author of the Trea- 
 tise of Human Nature, though he saw no reason for this 
 belief, but many against it, could hardly conquer it in, hi« 
 
2SS OF THE HUMAN MIKD. 
 
 speculative and solitary moments ; at other times he fairly 
 yielded to it, and confesses that he found himself under a 
 necessity to do so. 
 
 What shall we say then of this conception, and this be- 
 lief, which are so unaccountable and untractable ? I sec 
 nothing left but to conclude, that by an original principle 
 of our constitution, a certain sensation of touch both sug- 
 gests to the mind the conception of hardness, and creates 
 the belief of it : or, in other words, that this sensation is 
 a natural sign of hardness. And this I shall endeavour 
 more fully to explain. 
 
 SECTION in. 
 
 on TfATCRAI SIGNS. 
 
 As in artificial signs there is often neither similitude 
 between the sign and the thing signified, nor any connec- 
 tion that arises necessarily from the nature of the things ; 
 so it is also in natural signs. The word gold has no simil- 
 itude to the substance signified by it ; nor is it in its own 
 nature more fit to signify this than any other substance : 
 yet, by habit and custom it suggests this and no other. In 
 like manner, a sensation of touch suggests hardness, al- 
 though it hath neither similitude to hardness, nor, as far 
 as we can perceive, any necessary connection with it. The 
 difference betwixt these two signs lies only in this, that, 
 in the first, the suggestion is the efiect of habit and cus- 
 tom ; in the second, it is not the effect of habit, but of the 
 original constitution of our minds. 
 
 It appears evident from what hath been said on the 
 subject of language, that there are natural signs, as well 
 as artificial ; and particularly, that the thoughts, pur- 
 poses, and dispositions of the mind have their natural 
 signs in the features of the face, the modulation of the 
 voice, and the motion and attitude of the body : that with- 
 out a natural knowledge of the connection between these 
 signs, and the things signified by them, language could 
 
TOUCH. 3SS 
 
 acvep have been invented and established among men : 
 and, that the fine arts are all founded upon this connec- 
 tion, which we may call the natural language of mankind. 
 It is now proper to observe, that there are difiereni orders 
 of natural signs, and to point out the different classes into; 
 which they may be distinguished, that we may more dis- 
 tinctly conceive the relation between our sensations and 
 the things they suggest, and what we mean by calling 
 sensations signs of external things. 
 
 The first class of natural signs comprehends those 
 whose connection with the thing signified is established 
 by nature, but discovered-only by experience. The whole 
 of genuine philosophy consists in discovering such con- 
 nections, and reducing them to general rules. The great 
 lord Verulam had a perfect comprehension of this, when 
 he called it an interpretation of nature. No man ever 
 more distinctly understood, or happily expressed, the na- 
 ture and foundation of the philosophic art. What is all 
 we know of mechanics, astronomy, and optics, but con- 
 nections established by nature, and discovered by expe- 
 rience or observation, and consequences deduced from 
 them ? All the knowledge we have in agricultut-e, gar- 
 dening, chymistry, and medicine, is built upon the same 
 foundation. And if ever our philosophy concerning the 
 human mind is carried so far as to deserve the name of 
 science, which ought never to be despaired of, it must be 
 by observing facts, reducing them to general rules, and 
 drawing just conclusions from them. What we commonly 
 call natural causes, might, with more propriety, be called 
 natural signs, and what we call effects, the things signi- 
 fied.* The causes have no proper eflSciency or causality, 
 
 * The learned writer was no advocate for the doctrine, that a cause is 
 merely something antecedent ; and an effect merely something conseguent. 
 That causes possess an inherent power of producing effects we cannot know; 
 for we have, at present, no faculty of perceiving the nature of efficiency i 
 but of this we are assured, that every effect requires for its existence, its 
 own proper cause. A mechanical cause vf ill produce only a mechanical 
 effect, and a moral cause is requisite to produce a moral effect. I'here is 
 mot only a conjnnctioQ between causes and effects, but something in each 
 
 vol. I. 30 
 
23 Ji OF THB HUMAN MIXU. 
 
 as far as we know ; and all we can certainly affirm, is, 
 that nature hath established a constant conjunction be- 
 tween thera and the things called their effects ; and hath 
 giyen to mankind a disposition to observe those connec- 
 tions, to confide in their continuance, and to make use 
 of them for the improvement of our knowledge, and in- 
 crease of our power. 
 
 A second class is that wherein the connection between 
 the sign and the thing signified is not onlj established by 
 nature, but discovered to us by a natural principle, with- 
 out reasoning or experience. Of this kind are the natural 
 signs of human thoughts, purposes, and desires, which 
 have been already mentioned as the natural language of 
 mankind. An infant may be put into a fright by an angry 
 countenance, and soothed again by smiles and blandish- 
 ments. A child that has a good musical ear may be put 
 to sleep or to dance, may be made merry or sorrowful, by 
 the modulations of musical sounds. The principles of all 
 the fine arts, and of what we call a fine taste, may be re- 
 solved into connections of this kind. A fine taste may be 
 improved by reasoning and experience; but if the first 
 principles of it were not planted in our minds by nature, 
 it could never be acquired. Nay, we have already made 
 it appear, that a great part of this knowledge which we 
 have by nature, is lost by the disuse of natural signs, and 
 the substitution of artificial in their place. 
 
 A third class of natural signs comprehends those which, 
 though we never before had any notion or conception of 
 the things signified, do suggest it, or conjure it up, as it 
 yrere, by a natural kind of magic, and at once give us a 
 conception, and create a belief of it. I shewed formerly, 
 that our sensations suggest to us a sentient being or mind 
 to which they belong : a being which hath a permanent 
 existence, although the sensations are transient and of 
 abort duration : a being which is still the same, while its 
 
 cause which is designed by its Maker, to produce its own proper effect. 
 Thus, there is something in heat, which is calculated to make -water evap- 
 orate, rather than become ice ; but that the Creator could not have made 
 heat produce the effect ^fhieh we call freezing, who will pretend to say ! 
 
 Americait Ed. 
 
' TOUCH.' 235 
 
 sensations and other operations are varied ten tliousand 
 wajs : a being which hath the same relation to all that 
 infinite variety of thoughts, purposes, actions, affections, 
 enjoyments, and sufferings, which we are conscious of, or 
 can remember. The conception of a mind is neither an 
 idea of sensation nor of reflection ; for it is neither like 
 any of our sensations, nor like any thing we are conscious 
 of. The first conception of it, as well as the belief of it, 
 and of the common relation it bears to all that we are 
 conscious of, or remember, is suggested to every thinking 
 being, we do not know how. 
 
 The notion of hardness in bodies, as well as the belief 
 of it, are got in a similar manner i being by an original 
 principle of our nature, annexed to that sensation which 
 we have when we feel a hard body. And so naturally 
 and necessarily does the sensation convey the notion and 
 belief of hardness, that hitherto they have been confound- 
 ed by the most acute inquirers into the principles of hu- 
 man nature, although they appear, upon accurate reflec- 
 tion, not only to be different things, but as unlike as pain 
 is to the point of a sword. 
 
 It may be observed, that as the first class of natural 
 signs I have mentioned, is the foundation of true philos- 
 ophy, and the second, the foundation of the fine arts, or 
 of taste; so the last is the foundation of common sense; 
 a part of human nature which hath never been explained. 
 
 I take it for granted, tliat the notion of hardness, and 
 the belief of it, is first got by means of that particular sen- 
 sation, which, as far back as we can remember, does invari- 
 ably suggest it; and that if we had never had such a feeling, 
 we should never have had any notion of hardness. I think 
 it is evident, that we cannot, by reasoning from our sen- 
 sations, collect the existence of bodies at all, far less any 
 of their qualities. This hath been proved by unanswer- 
 able arguments by the bishop of Cloyne, and by the au- 
 thor of the Treatise of Human Nature. It appears as 
 evident, that this connection between our sensations and 
 the conception and belief of external existences^ cannot 
 
OF THE HITMAN MINB. 
 
 be produced bj babit, experience, education, or any prin- 
 ciple of human nature that hath been admitted by philos- 
 ophers. At the same time, it is a fact, that such sensa- 
 tions are invariably connected with the conception and 
 belief of external exi^stences. Hence, by all rules of just 
 reasoning, we must conclude, that this connection is the 
 effect of our constitution, and ought to be considered as an 
 original principle of human nature, till we find some more 
 general principle into which it may be resolved. 
 
 SECTION IV. 
 OF HAHDNESS, AND OTHER PRIMAKY q,UAIITIES. 
 
 Further I observe, that hardness is a quality, of which 
 we have as clear and distinct a conception as of anything 
 whatsoever. The cohesion of the parts of a body with 
 more or less force, is perfectly understood, though its 
 cause is not : we know what it is, as well as how it affects 
 the touch. It is therefore a quality of a quite different 
 order from those secondary qualities we have already 
 taken notice of, whereof we know no more naturally, than 
 that they are adapted to raise certain sensations in us. 
 If hardness were a quality of the same kind, it would be 
 a proper inquiry for philosophers, what hardness in bodies 
 is ? and wc should have had various hypotheses about it, 
 as well as about colour and heat. But it is evident that 
 any such hypothesis would be ridiculous. If any man 
 should say, that hardness in bodies is a certain vibration 
 ; of their parts, or that it is certain effluvia emitted by them 
 which affect our touch in the manner we feel : such hy- 
 pothesis would shock common sense ; because we all know, 
 that if the parts of a body adhere strongly, it is hard, al- 
 though it should neither emit effluvia, nor vibrate. Yet 
 at the same time, no man can say, but that effluvia, or 
 the vibration of the parts of a body, might have affected 
 our touch, in the same manner that hardness now does. 
 
TOUCH. 2S7 
 
 If it had so pleased the Author of our nature : and if 
 either of these hypotheses is applied to explain a second- 
 ary quality, such as smell, or taste, or sound, or colour, 
 or heat, there appears no manifest ahsurdity in the sup- 
 position. 
 
 The distinction betwixt primary and secondary quali- 
 ties hath had several revolutions. Democritus and Epi- 
 curus, and their followers maintained it. Aristotle and 
 the Peripatetics abolished it. Des Cartes, Malebranche, 
 and Locke, revived it, and were thought to have put it in 
 a very clear light. But bisliop Berkeley again discarded 
 this distinction, by such proofs as must be coilvincing to 
 those that hold the received doctrine of ideas. Yet, after 
 all, there appears to be a real foundation for it in the 
 principles of our nature. 
 
 Wliat hath been said of hardness, is so easily applicable, 
 not only to its opposite, softness, but likewise to rough- 
 ness and smoothness, to figure and motion, that we may 
 be excused from making the application, which would 
 only be a repetition of what hath been said. All these, 
 by means of certain corresponding sensations of touch, are 
 presented to the mind as real external qnalities ; the con- 
 ception and the belief of them are invariably connected 
 with the corresponding sensations, by an original princi- 
 ple of human nature. Their sensations have no name in 
 any language ; they have not only been overlooked by the 
 vulgar, but by philosophers ; or if they have been at all 
 taken notice of, they have been confounded with the ex- 
 ternal qualities which they suggest. 
 
 SECTION V. 
 or EXTENSION. 
 
 It is further to be observed, that hardness aud soft- 
 ness, roughness and smoothness, figure and motion, do 
 all suppose extension and cannot be conceived without it } 
 
23S OF THE HUMAN MIND. 
 
 jet I think it must, on the other band, be allowed, that 
 
 if we had never felt any thing hard or soft, rough or 
 
 smooth, figured or moved, we should never have had a 
 
 j conception of extension : so that as there is good ground 
 
 N to believe, that the notion of extension could not be prior 
 
 f to that of other primary qualities ; so it is certain that it 
 
 could not be posterior to the notion of any of them, being 
 
 / necessarily implied in them all. 
 
 Extension, therefore, seems to be a quality suggested 
 to us, by the very same sensations which suggest the 
 other qualities above mentioned. When I grasp a ball 
 in my hand, I perceive it at once hard, figured and ex- 
 tended. The feeling is very simple, and hath not the 
 least resemblance to any quality of body. Yet it suggests 
 to us three primary qualities perfectly distinct from one 
 another, as well as from the sensation which indicates 
 them. When I move my hand along the table, the feel- 
 ing is so simple, that I find it difficult to distinguish it 
 into things of different natures ; yet it immediately sug- 
 gests hardness, smoothness, extension, and motion, things 
 of very difierent natures, and all of them as distinctly 
 understood as the feeling which suggests them. 
 
 We are commonly told by philosophers, that we get 
 the idea of extension by feeling along the extremities of 
 a body, as if there was no manner of difBculty in the mat- 
 ter. I have sought, with great pains I confess, to find out 
 how this idea can be got by feeling, but I have sought in 
 vain. Yet it is one of the clearest and most distinct no- 
 tions we have ; nor is there any thing whatsoever, about 
 vhich the human understanding can carry on so many 
 long and demonstrative trains of reasoning. 
 
 The notion of extension is so familiar to us from in- 
 fancy, and so constantly obtruded by every thing we see 
 and feel, that we are apt to think it obvious how it comes 
 into the mind ; but upon a narrower examination we shall 
 find it utterly inexplicable. It is true we have feelings 
 of touch, which every moment present extension to the 
 mind ; but how they come to do so, is the question ; for 
 
TOUCH. 239 
 
 those feelings do no more resemble extension, than they 
 resemble justice or courage : nor can the existence of ex- 
 tended things be inferred from those feelings by any rules 
 of reasoning : so that the feelings we have by touch, can 
 neither explain how we get the notion, nor how we come 
 by the belief of extended things. < 
 
 What hath imposed upon philosophers in this matter, 
 is, that the feelings of touch, whicli suggest primary qual- 
 ities, have no names, nor are they ever reflected upon. 
 They pass fhrough the mind instantaneously, and serve 
 only to introduce the notion and belief of external things, 
 which by our constitution are connected with them. They 
 are natural signs, and the mind immediately passes to the 
 thing signified, without making the least reflection upon 
 the sign, or observing that there was any such thing. 
 Hence it hath always been taken for granted, that the 
 ideas of extension, figure, and motion, are ideas of sensa- 
 tion, which enter into the mind by the sense of touch, in 
 the same manner as the sensations of sound and smell do 
 by the ear and nose. The sensations of touch are so con- 
 nected, by our constitution, with the notions of extension, 
 figure and motion, that philosophers have mistaken the 
 one for the other, and never have been able to discern 
 that they were not only distinct things, but altogether un- 
 like. However, if we will reason distinctly upon this sub- 
 ject, we ought to give names to those feelings of touch ; 
 we must accustom ourselves to attend to them, and to re- 
 ilect upon them, that we may be able to disjoin them 
 from, and to compare them with, the qualities signified 
 or suggested by them. 
 
 The habit of doing this is not to be attained without 
 pains and practice ; and till a man hath acquired this hab- 
 it, it will be impossible for him to think distinctly, or to 
 judge right, upon this subject. 
 
 Let a man press his hand against the table : he feels it 
 hard. But what is the meaning of this ? the meaning 
 undoubtedly is, that he hath a certain feeling of touch* 
 from which he conoludes, without any reasoniug, or com- 
 
240 OF THE HUSiAN MIND. 
 
 paring ideas, that there is something external really ex- 
 isting, whose parts stick so firmly together that they can- 
 not be displaced without considerable force. 
 
 There is here a feeling and a conclusion drawn from 
 it, or some way suggested by it. In order to compare 
 these, we must view them separately, and then consider 
 by what tie they are connected and wherein they resem- 
 ble one another. The hardness of the table is the con- 
 clusion, the feeling is the medium by which we are led to 
 that conclusion. Let a man attend distinctly to this me- 
 dium, and to the conclusion, and he will perceive them to 
 be as unlike as any two things in nature. The one is a 
 sensation of the mind, which can have no existence but 
 in a sentient being ; nor can it exist one moment longer 
 than it is felt ; the other is in the table, and we conclude 
 without any dilBeulty, that it was in the table before it 
 was felt, and continues after the feeling is over. The one 
 implies no kind of extension, nor parts, nor cohesion ; the 
 other implies all these. Both indeed admit of degrees; 
 and the feeling, beyond a certain degree, is a species of 
 pain ; but adamantine hardness does not imply the least 
 pain. 
 
 And as the feeling hath no similitude to hardness, so 
 neither can our reason perceive the least tie or connec- 
 tion between them ; nor will the logician ever be able to 
 show a reason why we should conclude hardness from this 
 feeling, rather than softness, or any other quality what- 
 soever. But in reality all mankind are led by their con- 
 stitution to conclude hardness from this feeling. 
 
 The sensation of heat, and the sensation we have by 
 pressing a hard body, are equally feelings : nor can we 
 by reasoning draw any conclusion from the one, but what 
 may be drawn from the other : but, by our constitution, 
 we conclude from the first an obscure or occult quality, 
 of which we have only this relative conception, that it is 
 something adapted to raise in us the sensation of heat; 
 from the second, we conclude a quality of which we have 
 a clear and distinct conception, to wit^ the hardness of 
 the body. 
 
TOUCH. 241 
 
 SECTION VI. 
 
 OF EXTENSIOir. 
 
 To put this matter in another light, it may be proper 
 to try, whether from sensation alone we can collect any 
 notion of extension, figure, motion, and space. I take it 
 for granted, that a blind man hath the same notions of 
 iextension, figure, and motion, as a man that sees ; that 
 Dr. Saunderson had the same notion of a cone, a cyl- 
 inder, and a sphere, and of the motions and distances of 
 the heavenly bodies, as Sir Isaac Newton. 
 
 As sight therefore is not necessary for our acquiring 
 those notions, we shall leave it out altogether in our in- 
 quiry into the first origin of them : and shall suppose a 
 blind man, by some strange distemper, to have lost all 
 the experience and habits and notions he had got by 
 touch ,• nor to have the least conception of the existence, 
 figure, dimensions, or extension, either of his own body, 
 or of any other j but to have all his knowledge of exter- 
 nal things to Require anew, by means of sensation, and 
 the power of reason, which we suppose to remain en- 
 tire. 
 
 We shall, first, suppose his body fixed^immoveably in 
 one place, and that he can only have the feelings of touch> 
 by the application of other bodies to it. Suppose him 
 first to be pricked with a pin ,• this will, no doubt, give a 
 smart sensation : he feels pain ; but what can he infer 
 from it ? Nothing surely with regard to the existence or 
 figure of a pin. He can infer nothing from this species 
 of pain, which he may not as well infer from the gout or 
 sciatica. Common sense may lead him to think that this 
 pain has a cause ; but whether this cause is body or spir- 
 it, extended or unextended, figured or not figured, he 
 cannot possibly, from any principles he is supposed to 
 have, form the least conjecture. Having bad formerly no 
 
 vol. I. 31 
 
342 er the human minb. 
 
 notion of body or of extension, the prick of a pin can 
 give him none. / 
 
 Suppose, next, a body not pointed, but blunt, is applied 
 to his body with a force gradually increased until it 
 bruises him. What has he got by this, but another sen- 
 sation, or train of sensations, from which he is able to 
 conclude as little as from the former ? A schirrous tumour 
 in any inward part of the body, by pressing upon the adja- 
 cent parts, may give the same kind of sensation as the 
 pressure of an external body, without conveying any no- 
 tion but that of pain, which surely hath no resemblance 
 to extension. 
 
 Suppose, thirdly, that the body apfilied to him touches 
 a larger or a lesser part of his body. Can this give him 
 any notion of its extension or dimensions? To me it seems 
 impossible that it should, unless he had some previous no- 
 tion of the dimensions and figure of bis own body, to 
 serve him as a measure. When my two hands touch the 
 extremities of a body ; if I know them to be a foot asun- 
 der, I easily collect that the body is a foot long ; and if I 
 know them to be five feet asunder, that it is five feet long : 
 but if I know not what the distance of my hands is, I can- 
 not know the length of the object they grasp ; and if I 
 have no previous notion of hands at all, or of distance be- 
 tween them, I can never get that notion by their being 
 touched. 
 
 Suppose again, that a body is drawn along his hands or 
 face, while they are at rest. Can tliis give him any no- 
 tion of space or motion. It no doubt gives a new feeling; 
 but how it should convey a notion of space or motion, to 
 one who had none before, I cannot conceive. The blood 
 moves along the arteries and veins, and this motion, when 
 violent, is felt: but I imagine no man, by this feeling, 
 could get the conception of space or motion, if he had it 
 not before. Such a motion may give a certain succession 
 of feelings, as the colic may do ; but no feelings, nor any 
 combination of feelings, can ever resemble space or mo- 
 tion. 
 
TOUCH. 243 
 
 liCt us next suppose, that lie makes some instinctive 
 eflTort to move his head or his hand ; hut that no motion 
 follows, either on account of external resistance, or of 
 palsy. Can this effort convey the notion of space and 
 motion to one who never had it before ? Surely it cannot. 
 
 Last of all, let us suppose, that he moves a limb by 
 instinct, without having had any previous notion of space 
 or motion. He has here a new sensation, which accom- 
 panies the flexure of joints, and the swelling of muscles. 
 But how this sensation can convey into his mind the idea 
 of space and motion, is still altogether mysterious and 
 unintelligible. The motions of the heart and lungs are 
 all performed by the contraction of muscles, yet give no 
 conception of space or motion. An embryo in the womb 
 has many such motions, and probably the feelings that 
 accompany them, without any idea of space or motion. 
 
 Upon the whole, it appears, that our philosophers have 
 imposed upoh themselves, and upon us, in pretending to 
 deduce from sensation the first origin of our notions of 
 external existences, of space, motion, and extension, and 
 all the primary qualities of body, that is, the qualities 
 whereof we have the most clear and distinct conception. 
 These qualities do not at all tally with any system of the 
 human faculties that hath been advanced. They have no 
 resemblance to any sensation, or to any operation of our 
 minds ; and therefore they cannot be ideas either of sen- 
 sation, or of reflection. The very conception of them is 
 irreconcilable to the principles of all our philosophic sys- 
 tems of the understanding. The belief of them is no 
 less so. 
 
 SECTION VII. 
 or THE EXISTENCE OE A MATERIA! WORID. 
 
 It is beyond our power to say, when or in what order 
 fve came by our notions of these qualities. When we 
 
244 OF THE HUMAW MIND. 
 
 trace the operations of our minds as far back as memory 
 and reJiection can carry us, we find them already in pos- 
 session of our imagination and belief, and quite familiar 
 to the mind : but how they came first into its acquaint- 
 ance, or what has given them so strong a hold of our be- 
 lief, and what regard f hey deserve, are no doub( very im- 
 portant questions in the philosophy of human nature. 
 
 Sliall we, with the bishop of Cloync, serve them with 
 a ^uo wanmnto, and have them tried at the bar of phi- 
 losophy, upon the statute of the ideal system ? Indeed, in 
 this trial they seem to have come oif very pitifully. For 
 although they had very able counsel, learned in the law, 
 viz. Des Cartes, Malebranche, and Locke, who said 
 every thing they could for their clients ; the bishop of 
 Cloyne, believing them to be aiders and abetters of here- 
 sy and schism, prosecuted them with great vigour, fully 
 answered all that had been pleaded in their defence, and 
 silenced their ablest advocates, who seem for half a cen- 
 tury past to decline the argument, and to trust to the fa- 
 vour of the jury rather than to the strength of their 
 pleadings. 
 
 Thus, the wisdom of philosophy is set in opposition to 
 the common sense of mankind. The first pretends to de- 
 monstrate a pnor-i, that there can be no such thing as a 
 material world ; that sun, moon, stars, and earth, vege- 
 table and animal bodies, are, and can be nothing else but 
 sensations in the mind, or images of those sensations in 
 the memory and imagination; that, like pain and joy, 
 they can have no existence when they are not thought of. 
 The last can conceive no onierwise of this opinion, than 
 as a kind of metaphysical lunacy ; and concludes, that too 
 much learning is apt to maike men mad ; and that the 
 man who seriously entertains this belief, though in other 
 respects he may^be a very good man, as a man may be 
 who believes that be is made of glass ; yet surely he hath 
 a soft place in his understanding, and hath been hurt by 
 nuich thinking. 
 
TOUCH, 246 
 
 This opposition betwixt philosophy and common sense, 
 is apt to have a very unhappy influence upon the philos- ; 
 opher hiibself. He sees human nature in an odd, un- 
 amiable, and mortifying light. He considers himself, and 
 the rest of his species, as bom under a necessity of be- 
 lieving ten thousand absurdities and contradictions, and 
 endowed with such a pittance of reason, as is just suffi- 
 cient to make this unhappy discovery : and this is all the 
 fruit of his profound speculations. Such notions of hu- 
 man nature tend to slacken every nerve of the soul, to 
 put every noble purpose and sentiment out of countenance, 
 and spread a melancholy gloom over the whole face of 
 things. 
 
 If this is wisdom, let me be deluded with the vulgar. I 
 find something within me that recoils against it, and in- 
 spires more reverent sentiments of the human kind, and 
 of the universal administration. Common sense and rea- 
 son have both one author ; that almighty Author, in all 
 whose other works we observe a consistency, uniformity, 
 and beauty, which charm and delight the understanding : 
 there must therefore be some order and consistency in 
 the human faculties, as well as in other parts of his work- 
 manship. A man that thinks reverently of his own kind, 
 and esteems true wisdom and philosophy, will not be fond, 
 nay, will be very suspicious, of such strange and paradox- 
 ical opinions. If they are false, they disgrace philosophy ; 
 and if they are true, they degrade the human species, and 
 make us justly ashamed of our frame. 
 
 To what purpose is it for philosophy to decide against 
 common sense in this or any other matter ? The belief of 
 a material world is older, and of more authority, than 
 any principles of philosophy. It declines the tribunal of 
 reason, and laughs at all the artillery of the logician. It 
 retains its sovereign authority in spite of all the edicts of 
 philosophy, and reason itself must stoop to its orders. 
 Even those philosophers who have disowned the authori- 
 ty of our notions of an extern^al material world, confess 
 
246 or THE HUMAN MINI). 
 
 that they iind themselves under a necessity of submitting 
 to their power. 
 
 Methinks, therefore, it were better to make a virtue of 
 necessity ; and, since we cannot get rid of the vulgar no- 
 tion and belief of an external world, to reconcile our rea- 
 son to it as well as we can : for if Reason should stomach 
 and fret ever so much at this yoke, she cannot throw it 
 off; if she will not be the servant of Common Sense, she 
 must be her slave. 
 
 In order, therefore, to reconcile reason to common 
 sense in this matter, I beg leave to offer to the consider- 
 ation of philosophers these two observations. First, that 
 in all this debate about the existence of a material world, 
 it hath, been taken for granted on both sides, that this 
 same material world, if any such there be. must be the ex - 
 press im a ge of ou r senHi**^""? • *^^* ^e <^,^n havp nn oq^. 
 fieption o f any material thin g which is nnt Hkp <"fm^ spg- 
 sati on in our m inik,; and particularly, that the sensations 
 of touch are images of extension, hardness, figure and 
 motion. Every argument brought against the existence of 
 a material world, either by the bishop of Cloyne or by the 
 author of the Treatise of Human Nature, supposeth this. 
 If this is true, their arguments are conclusive and unan- 
 swerable: but, on the other hand, if it is not true, there 
 is no shadow of argument left. Have those philosophers, 
 then, given any solid proof of this hypothesis, upon which 
 the whole weight of so strange a system rests ? No. They 
 have not so much as attempted to do it. But, because 
 ancient and modern philosophers have agreed in this opin- 
 ion, they have taken it for granted. But let us, as he- 
 comes philosophers, lay aside authority; we need not 
 surely consult Aristotle or Locke, to know whether pain 
 be like the point of a sword. I have as clear a con- 
 ception of extension, hardness, and motion, as I have of 
 the point of a sword ; and, with some pains and prac- 
 tice, I can form as clear a notion of the other sensations 
 of touch, as I have of pain. When I do so, and compare 
 them together, it appears to me clear as daylight, that 
 
TOUCH. 247 
 
 the former are not of kin to the latter, nor resemble 
 them in any one feature. They are as unlike, yea, as 
 certainly and manifestly unlike, as pain is to the point of 
 a sword. It may true, that those sensations first intro- 
 duced the material world to our acquaintance j it may be 
 true, (hat it seldom or never appears without their com- 
 pany ; but, for all that, they are as unlike as the passion 
 of anther is to those features of the countenance which 
 attend it. 
 
 So that, in the sentence those philosophers have passed 
 against the material world, there is an error personce. 
 Their proof touches not matter, or any of its qual- 
 ities ; but strikes directly against an idol of their own 
 imagination, a material world made of ideas and sensa- 
 tions, which never had nor can have an existence. \ 
 
 Secondly, The very existence of our conceptions of 
 extension, figure, and motion, since they are neither ideas ' 
 of sensation nor reflection, overturns the whole ideal sys-' 
 tern, by which the material world hath been tried and 
 condemned : so that there hath been likewise in this sen- 
 tence an error juris. 
 
 It is a very fine and a just observation of Locke, that 
 as no human art can create a single particle of matter, 
 and the whole extent of our power over the material 
 world, consists in compounding, combining, and disjoin- 
 ing, the matter made to our hands ; so in the world of 
 thought, the materials are all made by nature, and can 
 only be variously combined and disjoined by us. So that it 
 is impossible for reason or prejudice, true or false philoso- 
 phy, to produce one simple notion or conception, which is 
 not the work of nature, and the result of our constitu- 
 tion. The conception of extension, motion, and the other 
 attributes of matter, cannot be the eflTect of error or prej- 
 udice ; it must be the work of nature. And the power 
 or faculty, by which we acquire those conceptions, must 
 be something different from any power of the human mind 
 that hath been explained, since it is neither sensation nor 
 reflection. • 
 
2iS or l-HE HUMASr MIND. 
 
 This I would therefore humbly proposei as an expert' 
 mentum crucis, by which the ideal system must stand or 
 fall ; and it brings the mater to a short issue : extension, 
 figure, motion, may, any one, or all of them, be taken for 
 the subject of this experiment. Either they are ideas of 
 sensation, or they are not. If any one of them can be 
 shown to be an idea of sensation, or to have the least re- 
 semblance to any sensation, I lay my hand upon my mouth, 
 and give up all pretence to reconcile reason to common 
 sease in this matter, and must suffer the ideal skepticism 
 to triumph. But if, on the other hand, they are not ideas 
 of sensation, nor like to any sensation, then the ideal sys- 
 tem is a rope of sand, and all the laboured arguments of 
 the skeptical philosophy, against a material world, and 
 against the existence of every thing but impressions and 
 ideas, proceed upon a false hypothesis. 
 
 If our philosophy concerning the mind be so lame with 
 regard to the origin of our notions of the clearest, most 
 simple, and most familiar objects of thought and the pow- 
 ers from which they are derived, can we expect that it 
 should be more perfect in the account it gives of the ori- 
 gin of our opinions and belief? We have seen already 
 some instances of its imperfection in this respect : and 
 perhaps that same nature which hath given us the power 
 to conceive things altogether unlike to any of our sensa- 
 tions or to any operation of our minds, hath likewise 
 provided for our belief of them, by some part of our con- 
 stitution hitherto not explained. 
 
 Bishop Berkeley hath proved, beyond the possibility 
 of reply, that we cannot by reasoning infer the existence 
 of matter from our sensations : and the author of the 
 Treatise of Human Nature hath proved no less clearly, 
 that we cannot by reasoning infer the existence of our 
 own or other minds from our sensations. But are we to 
 admit nothing but what can be proved by reasoning ? then 
 we must be skeptics indeed, and believe nothing at all. 
 The author of the Treatise of Human Nature appears to 
 me to be but a half skeptic. He hath not followed his 
 
TOUCH. 249 
 
 principles so far as they lead him : but after having, with 
 unparalleled intrepidity and siuccess, combated vulgar 
 prajudices ; when he had but one blow to strike, his cour- 
 age fails him, he fairly lays down his arms, and yields 
 himself a captive to the most common of all vulgar prej- 
 udices, I mean the belief of the existence of his own im- 
 pressions and ideas. 
 
 J beg, therefore, to have the honour of making an ad- 
 dition to the skeptical system, without which, ! conceive 
 it cannot hang together. I affirm, that the belief of the 
 existence of impressions and ideas, is as little supported 
 by reason, as that of the existence of minds and bodies. 
 No man ever did, or could offer any reason for this belief. 
 Des Cartes took it for granted, that he thought, and had 
 sensations and ideas : so have all his followers done. 
 Even the hero of skepticism hath yielded this point, I 
 crave leave to say, weakly and imprudently. I say so, 
 because I am persuaded that there is no principle of his 
 philosophy that obliged him to make this concession. 
 And what js there in impressions and ideas so formidable, 
 that this all-conquering philosophy, after triumphing over 
 every other existence, should pay homage to them ? Be- 
 sides, the concession is dangerous j for belief is of such 
 a nature, that if you leave any root, it will spread; and 
 you may more easily pull it up altogether, than say. 
 Hitherto shalt thou go, and no further: the existence of 
 impressions and ideas I give up to thee ; but see thou 
 pretend to nothing more. A thorough and consistent 
 skeptic will never, therefore, yield this point ; and while 
 he holds it, you can never oblige him to yield any thing 
 else. 
 
 To such a skeptic I have nothing to say ; but of the 
 semi-skeptics, I should beg leave to know, why they be- 
 lieve the existence of their impressions and ideas. The 
 true reason I take to be, because they cannot help it ; and 
 the same reason will lead them to believe many other 
 things. 
 
 TOI. I. 33 
 
350 or THE HtJMAlV MINB. 
 
 All reasoning must be from first principles ; and for 
 first principles no other reason can be given but this, 
 that, by the constitution of our nature, we are under a 
 necessity of assenting to them. Such principles are parts 
 of our constitution, no less than the power of thinking: 
 reason can neither make nor destroy them ; nor can it 
 do any thing without them : it is like a telescope, which 
 may help a man to see farther, who hath eyes; but with- 
 out eyes, a telescope shews nothing at all. A mathema- 
 tician cannot prove the truth of his axioms, nor can he 
 prove any thing, unless he takes them for granted. We 
 cannot prove the existence of our minds, nor even of our 
 thoughts and sensations. A historian, or a witness, can 
 prove nothing, unless it is taken for granted that the 
 memory and senses may be trusted. A natural philoso- 
 pher can prove nothing, unless it is taken for granted that 
 the course of nature is steady and uniform. 
 
 How or when I got such first principles, upon which I 
 build all my reasoning, I know not ,• for I had them be- 
 fore I can remember: but I am sure they are parts of 
 my constitution, and that I cannot throw them off. That 
 our thoughts and sensations must have a subject, which 
 we call ourself, is not therefore an opinion got by reason- 
 ing, but a natural principle. That our sensations of touch 
 indicate something external, extended, figured, hard or 
 soft, is not a deduction of reason, but a natural principle. 
 The belief of it, and the very conception of it, are equally 
 parts of our constitution. If we are deceived in it,, we 
 are deceived by him that made us, and there is no remedy. 
 
 I do not mean to affirm, that the sensations of touch 
 do from the very first suggest the same notions of body 
 and its qualities, which they do when we are grown up. 
 Perhaps nature is frugal in this, as in her other opera- 
 tions. The passion of love, with all its concomitant sen- 
 timents and desires, is naturally suggested by the percep- 
 tion of beauty in the other sex. Yet the same perception 
 does not suggest the tender passion till a certain period 
 
ToreH. 251 
 
 of life. A blow given to au infant, raises grief and lam- 
 entation ; but when he grows np, it as naturally stirs re" 
 sentment, and prompts him to resistance. Perhaps a 
 child in the womb, or for some short period of its exist- 
 ence, is merely a sentient being: the faculties, by which 
 it perceives an external world, by which it reflects on its 
 own thoughts, and existence, and relation to other things, 
 as well as its reasoning and moral faculties, unfold them- 
 selves by degrees ; so that it is inspired with the various 
 principles of common sense as with the passions of love 
 and resentment, when it has occasion for them. 
 
 SECTION vni. 
 
 OF THE SYSTEMS OF PHIIO SOPH BBS CONCEKNTNG THE 
 
 SENSES. 
 
 All, the systems of philosophers about our senses and 
 their objects have split upon this rock, of not distinguish- 
 ing properly sensations which can have no existence but 
 when they are felt, from the things suggested by them. 
 Aristotle, with as distinguishing a head as ever applied 
 to philosophical disquisitions, confounds these two ; and 
 makes every sensation to be the form, without the mat- 
 ter, of the thing perceived by it : as the impression of a 
 seal upon wax has the form of the seal, but nothing of 
 the matter of it ; so he conceived our sensations to be 
 impressions upon the mind, which bear the image, like- 
 ness, or form of the external thing perceived, without the 
 matter of it. Colour, sound, and smell, as well as extension, 
 figure, and hardness, are, according him, various forms of 
 matter : our sensations are the same forms imprinted on 
 the mind, and perceived in its own intellect. It is evident 
 from this that Aristotle made no distinction between pri- 
 mary and secondary qualities of bodies, although that dis- 
 tinction was made by Democritus, Epicurus, and others 
 of the ancients. 
 
2^3 OF THE HUMAW MIT7D. 
 
 Des Cartes, Malebratiche, and Locke, revived tVie dis- 
 tinction between primary and secondary qualities. But 
 they made the sccosidary qualities mere sensations, and 
 the primary ones resemblances of our sensations. They 
 maintained that colour, sound, and heat, are not any thing 
 in bodies, but sensations of the mind: at the same lime, 
 they acknowledged some particular texture or moditica- 
 tion of the body, to be the cause or occasion of those sensa- 
 tions ; but to this modification they gave no name. Where- 
 as by (he vulgar, the names of colour, heat, and sound, are 
 but rarely applied to the sensations, and most commonly 
 to those unknown causes of them ; as hath been already 
 explained. The constitution of our nature leads us rather 
 to attend to the things signified by the sensation, than to 
 the sensation itself, and to give a name to the former 
 rather than to the latter. Thus we see, that with regard 
 to secondary qualities, these philosophers thought with 
 the vulgar, and with common sense. Their paradoxes 
 were only an abuse of words. For when they maintain, 
 as an important modern discovery, that there is no heat 
 in the fire, they mean no more than that the fire does not 
 feel heat, which every one knew before. 
 
 "With regard to primary qualities, these philosophers 
 erred more grossly : they indeed believed the existence 
 of those qualities ; but they did not at all attend to the sen- 
 sations that suggest them, which having no names, have 
 been as little considered as if they had no existence. They 
 ■were aware, that figure, extension, and hardness, are 
 perceived by means of sensations of touch j whence they 
 rashly concluded, that these sensations must be images 
 and resemblances of figure, extension, and hardness. 
 
 The received hypothesis of ideas naturally led them to 
 this conclusion ; and indeed cannot consist with any other ; 
 for, according to that hypothesis, external things must 
 be perceived by means of images of them in the mind ; 
 and what can those images of external things in the mind 
 be, but the sensations by which we perceive them J 
 
TOUCH. 2SS 
 
 This however was to draw a conclusion from a hy- ; 
 pothesis against fact. We need not have recourse to any 
 hypothesis to know what our sensations are, or what they 
 are like. By a proper degree of reilection and attention, 
 we may understand them perfectly, and be as certain that 
 they are not like any quality of body, as we can be, that 
 the toothaeh ia not like a triangle. How a sensation 
 should instantly make us conceive and believe the exist- 
 ence of an external thing altogether unlike to it, I do not 
 pretend to know ; and when I say that the one suggests 
 the other, I mean not to explain the manner of their con- 
 nection, but to express a fact, which every one may be 
 conscious of ; namely, that, by a law of our nature, such 
 a conception and belief constantly and immediately follow 
 the sensation. 
 
 Bishop Berkeley gave new light to this subject, by 
 shewing, that the qualities of an inanimate thing, such 
 as matter is conceived to be, cannot resemble any sensa^ 
 tion ; that it is impossible to conceive any thing like the 
 sensations of our minds, but the sensations of other minds. 
 Every one that attends properly to his sensations must 
 assent to this; yet it had escaped all the philosophers 
 that came before Berkeley ; it had escaped even the in- 
 genious Locke, who had so much practised reflection on 
 the operations of his own mind. So difficult it is to at- 
 tend properly even to our own feelings. They are so ac- 
 customed to pass through the mind unobserved, and in- 
 stantly to make way for that which nature intended them 
 to signify, that it is extremely difficult to stop, and sur- 
 vey them ; and when we think we have acquired this 
 power, perhaps the mind still fluctuates between the sen- 
 sation, and its associated quality, so that they mix to- 
 gether, and present something to the imagination that is 
 compounded of both. Thus in a globe or cylinder, whose 
 opposite sides are quite unlike in colour, if you turn it 
 slowly, the colours are perfectly distinguishable, and their 
 dissimilitude is manifest j but if it is turned fast, they 
 
354 or THE HUMATf MIND. 
 
 lose their distinction, and seem to be of one and the same 
 colour. 
 
 No succession can be more quick, than that of tangible 
 qualities to the sensations with which nature has associ- 
 ated them. But when one has once acquired the art of 
 making them separate and distinct objects of thought, he 
 ■will then clearly perceive, that the maxim of bishop 
 Berkeley above mentioned, is self-evident; and (hat the 
 features of the face are not more unlike to a passion of 
 the mind whicb they indicate, than the sensations of touch 
 are to the primary qualities of body. 
 
 But let us observe what use (he bishop makes of this 
 important discovery. Why, he concludes, that we can 
 have no conception of an inanimate substance, such as 
 matter is conceived to be, or of any of its qualities; and 
 that there is the strongest ground (o believe that (here is 
 no existence in nature but minds, sensations, and ideas. 
 If there is any other kind of existences, it must be what 
 we neither have nor can have any conception of. But 
 how does this follow ? Why thus : we can have no con- 
 ception of any thing but what resembles some sensation 
 or idea in our minds ; but the sensations and ideas in our 
 minds can resemble nothing but the sensations and ideas 
 in other minds; therefore, (he conclusion is evident. 
 This argument, we see, leans upon two proposidons. 
 The last of them the ingenious author hath indeed made 
 evident to all that understand his reasoning, and can at- 
 tend to their own sensations: but (he first proposition he 
 never attempts to prove; it_is taken from thedoctrineu)f 
 ideas, which hath been so universally received by philos- 
 ophers, that it was thought to need no proof. 
 
 We may here again observe, that this acute writer ar- 
 gues from a hypothesis against fact, and against the com- 
 mon sense of mankind. That we can have no conception 
 of any thing, unless there is some impression, sensation 
 or idea, in our minds, which resembles it, is indeed an 
 opinion which bath been very generally received among 
 
TOUCH. 255 
 
 philosophers ; but it is neither self-evident, nor hath it 
 been clearly proved ; and therefore it had been more rea- 
 sonable to call in question this doctrine of philosophers, 
 than to discai-d the material world, and by that means 
 expose philosopliers to the rjdicule of all men, who will 
 not offer up common sense as a sacrifice to metaphysics. 
 
 "We ou.e;ht, however, to do this justice both to the bish- 
 op of Cloyne and to the author of the Treatise of Human 
 Nature, to acknowledge, that their conclusions are justly 
 drawn from the doctrine of ideas, which has been so uni- 
 versally received. On the other hand, from the charac- 
 ter of bishop Berkeley, and of his predecessors Des 
 Cartes, Locke, and Malebranche, we may venture to say, 
 that if they had seen all the consequences of this doctrine, 
 as clearly as the author before mentioned did, they would 
 have suspected it vehemently, and examined it more care- 
 fully than they appear to have done. 
 
 The theory of ideas, like the Trojan horse, had a spe- 
 cious appearance both of innocence and beauty ; but if 
 those philosophers had known that it carried in its belly 
 death and destruction to all science and common sense, 
 they would not have broken down their walls to give it 
 admittance. 
 
 That we have clear and distinct conceptions of exten- 
 sion, figure, motion, and other attributes of body, which 
 are neither sensations, nor like any sensation, is a fact of 
 which we may be as certain, as that we have sensations. 
 And that all mankind have a fixed belief of an external 
 material world, a belief which is neither got by reasoning 
 nor education, and a belief which we cannot shake off, 
 even when we seem to have strong arguments against it, 
 and no shadow of argument for it, is likewise a fact, for 
 which we have all the evidence that the nature of the 
 thing admits. These facts are phenomena of human na- 
 ture, from which we may justly argue against any hypoth- 
 esis, however generally received. But to argue from a 
 hypothesis against facts, is contrary to the rules of true 
 philosophy. 
 
Zi6 or THB HUMAN MIND. 
 
 CHAP. VI. 
 
 OF SEEING. 
 
 SECTION I. 
 THE EXCEULENCB AND DIGNITT OB THIS rACTJlTT. 
 
 The advances made in the knowledge of optics in the 
 last age, and in the present, and chiefly the discoveries of 
 Sir Isaac Newton, do honour, not to philosophy only, but 
 to human nature. Such discoveries ought for ever to put 
 to shame the ignoble attempts of our modern skeptics to 
 depreciate the human understanding, and to dispirit men 
 in the search of truth, by representing the human facul. 
 ties as fit for nothing, but to lead us into absurdities and 
 contradictions. 
 
 Of the faculties called the Jive senses, sight is without 
 doubt the noblest. The rays of light, which minister to 
 this sense, and of which, without it, we could never have 
 had the least conception, are the most wonderful and as- 
 tonishing part of the inanimate creation. We must be 
 satisfied of this, if we consider their extreme minuteness, 
 their inconceivable velocity, the regular variety of colours 
 wliich they exhibit, the invariable laws according to which 
 they are acted upon by other bodies, in their reflections^ 
 inflections and refractions, without the least change of 
 their original properties, and the facility with which they 
 pervade bodies of great density, and of the closest texture, 
 without resistance, without crowding or disturbing one 
 another, without giving the least sensible impulse to the 
 lightest bodies. 
 
 The structure of the eye, and of all its appurtenances, 
 the admirable contrivances of nature for performing all 
 its various external and internal motions, and the variety 
 in the eyes of different animals, suited to their several 
 
SEEING, S,57 
 
 natures and ways of life, clearly demonstrate llus organ 
 to be a masterpiece of nature's work. And he must be 
 Tery ignorant of what hath been discovered about it, or 
 liave a very strange cast of understanding, who can seri- 
 ously doubt, whether or not the rays of light and the eye 
 were made for one another, with consummate wisdom, 
 and perfect skill in optics. 
 
 If we shall suppose an order of beings, endued with ev- 
 ery human faculty but that of sight, how incredible would 
 it appear to such beings, accustomed only to the slow in- 
 formations of touch, that, by the addition of an organ, 
 consisting of a ball and socket of an inch diameter, they 
 might be enabled in an instant of time, without changing 
 their place, to perceive the disposition of a whole army, 
 or the order of a battle, the figure of a magnificent palace, 
 or all the variety of a landscape ? If a man were by feel- 
 ing to find out the figure of the peak of Teneriffe, or even 
 of St. Peter's church at Eome, it would be the work of a 
 lifetime. 
 
 It would appear still more incredible to such beings as 
 we have supposed, if they were informed of the discov- 
 eries which may be made by this little organ in things far 
 beyond the reach of any other sense. That by means of 
 it we can find our way in the pathless ocean ; that we 
 can traverse the globe of the earth, determine its figure 
 and dimensions, and delineate every region of it. Yea, 
 that we can measure the planetary orbs, and make dis- 
 coveries in the sphere of the fixed stars. 
 
 Would it not appear still more astonishing to such be- 
 ings, if they should be further informed, that, by means 
 of this same organ, we can perceive the tempers and dis- 
 positions, the passions and affections of our fellow-crea- 
 tures, even when they want most to conceal them ? That 
 when the tongue is taught most artfully to lie and dis- 
 semble, the hypocrisy should appear in the countenance 
 to a discerning eye ? And that by this organ we can often 
 perceive what is straight and what is crooked in the mind 
 as well as in the body ? How many mysterious things 
 
 Toi. I. S3 
 
258 01- THE HUMAN MIND. 
 
 must a blind man believe, if he will give credit to the rc" 
 lations of those that see? Surely he needs as strong a 
 faith as is required of a good Christian. 
 
 It is not therefore without reason, that the faculty of 
 seeing is looked upon, not only as more noble than the 
 other senses, but as having something in it of a nature 
 superior to sensation. The evidence of reason is called 
 seeing, not feeling, smelling^ or tasting. Yea, we are wont 
 to express the manner of the divine knowledge by seeing-, 
 as that kind of knowledge which is most perfect in us. 
 
 SECTION ir. 
 
 SIGHT DISCOVERS ALMOST NOTHING WHICH THE BLIND MAY NOT COM- 
 PREHEND. THE REASON OF THIS. 
 
 Notwithstanding what hath been said of the dignity 
 and superior nature of this faculty, it is worthy of our 
 observation, that there is very little of the knowledge ac- 
 quired by sight, that may not be communicated to a man 
 born blind. One who never saw the light, may be learn- 
 ed and knowing in every science, even in optics ; and may 
 make discoveries in every branch of philosophy. He may 
 understand as much as another man, not only of the order, 
 distances, and motions of the heavenly bodies ; but of the 
 nature of light, and of the laws of the reflection and re- 
 fraction of its rays. He may understand distinctly, how 
 those laws produce the phenomena of the rainbow, the 
 prism, the camera obscura, and the magic lanthorn, and 
 all the powers of the microscope and telescope. This is 
 a fact sufficiently attested by experience. 
 
 In order to perceive the reason of it, we must distin- 
 guish the appearance that objects make to the eye, from 
 the things suggested by that appearance ; and again, in 
 the visible appearance of objects, we must distinguish the 
 appearance of colour from the appearance of extension, 
 figure and motion. First, then, as to the visible appear- 
 ance of the fignre, and motion, and extension of bodies, I 
 
SEEING. 259 
 
 conceive that a man born blind may have a distinct no- 
 tion, if not of the very things, at least of something ex- 
 tremely like to them. May not a blind man be made to 
 conceive, that a body moving directly from the eye, or di- 
 rectly toward it, may appear to be at rest ? and that the 
 same motion may appear quicker or slower, according as 
 it is nearer to the eye or farther off", more direct or more 
 oblique ? May he not be made to conceive, that a plain 
 surface, in a certain position, may appear as a straight 
 line, and vary its visible figure, as its position, or the posi- 
 tion of the eye, is varied ? That a circle seen obliquely will 
 appear an ellipse ; and a square, a rhombus, or an oblong 
 rectangle ; Dr. Saunderson understood the projection of 
 the sphere, and the common rules of perspective; and if 
 he did, he must have understood all that I have mention- 
 ed. If there were any doubt of Dr. Saunderson's under- 
 standing these things, I could mention my having heard 
 him say in conversation, that he found great difBculty in 
 understanding Dr. Halley's demonstration of that propo- 
 sition, that the angles made by the circles of the sphere, 
 are equal to the angles made by their representatives in 
 the stereograpbic projection. But, said he, when I laid 
 aside that demonstration, and considered the proposition 
 in my own way, I saw clearly that it must be true. An- 
 otlier gentleman, of undoubted credit and judgment in 
 these matters, who had part in this conversation, remem- 
 bers it distinctly. 
 
 As to the appearance of colour, a blind man must be 
 more at a loss ; because he hath no perception that re- 
 sembles it. Yet he may, by a kind of analogy, in part 
 supply thisdefect. To those who see, a scarlet colour 
 signifies an unknown quality in bodies, that makes to the 
 eye an appearance, which they are well acquainted with, 
 and have often observed : to a blind man it signifies an 
 unknown quality, that makes to the eye an appearance, 
 which he is unacquainted with. But he can conceive the 
 eye to be variously affected by different colours, as the 
 nose is by different smells^ or the ear by different sounds, 
 
260 OF THE HUMAN MINI). 
 
 Thus he can conceive scarlet to differ from blue, as the 
 sound of a trumpet does from that of a drum; or as the 
 smell of an orange differs from that of an apple. It is 
 impossible to iinow vvlnuther a scarlet colour has the same 
 appearance to me which it hath to another man : and if 
 the appearances of it to diSerent persons differed as much 
 as colour does from sound, they might never be able to 
 discover this difference. Hence it appears obvious, that 
 a blind man might talk long about colours distinctly and 
 pertinently; and if you were to examine him in the dark 
 about tjie nature, composition, and beauty of them, he 
 might be able to answer, so as not to betray his defect. 
 
 "We have seen how far a blind man may go in the 
 knowledge of the appearances which (hings make to the 
 eye. As to the things which are suggested by them, or 
 inferred from them ; although he could never discover 
 them of liimself, yet he may understand them perfectly 
 by the information of others. And every thing of this 
 kind tliat enters into our minds by the eye, may enter into 
 his by the ear. Thus, for instance, he could never, if 
 left to the direction of his own faculties, have dreamed 
 of any such thing as light ; but he can be informed of 
 every thing we know about it. He can conceive, as 
 distinctly as we, the minuteness and velocity of its rays, 
 their various degrees of refrangibility and reilexibility, 
 and all the magical powers and virtues of that wonderful 
 element. He could never of himself have found out, that 
 there are such bodies as the sun, moon, and stars ; but 
 he may be informed of all the noble discoveries of astron- 
 omers about their motions, and tlie laws of nature by 
 which they are regulated. Thus it appears, that there 
 is very little knowledge got by the eye, which may not 
 be communicated by language to those who have no eyes. 
 
 If we should suppose, that it were as uncommon for 
 men to see, as it is to be born blind ; would not the few 
 who had this rare gift appear as prophets and inspired 
 teachers to the many ? We conceive inspiration to give a 
 man no new faculty, but to communicate to him in a new 
 
SEE INS. 261 
 
 way, and by extraordinary means, what the faculties com- 
 mon to mankind can apprehend, and what he can commu- 
 nicate to others by ordinary means. On the supposition 
 we have made, sight would appear to the blind very sim- 
 ilar to this ; for the few who had this gift, could commu- 
 nicate the knowledge acquired by it to those who had it 
 not. They could not indeed convey to the blind any dis- 
 tinct notion of the manner in which they acquired this 
 knowledge. A ball and socket would seem, to a blind 
 man, in this case, as improper an instrument for acquir- 
 ing such a variety and extent of knowledge, as a dream or 
 a vision. The manner in which a man who sees, discerns 
 so many things by means of the eye, is as unintelligible 
 to the blind, as the manner in which a man may be in-< 
 spired with knowledge by the Almighty, is to us. Ought^ 
 the blind man, therefore, without examination, to treat 
 all pretences to the gift of seeing as imposture ? Might 
 he not, if he were candid and tractable, find reasonable 
 evidence of the reality of this gift in others, and draw 
 great advantages from it to himself? 
 
 The distinction we have made between the visible ap- 
 pearances of the objects of sight, and things suggested by 
 them, is necessary to give us a just notion of the inten- 
 tion of nature in giving us eyes. If we attend duly to the | y 
 operation of our mind in the use of this faculty, we shall 
 perceive, that the visible appearance of oljjects is hardly 
 ever regarded by us. It is not at all made an object of 
 thought or reflection, but serves only as a sign to intro4 
 duce to the mind something else, which maybe distinctly 
 conceived by those who never saw. 
 
 Thus, the visible appearance of things in my room 
 varies almost every hour, according as the day is clear 
 or cloudy, as the sun is in the east, or south, or west, and 
 as my eye is in one part of the room or in another : but 
 I never think of these variations, otherwise than as signs 
 of morning, noon, or night, of a clear or cloudy sky. A 
 book or a chair has a different appearance to the eye, in 
 every different distance and positron , yet we conceive it 
 
262 OP THE HUMAN MIND. 
 
 to be still the same ; and, overlooking the appearance, we 
 immediately conceive the real figure, distance, and posi* 
 tion of the body, of which its visible or perspective ap- 
 pearance is a sign and indication. 
 
 When I see a man at the distance often yards, and af- 
 terward see him at the distance of a hundred yards, his 
 visible appearance in its length, breadth, and all its linear 
 proportions, is ten times less in the last case than it is in 
 the first : yet I do not conceive him one inch diminished 
 by this diminution of his visible figure. Nay, I do not 
 in the least attend to this diminution, even when I draw 
 from it the conclusion of liis being at a greater distance. 
 For such is the subtility of the mind's operation in this 
 \ icase, that we draw the conclusion, without perceiving 
 *that ever the premises entered into the mind. A thou- 
 sand such instances might be produced, in order to shew 
 that the visible appearances of objects are intended by 
 nature only as signs or indications; and that the mind 
 passes instantly to the things signified, without making 
 the least reflection upon the sign, or even perceiving that 
 there is any such thing. It is in a way somewhat sim- 
 ilar, that the sounds of a language, after it is become fa- 
 miliar, are overlooked, and we attend only to the things 
 signified by them. 
 
 It is therefore a just and important observation of the 
 bishop of Cloyne, that the visible appearance of objects 
 is a kind of language used by nature, to inform us of their 
 distance, magnitude, and figure. And this observation 
 Lath been very happily applied by that ingenious writer, 
 to the solution of some phenomena in optics, which had 
 before perplexed the greatest masters in that science. 
 The same observation is further improved by the judic- 
 ious Dr. Smith, in his Optics, for explaining the apparent 
 figure of the heavens, and the apparent distances and 
 magnitudes of objects seen with glasses, or by the na- 
 ^ ted eye. 
 
 Avoiding as much as possible the repetition of what 
 hath heen said by these excellent writers, we shall avail 
 
SEErSTG- 26 S 
 
 ourselves of the distinction between the signs that nature 
 useth in this visual language, and the things signified by 
 them ; and in what remains to be said of sight shall first 
 make some observations upon the signs. 
 
 SECTION ni. 
 
 or THE VlSIBtE APPEARANCES Ot OBJECTS. 
 
 In this section we must speak of things which are 
 never made the object of reflection, though almost every 
 moment presented to tlie mind. Nature intended them 
 only for signs ; and in the whole course of life they are 
 put to no other use. The mind has acquired a confirmed 
 and inveterate habit of inattention to them ; for they no 
 sooner appear than quick as lightning the thing signified 
 succeeds, and engrosses all our regard. They have no 
 name in language : and although we are conscious of 
 them when they pass through the mind, yet their passage 
 is so quick, and so familiar, that it is absolutely unheeded ; 
 nor do they leave any footsleps of themselves, either in 
 the memory or imagination. That this is the case with 
 regard to the sensations of touch, hath been shown in the 
 last chapter; and it holds no less with regard to the vis- 
 ible appearances of objects. 
 
 I cannot therefore entertain the hope of being intelli- 
 gible to those readers who have not, by pains and prac- 
 tice, acquired the habit of distinguishing the appearance 
 of objects to the eye, from the judgment which we form 
 by sight, of their colour, distance, magnitude, and figure. 
 The only profession in life wherein it is necessary to make 
 this distinction, is that of painting. The painter hath 
 occasion for an abstraction, with regard to visible objects, 
 somewhat similar to that which we here require: and 
 this indeed is the most difficult part of his art. For it is 
 evident, that if he could fix in his imagination the visible 
 appearance of objects, without confounding it with the 
 
264 or THE HUMAN MIND. 
 
 ; things signified bj that appearance, it would be as easy 
 for him to paint from the life, and to give every figure 
 its proper shading and relief, and its perspective propor- 
 tions, as it is to paint from a copy. Perspective shading, 
 giving relief, and colouring, are nothing else but copying 
 the appearance which things make to the eye. We may 
 therefore borrow some light on the subject of visible ap- 
 pearance from this art. 
 
 Let one look upon any familiar object, such as a book, 
 at different distances and in different positions : is he not 
 able to affirm, upon the testimony of his sight, that it is 
 the same book, the same object, whether seen at the dis- 
 tance of one foot or of ten, whether in one position or an- 
 other ; that the colour is the same, the dimensions the 
 same, and the figure the same, as far as the eye can 
 judge ? this surely must be acknowledged. The same in- 
 dividual object is presented to the mind, only placed at 
 diiferent distances, and in difierent positions. Let me 
 ask, in the next place, whether this object has the same 
 appearance to the eye in these different distances ? Infal- 
 libly it hath not. For, 
 
 ; First, however certain our judgment may be that the 
 colour is the same, it is as certain that it hath not the 
 same appearance at different distances. There is a cer- 
 tain degradation of the colour, and a certain confusion 
 and indistinctness of the minute parts, which is the nat- 
 ural consequence of the removal of the object to a greater 
 distance. Those that are not painters, or critics in paint- 
 ing, overlook this ; and cannot easily be persuaded, that 
 the colour of the same object hath a different appearance 
 at the distance of one foot and of ten, in the shade and in 
 the light. But the masters in painting know how, by the 
 degradation of the colour, and the confusion of the minute 
 parts, figures, which are upon the same canvas, and at 
 the same distance from the eye, may be made to represent 
 objects which are at the most unequal distances. They 
 know how to make the objects appear to be of the same 
 
sGEma. 265 
 
 colour, by making their pictures really of different colours, 
 according to their distances or shades. 
 
 Secondly, every one who is acquainted with the rules 
 of perspective, knows tliat the appearance of the figure 
 of the booli must vary in every different position: yet if, 
 you ask a man that has no notion of perspective, whether 
 the figure of it does not appear to his eye to be the same 
 in all its different positions ? he can with a good conscience 
 affirm, that it does. He hath learned to malve allowance 
 for the variety of visible figures arising from' the differ-' 
 ence of position, and to draw the proper conclusions from 
 it. But he draws these conclusions so readily and habit- 
 ually, as to lose sight of the premises ; and, therefore, 
 where he hatii made the same conclusion he conceives the 
 visible appearance must have been the same. 
 
 Thirdly, let us consider the apparent magnitude or di- 
 mensions of the book. Whether I view it at the distance 
 of one foot or of ten feet, it seems to be about seven inches 
 long, five broad, and one thick. I can judge of these di- 
 mensions very nearly by the eye, and I judge them to be 
 the same at both distances. But yet it is certain, that 
 at the distance of one foot, its visible length and breadth 
 is about ten times as great as at the distance often feet; 
 and consequently its surface is about a hundred times 
 as great. This great change of apparent magnitude is 
 altogether overlooked, and every man is apt to imagine, 
 that it appears to the eye of the same size at both dis- 
 tances. Further, when I look at the book, it seems 
 plainly to have three dimensions, of length, breadth, and 
 thickness ; but it is certain that the visible appearance 
 hath no more than two, and can be exactly represented 
 upon a canvas which hath only length and breadth. 
 
 In the last place, does not every man, by sight, per- 
 ceive the distance of the book from his eye ? Can he not 
 affirm with certainty, that in one case it is not above one 
 foot distant, that in another it is ten ? Nevertheless it ap- 
 pears certain, that distance from the eye. is no immediate 
 object of sight. There are certain things in the visible 
 
 vol. I. 84 
 
266 OF THE HUMAN MIND. 
 
 appearance, which are signs of distance from the eye, and 
 from which, as we shall afterward show, we learn by ex- 
 perience to judge of that distance within certain limits; 
 but it seems beyond doubt, that a man born blind, and 
 suddenly made to see, could form no judgment at first of 
 the distance of the objects which he saw. The young 
 man couched by Cheseldon, thought, at first, that every 
 thing he saw touched liis eye, and learned only by experi- 
 ence to judge of tlie distance of visible objects. 
 
 I have entered into this long detail, in order to shew, 
 that the visible appearance of an object is extremely dif- 
 ferent from the notion of it which experience teaches us 
 to form by sight ; and to enable the reader to attend to 
 the visible appearance of colour, figure, and extension, in 
 visible things, which is no common object of thought, but 
 must be carefully attended to by those who would enter 
 into the philosophy of this sense, or would comprehend 
 what shall be said upon it. To a man newly made to see, 
 the visible appearance of objects would be the same as to 
 us j but he would see nothing at all of their real dimen- 
 sions, as we do. He could form no conjecture, by means 
 of his sight only, how many inches or feet they Mere in 
 length, breadth, or thickness. He could perceive little 
 or nothing of their real figure ; nor could he discern that^; 
 this was a cube, that a sphere ; that this was a cone, and 
 that a cylinder. His eye could not inform him, that this 
 object was near, and that more remote. The habit of a 
 man or of a woman, which appeared to us of one uniform 
 colour, variously folded and shaded, would present to his 
 eye neither fold nor shade, but variety of colour. In a 
 word, his eyes, though ever so perfect, would at first give 
 him almost no information of things without him. They 
 wpuld indeed present the same appearances to him as 
 they do to us, and speak ^he same language ; but to him 
 it is an unknown language ; and therefore he would at- 
 tend only to the signs, without knowing the signification 
 of them : whereas to us it is a language perfectly famil- 
 iar ; and therefore we lake no notice of the signs^but at- 
 tend only to the thing signified by them. 
 
SEEING. 267 
 
 SECTION IV. 
 
 THAT COIOUR IS A qtlAIITT OF BODIES, NOT A SENSA- 
 TION OF THE MIND. 
 
 By colour, all men, who have not been tutored by mod- 
 ern philosophy, understand, not a sensation of the mind, 
 which can have no existence when it is not perceived, but 
 a quality or modification of bodies, which continues to be 
 the same, whether it is seen or not. The scarlet rose, 
 which is before me, is still a scarlet rose when I shut my 
 eyes, and was so at midnight when no eye saw it. The 
 colour remains when the appearance ceases : it remains 
 the same when tbe appearance changes. For when I 
 view this scarlet rose through a pair of green spectacles, 
 the appearance is changed, but I do not conceive the col- 
 our of the rose changed. To a person in the jaundice, it 
 has still another appearance j but he is easily convinced,- 
 that the change is in his eye, and not in the colour of the ob- 
 ject. Every different degree of li.^ht makes it have a differ- 
 ent appearance, and total darkness takes away all appear- 
 ance, but makes not the least change in the colour of the 
 body. We may, by a variety of optical experiments, change 
 the appearance of figure and magnitude in a body, as well 
 as that of colour ; we may make one body appear to be ten. 
 But all men believe, that as a multiplying glass does not 
 really produce ten guineas out of one, nor a microscope 
 turn a guinea into a ten pound piece, so neither does a 
 coloured glass change the real colour of the object seen 
 through it, when it changes the appearance of that colour. 
 The common language of mankind shows evidently, 
 that we ought to distinguish between the colour of a body, 
 which is conceived to be a fixed and permanent quality 
 in the body, and the appearance of that colour to the eye, 
 which may be varied a thousand ways, by a variation of 
 the light, of the medium, or of the eye itself. The per- 
 manent colour of the body is the cause, which, by the 
 
^68 or THE HUMAN MI\0. 
 
 mediation of various kinds or degrees of light, and of va« 
 pious transparent bodies interposed, produces all this va- 
 riety of appearances. When a coloured body is presented, 
 there is a certain apparition to the eye, or to the mind, 
 which we have called the appearance of colour. Mr. 
 Locke calls it an idea ; and indeed it may be called so 
 with the greatest propriety. This idea can have no ex- 
 istence but when it is perceived. It is a kind of thought, 
 and can only be the act of a percipiant or thinking being. 
 By the constitution of our nature, we are led to conceive 
 this idea as a sign of something external, and are impa^ 
 tient till we learn its meaning. A thousand experiments 
 for this purpose are made every day by children, even 
 before they come to the use of reason. They look at 
 things, they handle them, they put them in various posi- 
 tions, at different distances, and in different lights. The 
 ideas of sight, by these means, come to be associated with, 
 and readily to suggest, things external and altogether un- 
 like them. In particular, that idea which we have called 
 the appearance of colour, suggests the conce])tion and be- 
 lief of some unknown quality in the body, which occasions 
 the idea; and it is to this quality, and not to the idea, 
 that we give the name of colour. The various colours, 
 although in their nature equally unknown, are easily dis- 
 tinguished when we think or speak of them, by being as- 
 soeiated with the ideas which they excite. In like man- 
 ner, gravity, magnetism, and electricity, although all un- 
 known qualities, are distinguished by their different ef- 
 fects. As we grow up, the mind acquires a habit of pasS'^ 
 ing so rapidly from the ideas of sight to the external 
 things suggested by them, that the ideas are not in the 
 least attended to, nor have they names given them ia 
 common language. 
 
 When we think or speak of any particular colour, how- 
 ever simple the notion may seem to be, which is present- 
 ed to the imagination, it is really in some sort compound- 
 ed. It involves an unknown cause, and a known effect. 
 The name of colour belongs indeed to the cause ouly^ an4 
 
SEEING. 269 
 
 not to the effect. But as the cause is unknown, we can 
 form no distinct conception of it, but bj its relation to / 
 the known effect. And therefore both go together in the i 
 imagination, and are so closely united, that they are mis-| 
 taken for one simple object of thought. When I would 
 conceive those colours of bodies which we call scarlet and 
 blue ; if I conceived them only as unknown qualities, I 
 could perceive no distinction between the one and the 
 other. I must therefore, for the sake of distinction, join 
 to each of them, in my imagination, some effect or some 
 relation that is peculiar. And the most obvious distinc- 
 tion is, the appearance which one and the other makes to 
 the eye. Hence the appearance, is, in the imagination, 
 so closely united with the quality called a scarlet colour, 
 that they are apt to be mistaken for one and the same 
 thing, although they are in reality so different and so un- 
 like, that one is an idea in the mind, the other is a qual- 
 ity of body. 
 
 I conclude, then, that colour is not a sensation, but a 
 secondary quality of bodies, in the sense we have already 
 explained ; that it is a certain power or virtue in bodies, 
 that in fair daylight exhibits to the eye an appearance, 
 which is very familiar to us, although it hath no name. 
 Colour differs from other secondary qualities in this, that 
 whereas the name of the quality is sometimes given to 
 the sensation which indicates it, and is occasioned by it, 
 we never, as far as I can judge, give the name o£ colour 
 to the sensation, but to the quality only. Perhaps the 
 reason of this may be, that the appearances of the same 
 colour are so various and changeable, according to the 
 different modifications of the light, of the medium, and 
 of the eye, that language could not afford names for them. 
 And indeed they are so little interesting, that they are 
 never attended to, but serve only as signs to introduce the 
 things signified by them. Nor ought it to appear incred- 
 ible, that appearances so frequent and so familiar should 
 have no names, nor be made objects of thought j since 
 
370 »F THE HUMAN MIND. 
 
 jVe have before shewn, that this is true of many sensa- 
 tions of touch, which are no less frequent, nor less fa- 
 miliar. 
 
 SECTION V. 
 AN INFEBENCE FROM THE PRECEDING. 
 
 From what liath been said about colour, we may infer 
 two things. The first is, that one of the most remarka- 
 ble paradoxes of modern philosophy, which hath been 
 universally esteemed as a great discovery, is, in reiiHty, 
 Avlien examined to the bottom, nothing else but an abuse 
 of words. The paradox I mean is, that colour is not A 
 quality of bodies, but only an idea in the mind. We have 
 shown, that the word colour, as used by the vulgar, can- 
 not signify an idea in the mind, but a permanent quality 
 of body. We have shown, that there is really a perma- 
 nent quality of body, to which the common use of this 
 word exactly agrees. Can any stronger proof be desired, 
 that this quality is that to which the vulgar give the name 
 of colour'? If it should be said, that tliis quality, to which 
 Ave give the name of colour', is unknown to the vulgar, 
 and therefore can have no name among them ; I answer, 
 it is indeed known only by its effects ; that is by its ex- 
 citing a certain idea in us : but are lliere not nutiiberless 
 qualities of bodies, which are known only by their effects, 
 to which, notwithstanding, we find it necessary to give 
 names? Medicine alone might furnish us with a hundred 
 instances of this kind. Do not the words astringent, 
 narcotic, epispastic, caustic, and innumerable others, sig^ 
 nify qualities of bodies, which are known only by their 
 effects upon animal bodies? Why then should not the 
 vulgar give a name to a quality, whose effects are every 
 moment perceived by their eyes ? We have all the reason 
 therefore, that the nature of the thing admits, to think 
 that the vulgar apply the name of colour to that quality 
 
of bodies which excites in us what the philosophers call 
 the idea of colour. And that there is such a quality in 
 bodies, all philosophers allow* who allow that there is any 
 sueli thing as body. Philosophers have thought lit to 
 leave that quality of bodies, which the vulgar call colour, 
 without a name, and to give the name colour to the idea 
 or appearance, to which, as we have shewn, the vulgar 
 give no name, because they never make it an object of 
 thought or reflection. Hence it appears, that when phi- 
 losophers affirm that colour is not in bodies, but in the 
 mind ; and the vulgar affirm, that colour is not in the 
 mind, but is a quality of bodies ; there is no diflerence 
 between them about things, but only about the meaning 
 of a word. 
 
 The vulgar have undoubted right to give names to 
 things which they are daily conversant about ; and phi- 
 losophers seem justly chargeable with an abuse of lan- 
 guage, when they change the meaning of a common word, 
 without giving warning. 
 
 If it is a good rule, to think with philosophers, and 
 speak with the vulgar, it must be right to speak with the 
 vulgar, when we think with them, and not to shock them 
 by philosophical paradoxes, which, when put into com- 
 mon language, express only the common sense of man- 
 kind. 
 
 If you ask a man that is no philosopher, what colour 
 is ? or, what makes one body appear white, another scar- 
 let ? he cannot tell. He leaves that inquiry to philoso- 
 phers, and can embrace any hypothesis about it, except 
 that of our modern philosophers, who affirm, that colour 
 is not in body, but only in the mind. 
 
 Nothing appears more shocking to his apprehensioOf 
 than that visible objects should have no colour, and that 
 colour should be in that which he conceives to be invisi- 
 ble. Yet this strange paradox is not only universally 
 received, but considered as one of the noblest discoveries 
 of modern philosophy. The ingenious Addison, in the 
 Spectator, No. ii3, spciaks thus of it. " I have here sup- 
 
S7a or THE HUMAKT MIND. 
 
 posed, that my reader is acquainted with that great mod- 
 ern discovery, which is at present universally acknowl- 
 edged by all the inquirers into natural philosophy, name- 
 ly, that light and colours, as apprehended by the imag- 
 ination, are only ideas in the mind, and not qualities that 
 have any existence in matter. As this is a truth, which 
 has been proved incontestably by many modern philoso- 
 phers, and is indeed one of the finest speculations in that 
 science, if the English reader would see the notion ex- 
 plained at large, he may find it in the eighth, chapter of 
 the second book of Locke's Essay on the Human Under- 
 standing." 
 
 Mr. Locke and Mr. Addison are writers who have de- 
 served so well of mankind, that one must feel some unea- 
 siness in differing from them, and would wish to ascribe 
 all the merit that is due to a discovery upon which they 
 put so high a value. And indeed it is just to acknowledge, 
 that Locke, and other modern philosophers on the sub- 
 ject of secondary qualities, have the merit of distinguish- 
 ing more accurately than those that went before them, 
 between the sensation in the mind, and that constitution 
 or quality of bodies which gives occasion to the sensation. 
 They have shown clearly, that these two things are not 
 only distinct, but altogether unlike : that there is no 
 similitude between the effluvia of an odorous body, and 
 the sensation of smell, or between the vibrations of a 
 sounding body, and the sensation of sound ; that there 
 can be no resemblance between the feeling of heat and 
 the constitution of the heated body which occasions it : 
 or between the appearance which a coloured body makes 
 to the eye, and the texture of the body, Avhich causes 
 that appearance. 
 
 Nor was the merit small of distinguishing these things 
 accurately ; because, however different and unlike in their 
 nature, they have been always so associated in the imag- 
 ination, as to coalesce as it were into one two-faced form, 
 which, from its amphibious nature, could not justly be 
 appropriated either to body or mind; and until it was 
 
SfeEINCf. 278 
 
 ppoiierly (lisUnguished into its different constituent parts, 
 it was impossible to assign to either their just shares in 
 it. None of the ancient philosophers had made this dis- 
 tinction. I'he followers of Democritus and Epicurus 
 conceived the forms of heal, and sound, and colour, to be 
 in the mind only, but that our senses fallaciously repre- 
 sented them as being in bodies. The Peripatetics imag- 
 ined, that those forms are really in bodies ; and that the 
 images of them are conveyed to the mind by our senses. 
 
 The one system made the senses naturally fallacious 
 and deceitful : the other made the qualities of body to re- 
 semble the sensations of the mind. Nor was it possible 
 to find a third, without making the distinction we have 
 mentioned ; by which indeed the errors of both these an- 
 cient systems are avoided, and we are not left under the 
 hard necessity of believing, either, on the one hand, that 
 our sensations are like to the qualities of body, or on the 
 other, that God hath given us one faculty to deceive us, 
 and another to detect the cheat. 
 
 We desire, therefore, with pleasure, to do justice to 
 the doctrine of Locke, and other modern philosophers, 
 with regard to colour, and other secondary qualities, and 
 to ascribe to it its due merit, while we beg leave to cen- 
 sure the language in which they have expressed their 
 doctrine. When they had explained and established the 
 distinction between the appearance which colour makes 
 to the eye, and the modification of the coloured body, 
 which, by the laws of nature, causes that appearance ; 
 the question was, whether to give the name of colour to 
 the cause, or to the effect ? By giving it, as they have 
 done, to the effect, they set philosophy apparently in op- 
 position to common sense, and expose it to the ridicule of 
 the vulgar. But had they given the name of colour to 
 the cause, as they ought to have done, they must then 
 have affirmed, with the vulgar, that colour is a quality 
 of bodies ; and that there is neither colour, nor any thing 
 like it, in the mind. Their language, as well as their 
 sentiments, would have been) perfectly agreeable to the 
 
 TOX. I. SB 
 
274 OF THE HUMAX MIND. 
 
 common apprebensions of mankind, and (.rue philosopLy 
 would have joined hands with common sense. As Locke 
 wa.s no enemj to common sense, it may be presumed, that> 
 in this instance, as in spme others, he was seduced by 
 some received hypothesis : and, that this was actually the 
 case, will appear in the following section. 
 
 SECTION VI. 
 
 THAT NONE OF OUR SENSATIONS ARE RESEMBLANCES OF ANY OF THE 
 QUALITIES OF BODIES. 
 
 A SECONP inference is, that although colour is really a 
 quality of body, yet it is not represented to the mind by 
 an idea or sensation that resembles it ; on the contrary, 
 it is suggested by an idea which does not in the least re- 
 semble it. And this inference is applicable, not to colour 
 only, but to all the qualities of body which we have ex- 
 amined. 
 
 It deserves te be remarked, that, in the analysis we 
 have hitherto given of the operations of the five senses, 
 and of the qualities of bodies discovered by them, no in- 
 stance hath occurred, either of any sensation which resem- 
 bles any quality of body, or of any quality of body whose 
 image or resemblance is conveyed to the mind by means 
 of the senses. 
 
 There is no phenomenon in nature more unaccountable, 
 than the intercourse that is carried on between the mind 
 and the external world : there is no phenomenon which 
 philosophical spirits have shown greater avjdity to pry 
 into and to resolve. It is agreed by all, that this inter- 
 course is carried on by means of the senses ; and this 
 satisfies the vulgar curiosity, but not the philosophic. 
 Philosophers must have some system, some hypothesis, 
 that shews the manner in which our senses make us ac- 
 quainted with external things. All the fertility of hu- 
 man invention seems to have produced only one hypothe- 
 sis for this purpose, which therefore hath been universal- 
 ly received : and that is, that the miqd, like a mirror, 
 
SEEING. 375 
 
 receives the images of tilings from without, by means of 
 the senses : so that their use must be to convey these im- 
 ages into the mind. 
 
 Whether to these images of external tliitags in the mind, 
 we give the name of sensible forms or sensible species, 
 with the Peripatetics, or the name of ideas of sensation, 
 with Locke; or whether, with later philosophers, we 
 distinguish sensations, which are immediately conveyed 
 by the senses, from ideas of sensation, which are faint 
 copies of our sensations retained in the memory and im- 
 agination ; these are only differences about words. The 
 hypothesis I have mentioned is common to all these dif- 
 ferent systems. 
 
 The necessary and allowed consequence of this hypoth- 
 esis is, that no material thing, nor any quality of mate- 
 rial things, can be conceived by us or made an object of 
 thought, until its image is conveyed to the mind by means 
 of the senses. ' We shall examine this hypothesis partic- 
 ularly afterward, and at this time only observe, that, in 
 consequence of it, one would naturally expect, that to 
 every quality and attribute of body we know or can con- 
 ceive, there should be a sensation corresponding, which 
 is the image and resemblance of that quality; and that 
 the sensations which have no similitude or resemblance 
 to body, or to any of its qualities, should give us no con- 
 ception of a material world, or of any thing belonging to 
 it. These things might be expected as the natural con- 
 sequences of the hypothesis we have mentioned. 
 
 Now we have considered, in this and the preceding 
 chapters, extension, figure, solidity, motion, hardness, 
 roughness, as well as colour, heat and cold, sound, taste, 
 and smell. We have endeavoured to shew, that our na- ' 
 ture and constitution lead us to conceive these as quali- ' 
 ties of body, as all mankind have always conceived them 
 to be. We have likewise examined, with great atten- 
 tion, the various sensations we have by means of the five 
 senses, and are not able to find among them all, one sin- 
 gle image of body, or of any of its qualities. From 
 
376 OF THE HUMAlf MIND. 
 
 whence then come those images of body and of its qual« 
 ities iuio the mind ? Let philosophers resolve this ques- 
 tion. All I can say is, that they come not by the senses. 
 I am sure that by proper attention and care I may know 
 my sensations, and be able to adirm with certainty what 
 they resemble, and what they do not resemble. I have 
 examined themone by one, and compared them with mat- 
 ter and its qualities ; and I cannot find one of them that 
 confesses a resembling feature. 
 
 A truth so evident as this, that our sensations are not 
 images of maUer, or of any of its qualities, ought not to 
 yield to a hypothesis such as that above mentioned, how- 
 ever ancient, or however universally received by philost 
 ophers I nor can there be any amicable union between 
 the two. This will appear by some reflections upon the 
 spirit of the ancient and modern philosophy concerning 
 sensation. 
 
 During (he reign of the Peripatetic philosophy, our 
 sensations were not minutely or accurately examined. 
 The attention of philosophers, as well as of the vulgar, 
 was turned to the things signified by them : therefore, ia 
 consequence of the common hypothesis, it was taken for 
 granted, that all the sensations we have from external 
 things, are the forms or images of these external things. 
 And thus the truth we have mentioned, yielded entirely 
 to the hypothesis, and was altogether suppressed by it. 
 
 Des Cartes gave a noble example of turning our atten* 
 tion inward, and scrutinizing our sensations, and this ex- 
 ample hath been very worthily followed by modern phi- 
 losophers, particularly by Malebranche, Locke, Berke-- 
 ley, and Hume. The effect of this scrutiny hath been 
 a gradual discovery of the truth above mentioned, to 
 wit, the dissimilitude between the sensations of our 
 ininds, and the qualities or attributes of an insentient 
 inert substance, such as we conceive matter to be. But 
 this valuable and useful discovery, in its different stages, 
 Lath still been unhappily united to the ancient hypothe- 
 sis; and, from this inauspicious match of opinions^ so un- 
 
SEGIX6. 277 
 
 friendly and discordant in their natures, have arisen those 
 monsters of paradox and skepticism with which the mod- 
 ern philosophy is too justly chargeable. 
 
 Locke saw clearly, and proved incontestably, that the 
 sensations we have by taste, smell, and hearing, as well 
 as the sensations of colour, heat and cold, are not resem- 
 blances of any thing in bodies ; and in this he agrees with 
 Des Cartes and Malebranche, Joining this opinion with 
 the hypothesis, it follows necessarily, that three senses 
 of the five are cut off from giving us any intelligence of 
 the material world, as being altogether inept for that 
 office. Smell, and taste, and sound, as well as ^¥cll a» 
 colour and heat, can have no more relation to body, than 
 anger or gratitude J nor ought the former to be called 
 qualities of body, whether primary or secondary, any- 
 more than the latter. For it was natural and obvious to; 
 argue thus from that hypothesis : if heat, and colour, and 
 sound, are real qualities of body, the sensations, by which 
 we perceive them, must be resemblances of those quali- 
 ties : but these sensations are not resemblances ; there- 
 fore those are not real qualities of body. 
 
 We see then, that Locke, having found that the ideas 
 of secondary qualities are no resemblances, was compelled, 
 by a hypothesis common to all philosophers, to deny that 
 they are real qualities of body. It is more difficult to 
 assign a reason, why, after this, he should call them sec- 
 ondary qualit^s ; for this name, if I mistake not, was of 
 his invention. Surely he did not mean that they were 
 se^condary qualities of the mind ; and T do not see with 
 what propriety, or even by what tolerable license, he 
 could call them secondary qualities of body, after finding 
 that they were no qualities of body at all. In this, ho, 
 seems to have sacrificed to common sense, and to have 
 been led by her authority, even in opposition to bis hypoth- 
 esis. The same sovereign mistress of our opinions that 
 led this philosopher to call those things secondary quali- 
 ties of body, which, according to his principles and rea- 
 sonings, were no qualities of body at all, hath led, not the 
 vulgar of all ages only, but philosophers also, and even 
 
278 OF THE HUMAN MIND. 
 
 the disciples of Loeke, to believe them to be real qualities 
 I of bod^' : she hath led them to investigate, bj_experlments, 
 the nature of colour, and sound, and heat, ih bodies. Nor 
 ihath.this investigation been fruitless, as it must iiave been, 
 if there had been no such thing in bodies: on the con- 
 trary, it hath produced very noble and useful discoveries, 
 which make a very considerable part of natural philoso- 
 phy. If then natural philosophy be not a dream, there 
 is something in bodies, which we call colour, and heat, 
 and sound. And if this be so, the hypothesis from which 
 the contrary is concluded must be false : for the argu- 
 ment, leading to a false conclusion, recoils against the 
 hypothesis from which it was drawn, and thus directs its 
 force backward. If the qualities of body were known (o 
 us only by sensations that resemble them, then colour, 
 {ind sound, and heat, could be no qualities of bodyj but 
 these are real qualities of body ; and therefore the qual- 
 ities of body are not known only by means of sensations 
 ^hat resemble them. 
 
 But to proceed : what Locke had proved with regard 
 to the sensations we have by smell, taste and hearing, 
 bishop Berkeley proved no less unanswerably with re- 
 gard to all our other sensations ,• to wit, that none of 
 them can in the least resemble the qualities of a lifeless 
 and insentient being, such as matter is conceived to be. 
 Mr. Hume hath confirmed (his by his authority and rea- 
 soning. This opinion surely looks with a very malign 
 aspect upon the old hypothesis; yet that hypothesis 
 hath still been retained, and conjoined with it. And 
 what a brood of monsters hath this produced. 
 
 The firstborn of this union, and perhaps the jnost 
 •harmless, was, that the secondary qualities of body were 
 mere sensations of the mind. To pass by Malebranche's 
 notion of seeing all things in the ideas of the divine mind, 
 as a foreigner never naturalized in this island : the next 
 was Berkeley's system, that extension, and figure, and 
 hardness and motion ; that land, and sea, and houses, 
 and our own bodies, as well as those of our wives, 
 
SEEING. 279 
 
 and children, and friends, are nothing but ideas of the 
 mind ; and that there is nothing existing in nature, but 
 minds and ideas. 
 
 The progeny that followed, is still more frightful ', so 
 that it is surprising, that one could be found who had the 
 courage to act the midwife, to rear it up, and to usher it 
 into the world. No causes nor effects ; no substances, 
 material or spiritual ; no evidence even in noathematieal 
 . demonstration ; no liberty nor active power ; nothing 
 existing in nature, but impressions and ideas following 
 each other, without time, place, or subject. Surely no 
 age ever produced such a system of opinions, justly de- 
 duced with great acuteness, perspicuity, and elegance, 
 from a principle universally received. The hypothesis 
 we have mentioned, is th« father of them all. The dis- 
 similitude of our sensations and feelings to external things, 
 is the innocent mother of most of them. 
 
 As it happens sometimes in an arithmetical operation, 
 that two errors balance one another, so that the conclu- 
 sion is little or nothirtg affected by them ; but when one 
 of them is corrected, and the other left, we are led farther 
 from the trutir, than by both together: so it seems to 
 have happened in the Peripatetic philosophy of sensation, 
 compared with the modern. The Peripatetics adopted 
 two errors ; but the last served as a corrective to the. first, 
 and rendered it mild and gentle | so that their system 
 had no tendency to skepticism. The moderns liave re- 
 tained the first of those errors, but have gradually de- 
 tected and corrected the last. The consequence hath, 
 been, that the light we have struck out hath created dark- 
 ness, and skepticism hath advanced hand in hand with 
 knowledge, spreading its melancholy gloom first over the 
 material world, and at last over the whole face of nature. 
 Such a phenomenon as this, is apt to . stagger even the 
 lovers of light and knowledge, while its cause is latent ; 
 but when that is detected, it may give hopes, that this 
 darkness shallnot be everlasting, but that it shall be suc- 
 ceeded by a more permaoent light. 
 
280 O* THE HUMAN MINIT. 
 
 SECTION VII. 
 or VISIBLE riGUKE AN0 EXTENSION. 
 
 ALTHOUGH there is no resemblance, nor, as far as we 
 know, any necessary connection, between that quality in 
 a body which we call its colour, and the appearance which 
 that colour makes to the eye ; it is quite otherwise with 
 regard to its figure and magnitude. There is certainly 
 a resemblance, and a necessary connection, between the 
 visible figure and magnitude of a body, and its real fig- 
 ure and liiagnitude ; no man can give. a^ reason why a 
 scarlet colour affects the eye in the manner it does ; no 
 man can be sure that it affects his eye in the same man- 
 ner as it affects the eye of another, and that it has the 
 same appearance to him as it has to another man ; but 
 we can assign a reason why a circle placed obliquely to 
 the eye, should appear in the form of an ellipse. The 
 visible figure, magnitude, and position, may, by mathe- 
 matical reasoning, be deduced from the real ; and it may 
 be demonstrated, that every eye that sees distinctly and 
 perfectly, must, in the same situation, see it under this 
 form, and no other. Nay, we may venture to afiirm, that 
 a man born blind, if he were instructed in mathematics, 
 would be able to determine the visible figure of a body, 
 when its real figure, distance, and position, are given. Dr. . 
 Saunderson understood the projection of the sphere, and 
 perspective. Now, I require no more knowledge in a 
 blind man, in order to his being able to determine the vis- 
 ible figure of bodies, than that he can project the outline 
 of a given body, upon the surface of a hollow sphere, 
 whose centre is in the eye. This projection is the visible 
 figure he wants,- for it is the same figure with that whicb 
 is projected upon the tunica retina in vision. 
 
 A blind man can conceive lines drawn from every point 
 of the object to the centre of the eye, making angles^ 
 
SEiiiirG. 381 
 
 He can conceive, that the length of the 6bject wiH appear 
 greater or less in proportion to (he angle which it sub- 
 tends at the eye ; and that, in like manner, the breadth, 
 and in general the distance of any one point of the object 
 from any other point, will appear greater or less, in pro- 
 portion to the angles Which those distances subtend. He 
 can easily be made to conceive, that the visible appear- 
 ance has no thickness, any more than a projection of the 
 sphere, or a perspective draught. He may be informed, 
 that the eye, rnitil it is aided by experience, does not rep- f 
 resent one object as nearer or more remote than another. ' 
 Indeed he would probably conjecture this of himself, and 
 be apt to think, that the rays of light mu»t make the 
 same impression upon the eye, whether they come from 
 a greater or less distanee. 
 
 These are all the principles which we suppose our 
 blind mathematician to havej and these he may certain- 
 ly acquire by information and reflection. It is no less 
 certain, that from these principles, having given the real 
 ilgure and magnitude of a body, and its position i^nd dis- 
 tance with regard to the eye, be can lind out its visible 
 figure and magnitude. He can demonstrate in general, 
 from these principles, that the vislible figUre of all bodies 
 will be the same with that of their projection upon the 
 surface of a hollow sphere, when the eye is placed' in the 
 centre. And he can demonstrate, that their visible niag- 
 njtude will be greater or less, according as their projec- 
 tion occupies a greater or less part of the surface of this 
 sphere. 
 
 To set this matter in another light, let us distinguish 
 betwixt the posffion of objects with i^egSfd to the eye, 
 and their Mstmnee from it. Objects that lie in the same 
 right line dt<awn from the centre of the eye, have the same 
 p&sitioii; however different their distances from the eye may 
 be: but objects which lie in different right lines drawn 
 from the eye's centre, have a different position ; and this 
 diffcFenee of position is greater or le«s, in proportion to the 
 angle made at the eye by the right lines mentio'ned. Hav- 
 
 voi. I. 36 
 
282 OF THE HUMAN MINB. 
 
 ing thus defined what we mean by the position of objects 
 with regard to the eye, it is evident, that as the real fig- 
 ure of a body consists in the situation of its several parts 
 with regard to one another, so its visible figure consists 
 in the position of its several parts with regard to the eye | 
 and as he that hath a distinct conception of the situation 
 of the parts of the body with regard to one another, must 
 have a distinct conception of its real figure ; so he that 
 conceives distinctly the position of its several parts with 
 regard to the eye, must have a distinct conception of its 
 visible figure. Now, there is nothing surely to hinder a 
 blind man from conceiving the position of the several parts 
 of a body with regard to the eye, any more than from con- 
 ceiving their situation with regard to one another; and 
 therefore I conclude, that a blind man may attain a distinct 
 conception of the visible figure of bodies. 
 
 Ahhough we think the arguments that have been of- 
 fered are sufficient to prove, that a blind man may con- 
 ceive the visible extension and figure of bodies ; yet, in 
 order to remove some prejudices against this truth, it 
 will be of use to compare the notion which a blind math- 
 ematician might form to himself of visible figure, with 
 that which is presented to the eye in vision, and to ob- 
 serve^ wherein they differ. 
 
 First, visible figure is never presented to the eye but 
 in conjunction with colour ; and although there be no con- 
 nection between them from the nature of the things, yet, 
 having so invariably kept company together, we are hard- 
 ly able to disjoin them even in our imagination. What 
 mightily increases this difficulty is, that we have never 
 been accustomed to make visible figure an object of 
 thought. It is only used as a sign, and, having served 
 this purpose, passes away, without leaving a trace behind. 
 The drawer or designer, whose business it is to hunt this 
 fugitive form, and to take a copy of it. finds how difficult 
 his task is, after many years labour and practice. Hap- 
 py ! if at last he can acquire the art of arresting it in his 
 imagination, until he can delineate it. For then it is 
 
SEEINS. ^3 
 
 evident, that he must he able to draw as accurately from 
 the life as from a copy. But how few of the professed 
 masters of desigoing are ever able to arrive at this degree 
 of perfection ! It is uo wonder, then, that we should find 
 so great difficulty in conceiving this form apart from its 
 constant associate, when it is so difficult to conceive it all. 
 But our blind man's notion of visible figure will not be 
 associated with colour, of which he hath no conception ; 
 but it will perhaps be associated with hardness or smooth- 
 ness, with which he is actjuainted by touch. These dif- 
 ferent associations are apt to impose upon us, and to make 
 things seem different, which in reality are the same. 
 
 Secondly, the blind man forms the notion of visible 
 figure to himself, by thought, and by mathematical rea- 
 soning from principles ; whereas the man that sees has it 
 presented to his eye at once, without any labour, without 
 any reasoning, by a kind of inspiration. A man may form 
 to himself the notion of a parabola, or a cycloid, from the 
 mathematical definition of those figures, although he had 
 never seen them drawn or delineated. Another, who 
 knows nothing of the mathematical definition of the fig- 
 ures, may see them delineated on paper, or feel them cut 
 out in wood. Each may have a distinct conception of the 
 figures, one by mathematical reasoning, the other by 
 sense. Now, the blind man forms his notion of visible 
 figure in the same manner as the first of these formed 
 his notion of a parabola or a cycloid, which he never saw. 
 
 Thirdly, visible figure leads the man that sees, direct- 
 ly to the conception of the real figure, of which it is a 
 sign. But the blind man's thoughts move in a contrary 
 direction. For he must first know the real figure, dis- 
 tance, and situation, of the body, and from thence he 
 slowly traces out the visible figure by mathematical rea- 
 soning. Nor does his nature lead him to conceive this 
 visible figure as a sign ) it is a creature of his own reasoa 
 and imagination. 
 
SS4 OF THE HUMAN UlSO, 
 
 SECTION VIII. 
 
 SOME QUERIES CONCERNING VISIBLE FIGURE ANSWERED. 
 
 It may be asked, what kind of thing is this visible (Igr 
 ure? Is it a sensation, or an idea? Ifitisanidea, fi-oniwhat 
 sensation is it copied ? These questions may seem trivial or 
 impertinent to one who does not know, that there is a tribu- 
 nal of inquisition erected by certain modern philosophers, 
 before which every thing in nature, must answer. The ar- 
 ticles of inquisition are few indeed, but very dreadful in 
 their consequences. They are only these j Is the prisoner 
 an impression or an idea ? If an idea, from what impression 
 copied? Now, if it appears that the prisoner is neither an 
 impression, nor an idea copied from some impression, im- 
 mediately, without being allowed to offer any thing in 
 arrest of judgment, he is sentenced to pass out of exist- 
 ence, and to he, in all time to come, an empty unmeaning 
 sound, or the ghost of a departed entity. 
 
 Before this dreadful tribunal, cause and effect, time 
 and place, matter and spirit, have been tried and cast : 
 how then shall such a poor flimsy form as visible ligure 
 stand before it ? It must even plead guilty, and confess 
 that it is neither an impression nor an idea. For, alas ! 
 it is notorious, that it is extended in length and breadth; 
 it may be long or short, broad or narrow, triangular, 
 quadrangular, or circular: and therefore, unless ideas 
 and impressions are extended and figured, it cannot be- 
 long to that category. 
 
 If it should still be asked, to what category of beings 
 does visible figure then belong ? I can only, in answer, 
 give some tokens, by which those who are better ac- 
 quainted with the categories, may phance to find its place. 
 It is, as we have said, the position of the several parts of 
 a figured body, with regard to the eye. The different posi- 
 jtions of the several parts of the body with regard to the 
 
SEEING. 285 
 
 eye, when put together, make a real figure, which is truly 
 extended in the length and hrcadth, and which represents 
 a figure that is extended in length, breaddi, and thickness. 
 In like manner, a projection of the sphere is a real fig- 
 ure, and hatli length and breadth, but represents the 
 sphere, which hath three dimensions. A projection of 
 the sphere, or a perspective view of a palace, is a rcpre- 
 senlative in the very same sense as visible iigure is, and; 
 wherever they have their lodgings in the categories, this' 
 will be found to dwell next door to them. 
 
 It may further be asked, whether there he any sensa- 
 tion proper to visible figure, by which it is suggested in 
 vision ? Or by what means it is presen<ed to the mind ? 
 This is a question of some importance, in order to our 
 having a distinct notion of the faculty of seeing: and to 
 give all the light to it we can, it is necessary to compare 
 this sense with other senses, and to make some supposi- 
 tions, by which we may be enabled to distinguish things 
 that are apt to be confounded, although they are totally 
 difierent. 
 
 There are three of our senses which give us intelligence 
 of things at a distance : smell, hearing, and sight. In 
 smelling, and in hearing, we have a sensation or impres* 
 sion upon the mind, which, by our constitution, we con- 
 ceive to be a sign of something external : but the posi- 
 tion of this external thing, with regard to the organ of 
 sense, is not presented to the mind along with the sensa- 
 tion. When I hear the sound of a coach, I could not, 
 previous to experience, determine whether the sounding 
 body was above or below, to the right hand or to the left. 
 So that the sensation suggests to me some external ob- 
 ject as the cause or occasion of it; but it suggests not the 
 position of that object, whether it lies in this direction or in 
 that. The same thing may be said with regajrd to smell- 
 ing. But the case is quite different with regard to see- 
 ing. When I see an object, the appearance which the 
 colour of it makes, may be called the sensation, which 
 suggests to me some external thing as its cause; but it 
 
386 •r THE HUMAN MINB. 
 
 suf^gests likewise the individual direction and position of 
 this cause with regard to the eye. I know it is precisely 
 in such a direction, and in no other. At the same time, 
 I am not cousciuus of any thing that can be called sensa- 
 tion, but the sensation of colour. The po.silion of Jhe 
 coloured thing is no sensation, but it is by (he laws of 
 niy constitution presented to tlie inind along with the 
 colour, without any additional sensation. 
 
 Let us suppose, that the eye were so constituted, that 
 the rays coming from any one point of the object were not, 
 as they are in our eyes, collected in one point of the re- 
 tina, but diffused over the whole : it is evident to those 
 ■who understand the structure of the eye, that such an 
 eye as we have supposed, would shew the colour of a body 
 as our eyes do, but that it would neither slicw figure nor 
 position. The operation of such an eye would be pre- 
 cisely similar to that of hearing and smell ; it would give 
 no perception of figure or extension, but merely of colour. 
 Nor is the supposition we have made altogether imagin- 
 ary : for it is nearly the case of most people who have 
 cataracts, whose crystalline, as Mr. Clieseldon observes, 
 does not altogether exclude the rays of light, but diffuses 
 them over the retina, so that such persons see things as 
 one does through a glass of broken jelly ; they perceive 
 the colour, but nothing of the figure or magnitude of 
 objects. 
 
 Again, if we should suppose, that smell and sound were 
 conveyed in right lines from the objects, and that every 
 sensation of liearing and smell suggested the precise di- 
 rection or position of its object ; in this case the opera- 
 tions of hearing and smelling would be similar to that of 
 seeing : we should smell and hear the figure of objects, 
 in the same sense as now we see it ; and every smell and 
 sound would be associated with some figure in the imag- 
 ination, as colour is in our present state. 
 
 We have reason to believe, that the rays of light make 
 some impression upon the retina ; but we are not con- 
 scious of this impression ; nor have anatomists or philos- 
 
SEEiNe. 287 
 
 ephers been able to discover the nature and effects of it ; 
 whether it produces a vibration in the nerve, or the mo- 
 tion of some subtile fluid contained in the nerve, or some- 
 thing different from either, Co which we cannot give a 
 name. Whatever it is, we shall call it the material im- 
 pression; remembering carefully, that it is not an im- 
 pression upon the mind, but upon the body; and that it 
 is no sensation, nor can resemble sensation, any more 
 than figure or motion can resemble thought. Now, this 
 material impression, made upon a particular point of the 
 retina, by the laws of our constitution, suggests two things 
 to the mind, namely, the colour, and the position of some 
 external object. No man can give a reason, why the , 
 same material impression might not have suggested sound, 
 or smell, or either of these, along with the position of the 
 object. That it should suggest colour and position, and 
 nothing else, we can resolve only in our constitution, or 
 the will of our Maker. And since there is no necessary 
 connection between these two things suggested by this 
 material impression, it might, if it had so pleased our 
 Creator, have suggested one of them without the other. 
 Let us suppose, therefore, since it plainly appears to be 
 possible, that our eyes had been so framed, as to suggest to 
 us the position of the object, without suggesting colour, 
 or any other quality : what is the consequence of this 
 supposition? It is evidently this, that the person endued 
 with Fuch an eye, would perceive the visible figure of 
 bodies, without having any sensation or impression made 
 npon his mind. The figure he perceives is altogether ex- 
 ternal ; and therefore cannot be called an impression upon 
 the mind, without the grossest abuse of language. If it 
 should be said, that it is impossible to perceive a figure, 
 unless there be some impression of it upon the mind ; I 
 beg leave not to admit the impossibility of this, without 
 some proof: and I can find none. Neither! can I conceive 
 what is meant by an impression of figure upon the mind. 
 I can conceive an impression of figure upon wax^ or upon 
 any body that is fit to receive it j but an impression of it 
 
288 or THE HDMAN MIND. 
 
 upon the mind, is to me quite unintelligible ; andalthougtt 
 I form the most distinct conception of the figure, 1 can- 
 not, upon the strictest examination, find any impression 
 of it upon my mind. 
 
 If we suppose, last of all, that the eye hath the power 
 restored of perceiving colour, 1 apprehend that it will be 
 allowed, that now it perceives figure in the very same 
 manner as before, with this difference only, that colour is 
 always joined with it. 
 
 In answer, therefore, to the question proposed, there 
 seems to be no sensation that is appropriated to visible 
 figure, or whose office it is to suggest it. It seems to be 
 suggested immediately by the material impression upon 
 the organ, of which we are not conscious : and why may 
 not a material impression upon the retina suggesi visible 
 figure, as well as the material impression made upon the 
 hand, when we grasp a ball, suggests real figure ? In the 
 one case, one and the same material impression suggests 
 both colour and visible figure ; and in the other case, one 
 and the same material impression suggests hardness, heat, 
 or cold, and real figure, all at the same time. 
 
 We shall conclude this section with another question 
 upon this subject. Since the visible figure of bodies is a 
 real and external object to the eye. as their tangible fig- 
 ure is to the touch ; it may be asked, whence arises the 
 difiSculty of attending to the first, and the facility of at- 
 tending to the last? It is certain, that the first is more 
 frequently presented to the eye, than the last is to the 
 touch; the first is as distinct and determinate an object 
 as the last, and seems in its own nature as proper for 
 speculation. Yet so little hath it been attended to, that 
 it never had a name in any language, until bishop Berke- 
 ley gave it that which we have used after his example, 
 to distinguish it from the figure which is the object of 
 touch. 
 
 The difiiculty of attending to the visible figure of bodies, 
 aiid making it an object of thought, appears so similar 
 to that which we find in attending to our sensations, that 
 
SEErVG. 289 
 
 both have [probably like causes. Nature intended- the vis- 
 ible figure as a sign of tlie tangiMe ligure and situation; 
 of bodies, and hath taught us by a kind of instinct to put; 
 it always to this use. Hence it happens, that the mindi 
 passes over it with a rapid motion, to attend to the things 
 signified by it. It is as unnatural to the mind to stop at 
 the visible figure, and attend to it. as it is to a spherical 
 body to stop upon an inclined plane. There is an inward 
 principle, which constantly carries it forward, and whicli 
 cannot be overcome but by a contrary force. 
 
 Tliere are other external things which nature intend'ed 
 for signs ; and we find this common to them ail. that the 
 mind' is disposed to overlook them, and to attend only to 
 the things signified by them. Thus there are certaia 
 modifications of the human face, which are natural signs 
 of the present disposition of the mind. Every man un- 
 derstands the meaning of these signs, but not one of a 
 hundred ever attended to the signs themselves, or knows 
 any thing about them. Hence you may find many an ex- 
 cellent practical physiognomist, who knows nothing of 
 the proportions of a face, nor can delineate or describe 
 the expression of any one passion. 
 
 An excellent painter or statuary can tell, not only what 
 are the proportions of a good face, but what changes 
 every passion makes in it. This, however, is one of the 
 chief mysteries of his art, to the acquisition of which, in- 
 finite labour and attention, as well as a happy genius, are 
 required. But when he puts his art in practice, and hap- 
 pily expresses a passion by its proper signs, everyone un- 
 derstands the meaning of these signs, without art, and 
 without reflection. 
 
 "What has been said of painting, might easily be ap- 
 plied to all the fine arts. The difficulty in them all con- 
 sists in knowing and attending to those natural signs 
 whereof every man understands the meaning. 
 
 We pass from the sign to the thing signified, with ease, 
 and by natural impulse ; but to go backward from tb* 
 
 TOl. I. 37 
 
390 o;f the human mins. 
 
 thing signified to the sign, is a work of labour and diffi- 
 culty. Visible figure, therefore, being intended by nature 
 to be a sign, we pass on immediately to the thing signi- 
 fied, and cannot easily return to give any attention to the 
 sign. 
 
 Nothing shews more clearly our indisposition to attend 
 to visible figure and visible extension than this, that al- 
 though mathematical reasoning is no less applicable to 
 them, than to tangible figure and extension, yet they have 
 entirely escaped the notice of mathematicians. While that 
 figure and that extension which are objects of touch, have 
 been tortured ten thousand ways for twenty centuries, and 
 a very noble system of science has been drawn out of 
 them ; not a single proposition do we find with regard to 
 the figure and extension which are the immediate objects 
 of sight. 
 
 When the geometrician draws a diagram with the 
 most perfect accuracy ; when he keeps bis eye fixed upon 
 it, while he goes through a long process of reasoning, and 
 demonstrates the relations of the several parts of his fig- 
 ure; he does not consider, that the visible figure present- 
 ed to his eye, is only the representative of a tangible fig- 
 ure, upon which all his attention is fixed ; he does not 
 consider that these two figures have really different prop- 
 erties ; and that what he demonstrates to be true of the 
 one, is not true of the other. 
 
 This perhaps will seem so great a paradox, even to 
 mathematicians, as to require demonstration before it can 
 be believed. Nor is the demonstration at all difficult, if 
 the reader will have patience to enter but a little into the 
 mathematical consideration of visible figure, which we 
 shall call the geometry of visibles. 
 
8EEIXC. 291 
 
 SECTION IX. 
 OF THE GEOMETRY OF VISIBLES. 
 
 In this geometry, the definitions of a point; of a line, 
 whether straight or curve ; of an angle, whether acute, 
 or right, or obtuse ; and of a circle, are the same as ia 
 common geometry. The mathematical reader will easily 
 enter into the whole mystery of this geometry, if he at- 
 tends duly to these few evident principles. 
 
 1. Supposing the eye placed in the centre of a sphere, 
 every great circle of the sphere will have the same ap- 
 pearance to the eye as if it was a straight line. For the 
 curvature of the circle being turned directly toward the 
 eye, is not perceived by it. And for the same reason, any 
 line which is drawn in the plane of a great circle of the 
 sphere, whether it be in reality straight or curve, will 
 appear straight to the eye. 3. Every visible right line 
 will appear to coincide with some great circle of the 
 sphere ; and the circumference of that great circle, 
 evei} when it is produced until il returns into itself, will 
 appear to be a continuation of the same visible right line, 
 all the parts of it being visibly in directum. For the eye \ 
 perceiving only the position of objects with regard to it- j 
 self, and not their distance, will see those points in the 
 same visible place whicii have the same position with re- 
 gard to the eye, how different soever their distances from 
 it may be. JVow, since a plane passing through the eye 
 and a given visible right line, will be the plane of some 
 great circle of the sphere, every point of the visible right 
 line will have the same position as some point of the great 
 circle ; therefore they will both have the same visible 
 place, and coincide to the eye : and the whole circumfer- 
 ence of the great circle continued even until it returns 
 into itself, will appear to be a continuation of the same 
 /Visible right line. 
 
293 OF THE HUMAN MIND. 
 
 Hence it follows : 
 
 3. That every visible right line, when it is continued 
 in directum, as far as it may be continued, will be repre- 
 sented by a great circle of a sphere, in whose centre the 
 eye is placed. It follows, 
 
 4. That tiie visible angle comjireliended under two visi- 
 ble right lines, is equal to the spherical angle compre- 
 Lcnded under fche two great circles which are the repre- 
 sentatives of these visible lines. For since the visible 
 lines appear to coincide with the great circles, the visible 
 angle comprehended under the former, must be equal to 
 the visible angle comprehended under the latter. Butthe 
 vijsible angle comprehended under the two great cij'cles, 
 when seen from the centre, is of the same magnitude with 
 the spherical angle which they really comprehend, as 
 jnathematicians know j therefore the visible angle made 
 by any two visible lines, is wjual to the spheiical angle 
 inade by the two great circles of the sphere wliieh are 
 their representatives. 
 
 6. Hence it is evident, that every visible rlglit-lined 
 triangle, will coincide in all its parts with some spherjcaj 
 triangle. The sides of the one .will appear equal to the 
 sides of the other, and the angles of the one to the angles 
 of the other, each to each ; and therefore the whole of ihe 
 jone triangle will appear equal to the whole of the other. 
 
 1 In a word, to the eye they will be one and the same, and 
 
 have the same mathematical properties. The properties 
 
 / therefore of visible right-lined triangles, are not tlie same 
 
 Avith the properties of plain triangles, but are the same 
 
 with those of spherical trianj^les. 
 
 t— 6. Ewwy lesser cii-ele of the spliere, will appear a eir- 
 de to the eye, placed, as we have supposed all along, in 
 the centre of the sphere. And, on the other hand, every 
 visible circle will appear to coincide with some lessee 
 BJrfile of the sphere. 
 
 7. Moreover, the whole surface of the sphere will rep- 
 resent tlie whole of visible space : for since every visible 
 
SEEIN8. 295 
 
 point coincides wUli some point of the sui-face of the 
 sphere, and has the same visible plaoe, it follows, that all 
 the parts of the spherical surface taken together, will \ 
 represent all possible visible places, that is, the whole of ] 
 visible space. And from this it follows, in the last place, ' 
 
 8. That every visible figure will be represented by that I 
 part of the surface of the sphere, on which it might be \ 
 projected, the eye being in tlie centre. And every such ' 
 visible figure will bear the same ratio to the whole of 
 visible space, as the part of tlie spherical surface which 
 represents it, bears to the whole spherical surface. 
 
 The mathematical reader, I hope, will enter into these 
 principles with perfect faeility, and will as easily perceive, 
 that the following propositions with regard to visible fig- 
 ure and space, which we offer only as a specimen, may be 
 mathematically demonstrated from them, and are not 
 less true nor less evident than the propositions of Euclid, 
 with regard to tangible figures. 
 
 Prop. 1. Every right line being produced, will at last 
 return into itself. 
 
 2. A right line returning into itself, is the longest pos- 
 sible right line ; and all other right lines bear a finite 
 ratio to it. 
 
 3. A right line returning into itself, divides the whole 
 of viiiible s[)aee ioto two equal parts, which will both be 
 oompreliended under this right line. 
 
 4. Tlie whole of visible space bears a finite ratio to any 
 part of it. 
 
 5. Any two right lines being produced, will meet in two 
 points, and mutually bisect each other. 
 
 6. If two lines be parallel, that is, every where equally 
 distant from each other, they cannot both be straiglit. 
 
 7. Any right line being given, a point may be found, 
 which is at the same distance from all the points of the 
 given right line. 
 
 8. A circle may be parallel to a right line, that is, may 
 be equally distant from it in all its parts. 
 
 9. Bight-lined traaogles that are similar, are also equal. 
 
294 »F THE HTJMAK MIKB. 
 
 10. Of every riglit-litied triangle, (he three angles taken 
 together, are greater than two right angles. 
 
 11. The angles of a right-lined triangle, may all be 
 right angles, or all obtuse angles. 
 
 13. Unequal circles are not as ilie squares of their di- 
 ameters, nor are their circumferences in the ratio of 
 their diameters. 
 
 This small specimen of the geometry of visibles, is in- 
 tended to lead the reader lo a clear and distinct concep- 
 tion, of the the figure and extension which is presented to 
 the mind by vision ; and lo demonstrate the truth of what 
 we have affirmed above, namely, that those figures and 
 that extension which are the immediate objects of sight, 
 are not the figures and the extension about which com- 
 mon geometry is employed ; that the geometrician, while 
 he looks at his diagram, and demonstrates a proposition, 
 hath a figure presented to hr« eye, which is only a sign 
 and representative of a tangible figure ; that he gives not 
 the least attention to the first, but attends only to the 
 last j and that these two figures have different proper- 
 ties, so that what he demonstrates of the one, is not true 
 of the other. 
 
 It deserves, however, to be remarked, that as a small 
 part of a spherical surface differs not sensibly from a plain 
 surface ; so a small part of visible extension differs very 
 little from that extension in length and breadth, which is 
 the object of touch. And it is likewise to be observed, 
 that the human eye is so formed, that an object which i» 
 seen distinctly and at one view, can occupy but a small 
 part of visible space : for we never see distinctly what is 
 at a considerable distance from the axis of the eye j and 
 therefore, when we would see a large object at one view, 
 the eye must be at so great a distance, Ihat the object oc- 
 cupies but a small part of visible space. From these 
 two observations, it follows, that plain figures which are 
 seen at one view, when their planes are not oblique, but 
 direct to the eye, differ little from the visible figures 
 which they present to the eye. The sever al liuesin the 
 
SEEING. 295 
 
 tangible figure have very nearly the same proportion to 
 each other as in the visible ; and the angles of the one 
 are very nearly, although not strictly and mathematically, 
 equal to those of the other. Although (herefore we have 
 found many instances of natural signs which have no si-i 
 militude to the things signified, this is not the case with' 
 resrard to visible figure. Tt hath in all eases such a simile 
 itude to the thing signifi<'d by it, as a plan or profile hath 
 to that which it represents ; and in some cases the sign 
 and thing signified have to all sense the same figure and 
 the same proportions. If we eould find a being endued 
 with sight only, without any other external sense, and 
 capable of reflecting and reasoning upon what he sees, 
 the notions and philosophical speculations of such a being, 
 might assist us in the difficult task of distinguishing the 
 perceptions which we have purely by sight, from those 
 which derive their origin from other senses. Let us 
 suppose such a being, and conceive, as well as we can, 
 what notion he would have of visible objects, and what 
 conclusions he would deduce from them. We must not 
 conceive him disposed by his constitution, as we are, to 
 consider the visible appearance as a sign of something 
 else : it is no sign to him, because there is nothing sig- 
 nified by it ; and therefore we must suppose him as much 
 disposed to attend to the visible figure and extension of 
 bodies as we are disposed to attend to their tangible fig- 
 ure and extension. 
 
 If various figures' were presented to his sense, he 
 might, without doubt, as they grow familiar, compare 
 them together, and perceive wherein they agree, and 
 wherein they difier. He might perceive visible objects 
 to have length and breadth, but could have no notion of 
 a third dimension, any more than we can have of a fourth. 
 All visible objects would appear to be terminated by lines, 
 straight or curve : and objects terminated by the same 
 visible lines, would oeeupy the same place, and fill the 
 same part of visible space. It would not be possible for 
 
•r THE HUMAN MINB. 
 
 bira to conceive one object to be beliind another, or one 
 to be nearep, anotber more distant. 
 
 To us, who conceive three diiaensions, a line may be 
 conceived straight ; or it may be conceived incurvated in 
 one dimension, and straight in another f or, lastly, it maj 
 be incurvated in two dimensions. Suppose a line, to be 
 drawn upward and downward, its length inake& one di.- 
 mension, which we shall call upward and downward; 
 and there are two dimensions remaining, according te 
 which it may be straight or curve. It may be bent 
 to the right or to the left ; and if it has no bending 
 either to right or left, it is straight in this dimensioDi, 
 But supposing it straight in this dimension of right and 
 left, there is still another dimension remaining, in which 
 it may be curve ; for it may be bent backward or for- 
 ward. When we conceive a tangible straight line, we 
 exclude curvature in either of these two dimensions : and 
 as what is conceived to be excluded, must be conceiv- 
 ed, as well as what is conceived to be included, it fol- 
 lows, that all the three dimensions enter into our con- 
 ception of a straight line. Its length is one dimension, 
 its sfraightness in two other dimensions is included, or 
 curvature in these two dimensions excluded, in the con- 
 ception of it. 
 
 The being we have supposed, having no conception of 
 more than two dimensions, of which the length of a line 
 is one, cannot possibly conceive it cither straight or curve 
 in more than one dimension : so that in this conception of 
 a right line, curvature to the right hand or left is excluded; 
 but curvature backward or forward cannot be excluded, 
 because he neither hath, nor can have any conception of 
 such curvature. Hence we see the reason that a lin§f,. 
 which is straight to the eye, may return into itself: for 
 its being straight to the eye, implies only straightness in 
 one dimension ; and a line, which is straight in one div 
 mension, may, notwithstanding, be curve in auothec di- 
 menston, and so may return into itsel£ 
 
SEEING. 397 
 
 To us, who conceive three dimensions, a sur£iee is that 
 which hath length and breadth, excluding ttiickness : and 
 a surface may be either plain in this third dimension, or 
 it may be incurvated : so that the notion of a third di- 
 mension enters int« our conception of a surface ; for it is 
 only by means of this third dimension, that we can dis- 
 tinguish surfaces into plain and curve surfaces ; and nei- 
 ther one nor the olher can be eonceived, without conceiv- 
 ing a third dimension. 
 
 ITie being we have supposed having no eoneeption of 
 a third dimension, his visible figures have length and 
 breadth indeed ; but thickness is neither included nor 
 excluded, being a thing of which he has no cooeeption. 
 And therefore visible figures, although they have length 
 and breadth, as surfaces have, yet they are tieithei- plain 
 surfaces, nor curve surfaces. For a curve surface implies 
 curvature in a third dimension, and a plain sur£a>ee im- 
 plies the want of eurvature in a third dimension ; aad 
 such a being can conceive neither of these, because he 
 has no conception of a third dimension. Moreover, al- 
 tbougli he hath a distinct conp«pilion of the inelination of 
 two lines which make an angle, yet he can neither iCod- 
 ceive a plain angle nor a sphefical angle. Even his no- 
 tion of a point is somewhat less determined than oars. Ifl 
 the notion of a point, we exclude length, breadth, and 
 thickness; he excludes length and breaidth.ihut «annot 
 either exclude or include thickness, because he hatji no 
 eomscptioH of it. 
 
 Having thus settled the notions which such a being as 
 we have supposed might form of mathematical points, 
 lines, angles and figures, it is easy to see, that by com- 
 paring these together, and reasoning about them, he 
 might discover their relations, and form gemnetrieal eon- 
 «i-usions, built upon self-evidetrt principles. He naight like- 
 •wise, without doubt, have the same notion of numbers as we 
 have, and form a system of arithntetic. It is not material 
 to say in what order he migtit proeeed in «ueh discov- 
 eries, or how muefa time and fiains heraigbt employ about 
 TOX. I. 38 
 
298 OF THE HUMAN MIND. 
 
 them ; but what such a being, by reason and ingenuity, 
 without any materials of sensation but those of sight only, 
 might discover. 
 
 As it is more difficult to attend to a detail of possibili- 
 ties, than of facts even of slender authority, I shall beg 
 leave to give an extract from the travels of Johannes 
 Budolphns Anepigraphus, a Rosicrueian philosopher, who 
 having by deep study of the occult sciences, acquired the 
 art of transporting himself to various sublunary regions, 
 and of conversing with various orders of intelligences, in 
 the course of his adventures, became acquainted with an 
 order of beings exactly such as I have supposed. 
 
 How they communicate their sentiments to one anoth- 
 er, and by what means he became acquainted with their 
 language, and was initiated into their philosophy, as well 
 as of many other particulars, which might have gratified 
 the curiosity of his readers, and perhaps added credibil- 
 ity to his relation, he hath not thought fit to inform us; 
 these being matters proper for adepts only to know. 
 
 His account of their philosophy is as follows : 
 
 "The Idomenians," saith he, " are many of them very 
 ingenious, and much given to contemplation. In arith- 
 metic, geometry, metaphysics, and physics, they have 
 most elaborate systems. In the two latter, indeed, they 
 have had many disputes, carried on with great subtilty, 
 and are divided into various sects ; yet in the two former 
 there hath been no less unanimity than among the human 
 spepies. Their principles relating to numbers and arith- 
 metic, making allovrance for their notation, differ in noth- 
 ing from ours : but their geometry differs very consider- 
 ably." 
 
 As our author's account of the geometry of the Idomen- 
 ians agrees in every thing with the geometry of visibles, 
 of which we have already given a specimen, we shall 
 pass over it. He goes on thus : " Colour, extension, and 
 figure, are conceived to be the essential properties of 
 body. A very considerable sect maintains, that colour is 
 the essence of body. If there had been no colour, say 
 
SEEING. 299 
 
 they, there had been no perception or sensation. Colour 
 IS all that we perceive, or can conceive, that is peculiar 
 to body J extension and iigure being modes common to 
 body and to empty space. And if we should suppose a 
 body to be annihilated, colour is the only thing in it 
 that can be annihilated ; for its place, and consequently 
 the figure and extension of that place, must remain, and 
 cannot be imagined not to exist. These philosophers hold 
 space to be the place of all bodies, immoveable and in- 
 destructible, without figure, and similar in all its parts, 
 incapable of increase or diminution, yet not unmeasurable : 
 for every the least part of space bears a finite ratio to the 
 whole. So that with them the whole extent of space is 
 the common and natural measure of every thing that hath 
 length and breadth, and the magnitude of every body and 
 of every figure is expressed by its being such a part of 
 the univferse. In like manner, the common and natural 
 measure of length, is an infinite right line, which, as 
 hath been before observed, returns into itself, and hath 
 no limits, but bears a finite ratio to every other line. 
 
 " As to their natural philosophy, it is now acknowl- 
 edged by the wisest of them to have been for many ages 
 in a very low state. The philosophers observing* that 
 one body can difier from another only in colour, figure, 
 or magnitude, it was taken for granted, that all their 
 particular qualities must arise from the various combina- 
 tions of these their essential attributes. And therefore 
 it was looked upon as the end of natural philosophy, to 
 shew how the various combinations of these three quali- 
 ties in difierent bodies produced all the phenomena of 
 nature. It were endless to enumerate the various sys- 
 tems that were invented with this view, and the disputes 
 that were carried on for ages ; the followers of every sis- 
 tem exposing the weak sides of other systems, and pal- 
 liating those of their own, with great art. 
 
 " At last, some free and facetious spirits, wearied with 
 eternal disputation, and the labour of patching and prop- 
 ping weak systems, begap to complain of the subtilty of 
 
300 OF THE HUMAN MIND, 
 
 nature ; of the infinite changes that bodies undergo in 
 figure, colour, and magnitude ; and of the difficulty of 
 accounting for these appearances, making this a pretence 
 for giving up all inquiries into the causes of things, as 
 vain and fruitless. 
 
 " These wits had ample matter of mirth and ridicule • 
 in the systems of philosophers, and finding it an easier 
 task to pull down than to build up and support, and that 
 every sect furnished them with arms and auxiliaries to 
 destroy another, they began to spread mightily, and went 
 on with great success. Thus philosophy gave way to 
 skepticism and irony, and those systems which 'had been 
 the work of ages, and the admiration of the learned, be- 
 came the jest of the vulgar: for even the vulgar readily 
 took part in the triumph over a kind of learning which 
 they had long suspected, because it produced nothing but 
 wrangling and altercation. The wits having now acquir- 
 ed great reputation, and being flushed with success, began 
 to think the triumph incomplete, until every preienoe to 
 knowledge was overturned ; and accordingly began their 
 attacks upon arithmetic, geometry, and even upon the 
 common notions of untaught Idomenians. So difficult it 
 hath always been, says our author, for great conquerors 
 to know where to stop. 
 
 " In the mean time, natural philosophy began to rise 
 from its ashes, under the direction of a person of great 
 genius, who is looked upon as having had something in 
 in him above Idouieniau nature. He observed, that the 
 Idomenian faculties were certainly intended for contem- 
 plation, and that the works of nature were a nobler sub- 
 ject to exercise thoni upon, than the follies of systems, or 
 the errors of the learned ; and being sensible of the diffi- 
 culty of finding out the causes of natural things, he pro- 
 posed, by accurate observation of the phenomena of na- 
 ture, to find out the rules according to which they hap- 
 pen, without inquiring into the causes of those rules. In 
 this he made considerable progress himself, and planned 
 out much work for his followers^ who call Iheiaseilres in- 
 
S£Ei?r6. 301 
 
 ductive philosophers. The skeptics look with envy upon 
 this rising sect, as eclipsing their reputation, and threat- 
 ening to limit their empire ; but they are at a loss on 
 what hand to attack it. The vulgar begin to reverence 
 it, as producing useful discoveries. 
 
 •' It is to be observed, that every Idomenian firmly be- 
 lieves, that two or more bodies may exist in the same 
 place. For this they have the testimony of sense, and 
 they can no more doubt of it, than they can doubt whether 
 they have any perception at all. They often see two 
 bodies meet, and coincide in the same place, and separate 
 again^ without having undergone any change in their sen- 
 sible qualities by this penetration. When two bodies 
 meet, and occupy the same place, commonly one only ap- 
 pears in that plaee, and the other disappears. That 
 which continues to appear is said to overcome, the other 
 to be overcome." 
 
 To this quality of bodies they gave a name, which our 
 author tells us hath no word answering to it in any human 
 language. And therefore, after making a long apology, 
 which I omit, he begs leave to call it the overcoming quality 
 of bodies. He assures us, that " the speculations which had 
 been raised about this single quality of bodies, and the 
 hypotheses contrived to account for it, were sufficient to 
 fill many volumes. Nor have there been fewer hypoth- 
 eses invented by their philosophers, to account for the 
 changes of magnitude and figure ; which, in most bodies 
 that move, they perceive to be in a continual fluctu- 
 ation. The founder of the inductive sect, believing it 
 to be above the reach of Idomenian faculties,' to dis- 
 cover the real causes of these phenomena, applied himself 
 to find from observation, by what laws they are connect- 
 ed together ; and discovered many mathematical ratios 
 and relations concerning the motions, magnitudes, figures, 
 and overcoming quality of bodies, which constant expe- 
 rience confirms. But the opposers of this sect choose 
 rather to content themselves with feigned causes of these 
 phen«inena> than to acknowledge the real laws whereby 
 
302 OT THE HUMAN MIND. 
 
 they are governed, which humble their pride, by being 
 confessedly unaccounfable." 
 
 Thus far Johannes Kudolphus Anepigraphus. Whether 
 this Anepigraphus be the same who is recorded among 
 the Greek aleh^ mistical writers not yet published, by 
 Borrichius, Fabricius, and others, I do not pretend to 
 determine. The identity of their name, and the simili- 
 itude of their studies, although no slight arguments, yet 
 are not absolutely conclusive. Nor will I take upon me 
 to judge of the narrative of this learned traveller by the 
 external marks of his credibility; I shall confine myself 
 to those which the critics call internal. It would even 
 be of small importance to inquire, whether the Idomen- 
 ians have a real, or only an ideal existence ; since this is 
 disputed among the learned with regard to things with 
 which we are more nearly connected. The important ques- 
 tion is, whether the account above given, is ajust account 
 of their geometry and philosophy ? We have all the fac- 
 ulties which they have, with the addition of others which 
 they have not ,• we may therefore form some judgment of 
 their philosophy and geometry, by separating from all 
 others, the perceptions we have by sight, and reasoning 
 upon them. As far as I am able to judge in this way, 
 after a careful examination, their geometry must be such 
 as Anepigraphus hath described. Nor does his account 
 of their philosophy appear to contain any evident marks 
 of imposture ; although here, no doubt, proper allowance 
 is to be made for liberties which travellers take, as well 
 as for involuntary mistakes which they are apt to fall into. 
 
 SECTION X. 
 or THE PARAllBI MOTION OF THE EYES. 
 
 Having explained, as distinctly as we can, visible fig- 
 ure, and shewn its connection with the thing signified by 
 it, it will be proper next to consider some phenomena of 
 the eyeSj and of vision, which have cooimouly been re- 
 
SEEING. 303 
 
 fepred to custom, to anatomical or to meelianical causes ; 
 but which, as I conceive, must be resolved into original 
 powers and principles of Ibe human mind ; and therefore 
 belong ppoperlj' to the subject of this inquiry. 
 
 The first is, the parallel motion of the eyes ; by which 
 when one eye is turned to the right or left, upward or 
 downward, or straight forward, the other always goes 
 along with it in the same direction. We see plainly, 
 when both eyes are open, that they are always turned the 
 same way, as if both were acted upon by the same motive 
 force : and if one eye is shut, and the hand laid upon it, 
 while the other turns various ways, we feel the eye that 
 is shut turn at the same time, and that whether we will 
 or not. What makes this phenomenon surprising is, that 
 it is acknowledged by all anatomists, that the muscles 
 which move the two eyes, and the nerves which serve 
 these muscles, are entirely distinct and unconnected. It 
 would be thought very surprising and unaccountable, to 
 see a man, who, from his birth, never moved one arm, 
 without moving the other precisely in the same manner, 
 so as to keep them always parallel : yet it would not be 
 more difficult to find the physical cause of such motion of 
 the arms, than it is to find the cause of the parallel mo- 
 tion of the eyes, which is perfectly similar. 
 
 The only cause that hath been assigned of this parallel 
 motion of the eyes, is custom. We find by experience, it 
 is said, when we begin to look at objects, that, in order 
 to have distinct vision, it is necessary to turn both eyes 
 the same way ; therefore we soon acquire the habit of do- 
 ing it constantly, and by degrees lose the power of doing 
 otherwise. 
 
 This account of the matter seems to be insufficient; 
 because habits are not got at once ; it takes time to ac- 
 quire and to confirm them ; and if this motion of the 
 eyes were got by habit, we should see children, when 
 they are born, turn their eyes different ways, and move 
 one without the other, as they do their hands or legs. I 
 know some have affirmed that they are apt to do so. But 
 
304 OF TittE HUMAN MIND. 
 
 I have never found it true from my own observation, 
 although I have taken pains to make observations of 
 this kind, and have had good opportunities. I have 
 likewise consulted experienced midwives, mothers and 
 nurses, and found tliem agree, that they had never ob- 
 served distortions of this kind in the eyes of children, 
 but wlien they had reason to suspect convulsions, or some 
 preternatural cause. 
 
 It seems therefore to be extremely probable, that pre- 
 vious to custom, there is something in the constitution, 
 some natural instinct, which directs us to move both 
 eyes always the same way. 
 
 We know not how the mind acts upon the body, nor by 
 what power the muscles are contracted and relaxed ; but 
 we see that in some of the voluntary, as well as in some 
 of the involuntary motions, this power is so directed, that 
 many muscles which have no material tie or connection, 
 act in concert, each of them being taught to play its part 
 in exact time and measure. Nor doth a company of ex- 
 pert players in a theatrical performance, or of excellent 
 musicians in a concert, or of good dancers in a country 
 dance, with more regularity and order, conspire and con- 
 tribute their several parts, to produce one uniform effect, 
 than a number of muscles do, in many of the animal func- 
 tions, and in many voluntary actions. Yet we see such 
 actions no less skilfully and regularly performed in chil' 
 dren, and in those who know not that they have such 
 muscles, than in the most skilful anatomist and phys- 
 iologist. 
 
 "Who taught all the muscles that are concerned in suck- 
 ing, in swallowing our food, in breathing, and in the sev- 
 eral natural expulsions, to act their part in such regular 
 order, and exact measure ? It was not custom surely. It 
 was that same powerful and wise Being who made the 
 fabric of the human body, and fixed the laws by which 
 the mind operates upon every part of it, so that they may 
 answer the purposes intended by them. And when we see, 
 in so many other instances, a system of unconnected 
 
SEEisre* 305 
 
 muscles conspiritig so wotK^erfnJly.in tlieir several func- 
 tions, without the aid of h?iWt, it needs not be thought 
 strange, that the muscle of the eye should, without this 
 aid, conspire to give that direction to the eyes, without 
 which they could not answer their end. 
 
 We see a like conspiring action in the muscles which 
 contract the pupils of the two eyes ; and in those muscles, 
 whatever they he, by which the conformation of the eyes 
 is varied, according to the distance of objects. 
 
 It ought however to be observed, that although it ap- 
 pears to be by natural instinct that both eyes are always 
 turned the same way, there is still some latitude left for 
 custom. 
 
 What we have said of the parallel motion of the eyes, 
 is not to be understood so strictly, as if nature directed 
 us to keep their axes always precisely and mathematically 
 parallel to each other. Indeed, although they are always 
 nearly parallel, they hardly ever are exactly so. When 
 we look at an object, the axes of the eyes meet in that 
 object,- and therefore, make an angle, which is always 
 small, but will be greater or less, according as the object 
 is nearer or more remote. Nature hath very wisely left 
 us the power of varying the parallelism of our eyes a little, 
 so that we can direct them to the same point, whether 
 remote or near. This, no doubt, is learned by custom ; 
 and accordingly we see, that it is a long time before chil- 
 dren get this habit in perfection. 
 
 This power of varying the parallelism of the eyes is 
 naturally no more than is sufficient for the purpose intend- 
 ed by it ; but by much practice and straining, it may be 
 increased. Accordingly we see, that some have acquired 
 the power of distorting their eyes into unnatural direc- 
 tions^ as others have acquired the power of distorting 
 their bodies into unnatural postures. 
 
 Those who have lost the sight of an eye, commonly 
 
 lose what they had got by custom, in the direction of 
 
 their eyes, but retain what they had by nature ; that is, 
 
 although their eyes turn and move always together; yet 
 
 Tox. I. 39 
 
306 OF THE HUMAN MINB. 
 
 when they look upon an object, the blind eye will often have 
 a very small deviation from it ; which is not perceived 
 by a slight observer, but may be discerned by one accus- 
 tomed to make exact observations in, these matters. 
 
 SECTION Xt. 
 OF OUR SEEING OBJECTS EBECT BY INVERTED IMAGES. 
 
 Another phenomenon which hath perplexed philoso- 
 phers, is. our seeing objects erect, when it is well known 
 that their images or pictures upon the tunica retina of 
 the eye are inverted. 
 
 The sagacious Kepler first made the noble discovery, 
 that distinct but inverted pictures of visible objects, arc 
 formed upon the retina bv the rays of light coming from 
 the object. The same great philosopher demonstrated 
 from the principles of optics, how these pictures are form- 
 ed, to wit, fiat the rays coming from anyone point of the 
 object, and falling uf>on the various parts of the pupil, 
 are, by the cornea and crystalline, refracted so as to meet 
 again in one point of the retina, and there paint the col- 
 our of that point of the object from which they come. As 
 the rays from different points of the object cross each 
 other before they come to the retina, the picture they 
 form must be inverted ; the upper part of the object be- 
 ing painted upon the lower part of the retina, the right 
 side of the object upon the left of the retina, and so of 
 the other parts. 
 
 This philosopher thought that we see objects erect by 
 means of these inverted pictures, for this reason, that as 
 the rays from different points of the object cross each 
 other, before they fall upon the retina, we conclude that 
 the impulse which we feel upon the lower part of the re- 
 tina, comes from above ; and that the impulse which we 
 feel upoa the higher part, comes from below. 
 
SEEiNe. 307 
 
 Dc9 Cartes afterward gave tlie same solution of this 
 plienomenoii,aiicl illustrated it by the judgment wliieli we 
 form of the position of objects which we feel with our 
 arms crossed, or with two sticks that cross each other. 
 
 But we cannot acquiesce in this solution. First, be- 
 cause it supposes our seeing things erect, to be a deduc- 
 tion of reason, drawn from certain premises : whereas it 
 seems to be an immediate perception. And, secondly, 
 because the premises from which all mankind are sup- 
 posed to draw this conclusion, never entered into the 
 minds of the far greater part, but are absolutely unknown 
 to them. We have no feeling or perception of the pic- 
 tures upon the retina, and as little surely of the position 
 • of them. In order to see objects erect, according to the 
 principles of Kepler or Des Cartes, we must previously 
 know, that the rays of light come from the object to the 
 eye in straight lines ; we must know, that the rays from 
 different points of the object cross one another, before 
 they form the pictures upon the retina; and lastly, we 
 must know, that these pictures are really inverted. Now, 
 ^though all these things are true, and known to philoso- 
 phers, yet (hey are absolutely unknown to the far great- 
 est part of mankind : nor is it possible that they who are 
 absolutely ignorant of them, should reason from them, 
 and build conclusions upon them. Since therefore visible 
 objects appear erect to the ignorant as well as to the 
 learned, this cannot be a conclusion drawn from premises 
 which never entered into the minds of the ignorant. We 
 have indeed had occasion to observe many instances of 
 conclusions drawn, either by means of original principles, 
 or by habit, from premises Avhieh pass through the mind 
 very quickly, and which are never made the objects of 
 reflection ; but surely no man will conceive it possible to 
 draw conclusions from premises which never entered into 
 the mind at all. 
 
 Bishop Berkeley having justly rejected this solution, 
 gives one founded upon his own priaciples ; wherein he is 
 
308 OF THE HUMAN MIMB. 
 
 followed by the judicious Dp. Smith in his Optics; and 
 this we shall next explain and examine. 
 
 That ingenious writer conceives the ideas of sight to 
 be altogether unlike those of touch. And since the no- 
 tions we have of an object by these different senses have 
 no similitude, we can learn only by experience how one 
 sense will be affected, by what, in a certain manner, afr 
 fects the other. Figure, position, and even number, in 
 tangible objects, are ideas of touch ; ariff although^ there 
 is no similitude between these and the ideas of sight, yet 
 we learn by experience, that a triangle affects the sight 
 in such a manner, and that a square affects it in such an- 
 other manner : hence Ave judge that which affects it in 
 the first manner, to be a triangle, and that which affects , 
 it in the second, to be a square. In the same way, find- 
 ing from experience, that an object in an erect position, 
 affects the eye in one manner, and the same objeet in an in- 
 verted position, affects it in another, we learn to judge, by 
 the manner in which the eye is affected, whether the object 
 is erect or inverted. In a word, visible ideas, according to 
 this author, are signs of the tangible ; and the mind pass- 
 eth from the sign to the thing signified, not by means of any 
 similitude between the one and the other, nor by any nat- 
 ural principle ; but by having found them constantly con- 
 joined in experience, as the sounds of a language are with 
 the things they signify. So that if the images upon the rer 
 Una had been always erect, they would have shewn the 
 objects erect, in the manner as they do now that they are 
 inverted : nay, if the visible idea which we now have 
 from an inverted object, had been associated from the be- 
 ginning with the erect position of that object, it would 
 have signilied an erect position, as readily as it now sig- 
 nifies an inverted one. And if the, visible appearance of 
 two shillings had been found connected from the b^lP- 
 ning with the tangible idea of one shilling, that appear- 
 ance would as naturally and readily have signified the 
 unity of the object, as now it signifies its duplicity. 
 
SEEING. 309 
 
 Tins opinion is undoubtedly very ingenious; and, if it 
 is just, serves to resolve, not only the phenomenon now 
 under consideration, but likewise that which we shall 
 next consider, our seeing objects single with two eyes. 
 
 It is evident, that in this solution it is supposed, that 
 we do not originally, and previous to acquired habits, see 
 things either erect or inverted, of one figure or another, 
 single or double, but learn from experience to judge of 
 their tangible position, figure, and number, by certain 
 visible signs. 
 
 Indeed, it must be acknowledged to be extremely diffii 
 cult to distinguish the immediate and natural objects of 
 sight, from the conclusions which we have been aceus-f 
 tomed from infancy to draw from them. Bishop Berke- 
 ley was the first that attempted to distinguish the one 
 from the other, and to trace out the boundary that di- 
 vides them. And, if in doing so, he hath gone a little td 
 the right hand or to the left, this might be expected i« 
 a subject altogether new, and of the greatest subtilty. 
 The nature of vision hath received great light from thi^ 
 distinction ; and many phenomena in optics, which before; 
 appeared altogether unaccountable, have been clearly and 
 distinctly resolved by it. It is natural, and almost una- 
 voidable, to one who hath made an important discovery 
 in philosophy, to carry it a little beyond its sphere, and 
 to apply it to the resolution of phenomena which do not 
 fall within its province. Even the great IVewton, when 
 he had discovered the universal law of gravitation, and 
 observed how many of the phenomena of nature depend 
 upon this, and other laws of attraction and repulsion, 
 could not help expressing his conjecture, that all the phe- 
 nomena of the material world depend upon attracting and 
 repelling forces in the particles of matter. And I suspect \ 
 that the ingenious bishop of Cloyne, having found so many I 
 phenomena of vision reducible to the constant association 
 of the ideas of sight and touch, carried this principle a 
 little beyond its just limits. 
 
310 OF THE HITMAN MIND. 
 
 In order to judge as well as we can, whether it is so, 
 let us suppose such a blind man as Dr. Saunderson, hav- 
 ing all the knowledge and abilities which a blind man may 
 have, suddenly made to see perfectly. Let us suppose 
 him kept from all opportunities of associating iiis ideas 
 of sight with those of toucii, until the former become a 
 little familiar ; and tbe first surprise, occasioned by ob- 
 jects so new, being abated, he has time to canvass them, 
 and to compare them, in his mind, with the notions which 
 he formerly had by touch ; and in particular to compare, 
 in his mind, that visible extension which his eyes present, 
 with the extension in length and breadth with which he 
 was before acquainted. 
 
 We have endeavoured to prove, that a blind man may 
 form a notion of the visible extension and figure of bodies, 
 from the relation which it bears to their tangible exten- 
 sion and figure. Much more, when this visible extension 
 and figure are presented to his eye, will he be able to 
 compare them with tangible extension and figure, and to 
 perceive, that the one has length and breadth as well as 
 the other; that the one may be bounded by lines, either 
 straight or curve, as well as the other. And therefore, 
 he will perceive, that there may be visible as well as 
 tangible circles, triangles, quadrilateral and multilateral 
 figures. And although the visible figure is coloured, and 
 the tangible is not, they may, notwithstanding, have the 
 same figure, as two objects of touch may have the same 
 figure although one is hot and the other cold. 
 
 We have demonstrated, that the properties of visible 
 
 figures differ from those of the plain figures which they 
 
 represent ; but it was observed at the same time, that 
 
 when the object is so small as to be seen distinctly at one 
 
 . Tiew, and is placed directly before the eye, the difference 
 
 A between the visible and tangible figure is too small to be 
 
 1 perceived by the senses. Thus, it is true, that of every 
 
 visible triangle, the three angles are greater than two 
 
 right angles ; whereas, in a plain triangle, the three aa? 
 
 gles are equal to two right angles : but, when the visible 
 
SEElNft. 311 
 
 triangle is small, its three angleswillbe so nearly equal to 
 two right angles, that the sense cannot discern thedifier> 
 ence. In like manner, the circumferences of unequal visible 
 circles are not. but those of plain circles are, in the ratio of 
 their diameters ; yet in small visible circles, the circumfer- 
 ences are very nearly in the ratio of their diameters ; and 
 the diameter hears the same ratio to the circumference, 
 as in a plain circle, very nearly. 
 
 Hence it appears, that small visible figures, and such 
 only fan be seen distinctly at one view, have not only a 
 resemblance to the plain tangible figures which have the 
 same name, but are to all sense the same. So that if Dr. 
 Saunderson had been made to see, and attentively had view- 
 ed the figures of the first book of Euclid, he might, by 
 thought and consideration, without touching them, have 
 found out thai they were the very figures he was before 
 so well acquainted with by touch. 
 
 When plain figures are seen obliquely, their visible fig- 
 ure differs more from the tangible ; and the representa- 
 tion which is made to the eye, of solid figures, is still 
 more imperfect; because visible extension hath not three, 
 but two dimensions only. Yet, as it cannot be said that 
 an exact picture of a man hath no resemblance of the 
 man, or that a f)erspective view of a house hath no re- 
 semblance of the house ; so it cannot be said, with any 
 propriety, that the visible figure of a man, or of a house, 
 hath no resemblance of the objects which they represent* 
 
 Bishop Berkeley therefore proceeds upon a capital mis- 
 take, in supposing that there is no resemblance betwixt 
 the extension, figure, and position which we see, and that 
 which we perceive by touch. 
 
 We may further observe, that bishop Berkeley's sys- 
 tem, with regard to material things, must have made him 
 see this question, of the erect appearance of objects, in a 
 very different light from that in which it appears to those 
 who do not adopt his system. 
 
 In his theory of vision, he seems indeed to allow, that 
 there is an exteroal material world : but he believed that 
 
313 OF THE HTTMAN MI\D. 
 
 this external world is tangible only, and not visible ; and 
 that the visible world, the proper object of sight, is not 
 external, but in the mind. If this is supposed, he that af- 
 firms that he sees things erect and not inverted, aiBrms 
 that there is a top and a bottom, a right and a left in the 
 mind. Now, I confess I am not so well acquainted with 
 the topography of the mind, as to be able to affix a mean- 
 ing to these Avords when applied to it. 
 
 We shall therefore allow, that if visible objects were 
 not external, but existed only in the mind, they could 
 have no figure, or position, or extension ; and that it 
 would be absurd to affirm, that they are seen either erect 
 or inverted ; or that there is any resemblance between 
 them and the objects of touch. But when we propose 
 the question, Why objects are seen erect and not invert- 
 ed ? we take it for granted, that we are not in bishop 
 Berkeley's ideal world, but in that world which men, 
 who yield to the dictates of common sense, believe them- 
 selves to inhabit. We take it for granted, that the ob- 
 jects both of sight and touch, are external, and have a 
 certain figure, and a certain position with regard to one 
 another, and with regard to our bodies, whether we per- 
 ceive it or not. 
 
 When I hold my walking-cane upright in my hand, and 
 look at it, I take it for granted, that I see and handle the 
 same individual object. When I say that I feel it erect,- 
 my meaning is, that I feel the head directed from the 
 horizon, and the point directed toward it : and when I 
 say that I see it erect, I mean that I see it with the head 
 directed from the horizon and the point toward it. I 
 conceive the horizon is a fixed object both of sight and 
 touch, with relation to which, objects are said to be high 
 or low, erect or inverted : and when the question is asked. 
 Why I see the object erect, and not inverted ? it is the 
 same as if you should ask. Why I see it in that position 
 which it really hath ? or. Why the eye shows the real 
 position of objects, and doth not show them in an inverted 
 
S£ETNe. 313 
 
 position, as they are seen by a common astronomical fel- 
 esco|ie, OP as their pictures are seen upon the retina of 
 an eye when it is dissected. 
 
 SECTIUN XII. 
 THE SAME SUBJECT COSTTINlTED. 
 
 It is impossible to give a satisfactory answer to this 
 question, otherwise than by pointing out the laws of na- 
 ture which take place in vision ; for by these the phe- 
 nomena of vision must be regulated. 
 
 Therefore I answer, first, That by a law of nature 
 the rays of light proceed from every point of the object 
 to the pupil of (he eye in straight lines. Secondly, That 
 by the laws of nature the rays coming from any one point 
 of the object to the various parts of the pupil, are so re- 
 fracted, as to meet again in one point of the retina; and 
 the rays from diiferent points of the object, first crossing 
 each other, and then proceeding to as many different 
 points of the retina, form an inverted picture of the ob- 
 ject. 
 
 So far the principles of optics carry us; and experience 
 further assures us, that if there is no such picture upon 
 the retina, there is no vision ; and that such as the pio- ; 
 ture on the retina is, such is the appearance of the object, 
 in colour and figure, dii^tinctness or indistinctness, bright, 
 ness or faintness. 
 
 It is evident, therefore, that the pictures upon the re- 
 tina are, by the laws of nature, a mean of vision ; but in 
 what way they accomplish their end, we are totally ig- 
 norant. Philosophers conceive, that the impression made 
 on the retina by the rays of light, is communicated to the 
 optic nerve, and by the optic nerve conveyed to some 
 part of the brain, by them called the sensorium; and that 
 the impression thus conveyed to the sensorium is im- 
 mediately perceived by the mind, which is supposed t© 
 yoi. I, ■ . 4iO 
 
314 OF THE HUMAN MI1V». 
 
 reside there. But we know nothing of the seat of the 
 soul : and we are so far from perceiving' immediately what 
 is transacted in the brain, that of all parts of the human 
 body we know least about it. It is indeed very probable, 
 that the optic nerve is an insf riiment of vision no less nec- 
 essary than the retina; and that some impression is 
 made upon it. by means of the pictures on the retina. 
 Bu( of what kind this impression is, we know nothing. 
 
 There is not (he least probability, that there is any 
 picture or image of the object either in the optic nerve 
 or brain. The pictures on the retina are formed by the 
 rays of light ; and whether we suppose, with some, that 
 their impulse upon the retina causes some vibration of 
 the fibres of the optic nerve ; or, with others, that it gives 
 motion to some subtile fluid contained in the nerve ; nei- 
 ther that vibration, nor this motion, can resemble the. 
 visible object which is presented to the mind. Koris 
 there any probability, that the mind perceives the pictures 
 upon the retina. These pictures are no more objects of 
 onr perception, than the brain is, or the optic nerve. No 
 man ever saw the pictures in his .own eye, nor indeed the 
 pictures iii the eye of another, until it was taken out of 
 the bead and duly prepared. 
 
 It is very strange, that philosophers, of all ages, sliould 
 have agreed in this notion^ That the images of external 
 objects are conveyed by the organs of sense to the brain, 
 and are the^-e perceived by the mind. Nothing can be 
 more imphilosopbical. For, first. This notion hath no 
 foundation in fact and observation. Of all the organs of 
 sense, the eye only, as far as we can discover, forms any 
 kind of image of its object ; and the images formed by 
 the eye are not in the brain, but only in the bottom of the 
 eye ; nor are Ihey at all perceived or felt by the mind. 
 Secondly, It is as difficult to conceive how the mind per- 
 ceives images in the brain, as how it perceives things 
 more distant. If any man will shew how the mind n:ay 
 perceive images in the brain, I will undertake to shew 
 how it may perceive the most distant objects : for if ve 
 
SEEixe. 315 
 
 give eyes to the mind, to perceive what is transacted at 
 home in its dark chamber, why may we not make these ( 
 eyes a little longer sighted ? and then we shall have no 
 occasion for that unphilosophidal fiction of images in the ; 
 brain. In a word, the manner and mechanism of the 
 mind's perception is quite beyond our comprehension : and 
 this way of explaining it by images in the brain, seems 
 to be founded upon very gross notions of the mind, and 
 its operations ; as if the supposed images in the brain, by 
 a kind of contract, formed similar impressions or images 
 of objects upon the mind, of which impressions it is sup- 
 posed to be conscious. 
 
 We have endeavoured to shew, throughout the course 
 of tills inquiry, that the impressions made upon the mind 
 by means of the five senses, have not the least resemblance 
 to the objects of sense : and therefore, as we see no shadow 
 of evidence, that there are any such images in the brain, 
 so we see no purpose, in philosophy, that tbe supposition 
 of them can answer. Since the picture upon the retina 
 therefore, is neither itself seen by the mind, nor produces 
 any impression upon the brain or sensorium, which is seen 
 by the mind, nor makes any impression upon the mind 
 that resembles the object, it may still be asked. How 
 this picture upon the retina causes vision ? 
 
 Bef6re we answer this question, it is proper to observe, 
 that in the operations of the mind, as well in those of 
 bodies, we must often he satisfied with knowing, that cer- 
 tain things are connected, and invariably follow one 
 another without being able to discover the chain that 
 goes between them. It is to such connections that we 
 give the name of laws of nature ; and when we say that 
 one thing produces another by a law of nature, this sig- 
 nifies no more, but that one thing, which we call in pop- 
 ular language the cause, is constantly and invariably fol- 
 lowed by another which we call the effect ; and that we 
 know not how they are connected. Thus, we see it is a 
 fact, that bodies gravitate toward bodies ; and that this 
 gravitation is regulated by certain mathematical propor- 
 
S16 OF THE HUMAN M1N0. 
 
 tions, according (o (he distances of the bodies from each 
 othei', and theii- quantities of inatlor. Being unable to 
 discover the cause of tijis giavitaiion, and presuming that 
 it is the inintediate u])e;'aliun, either of tlie Author of na- 
 ture, or of some subordinate cause, which we have not 
 hitherto been able to reach, we call it a law of nature. 
 If any philosopher should hereafier be so happy as to 
 discover the cause of gravitai ion, this can only be done by 
 discovering some more general law of nature, of which 
 the gravitation of bodies is a necessary consequence. In 
 every chain of natural causes, the highest link is a pri. 
 inary law of nature, and the highest link which we can 
 trace, by just induction, is either this primary law of na- 
 ture, or a necessary consequence of it. To trace out the 
 laws of nature, by induction, from the phenomena of na- 
 ture, is all tliat true philosophy aims at, and all that it 
 can ever reach. 
 
 There are laws of nature by which the operations of 
 the mind are regulated ; there are also laws of nature 
 that govern the material system : and as the latter are the 
 ultimate conclusions which the human faculties can reach 
 in thephilosopl)y of bodies, so the former are the ultimate 
 conclusions we can reach in the philosophy of minds. 
 
 To return, therefore, to the question above proposed, 
 we may see, from what hath been just now observed, that 
 it amounts to this. By what law of nature is a picture 
 upon the retina, the mean or occasion of my seeing an 
 external object of the same figure and colour, in a con- 
 trary position, and in a certain direetiun from the eye? 
 
 It will, without doubt, he allowed, that I see the whole 
 object in the same manner and by the same law by which 
 I see any one point of it. Now, I know it to be a fact, 
 that, ill direct vision, I see every point of the object in 
 the direction of the right line that passeth from the cen- 
 tre of the eye to that point of the object : and I know 
 likewise, from optics, that the ray of light that comes 
 to the centre of my eye, passes on to the retina in the 
 same direction. Hence it appears to be a fact, that every 
 
sEEiNe. 317 
 
 point of the object is seen in the direction of a right line 
 passing from the picture of that point on tlie retina through 
 the centre of the eye. As this is a fact that holds uni- 
 versally and invariably, it must either be a law of nature, 
 or the necessary consequence of some more general law 
 of nature. And according to the just rules of philoso- 
 phizing, we may hold it for a law of nature, until some 
 more general law be discovered, whereof it is a necessary 
 consequence, which I suspect can never be done. 
 
 Thus we see, that the phenomena of vision lead us by 
 the hand to a law of nature, or a law of our constitution, 
 of which law our seeing objects erect by inverted images, 
 is a necessary consequence. For it necessarily follows, 
 from the law we have mentioned, that the object whose 
 picture is lowest on the retina, must be seen in the high- 
 est direction from the eye ; and that the object whose 
 picture is on the right of the retina, must be seen on the 
 left ; so that if the pictures had been erect in the retina, 
 we should have seen the object inverted. My chief in- 
 tention in handling this question, was to point out this 
 law of nature ; which, as it is a part of the constitution 
 of the human mind, belongs properly to the subject of 
 this inquiry. For this reason, I shall make some further 
 remarks upon it, after doing justice to the ingenious Dr. 
 Porterfield, who, long ago, in the Medical Essays, or 
 more lately in his Treatise of the Eye, pointed out, as a 
 primary law of our nature. That a visible object appears 
 in the direction of a right line perpendicular to the retina 
 at that point where its image is painted. If lines drawn 
 from the centre of the eye to all parts of the retina be 
 perpendicular to it, as they must be very nearly, this co- 
 incides with the law we have mentioned, and is the same 
 in other words. In order, therefore, that we may have 
 a more distinct notion of this law of our constitution, we 
 may observe, 
 
 1. Tliat we can give no reason why the retina is, of all 
 parts of the body, the only one on which pie( ures made 
 by the rays of light cause vision ; and therefore we must 
 
SIS or THE HUMAN MINB. 
 
 resolve (his solely into a law of our constitution. We 
 may form such pictures by means of optical glasses, upon 
 the hand, or upon any other part of the body ; but they 
 are not felt, nor do they produce any thing like vision. 
 A picture upon the retina is as little felt as one upon the 
 hand ; but it produces vision ; for no other reason tliat 
 we know, but because il is destined by the wisdom of na- 
 ture to this purpose. The vibrations of the air, strike 
 upon the eye, the palate, and the olfactory membrane, 
 with the same force as upon the memhrani tymyani of the 
 ear : the impression they make upon the last, produces 
 the sensation of sound; but their impressions upon any 
 of the former, produce no sensation at all. This may 
 be extended to all the senses, whereof each hath its pe- 
 culiar laws, according to which, the impressions made 
 upon the organ of that sense, produce sensations or per- 
 ceptions in tlie mind, tliat cannot be produced by impres- 
 sions made upon any other organ. 
 
 3. We may observe, that the laws of perception, by 
 the different senses, are very different, not only in respect 
 of the nature of the objects perceived by them, but like- 
 wise in respect of the notices they give us of the distance 
 and situation of the object. In all of them the object is 
 conceived to be external, and to have real existence, in- 
 dependent of our perception : but in one, the distance, 
 figure and situation of the object, are all presented to the 
 mind ; in another, the figure and situation, but not the 
 distance; and in others, neither figure, situation, nor 
 distance. In vain do we attempt to account for these 
 varieties in the manner of perception by the different 
 senses, from principles of anatomy or natural philosophy. 
 They must at last be resolved into the will of our Maker, 
 who intended that our powers of perception should have 
 certain limits, and adapted the organs of perception, and 
 the laws of nature by which they operate, to his wise 
 purposes. 
 
 When we hear an unusual sound, the sensation indeed 
 is in the mind, but we know that there is something '^ex- 
 
SBEINS. 319 
 
 ternal that produced this sound. At the same time, our 
 hearing does not inform us, whether the sounding body is 
 near or at a distance, in this direction or that ; and there- 
 fore we look round to dis cover it. 
 
 If any new phenomenon appears in the heavens, we see 
 exactly its colour, its apparent place, magnitude, and fig- 
 ure, but we see not its distance. It may be in the atmosphere, 
 it may be among the planets, or it may be in the sphere 
 of the iixed stars, for any thing the eye can determine. 
 
 The tesli mony of the sense of touch reaches only to ob- 
 jects that are contiguous to the organ, but with regard 
 to them, is more precise and determinate. When we feel 
 a body with our hand, we know the figure, distance, and 
 position of it, as well as whether it is rougli or smooth^ 
 hard or soft, hot or cold. 
 
 The sensations of touch, of seeing and hearing, are all 
 in the mind, and can have no existence but when they are 
 perceived. How do they all constantly and invariably 
 suggest the conception and belief of external objects 
 which exist whether they are perceived or not? No phi- 
 losopher can give any other answer to (his, but that such 
 is the constitution of our nature. How do we know, that 
 the object of touch is at the finger's end, and no where 
 else ? That the object of sight is in such a direction from 
 the eye. and in no other, but may be at any distance ? and 
 that the object of hearing may be at any distance, and in 
 any direction ? Not by custom surely ; not by reasoning, 
 or comparing ideas, but by the constitution of our na- 
 ture. How do we perceive visible objects in the direc- 
 tion of right lines perpendicular to that part of the retina 
 on which the rays strike, while we do not perceive the 
 objects of hearing in lines perpendicular to the membranes 
 tympani, upon which the vibrations of the air strike? 
 Because such are the laws of our nature. How do we 
 know the parts of our bodies aflTected by particular pains? 
 Not by experience or by reasoning, but by the constitu- 
 tion of nature. The sensation of pain» is» no doubt, in 
 the mind, and eaamt be said to have any i:elation> frooi 
 
328 or THE HUMAN MIND. 
 
 its own nature, to any paft of the body: but this sensa- 
 tion, bj' oup constitution, gives a perception of some par- 
 ^ ticular part of the body, whose disorder causes the uneasy 
 sensation. If it were not so, a man who never before felt 
 cither the gout or the toothach, when he is first seized 
 with the gout in his toe, might mistake it for the toothach. 
 Every sense, therefore, hath its peculiar laws and lim- 
 its, by the constitution of our nature ; and one of the laws 
 of sight is, that we always see an object in the direction 
 of a right line passing from its image on the retina 
 through the centre of the eye. 
 
 3. Perhaps some readers will imagine, that it is easier, 
 and will answer the purpose as well, to conceive a law of 
 nature, by which we shall always see objects in the place 
 in which they are, and in their true position, without hav- 
 ing recourse to images on the retina, or to the optical 
 centre of the eye. 
 
 To this I answer, that nothing can be a law of nature 
 which is contrary to fact. The laws of nature are the 
 most general facts we can discover in the operations of 
 nature. Like other facts, they are not to be hit upon by 
 happy conjecture, but justly deduced from observation: 
 like other general facts, they are not to be drawn from 
 a few particulars, but from a copious, patient, and cau- 
 tious induction. That we see things always in their true 
 place and position, is not fact ; and therefore it can be no 
 law of nature. In a plain mirror. I see myself, and other 
 things, in places very different from those they really oc- 
 cupy. And so it happens in every instance, wherein the 
 rays coming from the object are either reflected or re- 
 fracted before falling upon the eye. Those who know any 
 thing of optics, know that, in all such cases, the object 
 is seen in the direction of a line passing from the centre 
 of the eye. to the noint where the rays were last reflected 
 or refracted : and that upon this all the powers of the 
 telescone and microscope depend. 
 
 Shall we say, then, that i( is a law of nature, that the 
 objeet is seea in the direction which the rays have when 
 
SEEING* o3± 
 
 they fall on (he eye, or rather in the direclion contrary 
 to (hat of the rays when they fall upon the eye? No. 
 This is not true, and therefore it is no law of nature. For 
 the rays, from any one point of the object, come to all 
 parts of the pujul ; and therefore must have different di- 
 rections : but we see the object only in one of these di- 
 rections, to wit, in the direction of the rays that come to 
 the centre of the eye. And this holds true, even when 
 the rays that should pass through the centre are stopped, 
 and the object is seen by rays that pass at a distance from 
 the centre. 
 
 Perhaps it may still he imagined, that although we are 
 not made so as to see objects always in their i rue place, nor 
 so as to see them precisely in the direction of the rays when 
 they fall upon the cornea ; yet we may be so made, as to see 
 the object in the direction which the rays have when they 
 fall upon the retina, after they have undergone all their re- 
 fractions in the eye, that is, in the direction in which the 
 rays pass from the crystalline to the retina. But neither is 
 this true ; and consequently it is no law of our constitutioiii 
 In order to see that it is not true, we must conceive all 
 the rays thatpassfrom the crystalline to one point of the 
 retina, as forming a small cone, whose base is upon the 
 back of the crystalline, and whose vertex is a point of the 
 retina. It is evident that the rays which form the pic*- 
 ture in this point, have various directions, even after they 
 pass the crystalline ; yet the object is seen only in one of 
 these directions, to wit, in the direction of the rays that 
 come from the centre of the eye. Nor is this owing to 
 any particular virtue in the central rays, or in the centre 
 itself; for the central rays may be stopped. When they 
 are stopped, the image will be formed upon the same 
 point of the retina as before, by rays that are not central^ 
 nor have the same direction which the central rays had: 
 and in this case the object is seen in the same direction 
 as before, although there are now no rays coining in that 
 direction. 
 
 vox. I. 41 . 
 
322 BT THE HUMAK MIKO. 
 
 From ibis induction we conclude, that our seeing aa 
 object in tbat particular direction in which we do see it, 
 is not owing to any law of nature by which we are made 
 to see it in the direction of the rays, either before their 
 refractions in the eye, or after, but to a law of our nature, 
 by which we see the object in the direction of the right 
 line that passeth from the picture of the object upon the 
 retina to the centre of the eye. 
 
 The facts upon which I ground this induction, are taken 
 from some curious experiments of Scheiner, in his Fun- 
 dament. Optic, quoted by Dr. Porterfield. and conliriued 
 by his experience. I have also repeated these experi- 
 ments, and found them to answer. As they are easily 
 made, and tend to illustrate and confirm the law of nature 
 I have mentioned, I shall recite them as briefly and dis- 
 tinctly as I can. 
 
 Experiment 1. Let a very small object, such as the head 
 of a pin, well illuminated, be fixed at such a distance from 
 the eye, as to be beyond the nearest limit, and within the 
 farthest limit of distinct vision : for a young eye, not near 
 sighted, the object may be placed at the distance of 
 eighteen inches. Let the eye be kept steadily in one 
 place, and take a distinct view of the object. We know, 
 from the principles of optics, that the rays from any one 
 point of this object, whether thejpass through the centre 
 of the eye, or at any distance from the centre which the 
 breadth of the pupil will permit, do all unite again in one 
 point of the retina. We know also, that these rays have 
 different directions, both before they fall upon the eye, 
 and after they pass through the crystalline. 
 
 Now we can see the object by any one small parcel of 
 these rays, excluding (he rest, by looking through a small 
 pinhole in a card. Moving this pinliole over the various 
 parts of the pupil, we can see the object, first by the rays 
 that pass above the centre of the eye, then by the central 
 pays, then by the rays that pass below the centre, and id 
 like manner by the rays that pass on the right and left of 
 the centre. Thus, we view this object, successively, by 
 rays that are central, and by rays that are not central ', 
 
SEEIN&. 3i& 
 
 by pays that have different directions, and are variously 
 Inclined to each other, both when they fall upon the cor- 
 nea, and when they fall upon the retina ; but always by 
 rays which fall upon the same point of the retina. And 
 what is the event ? It is this, that the object is seen in 
 the same individual direetion, whether seen by all these 
 rays together, or by any one parcel of them. 
 
 Experiment 2, Let the object above mentioned be now 
 placed w ithin the nearest limit of distinct vision, that is, 
 for an eye that is not near sighted, at the distance of four 
 or five inches. We know, that in this case, the rays com- 
 ing from one point of the object, do not meet in one point 
 of the retina, but spread over a small circular spot of it I 
 the central rays occupying the centre of this circle, the 
 rays that pass above tlie centre occupying the upper part 
 of the circular spot, and so of the rest. And we know 
 that the object is in this ease seen confused, every point 
 of it being seen, not in one, but in various directions. To 
 remedy this confusion, we look at the object through the 
 pinhole, and while we move the pinhole over the various 
 parts of the pupil, the object does not keep its place, but 
 seems to move in a contrary direction. 
 
 It is here to be observed, that when the pinhole is 
 carried upward over the pupil, the picture of the object 
 is carried upward upon the retina, and the object at the 
 same time seems to move downward, so as to be always 
 in the right line passing from the picture through the 
 centre of the eye. It is likewise to be observed, that the 
 rays which form the upper and the lower pictures upon 
 the retina, do not cross each other as in ordinary vision ; 
 yet still the higher picture shews the object lower, and 
 the lower picture shews the object higher, in the same 
 manner as when the rays cross each other. "Whence we 
 may observe, by the way, that this phenomenon of our 
 seeing objects in a position contrary to that of their pic- 
 tures upon the retina, does not depend upon the crossing 
 of the rays, as Kepler and Des Cartes conceived. 
 
 Epcperiment 3. Other things remaining as in the last 
 experiment; make three pinholes iu a straight Hue, so 
 
eF THE HUMAJT MIND. 
 
 near, that the rays coming from the object through all 
 the holes, maj enler the pupi! at llie same time. In this 
 case we have a very curious plienomenon ; for the ohjecf is 
 seen triple with one eye. And if you make more holes with- 
 in the breadth of ihe pupil, you will see as many objects 
 as there are holes. However, we shall suppose them only 
 three ; one on the right, one in the middle, and one on 
 the left ; in which case, you see three objects standing in 
 a line from right to left. 
 
 It is here to be observed, that there are three pictures 
 on the retina; that on the left being formed by liie rays 
 which pass on the left of the eye's centre ; (he niiddle 
 picture being formed by the central rays, and the right 
 hand picture by the rays which pass on the right of the 
 eye's centre. It is farther to he observed, that the object 
 which appears on the right, is not that which is seen 
 through the hole on the right, but that which is seen 
 through the hole on the left ; and in like manner, the 
 left hand object is seen through the hole on the right, as 
 is easily proved by covering the holes successively. So 
 that, whatever is the direction of the rays which form 
 the right hand and left hand pictures, still the right hand 
 picture shows a left hand object, and the left hand pic- 
 ture shows a right hand object. 
 
 Experiment *. It is easy to see how the two last ex- 
 periments may be varied, by placing the object beyond 
 the farthest limit of distinct vision. In order to make 
 this experiment, I looked at a candle at the distance of 
 ten feet, and put the eye of my spectacles behind the card, 
 that the rays from the same point of the object might 
 meet, and cross each other, before they reach the retina. 
 In this case, as in the former, the candle was seen triple 
 through the three pinholes ; but the candle on the right 
 was seen throught the hole on the right ; and, on the con- 
 trary, the left hand candle was seen through the hole on 
 the left. In this experiment, it is evident, from the prin- 
 ciples of optics, that the rays forming the several pic- 
 tures on the retina, cross each other a liltle before they 
 reach the retina ; and therefore the left hand picture is 
 
formed by the rays which pass through the hole on the 
 right: so that the position of the pictures is contrary to 
 that of the holes by which they are formed, and therefore 
 is also contrary to that of their objects, as we have found 
 it to be in the former experiments. 
 
 These experiments exhibit several uncommon phenom- 
 ena, that regard the apparent place, and the direction of 
 visible objects from the eye ; phenomena that seem to be 
 most contrary to the common rules of vision. When we 
 look at the same time through three holes that are in a 
 right line, and at certain distances from each other, we 
 expect, that the objects seen through them should really 
 be, and should appear to be, at a distance from each other: 
 yet, by the first experiment, we may, through three such 
 holes, see the same object, and the same point of that 
 object ; and through all the three it appears in the same 
 individual place and direction. 
 
 When the rays of light come from the object in right 
 lines to the eye, without any reflection, inflection, or re- 
 fraction, we expect, that the object should appear in its 
 real and proper direction from the eye; and so it com- 
 monly does. But in the second, third, and fourth experi- 
 ments, we see the objeet in a direction which is not its true 
 and real direction from the eye, although the rays come 
 from the object to the eye, without any inflection, reflec- 
 tion, or refraction. 
 
 When both the object and the eye are fixed without 
 the least motion, and the medium unchanged, we expect 
 that the object should appear to rest, and keep the same 
 place : yet in the second and fourth experiments, when 
 both the eye and the object are at rest, and the medium 
 unchanged, we make the object appear to move upward 
 or downward, or in any direction we please. 
 
 When we look at the same time, and with the same 
 eye, through holes that stand in a line from right to 
 left, we expect, that the object seen through the left 
 hand hole, should appear on the left, and the object seen 
 through the right hand hole, should appear on the right : 
 yet in the third experiment^ we find the direct contrary. 
 
326 OF THE HUMAN MINB. 
 
 Although many instances occur io seeing the same ob- 
 ject double with two eyes, we always expect, that it should 
 appear single when seen only by one eye : yet in the sec- 
 ond and fourth experiments, we have instances wherein 
 the same object may appear double, triple, or quadruple 
 to one eye, without the help of a polyhedron or multiply- 
 ing glass. 
 
 All these extraordinary phenomena, regarding the di- 
 rection of visible objects from the eye, as well as those 
 that are common and ordinary, lead us to that law of na- 
 ture which I have mentioned, and are the necessary con' 
 sequences of it. And, as there is no probability that we 
 shall ever be able to give a reason why pictures upon the 
 retina make us see external objects, any more than pic- 
 tures upon the baud or upon the cheek ; or, that we shall 
 ever be able to give a reason, why we see the object in the 
 direction of a line passing from its picture through the 
 centre of the eye, rather thaa in any other direction. I 
 am therefore apt to look upon this law as a primary law 
 of our constitution. 
 
 To prevent being misunderstood, I beg the reader to 
 observe, that I do not mean to affirm, that the picture 
 upon the retina will make us sec an object in the direc- 
 tion mentioned, or in any direction, unless the optic nerve, 
 and the other more immediate instruments of vision, be 
 sound, and perform their functions. We know not well 
 what is the office of the optic nerve, nor in what manner 
 it performs that office ; but that it hath some part in the 
 faculty of seeing, seems to be certain ; because in an a7B- 
 aurosis, which is believed to be a disorder of the optic 
 nerve, tlie pictures on the retina are clear and distinct, 
 and yet there is no vision. 
 
 We know still less of the use and function of the cho- 
 roid membrane ; but it seems likewise to be necessary 
 to vision : for it is well known that pictures upon that 
 part of the retina where it is not covered by the choroid, 
 I mean at the entrance of the optic nerve, produce no 
 vision, any more than a picture upon the hand. We ae- 
 
SEEIN6. 327 
 
 knowledge, tLerefore, that the retina is not the last and 
 most immediate instrument of the mind in vision. There 
 are other material organs, whose operation is necessary to 
 seeing, even after the pictures upon tlie retina are form- 
 ed. If ever we come to know the structure and use of 
 the choroid membrane, the optic nerve, and the brain, 
 and what impressions are made upon them by means of 
 the pictures on the retina, some more links of the chain 
 may be brought within our view, and a more general law 
 of vision discovered : but while we know so little of the 
 nature and office of these more immediate instruments of 
 vision, it seems to be impossible to trace its laws beyond 
 the pictures upon the retina. 
 
 Neither do I pretend to say, that there may not be 
 diseases of the eye, or accidents, which may occasion our 
 seeing objects in a direction somewhat different from that 
 mentioned above. I shall beg leave to mention one in- 
 stance of this kind that concerns myself. 
 
 In May, 1761, being occupied in making an exact me- 
 ridian, in order to observe the transit of Venus, I rashly 
 directed to the sun, by my right eye, the cross hairs of a 
 small telescope. I had often done the like in my younger 
 days with impunity,- but I suffered by it at last, which 
 I mention as a warning to others. 
 
 I soon observed a remarkable dimness in that eye ; and 
 for many weeks, when I was in the dark, or shut my 
 eyes, there appeared before the right eye a lucid spot, 
 which trembled much like the image of the sun seen by 
 reilection from water. This appearance grew fainter, 
 and less frequent by degrees ; so that now there are sel- 
 dom any remains of it. But some other very sensible ef- 
 fects of this hurt still remain. For, first, the sight of 
 the right eye continues to be more dim than that of the 
 left. Secondly, the nearest limit of distinct vision is more 
 remote in the right eye than in the other j although, be- 
 fore the time mentioned, they were equal in both these 
 respects, as I had found by many trials. But, thirdly, 
 what I chiefly intended to meutioa, is, that a straight 
 
328 or THE HUMAN MINB. 
 
 line, in some circumstances, appears to the right eye to 
 have a curvature in it. Thus, when I look upon a mu- 
 sic-book, and, shutting my left eye, direct the right to a 
 point of the middle line of the five which compose the 
 staff of music ; the middle line appears dim indeed, at the 
 point to which the eye is directed, but straight ; at the 
 same time, the two lines above it, and the two below it, 
 appear to be bent outward, and to be more distant from 
 each other, and from the middle line, than at other parts 
 of the staff, to which the eye is not directed. Fourthly, al- 
 though I have repeated this experiment times innumera- 
 ble, wilhin these sixteen months, I do not find that custom 
 and experience take away this appearance of curvature 
 in straight lines. Lastly, this appearance of curvature 
 is perceptible when I look with the right eye only, but 
 not when I look with both eyes ; yet I see better with 
 both eyes together, than even with the left eye alone. 
 
 I have related this fact minutely as it is, without re- 
 gard to any hypothesis y because I think such uneommou 
 facts deserve to be recorded. I shall leave it to others 
 to conjecture the cause of this appearance. To me it 
 seems most probable, that a small part of the retina to- 
 ward the centre is shrunk, and that thereby the contig- 
 uous parts are drawn nearer to the centre, and to one 
 another, than they were before ; and tliat objects whose 
 images fall on these parts, appear at that distance from 
 each other which corresponds, not to the interval of the 
 parts in their present preternatural contraction^butto 
 their interval in their natural and sound state. 
 
 SECTION XIII. 
 or SEEING OBJECTS SINGIE WITH TWO EYES. 
 
 Another phenomenon of vision which deserve atten- 
 tion, is our seeing objects single with two eyes. There 
 are two pictures of the object, one ob each retina, and 
 
each picture by itself inalvcs us see an object in a certain 
 direction from the eye; yet both together commonly 
 make us see only one object. All the accounts or solu- 
 tions of this phenomenon given by anatomists and philos- 
 ophers^ seem to be unsatisfactory. I shall pass over the 
 opinions of Galen, of Gasscndus, of Baptisla Porta, and 
 of Rohault. The reader may see these examined and re- 
 futed by Dr. PorterfieW. I sliall examine Dr. Porter- 
 field's own opinion, bishop Berkeley's, and some others. 
 But it will be necessary first to ascertain the facts ; for 
 if we mistake the phenomena of single and double vision, 
 it is ten to one but this mistake will lead us wrong in as- 
 signing the causes. This likewise we ought carefully to 
 attend to, which is acknowledged in theory by all who have 
 any true judgment or just taste in inquiries of this nature, 
 but is very often overlooked in practice, namely, that in 
 the solution of natural phenomena, all the length that the 
 human faculties can carry us, is only this, that from par- 
 ticular phenomena, we may, by induction, trace out gen- 
 eral phenomeua, of which all the particular ones are nec- 
 essary consequences. And when we have arrived at the 
 most general phenomena we can reach, there we must stop^ 
 Ifit is asked. Why such a body gravitates toward the 
 earth ? all the answer that can be given, is. Because all 
 bodies gravitate toward the earth. This is resolving a par- 
 ticular phenomenon into a general one. If it should again 
 be asked, Why do all bodies gravitate toward the earth ? 
 we can give no other solution of this phenomenon, but 
 that all bodies whatsoever, gravitate toward each others 
 This is resolving a general phenomenon into a more gen- 
 eral one. If it should be asked, Why all bodies grav- 
 itate to one another ? we cannot tell ; but if we could 
 tell, it could only be by resolving this universal grav- 
 itation of bodies into some other phenomenon still 
 more general and of which the gravitation of all bodies 
 is a particular instance. The most general phenom- 
 ena we can reach, are what we call laws of na- 
 ture. So that the laws of nature are nothing else but 
 
 Toil. I. 42 
 
330 0»' THK HUMAN MIND. 
 
 the most general facts relating to (he operations of nature, 
 which include a great many particular facts under then). 
 And if in any case we should give the name of a IsiVf 
 of nature to a general phenomenon, which human indus- 
 try shall afterward trace to one more general, there is no 
 great harm done. The most general assumes the name 
 of a law of nature when it is discovered; and the less 
 general is contained and comprehended in it. Having 
 premised these things, we proceed to consider the phe- 
 nomena of single and double vision, in order to discover 
 some general principle to which they all lead, and of which 
 they are the necessary consequences. If we can discover 
 any such general principle, it must either be a law of na- 
 ture, or the necessary consequence of some law of nature ; 
 and its authority will be equal, whether it is the first or 
 the last. 
 
 1. We find, that when the eyes are sound and perfect, 
 and the axes of both directed to one point, an object 
 placed in that point is seen single ; and here we observe, 
 that in this case the two pictures which show the object 
 single, are in the centres of the retina. When two pic- 
 tures of a small object are formed upon points of the re- 
 tina, if they show the object single, we shall, for the sake 
 of perspicuity, call such two points of the retina, corres- 
 ponding points ; and where the object is seen double, we 
 shall call (be points of the retina on which the pictures 
 are formed, points that do not correspond. Now. in this 
 first phenomenon it is evident, that the two centres of 
 the retina are corresponding points. 
 
 2. Supposing the same things as in the last phenome- 
 non, other objects at the same distance from (he eyes as 
 that to which their axes are directed, do also appear 
 single. Thus, if I direct my eyes (o a candle placed at 
 the distance of ten feet ; and, while I look at this can- 
 dle, another stands at the same distance from my eyes, 
 within the field of vision ; I can, while I look at the first 
 candle, attend to the appearance which the second makes 
 to the eye ; and I find that in this case it always appears 
 
SEEixe. 331 
 
 single. It is here to be observed, that the pictures of the 
 second candle do not fall upon the centres of the retinoe, 
 but they both fall upon tiie same side of the centres, that 
 is, both to the right, or both to the left, and both are at 
 the same distance from the centres. This might easily 
 be demonstrated from the principles of optics. Henbe it 
 appears, that in this second phenomenon of single vision, 
 the corresponding points are points of the two retincB, 
 v^hich are similarly situate with respect to the two cen- 
 tres, being both upon the same side of the centre, and at 
 the same distance from it. It appears likewise from this 
 phenomenon, that every point in one retina corresponds 
 with that which is similarly sitnate in the other. 
 
 3. SupposiTig still the same things, objects which arc 
 mucli nearer to the eyes, or much more distant from 
 them, than that to which the two eyes are directed, ap- 
 pear double. Thus, if the candle is placed at the distance 
 of ten feet, and I hold my finger at arm's length between 
 my eyes and the candle ; when I look at the candle I see 
 my finger double ; and when I look at my finger I see the 
 candle double : and the same thing happens with regard 
 to all other objects at like distances, which fall within the 
 sphere of vision. In this phenomenon, it is evident to those 
 who understand the principles of optics, that the pictures 
 of the objects which are seen double, do not fall upon points 
 of the retince, which are similarly situate, but that the 
 pictures of the objects seen single do fall upon points 
 similarly situate. Whence we intler, that as the points 
 of the two retince, which are similarly situate with re- 
 gard to the centres, do correspond, so those which are 
 dissimilarly situate do not correspond. 
 
 4. It is to be observed, that although, in such cases as 
 are mentioned in the last phenomenon, we have been ac- 
 cnstomed from infancy to see objects double which we 
 know to be single ; yet custom, and experience of the 
 utiity of the object^ never take away this appearance of 
 duplicity. 
 
332 OF THE HUMAN MINU. 
 
 5. It may, however, be remarked, that tlie custom of 
 attending to visible appearances has a considerable effect, 
 and makes the phenomenon of double vision to be more 
 or less observed and remembered. Thus you may find a 
 man thai can say with a good conscience, that he never 
 saw things double all his life ; yet this very man, put in 
 the situation above mentioned, with his finger between 
 him and the candle, and desired to attend to the appear- 
 ance of the object which be does not look at, will, upon 
 the first trial, see the candle double, when he looks at his 
 finger ; and his finger double, when he looks at the can- 
 dle. Does he now see otherwise than he saw before ? 
 No surely ; but he now attends to what be never attended 
 to before. The same double appearance of an object 
 hath been a thousand times presented to his eye before 
 now ; but he did not attend to it ; and so it is as little an 
 object of his reflection and memory, as if it had never 
 happened. 
 
 When we look at an object, the circumjacent objects 
 may be seen at the same time, although more obscurely 
 and indistinctly : for the eye hath a considerable field of 
 vision, which it takes in at once. But we attend only to 
 the object we look at. The other objects which fall with- 
 in the field of vision, ai-e not attended to ; and therefore 
 are as if they were not seen. If any of them draws our 
 attention, it naturally draws the eyes at the same time; 
 for, in the common course of life, the eyes always follow 
 the attention : or if, at any time, in a reverie, they are sep- 
 arated from it, we hardly at that time see what is directly 
 before us. Hence we may see the reason, why the man 
 we are speaking of thinks that he never before saw an 
 object double. When he looks at any object, he sees it 
 single, and takes no notice of other visible objects at that 
 time, whether they appear single or double. If any of 
 them draws his attention, it draws his eyes at the same 
 time ; and as soon as the eyes are turned toward it, it 
 appears single. But in order to see things double, at 
 least in order to have any reflection or remembrance that 
 
SEEIXG. S38 
 
 {le did so, it is necessary that he should look at one object, 
 and at the same time attend to the fiunt appearance of 
 other objects which are within the field of vision. This 
 is a practice wliich perhaps he never used, nor attempt- 
 ed J and therefore he does not recollect that ever he saw 
 an object double. But when he is put upon giving this 
 attention, he immediately sees objects double in the same 
 manner, and with the very same circumstances, as they 
 who have been accustomed, for the greatest part of their 
 lives, to give this attention. 
 
 There are many phenomena of a similar nature, which 
 shew, that the mind may not attend to, and thereby, in 
 some sort, not perceive objects that strike the senses. I 
 had occasion to mention several instances of this in the 
 second chapter ; and I have been assured, by persons of the 
 best skill in music, that in hearing a tune upon the harp- 
 sichord, when they give attention to the treble, they do 
 not hear the base ; and when they attend to the base, they 
 do not perceive the air of the treble. Some persons are 
 so near sighted, that, in reading, they hold the book to 
 one eye, while the other is directed to other objects. Such 
 persons acquire the habit of attending, in this case, to the 
 objects of one eye, while they give no attention to those 
 of the other. 
 
 6. It is observable, that in all cases wherein we see an 
 object double, the two appearances have a certain position 
 with regard to one another, and a certain apparent or an- 
 gular distance. This apparent distance is greater or less 
 in different circumstances ; but in the same circumstances, 
 it is always the same, not only to the same, but to differ- 
 ent persons. 
 
 Thus in the experiment above mentioned, if twenty dif- 
 ferent persons, who see perfectly with both eyes, shall 
 place their finger and the candle at the distances above 
 expressed, and hold their heads upright ; looking at the 
 finger, they will see two candles, one on the right, an- 
 other on the left. That which is seen on the right, is 
 seen by the right eye, and that which is seen on the left. 
 
334 OF THE HUMAN MIND. 
 
 bj the left eye ; and they will see them at the same ap- 
 parent distance from each other. If again they looii at 
 the candle, they will see two fingers, one on the right, 
 and the other on the left; and all will see them at tiie 
 same apparent distance; the finger toward the left being 
 seen by the right eye, and the other by the left* If the 
 head is laid horizontally to one side, other circumstances 
 remaining the same, one appearance of the object seen 
 double, will be directly above the other. In a word, vary 
 the circumstances as you please, and the appearances are 
 varied to all the spectators in one and the same manner. 
 
 7. Having made many experiments in order to ascer- 
 tain the apparent distance of the two appearances of an 
 object seen double, I have found (hat in all cases this ap- 
 parent distance is proportioned to the distance between 
 the point of the retina, where the picture is made in one 
 eye, and the point which is situated similarly to that on 
 which the picture is made on the other eye. So that as 
 the apparent distance of two objects seen with one eye, 
 IS proportioned to the arch of the retina, which lies be- 
 tween their pictures : in like manner, when an object is 
 seen double with the two eyes, the apparent distance of 
 the two appearances is proportioned to the arch of either 
 retina, which lies between the picture in that retina, and 
 the point corresponding to that of the picture in the other 
 retina. 
 
 8. As in certain circumstances we invariably see one 
 object appear double, so in others we as invariably see 
 two objects unite in one ; and, in appearance, lose their 
 duplicity. This is evident in the appearance of the binoc- 
 ular telescope. And the same thing happens when any 
 two similar tubes are applied to the two eyes in a par- 
 allel direction ; for in this case we see only one tube. 
 And if two shillings are placed at the extremities of th« 
 two tubes, one exactly in the axis of one eye, acud the 
 other in the axis of the other eye, we shall see but one 
 shilling: If two pieces of coin, or other bodies, of dif- 
 farent colour, and of different figure, be properly placed 
 
SEEIXO. 335 
 
 in the two axes of the eyes, and at the extpemilies of the 
 tubeij, we shall see both the bodies in one and the same 
 place, each as it were spread over the other, without hid- 
 ing il ; and the colour will be that which is compounded 
 of the two colours. 
 
 9. From these phenomena, and from all the trials I 
 have been able to make, it appears evidently, that in per- 
 fect human eyes, the centres of the two retince correspond 
 and harmonize with one another; and that every other 
 point in one retina, doth correspond and harmonize with 
 the point which is similarly situate in the other ; in such 
 manner, that pictures falling on the corresponding points 
 of the two retince, shew only one object, even when there 
 are really two : and pictures falling upon points of the 
 retince which do not correspond, shew us two visible ap- 
 pearances, although there be but one object. So that 
 pictures, upon corresponding points of the two retinwi 
 present the same appearance to the mind as if they had 
 both fallen upon the same point of one retina ; and picr 
 tures upon points of the two retina, which do not corres- 
 pond, present to the mind the same apparent distance and 
 position of two objects, as if one of those pictures was 
 carried to the point corresponding to it in the other re- 
 tina. This relation and sympathy between correspond- 
 ing points of the two retince, I do not advance as an hy- 
 pothesis, but as a general fact or phenomenon of vision* 
 All the phenomena before mentioned, of single or double 
 vision^ lead to it, and are necessary consequences of it. It 
 holds true invariably in all perfect human eyes, as far as 
 I am able to collect from innumerable trials of various 
 kinds made upon my own eyes, and many made by others 
 at my desire. Most of the hypotheses that have beeo 
 contrived to resolve the phenomena of single and double 
 vision, suppose this general fact, while their authors were 
 not aware of it. Sir Isaac Newton, who was too judicious 
 a philosopher, and too accurate an observer, to have offer- 
 ed even a conjecture which did not tally with the facts 
 that had fallea under his obsiervatioQ^ proposes; a querj 
 
336 OF THB HTJMAIf MIND. 
 
 with respect to the cause of it, O^jtics, quer. 16. The 
 judicious Dr. Smith, in his Optics, lib. 1. $ 137. hath con- 
 firmed the truth of this general phenomenon from his 
 own experience, not only as to the apparent unity of ob- 
 jects whose pictures fall upon the corresponding points 
 of the retince, but also as to the apparent distance of the 
 two appearances of the same object when seen double. 
 
 This general phenomenon appears therefore to be 
 founded upon a very full induction, which is all the evi- 
 dence we can have for a fact of this nature. Before we 
 make an end of this subject, it will be proper to inquire, 
 first, whether those animals whose eyes have an adverse 
 position in their heads, and look contrary ways, have such 
 corresponding points in their retince'? Secondly, what is 
 the position of the corresponding points in imperfect hu- 
 man eyes, I mean in those that squint ? And, in the last 
 place, whether this harmony of the corresponding points 
 in the retina, be natural and original, or the efiect of cus- 
 tom ? And if it is original, whether it can be accounted 
 for by any of the laws of nature already discovered ? or 
 whether it is itself to be looked upon as a law of nature, 
 and a part of the human constitution ? 
 
 SECTION XIV. 
 OF THE lAWS or VISION IN BETJTE AW1MAI.S. 
 
 It is the intention of nature, in giving eyes to animals, 
 that they may perceive the situation of visible objects, or 
 the direction in which they are placed : it is probable, 
 therefore, that, in ordinary cases, every animal, whether 
 it has many eyes or few, whether of one structure or of 
 another, sees objects single, and in their true and proper 
 direction. And since there is a prodigious variety in the 
 structure, the motions, and the number of eyes in difier- 
 ent animals and insects, it is probable that the laws by 
 which vision is regulated, are not the same in all, but va- 
 rious, adapted to the eyes which nature hath given them« 
 
SEEING. 337 
 
 Mankind naturally turn their eyes always the same way, 
 so that the axes of the two eyes meet in one point. They 
 naturally attend to, op look at I hat object only which is 
 placed in the point where the axes meet. And whether 
 the object be more or less dislant, the configuration of the 
 eye is adapted to the distance of the object, so as to form 
 a distinct picture of it. 
 
 When we use our eyes in (liis natural way, the two pic- 
 tures of the object we look at, are formed upon the cen- 
 tres of the two relincB : and the two pictures of any con- 
 tiguous object are formed upon the points of the retince 
 which are similarly situate with regard to tlie centres. 
 Therefore, in order to our seeing olgects single, and in 
 their proper direction, with two eyes, it is sufficient that 
 we be so constituted, that objects whose pictures are 
 formed upon the centres of the two retinw, or upon points 
 similarly situate with regard to these centres, shall be 
 seen in the same visible place. And this is the constitu- 
 tion which nature hath actually given to human eyes. 
 
 When we distort our eyes from their parallel direction, 
 which is an unnatural motion, but may be learned by prac- 
 tice ; or when we direct the axes of the two eyes to one 
 point, and at the same time direct our attention to some 
 visible object much nearer or much more distant than 
 that point, which is also unnatural, yet may be learned ; 
 in these eases, and in these only, we see one object. double, 
 or two objects confounded into one. In these cases, the 
 two pictures of the same object are formed upon points 
 of the retince which are not similarly situate, and so the 
 object is seen double ; or the two pictures of different ob- 
 jects are formed upon points of the retince which are sim- 
 ilarly situate, and so the two objects are seen confounded 
 in one place. 
 
 Thus it appears, that the laws of vision in the human 
 constitution are wisely adapted to the natural u»ie of hu- 
 man eyes, but not to that use of them which is unnatural. 
 We see objects truly when we use our eyes in the natural 
 way ; but have false appearances presented to us when 
 
 vei. I. 43 
 
338 OF TUli HUMAN MIND. 
 
 we use them in a way that is unnatuf-al. We may rea- 
 sonably think, that the case is the same with other ani- 
 maisi But is it not unreasonable to thinii, that those 
 animals wliich naturally turn one eye toward one object, 
 and another eye toward another object, must thereby have 
 such false appearances presented to them, as we have 
 when we do so against nature ? 
 
 Many animals have their eyes by nature placed adverse 
 and immoveable, the axes of the two eyes being always di- 
 rected to opposite points- Do objects painted on the cen- 
 tres of the two retina appear to such animals as they do 
 to human eyes, in one and the same visible place? I think 
 it is highly probable that they do not ; and that they ap- 
 pear as they really are, in opposite places. 
 
 If we judge from analogy in this case, it will lead us 
 to think that there is a certain correspondence between 
 points of the two retinae, in such animals, but of a differ- 
 ent kind from that which we have found in human eyes. 
 The centre of one retina will correspond with tlie centre 
 of the other, in such manner, that (he objects whose pic- 
 tures are formed upon these corresponding points, shall 
 appear not to be in the same place, as in human eyes, but 
 in opposite places. And in the same manner will the su- 
 perior part of one retina correspond with the inferior 
 part of the other, and the anterior part of one with the 
 posterior part of the other. 
 
 Some animals, by nature, turn their eyes with equal 
 facility, either the same way, or different ways, as we 
 turn our hands and arms. Have such animals corres- 
 ponding points in their retina, and points which do not 
 correspond, as the human kind has ? I think it is prob- 
 able that they have not; because such a constitution in 
 them could serve no other purpose but to exhibit false 
 appearances. 
 
 If we judge from analogy, it will lead us to think, that 
 as such animals move their eyes in a manner similar to 
 that in which we move our arms, they have an immediate 
 and natural perception of the direction they give to their 
 
SEEING, 339 
 
 eyes, as we liave of tlie direction we give to our arms ; 
 and perceive the sil nation of visible objects by tiieir eyes, 
 in a manner similar to tliat in which we perceive the sit- 
 uation of tangible objects with our hands. 
 
 We cannot teach brute animals to use their eyes in any 
 other way than in that which nature hath taught <hem,- 
 nor can we teach them to communicate to us the appear- 
 ances which visible objects make to them, either in or- 
 dinary or in extraordinary cases. We have not there- 
 fore the same means of discovering (he lavfs of vision in 
 them, as in our own kind, but must satisfy ourselves with 
 probable conjectures: and what we have said upon this 
 subject, is cliiefly intended to shew, that animals to which 
 nature hath given eyes differing in their number, in tlieir 
 position, and in their natural motions, may very probably 
 be subjected to different laws of vision, adapted to the 
 peculiarities of their organs of vision. 
 
 SECTION XV. 
 SQ,UINTI]SrG CONSIDERED HYPOTHETIC Alt Y. 
 
 Whetheb there be corresponding points in the retince, 
 of those who have an involuntary squint ? and if there 
 are, whether they be situate in the same manner as in 
 those who have no squint ? are not questions of mere cu- 
 riosity. They are of real importance to the physician 
 who attempts the cure of a squint, and to the patient who 
 submits to the-cure. After so much has been said of the 
 strabismus, or squint, both by medical and by optical 
 writers, one might expect to find abundance of facts for 
 determining these questions. Yet I confess I have been 
 disappointed in this expectation, after taking some pains 
 both to make observations, and to collect those which 
 have been made by others. 
 
 Nor will this appear very strange, if we consider, that, 
 to make the observations which are necessary for deter- 
 
340 OV THE niTMATf MIND. 
 
 mining these questions, knowledge of (he piinciples of 
 optics, and of tlie laws of vision, must concur with oppor- 
 tuniiies rai'el^ to be met with. 
 
 Of those who squint, the far- greater part have no dis- 
 tinct vision with one eye. When this is the case, it is 
 impossible and indeed of no importance, to determine the 
 situation of the corresponding points. When both eyes 
 are good, they commonly differ so much in their direction, 
 that the same object ocannot be seen by both at the same 
 time ; and in this case it will be very difficult to deter- 
 mine the situation of the corresponding points ; for such 
 persons will probably attend only to the objects of one 
 eye. and the objects of the other will be as little regard- 
 ed as if they were not seen. 
 
 We have before observed, that when we look at a near 
 object, and attend to it, we do not perceive the double ap- 
 pearances of more distant objects, even when they are in 
 the same direction, and are presented to the eye at the 
 same time. It is probable that a squinting person, when 
 he attends to the objects of one eye, will, in like manner, 
 have his attention totally diverted from the objects of the 
 other; and that he will perceive them as little as we per- 
 ceive the double appearances of objects when we use our 
 eyes in tiie natural <vay. Such a person, therefore, un- 
 less he is so much a philosopher as to have acquired the 
 habit of attending very accurately to the visible appear- 
 ances of objects, and even of objects which he does not 
 look at, will not be able to give any light to the questions 
 now under consideration. 
 
 It is very probable that hares, rabbits, birds, and fishes, 
 whose eyes are fixed in an adverse position, have the nat- 
 ural faculty of attending at the same time to visible ob- 
 jects placed in different, and even in contrary directions; 
 because, without this faculty, they could not have those 
 advantages from the contrary direction of their eyes, 
 which nature seems to have intended. But it is not prob- 
 able that those who squint have any such natural faculty ; 
 because we find no such faculty in the rest of the species. 
 
SKEING. 341 
 
 We naturally attend to objects placed in the point where 
 the axes of the two eyes meet, and to them only. To 
 give attention to an object in a different direction is un- 
 natural, and not to be learned without pains and practice. 
 
 A very convincing proof of this may be drawn from a 
 fact now well known to philosophers : when one eye is 
 shut, there is a certain space within the field of vision, 
 where we can see nothing at all ; the space which is di- 
 rectly opposed to that part of the bottom of the eye where 
 the optic nerve enters. This defect of sight, in one part 
 of the eye, is common to all human eyes, and hath been 
 so from the beginning of the world j yet it was never 
 known, until the sagacity of the Abbe Mariotte discover- 
 ed it in the last century. And now when it is known, it 
 cannot be perceived, but by means of some particular ex- 
 periments, which require care and attention to make them 
 succeed. 
 
 What is the reason that so remarkable a defect of sight, 
 common to all mankind, was so long unknown, and is 
 now perceived with so much difficulty ? It is surely this, 
 that the defect is at some distance from the axis of the 
 eye, and consequently in a part of the field of vision to 
 which we never attend naturally, and to which we cannot 
 attend at all, withont the aid of some particular circum- 
 stances. 
 
 From what we have said, it appears, that to determine 
 the situation of the corresponding points in the eyes of 
 those who squint is impossible, if they do not see dis- 
 tinctly with both eyes ; and that it will be very difficult, 
 unless the two eyes differ so little in their direction, that 
 the same object may be seen with both at the same time. 
 Such patients I apprehend are rare ; at least there are 
 very few of them with whom I have had the fortune to 
 meet : and therefore, for the assistance of those who may 
 have happier opportunities, and inclination to make the 
 proper use of them, we shall consider the case of squint- 
 ing hypothetieally, pointing out the proper articles of in- 
 quiry, the observations that are wanted, and the conclu- 
 gious that may be drawn from them. 
 
542 OF THIi HUMAK MISTU. 
 
 1. It oiiglit to be inquiivd, Whether- the squinting per- 
 S0T1 sees equally well with both eyes ? and, if there be a 
 defect in one, the nature and degree of that defect ought 
 to be remarked. The experiments by which this may be 
 done, are so obvious, that I need not mention I hem. But 
 I would advise the observer to make the proper experi- 
 ments, and not to rely upon the testimony of the patient j 
 because I have found many instances, both of persons (hat 
 squinted, and others, who were found, upon trial, to have 
 a great defect in the sight of one eye, although they were 
 never aware of it before. In all the following articles, it 
 is supposed that the patient sees with both eyes so well, 
 as to be able to read with either, when the other is cov- 
 ered. 
 
 2. It ought to be inquired, Whether, when one eye is 
 covered, the other is turned directly to the object ? This 
 ought to be tried in both eyes successively. By this ob- 
 servation, as a touchstone, we may try the hypothesis 
 concerning squinting, invented by M. de la Hire, and 
 adopted by Boerhaave, and many others of the medical 
 faculty. 
 
 The hypothesis is, That in one eye of a squinting per- 
 son, the greatest sensibility and the most distinct vision 
 is not, as in other men, in the centre of the retina, but up- 
 on one side of the centre ; and that the turns the axis of this 
 eye aside from the object, in order that the picture of the 
 object may fall upon the most sensible part of the retina, 
 and thereby give the most distinct vision. If this is the 
 cause of squinting, the squinting eye will be turned aside 
 from the object, when the otfaei; eye is covered, as well 
 as when it is not. 
 
 A trial so easy to be made, never was made for more 
 than forty years ; but the hypothesis was very generally 
 received. So prone are men to invent hypotheses, and 
 so backward to examine them by facts. At last Dr. Ju- 
 rin having made the trial, found that persons who squint, 
 turn the axis of the squinting eye directly to the object, 
 when the other eye is covered. This fact is confirmed by 
 
SEEING. 343 
 
 Dr. Porterfield ; and I have found it verified in all the 
 instances that have fallen under mj observation. 
 
 3. It ought to be inquired. Whether the axes of the 
 two ejes follow one another, so as to have always the 
 same inclination, or make the same angle, when the per- 
 son looks to the right or to the left, upward or downward, 
 OP straight forward? By this observa(ion we may judge, 
 wheilier a squint is owing to any defect iw (he muscles 
 wiiich move (he eye, as some have supposed. In the fol- 
 lowing articles we suppose that the inclination of the 
 axes of the eyes is found to be always the same. 
 
 4. It ought to be inquired, Whether the person that 
 squints sees an object single or double? 
 
 If he sees the object double ; and if the two appear- 
 ances have an angular distance equal to the angle which 
 the axes of his eyes make with each other, it may be con- 
 cluded that he haih corresponding points in the retince off 
 his eyes, and that they have the same situation as in those 
 who have no squint. If the two appearances should have 
 an angular distance, which is always the same, but man- 
 ifestly greater or less than the angle contained under the 
 optic axes, this would indicate corresponding points in 
 the retina, whose situation is not the same as in those 
 who have no squint ; but it is difficult tojudge aeenratel; 
 of the angle which the optic axes make. 
 
 A squint, too small to be perceived, may oecaaion dou- 
 ble vision of objects : for if we speak strictly, every per- 
 son squints more or less, whose optic axes do not meet 
 exactly in the object which he looks at. 'I'hus, if a man 
 can only bring the axes of his eye* to be parallel, but 
 cannot make them converge in the least, he roust have a 
 small squint in looking at near objects, and will see them 
 double, while he sees very distant objects single. Again, 
 if the optic axes always converge so as to meet eight or 
 ten feet before the face at farthest, such a person will see 
 near objects single: but when he looks at very distant 
 objects, he will squint a little, and see them doubk. 
 
344 eF THE HUMAN MIND. 
 
 An instance of this kind is related by Aguilonius in hii 
 Optics ; who says, that he had seen a young man to whom 
 near objects appeared single, but distant objects appeared 
 double. 
 
 Dr. Briggs, in his Nova visionis theoria, having col- 
 lected from authors several instances of double vision, 
 quotes this from Aguilonius, as the most wonderful and 
 unaccountable of all, in so much that he suspects some 
 imposition on the part of the young man : but to those 
 who understand the laws by which single and double vis- 
 ion are regulated, it appears to be the natural effect of a 
 very small squint. 
 
 Double vision may always be owing to a small squint, 
 when the two appearances are seen at a small angular 
 distance, although no squint was observed : and I do not 
 remember any instances of double vision recorded by 
 authors, wherein any account is given of the angular dis' 
 tance of the appearances. 
 
 In almost all the instances of double vision, there is 
 reason to suspect a squint or distortion of the eyes, from 
 the concomitant circumstances, which we find to be one 
 or other of the following, the approach of death, or of a 
 deliquium, excessive drinking, or other intemperance, vio- 
 lent headach, blistering the head, smoking tobacco, blows 
 or wounds in the head. In all these cases, it is reasonable 
 to suspect a distortion of the eyes, either from spasm, or 
 paralysis in the muscles that move them. But although 
 it be probable that there is always a squint greater or 
 less where there is double vision ; yet it is certain that 
 there is not double vision always where there is a squint. 
 I know no instance of double vision that continued for 
 life, or even for a great number of years. We shall there- 
 fore suppose, in the following articles, that the squinting 
 person sees objects single. 
 
 5. The next inquiry then ought to be, Whether the 
 object is seen with both eyes at the same time, or only 
 with the eye whose axis is directed to it ? It hath been 
 taken for granted, by the writers upon the strabismus, 
 
SBEINO. 345 
 
 before Dp. Jurin, that those wlio squint, eominotily see ob- 
 jects single with both eyes at the same lime ; but 1 know 
 not one fact advanced by any writer which proves it. Dr. 
 Jurin is of a contrary opinion ; and as it is of consequence, 
 so it is very easy to determine this point in parliciilar in- 
 stances, Ijy this obvious experiment While the person 
 that squints looks steadily at an object, let the observer 
 carefully remark the direction of both his eyes, and ob- 
 serve their motions ; and let an opaque body be interpos- 
 ed between the object and the two eyes successively. If 
 the patient, notwithstanding this interposition, and with- 
 out changing the direction of the eyes, continues to see the 
 object all the time, it may be concluded that he saw it 
 with both eyes at once. But if the interposition of the 
 body between one eye and the object makes it disappear, 
 then we may be certain, that it was seen by that eye only. 
 In the two following articles, we shall suppose the first 
 to happen, according to the common hypothesis. 
 
 6. Upon this supposition, it ought to be inquired. 
 Whether the patient sees an object double in those cir- 
 cumstances wherein it appears double to them who have 
 no squint? Let him, for instance, place a candle at the 
 distance of ten feetj and holding his finger at arm's 
 length between him and the candle, let him observe, 
 when he looks at the candle, whether he sees his finger 
 with both eyes, and whether he sees it single or double ; 
 and when he looks at his finger, let him observe whether 
 he sees the candle with both eyes, and whether single 
 or double. 
 
 By this observation, it maybe determined, whether to 
 this patient, the phenomena of double as well as of sin- 
 gle vision are the same as to them who have no squint. 
 If they are not the same ; if he sees objects single with 
 two eyes, not only in the cases wherein they appear sin- 
 gle, but in those also wherein they appear double to other 
 men ; the conclusion to be drawn from this su))position is, 
 that his single vision does not arise from corresponding 
 
 TOi. I. 44 
 
3i6 OF THE HUMAN MIND. 
 
 points in the retina of his eyes j and that the laws of vis- 
 ion are not the same in hiui as in the rest of mankind, 
 
 7. If, on the other hand, he sees objects double in 
 those cases wherein they appear double to others, the 
 conclusion must be, that he hath corresponding points in 
 the relincE of his eyes, but unnaturally situate ; and their 
 situation may be thus determined. 
 
 "When he looks at an object, having the axis of one eye 
 directed to it, and the axis of the other turned aside from 
 it ; let us suppose a right line to pass from the object 
 through the centre of the diverging eye. We shall, for 
 the sake of perspicuity, call this right line tlie natural 
 axis of the eye : and it will make an angle with the real 
 axis, greater or less, according as his squint is greater 
 or less. We shall also call that point of the retina in 
 which the natural axis cuts it, the natural centre of the 
 retina; which will be more or less distant from the real 
 centre, according as the squint is greater or less. 
 
 Having premised these definitions, it will be evident to 
 those who understand the principles of optics, that in 
 this person the natural centre of one retina corresponds 
 with the real centre of the other, in the very same man- 
 ner as the two real centres correspond in perfect eyes | 
 and that the points similarly situate with regard to the 
 real centre in one retina, and the natural centre in the 
 other, do likewise correspond, in the very same manner 
 as the points similarly situate with regard to the two real 
 centres correspond in perfect eyes. 
 
 If it is true, as has been commonly affirmed, that one 
 who squints sees an object with both eyes at the same 
 time, and yet sees it single, the squint will most probably 
 be such as we have described in this article. And we 
 may further conclude, that if a person affected with such 
 a squint as we have supposed, could be brought to the 
 habit of looking straight, his sight would thereby be 
 greatly hurt. For he would then see every thing double 
 which he saw with both eyes at the same time ; and ob- 
 jects distant from one another, would appear to be con- 
 
SEEING. 3*7 
 
 founded together. His eyes are made for squinting, as 
 much as those of other men are made for looking straight j 
 and his sight A\ould be no less injured by looking straight 
 than that of another man by squinting. He can never see 
 perfectly when he does not squint, unless I he correspond- 
 ing points of his eyes sliould by custom change their place ; 
 but how small the probability of this is, will appear in the 
 17th section. 
 
 Those of the medical faculty who attempt the cure of 
 a squint, would do well to consider whether it is attended 
 with such symptoms as are above described. If it is, the 
 cure would be worse than the malady : for every on«f will 
 readily acknowledge, that it is better to put up with the 
 deformity of a squidt. than to purchase the cure by the 
 loss of perfect and distinct vision. 
 
 8. We shall now return to Dr. Jurin's hypothesis, and 
 suppose, that our patient, when he saw objects single not- 
 withstanding his squint, was found, upon trial, to have 
 seen them only with one eye. 
 
 We would advise such a patient, to endeavour, by re- 
 peated efforts, to lessen his squint, and to bring the axes 
 of his eyes nearer to a parallel direction. We have nat- 
 urally the power of making small variations in the incli- 
 nation of the optic axes ,■ and this power may be greatly 
 increased by exercise. 
 
 In the ordinary and natural use of our eyes, we can 
 direct their axes to a fixed star; in this case they must 
 be parallel : we can direct them also to an object six 
 inches distant from the eye ; and in this case the axes 
 must make an angle of fifteen or twenty degrees. We 
 see yotfug people in their frolics learn to squint, making 
 their eyes either converge or diverge, when they will, to a 
 very considerable degree. Why should it be more difficult 
 for a squinting person to learn to look straight when he 
 pleases ? If once, by an effort of his will, he can but les- 
 sen bis squint, frequent practice will make it easy to les- 
 sen it, and will daily increase his power. So that if he 
 begins this practice in youth, and perseveres in it, be may 
 
348 OF THE HUMAN MIND. 
 
 probably, aftei' some time, learn to direct both his eyes 
 to one object. 
 
 When he hath acquired this power, it will be no dlffi. 
 cult matter to determine, by proper observations, whether 
 the centres of (he relince, and other points similarly situ- 
 ate with regard to the centres, correspond, as in other 
 men. 
 
 9. Let us now suppose that he finds this to be the case; 
 and that he sees an object single with both eyes, when 
 the axes of both are directed to it. It will then concern 
 liim to acquire the habit of looking straight, as he hath 
 got the power, because he will thereby not only remove 
 a deformity, but improve his sight: and I conceive this 
 habit, like all others, may be got by frequent exercise. 
 He may practise before a mirror when alone, and in com- 
 pany he ought to have those about him, who will observe 
 and admonish him when he squints. 
 
 10. What is supposed in the 9th article, is not merely 
 imaginary : it is really the case of some squinting per- 
 sons, as will appear in the next section. Therefore it 
 ought further to be inquired, how it comes to pass, that 
 such a person sees an object which he looks at, only with 
 one eye, when both are open ? In order to answer this 
 question, it may be observed, first, whether, when he 
 looks at an object, the diverging eye is not drawn so close 
 to the nose, that it can have no distinct images? Or, 
 secondly, whether the pupil of the diverging eye is not 
 covered wholly, or in part, by the upper eyelid ? Dr. Ju- 
 rin observed instances of these cases in persons that 
 squinted, and assigns them as causes of their seeing the 
 object only with one eye. Thirdly, it may be observed, 
 whether the diverging eye is not so directed, that the 
 picture of the object falls upon that part of the retina 
 where the optic nerve enters, and where there is no vis- 
 ion ? This will probably happen in a squint wherein the 
 axes of the eyes converge, so as to meet about six inches 
 before the nose. 
 
SEEING. 349 
 
 11. In the last place it ought to be inquired, whether 
 such a person hath any distinct vision at all with the di- 
 verging eye, at the time he is looking at an object with 
 the other. 
 
 It may seem very improbable, that he should be able to 
 read with the diverging eye when the other is covered, 
 and yet, when both are open, have no distinct vision with 
 it at all. But this perhaps will not appear so improba- 
 ble, if the following considerations are duly attended to. 
 
 Let us suppose, that one who saw perfectly, gets, by a 
 blow on the head, or some other accident, a permanent 
 and involuntary squint. According to the laws of vision, 
 he will see objects double, and will see objects distant 
 from one another confounded together : but such vision 
 being very disagreeable, as well as inconvenient, he will 
 do every thing in his power to remedy it. For alleviating 
 such distresses, nature often teaches men wonderful ex- 
 periments, which the sagacity of a philosopher would be 
 unable to discover. Every accidental motion, every di- 
 rection or conformation of his eyes, which lessens the 
 evil, will be agreeable : it will be repeated, until it be 
 learned to perfection, and become habitual, even without 
 thought or design. Now, in this case, what disturbs the 
 sight of one eye, is the sight of the other ; and all the 
 disagreeable appearances in vision would cease, if the 
 light of one eye was extinct. The sight of one eye will 
 become more distinct and more agreeable, in the same 
 proportion as that of the other becomes faint and indis- 
 tinct. It may therefore be expected, that every habit 
 will, by degrees, be acquired, which tends to destroy 
 distinct vision in one eye, while it is preserved in the 
 other. These habits will be greatly facilitated, if one 
 eye was at first better than the other ; for in thai: case 
 the best eye will always be directed to the object which 
 he intends to look at, and every habit will be acquired 
 which tends to hinder his seeing it at all, or seeing it dis- 
 tinctly by the other at the same time. 
 
356 or THE HUMAN MIND. 
 
 I shall mention one or two habits, that may probablj 
 be acquired in such a case ; perhaps there are others 
 which we cannot so easily conjecture. First, by a small 
 increase or diminution of his squint, he may biing it to 
 correspond with one or other of the cases mentioned in 
 the last article. Secondly, the diverging eye maybe 
 brought to such a conformation as to be extremely short- 
 sighted, and consequently to have no distinct vision of 
 objects at a distance. I knew this to be the case of one 
 person that squinted ; but cannot say whether the short- 
 sightedness of the diverging eye was original, or acquired 
 by habit. 
 
 We see, therefore, that one who squints, and originally 
 saw objects double by reason of that squint, may acquire 
 such habits, that when he looks at an object, he shall see 
 it only with one eye : nay, he may acquire such habits, 
 that when he looks at an object with his best eye, he 
 shall have no distinct vision with the other at all. Whether 
 this is really the case, being unable to determine in the 
 instances that have fallen under my observation, I shall 
 leave to future inquiry. 
 
 I have endeavoured, in the foregoing articles, to de- 
 lineate such a process as is proper in observing the phe- 
 nomena of squinting. I know well by experience, that 
 this process appears more easy in theory, than it will be 
 found to be in practice ; and that in order to carry it on 
 with success, some qualifications of mind are necessary 
 in the patient, which are not always to be met with. But 
 if those who have proper opportunities, and inclination, 
 to observe such phenomena, attend duly to this process, 
 they may be able to furnish facts less vague and unin- 
 structive than those we meet with, even in authors of 
 reputation. By such facts, vain theories may be explod- 
 ed, and our knowledge of the laws of nature, which regard 
 the noblest of our senses, enlarged. 
 
SEEINO. , 351 
 
 SECTION XVI. 
 FACTS EEIATING TO SQUINTING. 
 
 Having considered the phenomena of squinting liypo- 
 thetically, and their connection ^vith corresponding points 
 in the retincE, I shall now mention tlie facts I have had 
 occasion to observe myself, or have met with in authors, 
 that can give any light to this subject. 
 
 Having examined above twenty persons that squinted, 
 I found in all of tbeni a defect in the sight of one eye. 
 Four only had so much of distinct vision in the weak eye, 
 as to be able to read with it when the other was covered. 
 The rest saw nothing at all distinctly with one eye. 
 
 Dr. Porterfield says, that this is generally the case of 
 people that squint : and I suspect it is so more generally 
 than is commonly imagined. Dr. Jurin, in a very judic- 
 ious'^ dissertation upon squinting, printed in Dr. Smith's 
 Optics, observes, that those who squint, and see objects 
 with both eyes, never see the same object with both at 
 the same time; that when one eye is directed straight 
 forward to an object, the other is drawn so close to the 
 nose, that the object cannot at all be seen by it, the im- 
 ages being too oblique and too indistinct to affect the eye. 
 In some squinting persons, he obsei-ved the diverging eye 
 drawn under the upper eyelid, while the other was di- 
 rected to the object. From these observations he con- 
 cludes, that " the eye is thus distorted, not for the sake 
 of seeing better with it, but rather to avoid seeing at all 
 with it as much as possible." From all the observations 
 be had made, he was satisfied, that there is nothing pe- 
 culiar in the structure of a squinting eye ; that the fault 
 is only in its wrong direction ; and that this wrong direc- 
 tion is got by habit. Therefore he proposes that meth- 
 od of cure which we have described in the 8lb and 9th 
 articles of the last section. He tells us that he had at- 
 tempted a cure after this method, upoa a young gentle- 
 
362 or THE HUMAN MINB. 
 
 man, with promising hopes of success ; but was inter- 
 rupted by his falling ill of the smallpox, of which he 
 died. 
 
 It were to be wished that Dr. Jurin had acquainted us, 
 whether he ever brought the .young man to direct the 
 axes of both eyes to the same object, and whether, in that 
 case, he saw the object single, and saw it with both eyes| 
 and that he had likewise acquainted us, whether he saw 
 objects double when his squint was diminished. But as 
 to these facts he is silent. 
 
 I wished long for an opportunity of trying Dr. Jurin's 
 method of curing a squint, without finding one ; having 
 always, upon examination, discovered so great a defect in 
 the sight of one eye of the patient as discouraged the 
 attempt. 
 
 But I have lately found three young gentlemen, with 
 whom I am hopeful this method may have success, if they 
 have patience and perseverance in using it. Two of them 
 are brothers, and before I had access to examine them, 
 had been practising this method by the direction of their 
 tutor, with such success, that the elder looks straight 
 when he is upon his guard : the younger can direct both 
 his eyes to one object ; but they soon return to their usual 
 squint. 
 
 A third young gentleman, who had never heard of this 
 method before, by a few days practice, was able to direct 
 both his eyes to one object, but could not keep them long 
 in that direction. All the three agree in this, that when 
 both eyes are directed to one object, (hey see it and the 
 adjacent ob ects single ; but when they squint, they see 
 obiects sometimes single and sometimes double. I ob- 
 served of all the three, that when they squinted most, 
 that is, in the way they had been accustomed to. the axes 
 of their eyes converged, so as to meet five or six inches 
 before the nose. It is probalde. that in this case, the 
 picture of the ob'cct in the diverging eye, must fall upon 
 that part of the retina where the optic nerve enters; and 
 therefore the object could not be seen by that eye. 
 
snEixe. 35S 
 
 All the three have some defect in the sight of one eye, 
 which none of them knew until I put them upon making 
 trials ; and when they squint, the best eye is always di- 
 rected to the object, and the weak eye is that which di' 
 verges from it. But when the best eye is covered, the 
 weak eye is turned directly to the object. Whether this 
 defect of sight in one eye, be the effect of its having been 
 long disused, as it must have been when they squinted ; 
 or whether some original defect in one eye might be the 
 occasion of their squinting, time may diseover. The two 
 brothers have found the sight of the weak eye improved 
 by using to read with it while the other is covered. The 
 elder can read an ordinary print with the weak eye ; the 
 other as well as the third gentleman, can only read a large 
 print with the weak eye. I have met with one other per- 
 son only who squinted, and yet could read a large print 
 with the weak eye. He is a young man, whose eyes are 
 both tender and weak-sighted, but the left much weaker 
 than the right. When he looks at any object, he always 
 directs the right eye to it, and then the left is turned to- 
 ward the nose so much, that it is impossible for him to 
 see the same object with both eyes at the same time. 
 When the right eye is covered, he turns the left directly 
 to the object; but he sees it indistinctly, and as if it had 
 a mist about it. 
 
 I made several experiments, some of them in the com- 
 pany and with the assistance of an ingenious physician, 
 in order to diseover, whether objects that were in the 
 axes of the two eyes, were seen in one place confounded 
 together, as in those who have no involuntary squint. 
 The object placed in the axis of the weak eye was a light- 
 ed candle, at the distance of eight or ten feet. Before 
 the other eye was placed a printed book, at such a dis- 
 tance that he could read upon it. He said, that while 
 he read upon the book, he saw the candle but very faintly. 
 And from what we could learn, these two objects did not 
 appear in one place, but had all that angular distance in 
 appearance which they had in reality. 
 
 vox. I. 45 
 
364 OF THE HUMAN MIND. 
 
 If this was really the ease, the conclusion fo be drawn 
 from it is, that the corresponding points in his eyes are not 
 situate in the same manner as in other men ; and t hat if 
 he could he brought to direct both eyes to one object, he 
 would see it double. But considering that the young mao 
 had never been accustomed to observations of this kind, 
 and that the sight of one eye was so imperfect. 1 do not 
 pretend to draw this conclusion with certainty from this 
 single instance. 
 
 All that can be inferred from these facts is. that of four 
 persons who squint, three appear to have nothing preter- 
 natural in the structure of their eyes. The centres of 
 the retincB. and the points similarly situate with regard 
 to the centres, do certainly correspond in the same man- 
 ner as in other men. So that if they can be broughJ (o 
 the habit of directing their eyes right to an object, they 
 will not only remove a deformity, but improve their sight. 
 "With regard to the fourth, the case is dubious, with some 
 probability of a deviation from the usual course of nature 
 in the situation of the corresponding points of his eyes. 
 
 SECTION xvir. 
 
 OF THE EFFECT OF CUSTOM IN SEEING OBJECTS SINGIE. 
 
 It appears from the phenomena of single and double 
 vision, recited in sect. 13. that our seeing an object sin- 
 gle with two eyes, depends upon these two things. Firat» 
 upon that mutual correspondence of certain points of the 
 retince which we have often described. Secondly, upon 
 Jhe two eyes being directed to the object so accurately, 
 that the two images of it fall upon corresponding points. 
 These two things must concur in order to our seeing an 
 object single with two eyes ; and as far as they depend upon 
 custom, so far only can single vision depend upon custom. 
 
 "With regard to the second, that is, the accurate direc- 
 tion of both eyes to the object, I think it must be ao- 
 
SEEIX6. 35i 
 
 knowledged that this is only learned by custom. Kature 
 haih wisely ordained the eyes to move in such a manner, 
 that their axes shall always be nearly parallel ; hut hath 
 left it in our power to vary their inclination a little, ac- 
 coi-ding to the distance of the object we look at. "With- 
 oul this power, objects would appear single at one par- 
 ticular distance only ; and at distances much less, or much 
 greater, would always appear double. The wisdom of 
 nature is conspicuous in giving us this power, and no 
 less conspicuous in making the extent of it exactly ade- 
 quate to the end. 
 
 The parallelism of the eyes, in general, is therefore 
 the work of nature, but that precise and accurate direc- 
 tion, which must be varied according to the distance of 
 the object, is the effect of custom. The power which na- 
 ture hath left us of varying the inclination of the optic 
 axes a little, is turned into a habit of giving them always 
 thai inclination which is adapted to the distance of the 
 object. 
 
 But it may be asked, what gives rise to this habit? 
 The only answer that can be given to this question is, 
 that it is found necessary to perfect and distinct vision. 
 A man who hath lost the sight of one eye, very often 
 loses the habit of directing it exactly to the object he 
 looks at, because that habit is no longer of use to him. 
 And if he should recover the sight of his eye, he would 
 recover this habit, by finding it useful. No part of the 
 human constitution is more admirable than that whereby 
 we acquire habits which are found useful without any de- 
 sign 6v intention. Children must see imperfectly at first ; 
 but, by using their eyes, they learn to use them in the 
 best manner, and acquire, without intending it, the habits 
 necessary for that purpose. Every man becomes most 
 expert in that kind of vision which is most useful to him 
 in his particular profession and manner of life. A min- 
 iature painter, or an engraver, sees very near objects bet- 
 ter than a sailor; but the sailor sees very distant objects 
 muelt better than they. A person that is short-sighted, 
 
SS6 or T^IB HUMAN MINI). 
 
 in looking at distant objects gets the habit of contracting 
 the aperture of his eyes, by almost closing his eyelids. 
 Why? For no other reason, but because this makes him 
 gee the object more distinct. In like manner, the reason 
 why every man acquires the habit of directing both eyes 
 accurately to the object, must be, because thereby he sees 
 it more perfectly and distinctly. 
 
 It remains to be considered, whether that correspond- 
 ence between certain points of the retincB, which is like- 
 wise necessary to single vision, be the effect of custom, 
 or an original property of human eyes. 
 
 A strong argument for its being an original property, 
 may be drawn from the habit just now mentioned, of di- 
 recting the eyes accurately to an object. This habit is 
 got by our finding it necessary to perfect and distinct 
 vision. But why is it necessary? For no other reason 
 but this, because thereby the two images of the object 
 falling upon corresponding points, the eyes assist each 
 other in vision, and the object is seen better by both to- 
 gether, tlian it could be by one ; but when the eyes are 
 accurately directed, the two images of an object fall upon 
 points that do not correspond, whereby the sight of one 
 eye disturbs the sight of the other, and the object is seen 
 more indistinctly with both eyes than it would be with 
 one. Whence it is reasonable to conclude, that this cor- 
 respondence of certain points of the retince, is prior to the 
 habits we acquire in vision, and consequently is natural 
 and original. We have all acquired the habit of direct- 
 ing our eyes always in a particular manner, which causes 
 single vision. Now, if nature hath ordained that we 
 should have single vision only, when our eyes are thus 
 directed, there is an obvious reason why all mankind should 
 agree in the habit of directing them in this manner. But 
 if single vision is the effect of custom, any other habit of 
 directing the eyes would have answered the purpose ; and 
 no account can be given why this particular habit should 
 be so universal; and it must appear very strange, that 
 no one instance hath been found of a persou who had ac- 
 
sEEixe. 357 
 
 quired the habit of seeing objects single with both eyes, 
 while they were directed in any other manner. 
 
 The judicious Or. Smith, in his excellent System of 
 Optics, maintains the contrary opinion, and ofiers some 
 reasonings and facts in proof of it. He agrees with bishop 
 Berkeley in attributing it entirely to cu^itom, that we see 
 objects single with two eyes, as well as that we see ob- 
 jects erect by inverted images. Having considered bishop 
 Berkeley's reasonings in the lith section, we shall now 
 beg leave to make some remarks on what Dr. Smith hath 
 said upon this subject, with the respect due to an author 
 to whom the world owes, not only many valuable discov- 
 eries of his own, but those of the brightest mathematical 
 genius of his age, which, with great labour, he generously 
 redeemed from oblivion. 
 
 He observes, that the question, why we see objects sin- 
 gle with two eyes ? is of the same sort with this, why we 
 hear sounds single with two ears ? and that the same an- 
 swer must serve both. The inference intended to be 
 drawn from this observation is, that as the second of these 
 phenomena is the effect of custom, so likewise is the first. 
 
 Now I humbly conceive that the questions are not so 
 much of the same sort, that the same answer must serve 
 for both ; and moreover, that our hearing single with two 
 ears, is not the effect of custom. 
 
 Two or aiore visible objects, although perfectly similar, 
 and seen at the very same time, may be distinguished by 
 their visible places ; but two sounds perfectly similar, and 
 heard at the same time, cannot be distinguished : for, 
 from the nature of sound, the sensations they occasion 
 must coalesce into one, and lose all distinction. If there- 
 fore it is asked, why we hear sounds single with two ears ? 
 I answer, not from custom ; but because two sounds which 
 are perfectly like and synchronous, liave nothing by which 
 they can be distinguished. But will this answer fit the 
 other question ? I think not. 
 
 The object makes an apj)earance to each eye, as the 
 sound makes an impression upon each earj so far the 
 
358 6F THE HUMAN MllfU. 
 
 two senses agree. But tbe visible appearances may be 
 distinguished by place, when perfectly like in other re- 
 spects ; the sounds cannot be distinguished ; and herein 
 the two senses differ. Indeed, if I he two appearances 
 have the same visiible place, they are, in that case, as in- 
 capable of distinction as the sounds were, and we see the 
 object single. But when they have not the same visible 
 place, they are perfectly distinguishable, and we see the 
 object double. AVe see the object single only, when the 
 eyes are directed in one particular manner ; while there 
 are many other ways of directing them within the sphere 
 of our power, by which we see the object double. 
 
 Dr. Smith justly attributes to custom that well known 
 fallacy in feeling, whereby a button pressed with two op- 
 posite sides of two contiguous fingers laid across is felt 
 double. I agree with him, that the cause of this appear- 
 ance is, that those opposite sides of the 6ngers have never 
 been used to feel the same object, but two different objects, 
 at the same time. And I beg leave to add, that as cus- 
 tom produces this phenomenon, so a contrary custom de- 
 stroys it : for if a man frequently accustoms himself to 
 feel (he button with his fingers across, it will at last be 
 felt single ; as I have found by experience. 
 
 It may be taken for a general rule, thai things which 
 are produced by custom, may be undone or changed by 
 disuse, or by a contrary custom. On the other hand, it 
 is a strong argument, that an effect is not owing to cus- 
 tom, but to the constitution of nature, when a contrary 
 custom long continued, is found neither to change nor 
 weaken it. I take this to be the best rule by which we 
 can determine the question presently under consideration. 
 I shall therefore mention two facts brought by Dr. Smith, 
 to prove that the corresponding points of the retina have 
 been changed by custom ; and then I shall mention some 
 facts tending to prove, that there are corresponding points 
 of the retince of the eyes originally, and that custom prp- 
 duces no change in them. 
 
S££INe. S59 
 
 " One fact is related upon the authority of Martin 
 Folkes, Esq. who was informed by Dr, Hepburn of Lynn, 
 that the Reverend Mr. Foster of Clinchwarton^ in that 
 neighbourhood, having been blind for some years of a 
 gutta Serena, was restored to sight by salivation : and that, 
 upon his iirst beginning to see« all objects appeared to 
 him double ; but afterward the two appearances approach- 
 ing by degrees, he came at last to see single, and as diS' 
 tinetly as he did before be was blind." 
 
 Upon this case 1 observe, first, that it does not prove 
 any change of the corresponding points of the eyes, un- 
 less we suppose, what is not aflSrmed, that Mr. Foster di. 
 rected his eyes to the object at first, when he saw double, 
 with the same accuracy, and in the same manner, that he 
 did afterward when he saw single. 2dly, If we should 
 suppose this, no account can be given, why at first the 
 two appearances should be seen at one certain angular 
 distance rather than another; or why this angular dis- 
 tance should gradually decrease, until at last the appear- 
 ances coincided. How could this eflect be produced by 
 custom ? But, thirdly, every circumstance of this case 
 may be accounted for, on the supposition that Mr. Foster 
 bad corresponding points in the retinw of his eyes from 
 the time he began to see, and that custom made no change 
 with regard to them'. We need only further suppose, 
 what is common in such eases, that by some years blind- 
 ness be had lost the habit of directing his eyes accurately 
 tO' an' object, and that lie gradually recovered this habit 
 when he came to see. 
 
 The second fact mentioned by Dr. Smitli, is taken from 
 Mr. Cheselden's Anatomy ; and is this : ** A gentleman 
 who, from a blow on the head, had' one eye distorted, 
 found every object appear doublle ; but by degrees the 
 most familiar ones became single; and iutime all objects 
 became so, without any amendment of the distortions 
 
 I observe here, that it is not said that the two appear- 
 ances gradually approached, and at last nnit«d> without 
 
360 OF THE HTJMAX MIND. 
 
 any amendment of the distortion. This would indeed 
 have been a decisive proof of a change in the correspond- 
 ing points of the retincB; and yet of such a change as 
 could not be accounted for from custom. But this is not 
 said ; and if it had been observed, a circumstance so re- 
 markable would have been mentioned by Mr. Cheselden, 
 as it was in the other case by Dr. Hepburn. "We may 
 therefore take it for granted, that one of the appearances 
 vanished by degrees, without approaching to the other. 
 And this I conceive might happen several ways. First, 
 the sight of tlie distorted eye might gradually decay by 
 the hurt ; so the appearances presented by that eye would 
 gradually vanish. Secondly, a small and unperceived 
 change in the manner of directing the eyes, might occa- 
 sion his not seeing the object with the distorted eye, as 
 appears from sect. 15. art. 16. Thirdly, by acquiring 
 the habit of directing one and the same eye always to the 
 object, the faint and oblique appearance, presented by the 
 other eye, might be so little attended to when it became 
 familiar, as not to be perceived. One of these causes, or 
 more of them concurring, might produce the effect men- 
 tioned, without any change of the corresponding points of 
 the eyes. 
 
 For these reasons, the facts mentioned by Dr. Smith; 
 although curious, seem not to be decisive. 
 
 The following facts ought to be put in the opposite 
 scale. First, in the famous case of the young gentleman 
 couched by Mr. Cheselden. after having had cataracts on 
 both eyes until he was thirteen years of age, it appears, 
 that he saw objects single from the time he began to see 
 with both eyes. Mr. Cheselden's words are : " And now 
 being lately couched of his other eye, he says, that ob- 
 jects at first appeared large to this eye, but not so large 
 as they did at first to the other ; and looking upon the 
 same object with both eyes, he thought it looked about 
 twice as large as with the first couched eye only, but not 
 double, that we can anywise discover." 
 
SEKixe. 361 
 
 Second]^, tlie three young gentlemen mentioned in the 
 last section, who had squinted, as far as I know, from 
 infancy ; as soon as they learned to direct hoth eyes to 
 an oljject, saw it single. In these four cases it appeiirs 
 evident, that the cent res of the retince corresponded orig- 
 inally, and hefore custom could produce any such effect ; 
 for Mr. Cheselden's young gentleman had never been ac- 
 customed to see at all before he was couched ; and the 
 other three had never been accustomed to direct the axes 
 of both eyes to the object. 
 
 Thirdly, From the facts recited in sect. 13. it appears, 
 that from the time we are capable of observing the phe- 
 nomena of single and double vision, custom makes no 
 change in them. 
 
 I have amused myself with such observations for more 
 than thirty years ; and in every ease wherein I saw the 
 object double at first, I see it is so to this day, notwith- 
 standing the constant experience of its being single. In 
 other cases where I know there are two objects, thei^e ap- 
 pears only one, after thousands of experiments. 
 
 Let a man look at a familiar object tlirough a polyhe- 
 dron or multiplying glass every hour of his life, the num- 
 ber of visible appearances will be the same at last as at 
 first : nor does any number of experiments, or length of 
 time, make the least change. 
 
 Effects produced by habit, must vary according as the 
 acts by which the habit is acquired are more or less fre- 
 quent : but the phenomena of single and double vision are 
 so invariable and uniform in all men, are so exactly reg- 
 ulated by mathematical rules, that I think we have good 
 reason to conclude, that they are not the effect of custom, 
 but of fixed and immutable laws of nature. 
 
 vox. I. 46 
 
 y 
 
562 OF TUB HUMAN MIND. 
 
 SECTION xvin. 
 
 «F DR. PORTERFIELD'S ACCOUNT OF SINGLE AND DOUBLE VISION. 
 
 Bishop Berkeley and Dr. Sinilh seem to attribute too 
 much to custom in vision ; Dr. Porterfield too little. 
 
 This in,^enious writer thinks, that, by aff original law 
 of our nature, antecedent to custom and experience, we 
 perceive visible objects in their true place, not only as to 
 their direction, but likewise as to their distance from the 
 eye: and therefore he accounts for our seeing objects 
 single, with two eyes, in this manner. Having the fac- 
 ulty of perceiving the object with each eye in its true 
 place, we must perceive it with both eyes in the same 
 place; and consequently must perceive it single. 
 
 He is aware, that this principle, although it accounts 
 for our seeing objects single with two eyes, yet does not 
 at all account for our seeing objects double : and whereas 
 other writers on this subject take it to be a sufficient 
 cause for double vision that we have two eyes, and only 
 find it difficult to a^^sign a cause for single vision ; on the 
 contrary Dr. Porterfield's principle throws all the diffi- 
 culty on the other side. 
 
 Therefore, in order to account for the phenomena of 
 double vision, he advances another principle, without sig- 
 nifying whether he conceives it to he an original law of 
 our nature, or the effi^ct of custom. It is, that our nat- 
 ural perception of the distance of objects from the eye, 
 is not extended to all the objects that fall within the field 
 of vision, but limited to that which we directly look atj 
 and that the circumjacent objects, whatever be their real 
 distance, are seen at the same distance with the object 
 Ave look at ; as if they were all in the surface of a sphere 
 whereof the eye is the centre. 
 
 Thus, single vision is accounted for by our seeing the 
 trufe distance of an object which we look at; and double 
 vision, by a false appearance of distance in objects which 
 we do not directly look at. 
 
sEEixe. 363 
 
 We agree with this learned and ingenious author, that 
 it is by a natural and original princi|)le that we see visible 
 objects in a certain direction from the eye, and honour 
 hiiu as the author of this discovery : but we cannot assent 
 to either of those principles by which he explains single 
 and double vision, for ihe following reasons : 
 
 1. Our having a natural and original perception of the 
 distance of objects from the eye, appears contrary to a 
 well attested fact: for the young gentleman couched by 
 Mr. Cheselden, iittagined at first, that whatever he saw* 
 touched his eye, as what he felt touched his hand. 
 
 2. The perception we have of tiie distance of objects 
 from the eye, whether it be from nature or custom, is not 
 so accurate and determinate as is necessary to produce 
 single vision. A mistake of the twentieth or thirtieth 
 part of the distance of a small object, such as a pin, ought, 
 according to Dr. Porterfield's hypothesis, to make it ap- 
 pear double. Very few can judge of the distance of a 
 visible object with such accuracy. Yet we never find 
 double vision produced by mistaking the distance of the 
 object. There are many cases in vision, even with the 
 naked eye, wherein we mistake the distance of an object 
 by one half or more : why do we see such objects single ? 
 When I move my spectacles from my eyes toward a small 
 object two or three feet distant, the object seems to ap- 
 proach, so as to be seen at last at about half its real dis- 
 tance, but is seen single at that apparent distance, as well 
 as when we see it with the naked eye at its real distance. 
 And when we look at an object with a binocular telescope, 
 properly fisted to the eyes, we see it single, while it appears 
 fifteen or twenty times nearer than it is. There are then 
 few cases wherein the distance of an object from the eye 
 is seen so accurately as is necessary for single vision, up- 
 on this hypothesis. This seems to be a conclusive argu- 
 ment against the account given of single vision. We find 
 likewise, that false judgmenj^s or fallacious appearances 
 of the distance of aa object^ do not produce double vis- 
 ion. 
 
364 OF THE HUMAN MIND. 
 
 This seems to be a conclusive argument against the ac- 
 count given of double vision. 
 
 3. The iierception we have of the linear distance of ob- 
 jects, seems to be wholly the effect of experience. This I 
 think hath been proved by bishop Berkeley and by Dr. 
 Smith ; and when we come to point out the means of 
 of judging distance by sight, it will appear that they are 
 all furnished by experience. 
 
 4. Supposing that by a law of our nature, the distance 
 of objects from the eye were perceived most accurately, 
 as well as their direction, it will not follow that we must 
 see the object single. Let us consider what means such 
 a law of nature would furnish for resolving the question, 
 Whether the objects of the two eyes are in one and the 
 same place, and consequently are not two, but one ? 
 
 Suppose ihen two right lines, one drawn from the cen- 
 tre of one eye (o its object, the other drawn, in like man- 
 ner from the centre of the other eye to its object. This 
 law of nature gives us the direction or position of each of 
 these right lines, and the length of each ; and this is all 
 that it'gives. These are geometrical data, and we may 
 learn from geometry what is determined by their means. 
 Is it then determined by these data, whether the two 
 right lines terminate in one and the same point, or not ? 
 No. truly. In order to determine (biff, we must have three 
 other data. We must know whether the two right 
 lines are in one plane ; we must know what angle they 
 make, and we must know the distance between the cen- 
 tres of the eyes. And, when these things are known, we 
 must apply the rules of trigonometry, before we can re- 
 solve the question, whether the objects of the two eyes 
 are in one and the same place 5 and consequently whether 
 they are two or one ? 
 
 5. That false appearance of distance into which double 
 vision is resolved, cannot be the effect of ' custom ; 
 for constant experience contradkts it : Neither hath 
 it the features of a law of nature; because it does 
 not answer any good purpose, nor indeed any pur- 
 
SEEIN®, 365 
 
 pose at all but to deceive us. But why should we seek 
 for arguments, in a question eoncei-ning what appears to 
 us, or does not appear ? The question is. At what distance 
 do the objects now in my eje apjtear? Do they all appear 
 at one distance, as if placed in the concave surface of a 
 sphere, the eye being in the centre ? Every man surely 
 may know this with certainty : and, if he will but give at- 
 tention to the testimony of his eyes, needs not ask a 
 philosopher, how visible objects appear to him. Now, it 
 is'very true, that if I look up to a star in the heavens, 
 the other stars that appear at the same time, do appear 
 in this manner ; yet this phenomenon does not favour 
 Dr. Porterfield's hypothesis; for the stars and heavenly 
 bodies, do not appear at their true distances when we 
 look directly to them anymore when they are seen 
 obliquely ; and if this phenomenon be an argument for 
 Dr. Porterfield's second priBciple, it must destroy the 
 first. 
 
 The true cause of this phenomenon will be given after- 
 ward : therefore, setting it aside for the present, let us put 
 another case. I sit in my room, and direct my eyes to 
 the door, which appears to be about sixteen feet distant : 
 at the same time I see many othef objects faintly and 
 obliquely; the floor, floor-cloth, the tsible which I write 
 upon, papers, standish, candle, &o. Now, do all tliese 
 objects appear at the same distance of sixteen feet ? Upon 
 the closest attention, I find they do not. 
 
 SECTION XIX. 
 
 OF DR. BRIGG'S THEORY, AND SIR ISAAC NEWTON'S CONJECTURE ON 
 THIS SUBJECT. 
 
 I AM afraid the reader, as well as the writer, is already 
 tired of the subject of single and double vision. The mul- 
 titude of theories advanced by authors of great name, 
 and the multitude of facts, observed without sufficient 
 skill in optics^ or related without attention to the most 
 
366 G¥ THE HUMAN MIND. 
 
 material and decisive circumstances, have equally con- 
 tributed to perplex it. 
 
 In order to bring it to some issue, I have, in the 13th 
 section, given a more full and regular deduction than had 
 been given heretofore, of the phenomena of single and 
 double vision, in those whose sight is perfect; and have 
 traced them up to one general principle, which appears 
 to be a law of vision in human eyes tl^t are perfect and 
 in their natural state. 
 
 In the 14th section I have made it appear, that, this 
 law of vision, although excellently adapted to the fabric 
 of human eyes, cannot answer the purposes of vision in 
 some other animals ; and therefore, very probably, is not 
 common to all animals. The purpose of the 15tb and 
 16lh sections is, to inquire, whether there be any de- 
 viation from this law of vision in those who squint ? a 
 question which is of real importance in the medical art, 
 as well as in the philosophy of vision ; but which, after 
 all that hath been observed and written on the subject, 
 seems not to be ripe for a determination, for want of 
 proper observations. Those who have had skill to make 
 proper observations, have wanted opportunities ; and those 
 vho have had opportunities, have wanted skill or atten- 
 tion. I have therefore thought it worth while to give a dis- 
 tinct account of the observations necessary for the deter- 
 mination of this question, and what conclusions may be 
 drawn from the facts observed. I have likewise collected, 
 and set in one view, the most conclusive facts that have 
 occurred in authors, or have fallen under my own bbserva- 
 tion. 
 
 It must be confessed, that these facts, when applied to 
 the question in hand, make a very poor figure ; and the 
 gentlemen of the medical faculty are called upon, for the 
 honour of their profession, and for the benefit of man- 
 kind, to add to them. 
 
 All the medical, and all the bptical writers, upon the 
 strabismus, that I have met witli, except Dr. Jurin, either 
 affirm, or take it for granted, that squinting persons see 
 the object with both eyes, and yet see it single. Dr. 
 
s££ixe. 367 
 
 Jurioi affirms, that squinting persons never see the object 
 with bolh e;^e3; and that if thej did, they would see it 
 double. If the common opinion be true, the cure of a 
 squint would be as pernicious to the sight of the patient, 
 as (he causing of a permanent squint would be to one 
 who naturalij had no squint : and therefore no physi- 
 cian ought to attempt such a cure; no patient ought to 
 submit to it. But if Dr. Jurin's opinion be true, most 
 young people that squint may cure themselves, by taking 
 some pains ; and may not only remove the deformity, but 
 at the same time improve their sight. If the common 
 opinion be true, the centres and other points of the two 
 retinae in squinting persons do not correspond as in other 
 men, and nature in them deviates from her common rule. 
 But if Dr. Jurin's opinion be true, there is reason to think, 
 that the same general law of vision which we have found 
 in perfect human eyes, extends also to those which squint. 
 It is impossible to determine, by reasoning, which of these 
 opinions is true ; or whether one may not be found true 
 in sonie patients, and the other in others. Here, expe- 
 dience and observation are our only guides ; and a de- 
 duction of instances, is the only rational argument. It 
 might therefore have been expected, that the patrons of 
 the contrary opinions should have given instances, in sup- 
 port of them, that are clear and indisputable : but I have 
 not found one such instance on either side of thequestion, 
 in all the authors I have niet with. I have given three in- 
 stances from my own observation, in confirmation of Dr. 
 Jurin's opinion, which adniit of no doubt ; and one, which 
 leans rather to the other opinion, but is dubious. And 
 here I must leave the matter to further observation. 
 
 In the 17th section, I have endeavoured to shew, that the 
 correspondence and sympathy of certain points of the 
 two retince, into which we have resolved all the phenom- 
 ena of single and double vision, is not, as Dr. Smith con- 
 ceived, the effect of custom, nor changed by custom, but 
 is a natural and original property of human eyes : and 
 in the last section, that it is not owing to an original and 
 natural perception of the true distance of objects from the 
 
368 OF THE HUMAN MIND. 
 
 eye, as Dr. Porterfield imagined. After this recapitula- 
 tion, which is intended to relieve the attention of the 
 reader, shall we enter into more theories upon this sub'-' 
 ject. 
 
 That of Dp. Briggs, first published in English, in the 
 Philosophical Transactions, afterward in Latin, under 
 the title of Nova visionis theoria, with a prefatory 
 epistle of Sir Isaac Newton to the author, amounts to 
 this, that the fibres of the optic nerves passing from cor- 
 responding points of the retince to the thai ami nervorum 
 optieorum, having the same length, the same tention, and 
 a similar situation, will have the same tone ; and there- 
 fore their vibrations, excited by the impression of the 
 rays of light, will be like unisons in music, and will pre- 
 sent one and the same image to the mind ; but the fibres 
 passing from parts of the retince, which do not corres- 
 pond, having different tentions and tones, will have dis- 
 cordant vibrations ; and therefore present different images 
 to the mind. 
 
 I shall not enter upon a particular examination of this 
 theory. It is enough to observe, in general, that it is a 
 system of conjectures concerning things of which we are 
 entirely ignorant ; and that all such theories in philoso- 
 phy deserve rather to be laughed at, than to be seriously 
 refuted. 
 
 From the first dawn of philosophy to this day, it hath 
 been believed that the optic nerves are intended to carry 
 the images of visible objects from the bottom of the eye 
 to the mind ; and that the nerves belonging to the organs 
 of the other senses have a like office. But how do we 
 know this? We conjecture it ; and taking this conjecture 
 for a truth, we consider how the nerves may best answer 
 this purpose. The system of the nerves, for many ages, 
 was taken to be a hydraulic engine, consisting of a bundle 
 of pipes, which carry to and fro a liquor called animal 
 spirits. About the time of Dr. Briggs, it was thought 
 rather to be a stringed instrument, composed of vibrating 
 chords, each of which had its proper tension and tone. 
 
SEEING. 369 
 
 But some, Avith as great probability, conceived it (o be a 
 wind instrument, wliicb iilajed its part bj tbe vibrations 
 of an elastic ether in the nervous librils. 
 
 These, I <hink, are all (be engines info which the ner- 
 vous system hath been moulded by philosophers, for con- 
 veying the images of sensible (hings from tbe organ to 
 the serasorium. And for all that we know of tbe mat- 
 ter, every man may freely choose which be thinks fittest 
 for tbe purpose ; for. from fact and experiment, no one 
 of Ibem can claim preference loanoilier. Indeed, they all 
 seem so unhandy engines for carrying images, that a man 
 would be tempted lo invent a new one. 
 
 Since therefore, a blind man maj guess as well in the 
 dark as one that sees, 1 beg leave lo offer anoiber con- 
 jecture touching- tbe nervous system, which I hope will 
 answer tbe purpose as well as those we have mentioned, 
 and which recommends itself by its simplicity. Why may 
 not the optic nerves, for instance, be made up of empty 
 tubes opening their mouths wide enough to receive the 
 rays of light which form- tbe image upon the retinae., and 
 gently conveying them safe, and in their proper order to 
 the very seat of the soul, until they flash in her face ? It is 
 easy for an ingenious philosopher to fit tlie caliber of these 
 empty tubes to the diameter particles of light, so as they 
 shall receive no grosser kind of matter. And if these 
 rays should be in danger of mistaking their way, an expe- 
 dient may also be found to prevent this. For it requires 
 no more than to bestow upon the tubes of the nervous 
 system a peristaltic motion, like that of the alimentary 
 tube. 
 
 It is a peculiar advantage of this hypothesis, that, al- 
 though all philosophers believe that the species or images 
 of things are conveyed by (be nerves to tbe soul, yet none 
 of their hypotheses shew how this may be done. For how 
 can the images of sound, taste, smell, colour, figure, and 
 all sensible qualities be made out of the vibrations of mu- 
 sical chords, or the undulations of animal spirits, or of 
 either ? We ought not to suppose means inadequate to the 
 
 vol. I. 47 
 
SyO OF THE HUMAN MIND. 
 
 end. Is it not as philosophical, and more intelligible, tw 
 conceive, that as the stomach receives its food, so the 
 soul receives her images by a kind of nervous degluti- 
 tion ? I might add. that we need only continue this peri- 
 staltic motion of the nervous tubes from the sensorium 
 to the extremities of the nerves that serve the muscles, 
 in order to account for muscular moiion. 
 
 Thus nature will be consonant to herself; and as sen- 
 sation will be the conveyance of the ideal aliment to (he 
 mind, so muscular motion will be the expulsion of the 
 recrementitious part of it. For who can deny,' that the 
 images of things conveyed by sensation, may after due 
 concoction, become fit to be thrown off by muscular mo- 
 tion ? I only give hints of these things to be ingenious, 
 hoping that in time this hypothesis may be brought up 
 into a system as philosophical, as that of animal spirits, 
 or the vibration of the nervous fibres. 
 
 To be serious : in the operations of nature, I hold the 
 theories of a philosopher, which are unsupported by fact, 
 in the same estimation with the dreams of a man asleep, 
 or the ravings of a madman. We laugh at the Indian 
 philosopher, who to account for the support of the earth, 
 contrived the hypothesis of a huge elephant, and to sup. 
 port the elephant, a huge tortoise. If we will candidly 
 confess the truth, we know as little of the operation of 
 the nerves, as he did of the manner in which the earth 
 is supported; and our hypothesis about animal spirits, or 
 about the tension and vibrations of the nerves, are as like 
 to be true, as his about the support of the earth. His 
 elephant was a hypothesis, and our hypotheses are ele- 
 phants. Every theory in philosophy, which is built on 
 pure conjecture, is an elephant; and every theory that is 
 supported partly by fact, and partly by conjecture, is like 
 Nebuchadnezzar's image, whose feet were partly of iron, 
 and partly of clay. 
 
 The great Newton first gave an example to philoso- 
 phers, which always ought to be, but rarely hath been 
 followed, by distinguishing his conjectures from his con- 
 
sEEiNe. 371 
 
 elusions, and putting the former by themselves, in the 
 modest form of queries. This is fair and legal ; but all 
 other philosophical traffic in conjecture, ought to be held 
 contraband and illicit. Indeed his conjectures have com- 
 monly more foundation in fact, and more verisimilitude, 
 tlian the <logmatical theories of most otljjer philosophers ; 
 and therefore we ought not to omit that which he hatli 
 offered concerning the cause of our seeing objects single 
 with two eyes, in the 15th query annexed to his Optics. 
 " Are not the species of objects seen with both eyes, 
 united where the optic nerves meet before they come into 
 the brain, the fibres on the right side of both nerves unit- 
 ing there, and after union going tlienee into tiie brain in 
 the nerve which is on the right side of the head, and the 
 fibres on the left side of both nerv«s uniting in the same 
 place, and after union going into the brain in the nerve 
 which is on the left side of the head ; and these two 
 nerves meeting in the brain in such a manner that their 
 fibres make but one entire species or picture, half of 
 which on the right side of the sensoriuin comes from the 
 right side of both eyes through the right side of both optic 
 nerves, to the place where the nerves meet, and from 
 thence on the right side of the head into the brain, and 
 ]the other half on the left side of the sensorium comes, in 
 like manner, from the left side of both eyes ? For the 
 optic nerves of such animals as look the same way with 
 both eyes, as men, dogs, sheep, oxen, &g. meet before 
 they come into the brain j but the optic nerves of such 
 animals as do not look the same way with both eyes, as 
 of fishes and of the cameleon, do not meet, if I am rightly 
 informed," 
 
 I beg leave to distinguish this query into two, which 
 are of very different natures ; one being purely anatom- 
 ical, the other relating to the carrying species or pictures 
 of visible objects to the sensorium. 
 
 The first question is, whether the fibres coming from 
 corresponding points of the two retincB, do not unite at 
 the place where the optic nerves meet, &uA continue united 
 
372 »r THE HUMAIf MIND. 
 
 from thence to the brain ; so that the right optic nerve, 
 after the meeting of (he two nerves, is composed of the 
 fibres coming from (he right side of both retinw, and the 
 lef( of ( he libres coming from the left side of both retinm'J 
 
 This is undoubtedly a curious and rational question ; be- 
 cause if we could find ground from anatomy to answer it 
 in the at!irma(ive, i( would lead us a siep forward in dis- 
 covering the cause of (he correspondence and sympathy 
 whicli (here is between certain points of the two retince. 
 For although we know not what is the particular func- 
 tion of the optic nerves, yet it is probable, that some im- 
 pression made upon (hem. and communicated along their 
 fibres, is necessary to vision : and whatever be the nature 
 of this impression, if two fibres are uni(ed into one, an 
 impression made upon one of them, or upon both, may 
 probably produce the same effect. Anatomists think it 
 a sufficient account of a sympathy between two parts of 
 the body, when they are served by branches of the same 
 nerve : we should then'fore look upon il as an important 
 discovery in anatomv, if it were found that the same nerve 
 sent branches (o the corresponding points of the retinas. 
 
 But hath any such discovery been made ? No, not so 
 much as in one subject, as far as I can learn. But in 
 several subjects, the contrary seems to have been discov- 
 ered. Dr. Porterfield hath given us two cases at length 
 from Vesalius, and one from Csesalpinus, wherein the 
 optic nerves, after touching one another as usual, appear- 
 ed (o be reflected back to the same side whence they came, 
 without any mixture of their fibres. Each of these per- 
 sons had lost an eye some lime before his death, and the 
 optic nerve belonging to that eye was shrunk, so that it 
 could be distinguished from the other at the place where 
 they met. Another case whicli the same author gives 
 from Vesalius, is etill more remarkable ; for in it the op- 
 tic nerves did not touch at all ; and yet, upon inquiry, 
 those wiio svere most familiar with the person in his life- 
 time, declared that he never complained of any defect of 
 sight, op of his seeing objects double. Diemerbroeck tells 
 
SEBINfi. 37S 
 
 us, that Aquapemlens and Yalverda likewise affirm, that 
 they have met with subjects wherein the optic nerves did 
 not touch. 
 
 As these observations were made before Sir Isaac New- 
 ton put this query, it is uncertain whether he was ignoT 
 rant of them, or whether he suspected some inaccuracy 
 in them, and desired that the matter might be more care- 
 fully examined. But from the following passage of the 
 most accurate Winslow, it does not appear, that later ob- 
 servations have been more favourable to his conjecture, 
 "The union of these [optic] nerves, by the small curva- 
 tures of their cornua, is very difficult to be unfolded in 
 human bodies. This union is commonly found to be very 
 close, but in some subjects it seems to be no more than 
 a strong adhesion, in others to be partly made by an in- 
 tersection or crossing of fibres. They have been found 
 quite separate ; and in other subjects, one of Ihem has 
 been found to be very much altered buih in size and col- 
 our, through its whole passage, the other remaining in 
 its natural state." 
 
 When we consider this conjecture of Sir Isaac Newton 
 by itself, it appears mure ingenious, and to have more 
 verisimilitude, than any thing that has been offered u)ion 
 the subject ; and we admire the caution and modesty of 
 the author, in proposing it only as a subject of inquiry : 
 but when we compare it with the observations of anato- 
 mists which contradict it, we are naturally led to this re- 
 flection, that if we trust to the conjectures of men of the 
 greatest genius in the operations of nature, we have only 
 the chance of going wrong in an ingenious manner. 
 
 The second part of the query is, Whether the two spe- 
 cies of objects from the two eyes are not, at the place 
 where the optic nerves meet, united into one species or 
 picture, half of which is carried thence to the sensorium 
 in the right optic nerve, and the other half in the left ? 
 and whether these two halves are not so put together 
 ^gain at the sensorium, as to make one species or picture ? 
 
OF THE HUMAPr MIND. 
 
 Here it seems natural to put the previous question, 
 What reason have we to believe, (hat pictures of objects 
 are at all carried to the sensorium, either by (he optic 
 nerves, or by any other nerves ? Is iL not possible, that 
 this great philosopher, as well as many of a lower form, 
 having been led into this opinion at iirst by education, 
 may have continued in it, because he never (houglit of 
 calling it in question ? 1 confess this was n»y own ease for 
 a considerable part of my life. But since I was led by 
 accident to think seriously what reason I had to believe 
 it, I could find none at all. It seems to be a mere hy- 
 pothesis, as much as the Indian philosopher's elephant. 
 I am not conscious of any pictures of external oh ects in 
 my sensorium, any more than in my stomach : the things 
 which I perceive by my senses, appear to be external, and 
 not in any part of the brain ; and my sensations, properly 
 so called, have no resemblance of external objects. 
 
 The conclusion from all that hath been said, in no less 
 than seven sections, upon our seeing objects single with 
 two eyes, is this, that, by an original property of human 
 eyes, objects painted upon the centres of the two veiince, 
 or upon points similarly situate with regard to the cen- 
 tres, appear in the same visible place ; that (he most 
 plausible attempts to account for this property of the eyes, 
 have been unsuccessful ; and therefore, that it must be 
 either a primary law of our constitution, or the conse- 
 quence of some more general law which is not yet dis- 
 covered. 
 
 We have now finished what we intended to say, both 
 of the visible appearance of things to the eye, and of the 
 laws of our constitution by which those appearances are 
 exhibited. But it was observed, in the beginning of this 
 chapter, that the visible appearances of objects serve only 
 as signs of their distance, magnitude, figure, and other 
 tangible qualities. The visible appearance, is that which 
 is presented to the mind by nature, according to those 
 laws of our constitution, which have been explained. But 
 
SEEING. S7B 
 
 the thing signified by that appearance, is that which is 
 presented to the mind by custom. 
 
 When one speaks to us in a language that is familiar, 
 we hear certain sounds, and this is all the effect that his 
 discourse has upon us by nature : but by custom we un- 
 derstand the meaning of these sounds; and therefore we 
 fix our attention, not upon the sounds, but upon the things 
 signified by them. In like manner, we see only the vis- 
 ible appearance of objects by nature ; but we learn by 
 custom to interpret these appearances, and to understand 
 their meaning. And when this visual language is learn- 
 ed, and becomes familiar, we attend only to the things 
 signified ; and cannot, without great difficulty, attend to 
 the signs by which they are presented. The mind passes 
 from one to the other so rapidly, and so familiarly, that 
 no trace of the sign is left in the memory, and we seem 
 i mined lately, and without the intervention of any sign, to 
 perceive the thing signified. 
 
 When F look at the apple-tree, which stands before 
 ray window, I periieive, at the first glance, its distance 
 and magnitude, the roughness of its trunk, the disposition 
 of its branches, the figure of its leaves and fruit. I seem 
 to perceive all these things immediately. The visible 
 appearance which presented them all to the mind, has 
 «ntirely escaped me; I cannot, without great difficulty, 
 and painful abstraction, attend to it, even when it stands 
 before me. Yet it is certain, that this visible appeatance 
 only, is presented to my eye by nature, and that I learn- 
 ed by custom to collect all the rest from it. Jf I had 
 never seen before now, I should not perceive either the 
 distance or tangible figure of the tree, and it would have 
 required the practice of seeing for many months, to 
 change that original perception which nature gave me by 
 my eyes, into that which I now have by custom. 
 
 The objects which we see naturally and originally, as 
 hath been before observed, have length and breadth, but 
 no thickness, nor di'^tance from the eye. Custom, by a kind 
 of legerdemain, withdraws gradually these original and 
 
376 OF THE HUMAN MIND. 
 
 proper objects of sight, and substitutes in their place ob- 
 jects of tuuch, which have length, breadth, and tiiickness^ 
 and a determinate distance from the e^e. By what means 
 this change is brought about, and what |«rinci|iles of the 
 human mind concur in it, we are next to inquire. 
 
 SECTION XX. 
 OF PEECEPTION IN GENERAIi. 
 
 Sensation, and the perception of external objects by 
 the senses, though very different in their nature, have 
 commonly been considered as one and the same thing. 
 The purposes of common life do not make it necessary to 
 distinguish them, and the received opinions of. philoso- 
 phers tend rather to confound tliem ; but, without attend- 
 ing carefully to this distinction, it is impossible to have 
 any just conception of the operations of our senses. The 
 most simple operations of the mind, admit not of a logical 
 definition : all we can do is to describe them, so as to lead 
 those who are conscious of them in themselves, to attend 
 to them, and reflect upon them : and it is oflen very dif- 
 ficult to describe them so as to answer this intention. 
 
 The same mode of expression is used to denote sensa- 
 tion and perception ; and therefore we are apt to look 
 tipon them as things of the same nature. Thus I feel a 
 pain; I see a tree: the first denoted) a sensation, the last 
 a perception. The grammatical analysis of both expres- 
 sions is the same, for both consist of an active verb and 
 an object. But. if we attend to the things signiffed by 
 these expressions, we shall find, that in the first, the dis- 
 tinction between the act and the ob ect is not real but 
 grammatical ; in the second, the distinction is not only 
 grammatical but real. 
 
 The form of the expression, I feel jtain, might seem 
 to imply, that the feeling is something distinct from the 
 pain felt j yet in reality, there is no distinction. As think- 
 
SEEING. 377 
 
 tng a thought is an expression whicli could signify no more 
 than thinking, so feeling a pain signifies no more than , 
 being pained. Wtiat we have said of pain is applicable 
 to every other mere sens'ation. It is difficult to give in- 
 stances, very few of our sensations having names ; and 
 where they have, the name being common to the sensa- 
 tion, and to something else which is associated with it. 
 But when we attend to the sensation by itself, and sepa- 
 rate it from other things whieh are conjoined with it in 
 the imagination, it appears to be something which can 
 have no existence hut in a sentient mind, no distinction 
 from the act of the mind by which it is felt. 
 
 Perception, as we here understand it, hath always an 
 object distinct from the act by whieh it is perceived ; an 
 object which may exist whether it be perceived or not. I 
 perceive a tree that grows before my window ; there is 
 here an object which is perceived, and an act of the mind 
 by which it is perceived ; and these two are not only dis- 
 tinguishable, but they are extremely unlike in their na- 
 tures. The object is made up of a trunk, branches, and 
 leaves ; hut the act of the mind, by which it is perceived, 
 hath neither trunk, branches, nor leaves. I am conscious 
 of this act of mind, and I can reflect upon it | but it is too 
 simple to admit of an analysis, and 1 cannot find proper 
 words to describe it. I find nothing titat resembles it so 
 much as the remembrance of the tree,or the imagination 
 of it. Yet both these differ essentially from perception ; 
 they differ likewise one from another. It is in vain that 
 a philosopher assures me, that the imagination of the tree, 
 the remembrance of it, and the perception of it, ai-e all 
 one, and differ only in degree of vivacity. I know the 
 contrary ; for I am as well acquainted with all the three, 
 as I am with the apartments of my own house. I know 
 this also, that the perception of an object implies both a 
 conception of its form, and a belief of its present exist- 
 ence. I know, moreover, that this belief is not the ef- 
 fect of argumentation and reasoning j it is the immediate 
 effect of my constitution. 
 
 Tox. J. 48 
 
S7S OF THE HUMAN MISTD. 
 
 I am aware, (hat this belief which I have in perception, 
 stands exposed to tlie strongettt batteries of skepticism. 
 But the^ malvc no great impression upon it. The slieplic 
 asks me, Whydo j'oii believe the existence of tiie external 
 object which you perceive ? This belief, sir, is none of 
 my manufacture ; it came from the mint of nature ; it 
 bears her image and superscription ; and, if it is. not 
 right, the fault is not mine : I even took it upon trust, 
 and without suspicion. Reason, says the skeptic, is the 
 only judge of truth, and you ought to throw off every 
 opinion and every belief that is not grounded on reason* 
 A¥hy, sir, should I believe the faculty of reason more 
 than that of perception ; they came both out of (he same 
 shop, and were made by the same artist ; and if he puts 
 one piece of false ware into my hands, what should hin- 
 der him from' putting ano(her ? 
 
 Perhaps the skeptic will agree to distrust reason, rath- 
 er than give any credit to perception. For, says he. since, 
 by your own concession, the object which you perceive^ 
 and (hat act of your mind by which you perceive it, are 
 quite different things, the one may exist without the oth- 
 er; and as the object may exist without being perceived, 
 so the perception may exist without an object. There 
 is nothing so shameful in a philosopher as to be deceived 
 and deluded ; and therefore you ought to resolve firmly 
 to withhold assent, and to throw off all his belief of ex- 
 ternal objects, which may be all delusion. For my part, 
 I will never attempt to throw it off; and although the 
 sober part of mankind will not be very anxious to know 
 my reasons, yet if they can be of use to any skeptic, they 
 are these. 
 
 First, Because it is not in my power: why (hen should 
 I make a vain attempt? It would be agreeable to fly to 
 the moon, and to make a visit to Jupiter and Saturn ; but 
 when I know that nature has bound me down by the law 
 of gravitation to this planet which I inhabit, I rest con- 
 tented, and quietly suffer myself to be carried along in its 
 erbit. My belief is carried along by perception, as irre- 
 
SEEiwe. 37* 
 
 sis(il)ly as my body by the earth. And the greatest 
 skeptic will find himself to be in the same condition. He 
 may struggle hard (o disbelieve the information of his 
 senses, as a man does to swim against a torrent; but ah ! 
 it is in vain. It is in vain that he strains every nerve, 
 and wrestles with nature, and with every object that 
 strikes upon his senses. For after all, when his strength 
 is spent in the fruit less attempt, he will be carried down 
 the torrent with the common herd of believers. 
 
 Secondly, I think it would not be prudent to throw off 
 this belief, if it were in my power. If nature intended to 
 deceive me, and impose upon me by false appearances, 
 and I, by my great cunning and profound logic, have 
 discovered the imposture; prudence woald dictate to 
 me in this case, even to put up this indignity done me 
 as quietly as I could, and not to call her' an impostor 
 to her face, lest she should be even with me anoth- ; 
 er way. For what do I gain by resenting this injury ? 
 You ought at least not to believe what she says. This 
 indeed seems reasonable if she intends to impose upon 
 me. But what is the consequence ? i resolve not to be- 
 lieve my senses. I break my nose against a post that 
 comes in my way ; I step into a kennel ; and, after twenty 
 such wise and rational actions,! am taken up and clapped 
 into a mad-house. Now, I confess I would rather make one 
 of the credulous fools whom nature imposes upon, than of 
 those wise and rational philosophers who resolve to with- 
 hold assent at all this expense. If a man pretends to be a 
 skeptic with regard to the informations of sense, and yet 
 prudently keeps out of harm's way as other men do, he 
 must excuse my suspicion, that he either acts the hypo- 
 crite, or imposes upon himself. For if the scale of his 
 belief were so evenly poised, as to lean no more to one 
 side than to the contrary, it is impossible that his actions 
 could be directed by any rules of common prudence. 
 
 Thirdly, AUhough the two reasons already mentioned 
 are perhaps two more than enough, I shall offer a third. 
 I gave im])lieit belief to the informations of nature by my 
 senses, for a considerable part of my life, before 1 had 
 
380 OF THE HUiMAN MIND. 
 
 learned so much logic as to be able to start a doubt con- 
 cerning them. And now, when I reflect upon what is 
 past, I do not find that I have been imposed upon by this 
 belief. I find, that without it I must have perished by a 
 thousand accidents. I find, that without it I should have 
 been no wiser now than when I was born. I should not 
 even have been able to acquire that logic which suggests 
 these skeptical doubts with regard to my senses. Therefore 
 I consider this instructive belief as one of the best gifts 
 of nature. I thank the Author of my being who bestow- 
 ed it upon me. before the eyes of my reason were opened, 
 and si ill bestows it upon me to be my guide, where reason 
 leaves me in the dark. And now I yield to the direction 
 of my senses, not from instinct only, but from confidence 
 and trust in a faithful and beneficent monitor, grounded 
 upon the experience of his paternal care and goodness. 
 
 In all this, I deal with the Author of my being, no oth- 
 wise tlian I thought it reasonable to deal with my parents 
 and tutors, 1 believed by instinct whatever they told me, 
 long before I had the idea of a lie, or thought of the pos- 
 sibility of their deceiving me. Afterward, upon reflec- 
 tion, I found they had acted like fair and honest people 
 who wished me well. I found that if I had not believed 
 what they told me, before I could give a reason of iny 
 belief, I had to this day been little better than a change- 
 ling. And although this natural credulity hath some- 
 times occasioned my being imposed upon by deceivers, 
 yet it hath been of infinite advantage to me upon the 
 whole; therefore I consider it as another good gift of 
 nature. And I continue to give that credit, from reflec- 
 tion, to those of whose integrity and veracity I have had 
 experience, which before I gave from instinct. 
 
 There is a much greater similitude than is commonly im- 
 agined, between the testimony of nature given by our senses, 
 and testimony of men given by language. The credit we 
 give to both is at first the effect of instinct only. When 
 we grow up, and begin to reason about them, the credit 
 given to human testimony is restrained, and weakened, by 
 the experience we have of deceit. But the credit given 
 
SEEING. 381 
 
 to the testimony of our senses, is established and con- 
 firmed by the uniformity and constancy of the laws of na- 
 ture. 
 
 Our perceptions are of two kinds : some are natural 
 and original, others acquired, and the fruit of experience. 
 When I perceive that this is the taste of cider, that of 
 brandy ; that this is the smell of an apple, that of an 
 orange; that this is the noise of thunder, that the ring- 
 ing of bells ; this the sound of a coach passing, that ihe 
 voice of such a friend ; these perceptions and others of 
 the same kind, are not original, they are acquired. But 
 the perception which I have by touch, of the hardness 
 and softness of bodies, of their extension, figure, and mo- 
 tion, is not acquired ; it is original. 
 
 In all our senses, the acquired perceptions are many 
 more than the original, especially in sight. By this sense 
 we perceive originally the visible figure and colour of 
 bodies only, and their visible place : but we learn to per- 
 ceive by the eye, almost every thing which we can perceive 
 by touch. The origiual perceptions of this sense, serve 
 only as signs to introduce the acquired. 
 
 The signs by which objects are presented to us in per- 
 ception, are the language of nature to man; and as, in 
 many respects, it hath a great afiinity with the language of 
 man to man ; so particularly in this, that both are partly 
 natural and original, partly acquired by cusloui. Our 
 original or natural perceptions are analogous to the nat- 
 ural language of man to man, of which we took notice in 
 the ith chapter; and our acquired perceptions are anal- 
 ogous to artificial language, which, in our mother tongue, 
 is got very mucli in the same manner with our acquired 
 perceptions, as we shall afterward more fully explain. 
 
 Not only men, but children, idiots, and brutes, acquire 
 by habit many perceptions which they had not originally. 
 Almost every employment in life, hath perceptions of 
 this kind that are peculiar to it. The shepherd knows 
 every sheep of his flock, as we do our acquaintance, and 
 can pick them out of another flock one by one. The 
 
S82 OF THE HUMAN MIND. 
 
 butcher knows by sight the weight and quality of his 
 beeves and sheep before they are killed. The farmer 
 perceives by his eye, very nearly the quantity of hay in a 
 rick, or of corn in a heap. The sailor sees the burden, 
 the built, and the distance of a ship at sea. while she is 
 a great way off. Every man accustomed to writing, dis- 
 tinguishes aoquaintanceby (heir hand- writing, as he does 
 by (heir faces. And the painter distinguishes in the 
 Avorks of bis art, the style of all the great masters. In 
 a word, acquired perception is very different in different 
 persons, according to the diversify of objects about which 
 they are employed, and the application they bestow in 
 observing them. 
 
 Perception ought not only to be distinguished from sen- 
 sation, but likewise from that knowledge of the objects of 
 sense which it got by reasoning. There is no reasoning in 
 perception, as hath been observed. The belief which is im- 
 plied in it, is the effect of instinct. But there are many 
 things, with regard to sensible objects, which we can infer 
 from what we perceive; and such conclusions of reason 
 ought to be distinguished from whatis merely perceived. 
 "When I look at the moon, I perceive her to be sometimes 
 circular, sometimes horned, and sometimes gibbous. This 
 is simple perception, and is the same in the philoso- 
 pher, and in the clown : but from these various appear- 
 ances of her enlightened part, I infer that she is really 
 of a spherical figure. This conclusion is not obtained 
 by simple perception, but by reasoning. Simple percep- 
 tion has the same relation to the conclusions of reason 
 drawn from our perceptions, as the axioms in mathematics 
 have to the propositions. I cannot demonstrate, that two 
 quantities which are equal to the same quantity, are equal 
 to each other; neither can I demonstrate, that the tree 
 which I perceive exists. But, by the constitution of my 
 nature, my belief is irresistibly carried along by my ap- 
 prehension of the axiom ; and by the constitution of -my 
 nature, my belief is no less irresistibly carried along by 
 my perception of the tree. All reasoning is from princi- 
 
pies. The first principles of mathematical reasoning are 
 inathentatical axioms and defini(ions ; and the first prin- 
 ciples of uU our reasoning about existences, are our per. 
 ceplions. The first principles of every kind of reasoning 
 are given us by nature, and are of equal authority wilh 
 the faculty of reason itself, which is also the gifl of na- 
 ture. The conclusions df reason are all built upon first 
 principles, andean have no other foundation. Most justly, 
 therefore, do such principles disdain to be tried by reason, 
 and laugh at the artillery of the logician, when it is 
 dij^ected against them. 
 
 When a long train of reasoning is necessary in demon- 
 strating a mathematical proposition, it is easily distin- 
 guished from an axiom, and they seem to be things of a 
 very different nature. But there are some propositions 
 which lie so near to axioms, that it is difilcult to say, 
 whether they ought to be held as axioms, or demonstrat- 
 ed as propositions. The same thing holds with regard to 
 perception, and the conclusions drawn from it. Some of 
 these conclusions follow our perceptions so easily, and are 
 so immediately connected with them, that it is difficult 
 to fix <lie limit which divides the one from (he other. 
 
 Perception, whether original or acquired, implies no 
 exercise of reason; and is common to men, children, j'| 
 idiots, and brutes. The more obvious conclusions drawn 
 from our perceptions, by reason, make what we call com- 
 mon understanding ; by which men conduct themselves in 
 the common afl^airs of life, and by which they are distin- 
 guished from idiots. The more remote conclusions which 
 are drawn from our perceptions, by reason, make what 
 we commonly call science in the various parts of nature, 
 whether in agriculture, medicine, mechanics, or in any 
 part of natural philosophy. When 1 see a garden in good 
 order, containing a great variety of things of the best kinds, 
 and in the most flourishing condition, I iramedia<ely con- 
 elude from these signs, the skill and industry of the gar- 
 dener. A farmer, when he rises in the morning, and per- 
 ceives that the neighbouring brook overflows his field. 
 
38* OF THE HUMAN MIXO. 
 
 concludes that a great deal of raia bath fallen in the 
 night. Perceiving his fence broken, and his corn trodden 
 down, he concludes that some of his own or his neigh- 
 bour's cattle have broken loose. Perceiving that his stable 
 door is broken open, and some of his horses gone, he con- 
 cludes that a thief has carried them off. He traces the 
 prints of his horses' feet in the <soft ground, and by them 
 discovers which road the thief hath taken. These are in- 
 stances of common understanding, which dwells so near 
 to perception, that it is difficult to trace the line which 
 divides the one from the other. In like manner, the 
 science of nature dwells so near to common understand- 
 ing that we cannot discern where the latter ends and 
 the former begins. I perceive that bodies, lighter 
 than water, swim in water, and that those which are 
 heavier sink. Hence I conclude, that if a body re- 
 mains wherever it is put under water, whether at the top 
 or bottom, it is precisely of the same weight with water. 
 If it will rest only when part of it is above water, it is 
 lighter than water. And the greater the part above 
 water is, compared with the whole, the lighter is the body. 
 If it had no gravity at all, it would make no impression 
 upon the water, but stand wholly above it. Thus, every 
 man, by common understanding, has a rule by whieh 
 he judges of the specific gravity of bodies which swim in 
 water : and a step or two more leads him into the science 
 of hydrostatics. 
 
 All that we know of nature, or of existences, may be 
 compared to a tree, which hath its root, trunk, and, 
 branches. In this tree of knowledge, perception is the 
 root, common understanding is the trunk, and the sciences 
 are the branches. 
 
SEEW6. 385 
 
 SliCTION XXI. 
 OP THE PROCESS OP NATURE IN PERCEPTION. 
 
 Although there is no reasoning in perception, yet 
 there are certain means and instruments, which, hy the 
 appointment of nature, must intervene ht-tween the ohject 
 and our perception of it; and, by these onr perceptions 
 are limited and regulated. First, if the ohect is not in 
 contact with the organ of sense, there must be some me- 
 dium which passes between them. Thus, in vision, the 
 rays of light ; in hearing, the vibrations of elastic air j 
 in smelling, the effluvia of the body smelled, must pass 
 from the object to the organ ; otherwise we have no per- 
 ception. Secondly, there must be some action or impres- 
 sion upon the organ of sense, either by the immediate, ap- 
 plication of the object, or by the medium that goes be- 
 tween them. Thirdly, the nerves which go from the 
 brain to the organ, must receive some impression by means 
 of that which was made upon the organ ; and probably, 
 by means of the nerves, some impression must be made 
 upon the brain. Fourthly, the impression made upon the 
 organ, nerves, and brain, is followed by a sensation. And, 
 last of all, this sensation is followed by the perception of 
 the object. 
 
 Thus our perception of objects is the result of a train 
 of operations ; some of which affect the body only, others 
 affect the mind. We know very little of the nature of 
 some of these operations ; we know not at all how they ai'C 
 connected together, or in what way they contribute to that 
 perception which is the result of the whole : but by the 
 laws of our constitution, we perceive objects in this, and 
 in no other way. 
 
 There may be other beings, who can perceive external 
 objects without rays of light, orvibrarions of air, or efflu- 
 via of bodies, without impressions on bodily organs, or 
 even without sensations. But we are so framed by the 
 
 vol. I. 49 
 
386 or THE HUMAN MIND. 
 
 Author of nature, that even when "we are surrounded 
 by external obeets, we may perceive none of them. Our 
 faculty of perceiving an object lies dormant, until it is 
 roused and stimulated by a certain corresponding sensa- 
 tion. Nor is this sensation always at hand to perform its 
 office ; for it enters inio the mind only in consequence of 
 a certain corres|)onding impression made on the organ of 
 sense by the ob ect. 
 
 Let us trace this correspondence of impressions, sen- 
 sations, and perceptions, as far as we can ; beginning with 
 that which is first in order, the impression made upon the 
 bodily organ. But, alas ! we know not of what nature 
 these impressions are, far less how they excite sensations 
 in the mind. 
 
 We know that one body may act upon another by pres. 
 sure, by percussion, by attraction, by repulsion and prob- 
 ably in many other ways, which we neither know, nor 
 have names to express. But in which of these ways ob- 
 jects, when perceived by us, act upon the organs of 
 sense, these organs upon the nerves, and the nerves 
 upbn the brain, we know not. Can any man tell me 
 how, in vision, the rays of light act upon the retina, 
 how the retincB acts upon the optic nerve, and how 
 the optic nerve acts upon the brain ? No man can. When 
 I feel the pain of the gout in my toe, I know that there 
 is some unusual impression made upon that part of my 
 body. But of what kind is it ? Are the small vessels 
 distended with some redundant elastic, or unelastic fluid? 
 Are the fibres unusually stretched ? Are they torn asunder 
 by force, or gnawed and corroded by some acrid humour I 
 I can answer none of these questions. All that I feel, is 
 pain, which is not an impression upon the body, but upon 
 the mind ; and all that I perceive by this sensation is» 
 that some distemper in my toe occasions this pain. But 
 as I know not the natural temper and texture of my toe 
 when it is at ease. I know as little what change or dis- 
 order of its parts occasions this uneasy sensation. la 
 like manner, in every other sensatiob, there is, without 
 
SBBINS. 387 
 
 doubt, some impression made upon the organ of sense; 
 but an impression of which we know not the nature. It 
 is too subtile to be discovered hy our senses, and we may 
 make a thousand conjectures without coming near the 
 truth. If we understood the structure of our organs of: 
 sense so minutely, as to discover what effects are produced i 
 upon them by external objects, this knowledge would; 
 contribute nothing to our perception of the object 5 for 
 they perceive as distinctly who know least about the man- 
 ner of perception, as (he greatest adepts. It is neeessiary 
 that the impression be made upon our organs, but not 
 that it be known. IValure carries on this part of the 
 process of perception^ without our consciousness or con- 
 currence. 
 
 But we cannot be unconscious of the next step in this 
 process, the sensation of the mind, which always imme- 
 diately follows the impression made upon the body. It is 
 essential to a sensation to be felt, and it can be nothing 
 more than we feel it to be. If we can only acquire (he 
 habit of attenditig to our sensations, we may know them 
 perfectly. But how are the sensations of the mind pro- 
 duced by impressions upon the body ? Of this we are ab-< 
 solutejy ignorant, having no means of knowing how the 
 body acts upon the mind, or the mind upon (he body. 
 When we consider the nature and attributes of both, they 
 seem to be so different, and so unlike, that we can find no 
 handle by which the one may lay hold of the other. There 
 is a deep and dark gulf between them, which our under- 
 standing cannot pass ; and the manner of (heir corres- 
 pondence and intercourse is absolutely unknown. 
 
 Experience teaches us, that certain impressions up- 
 on the body are constantly followed by certain sensa- 
 tions of the mind; and tha(, on the other hand, certain 
 determinations of the mind are constantly followed by 
 certain motions in the body : but we see not the chain 
 that ties these things together. Who knows but their 
 connection may be arbitrary, and owing to the will of our 
 Maker 7 Perhaps the same sensations ipight hare been 
 
y 
 
 388 . 01? THE HUMAN MIND. 
 
 connected with other impressions, or other bodily or- 
 gans. Perhaps we might have been so made, as to 
 taste with our fingers, to smell with our ears, and to hear 
 bj' the nose. Perhaps we might have been so made, as 
 to have all (he sensaiions and perceptions which we have, 
 without any impression made upon our bodily organs at 
 all. 
 
 However these things may be, if nature had given us 
 nothing more than impressions made upon the body, and 
 sensations in our minds corresponding to them, we should 
 in that ease have been merely sentient, but not percipient 
 beings. We should never have been able to form a concep- 
 tion of any external object, far less a belief of its exist- 
 ence. Our sensations have no resemblance to external 
 objects ; nor can we discover, by our reason, any neces- 
 sary connection between the existence of the former, and 
 that of the latter. 
 
 We might perhaps have been made of such a consti- 
 tution, as to have our present perceptions connected 
 with other sensations. We might perhaps have had the 
 perception of external objects, without either impressions 
 upon the organs of sense, or sensations. Or, lastly. The 
 perceptions we have, might have been immediately con- 
 nected with the impressions upon our organs, without any 
 intervention of sensations. This last seems really to be 
 the case in one instance, to wit, in our perception of the 
 visible figure of bodies, as was observed in the 8th sec- 
 tion of this chapter. 
 
 The process of nature in perception by the senses, may 
 therefore be conceived as a kind of drama, wherein some 
 things are performed behind the scenes, others are rep- 
 resented to the mind in different scenes, one succeeding 
 another. The impression made by the object upon the 
 organ, either by iiiimcdiale contact, or by some interven- 
 ing medisim, as well as tlie impression made upon the 
 nerves and brain, is performed behind the scenes, and the 
 mind sees notliing of it. But every such impression, by 
 the laws of the drama, is followed by a sensation, which 
 
SEEING. 389 
 
 is the first scene exhibited to the mind ; and this scene 
 is quickly succeeded by another, which is the perception 
 of the object. 
 
 In this drama, nature is the actor, we are spectators. 
 We know nothing of the machinery by means of which 
 every different impression upon the organ, nerves, and 
 brain, exhibits its corresponding sensation ; or of the ma- 
 chinery by meansof which each sensation exhibits itseop- 
 responding perception. "We are inspired with the sensation, 
 and we are inspired with the corresponding perception, by 
 means unknown. And because the mind passes immediate- 
 ly from the sensation to that conception and belief of the 
 object which we have in perception, in the same manner 
 as it passes from signs to the things signified by them, 
 we have therefore ealled our sensations signs of exter- 
 nal objects ; finding no word more to express the func- 
 tion which nature bath assigned them in perception, and 
 the relation which they bear to their corresponding ob- 
 jects. 
 
 There is no necessity of a resemblance between the 
 sign and the thing signified : an d indeed no sensation can 
 resemble any external object. But there are two things 
 necessary to our knowing things by means of signs. First, 
 That a real connection between the sign and thing signi- 
 fied be established, either by the course of nature, or by 
 the will and appointment of men. When they are con- 
 nected by the course of nature, it is a natural sign , 
 when by human appointment, it is an artificial sign. Thus 
 sraoke is a natural sign of fire ; certain features are nat- 
 ural signs of anger ; but our words, whether expressed 
 by articulate sounds or by writing, are artificial signs of 
 our thoughts and purposes. 
 
 Another requisite to our knowing things by signs is, 
 that the appearance of the sign to the mind, be followed 
 by the conception and belief of the thing signified. With- 
 out this, the sign is not understood or interpreted ; and 
 therefore is no sign to us, however fit in its own nature 
 for that purpose. 
 
S90 OF THE HUMAN MINB. 
 
 Now, there are three ways in which the mind passes 
 from (he appearance of a natural sign to the conception 
 and belief of (he thing signified ; bj original principles 
 of our constilution, by cus(om, and by reasoning. 
 
 Our original perceplions are got in (he first of these 
 wajs, our ae(iiiired perceptions in (he second, and all that 
 reason discovers of the course of nature, in the third. In 
 the first of (hese wavs. nature, by means of (he sensalions 
 of touch, informs us of (he hardness and softness of bodies ; 
 of (heir extension, figure, and ino(ion ; and of that sjiace 
 in whidi they move and are placed, as hath been already 
 explained in the fifth cha|)(er of tiiis inquiry. And in the 
 second of these ways she informs us, by means of our 
 eyes, of almost all the same things which originally we 
 eould perceive only by touch. 
 
 In order, therefore, to understand more particularly 
 how we learn to perceive so many things by the eye, 
 which originally could be perceived only by touch, it will 
 be proper, first, to point out the signs by which (hose 
 things are exhibited to the eye, and their connection with 
 the things signified by them; and, secondly, to consider 
 how the experience of this connection produces that habit 
 by which the mind, without any reasoning or reflection, 
 passes from the sign to the conception and belief of the 
 thing signified. 
 
 Of all (he acquired perceptions which we have by sight, 
 the most remarkable is the perception of the distance of 
 objects from the eyes; we shall therefore particularly 
 consider the signs by which (his perception is exhibited, 
 and only make some general remarks with regard to the 
 signs which are used in other acquired perceptions. 
 
 SECTION XXII. 
 
 OF THE SIGNS BY WHICH WE LEAHN TO PERCEIVE DISTANCE FKOM 
 THE JiYE. 
 
 It was before observed in general. That the original 
 perceptions of sight are signs which serve to introduce 
 
SEE1N8. 391 
 
 those that are acquired : but this is not to be understood 
 as if no other signs were employed for that purpose. 
 There are several motions of the eyes, whieh. in order 
 to disiinet vision, must be varied, according as the object^ 
 is more or les* distant ; and sneh motions being by habit 
 connected with the corresponding distances of the object, 
 become signs of those distances. These motions were 
 at first voluntary and unconfined ; but as the intention of 
 nature was, to produce perfect and distinct vision by their 
 means, we soon learn by experience to regulate them ac- 
 cording to that intention only, without the least reflec- 
 tion. 
 
 A ship requires a different trim for every variation of 
 the direction and sli'ength of the wind; and, if we may 
 be allowed to borrow that word, the eyes require a dif- 
 ferent trim for every degree of light, and forevery varia- 
 tion of (he distance of (he object, while it is within cer- 
 tain limits. The eyes are trimmed for a particular ob- 
 ject, by contracting certain muscles, and relaxing others, 
 as the ship is trimmed for a particular wind, by draw- 
 ing certain ropes and slackening others. The sailor 
 learns the trim of his ship, as we learn the trim of 
 our eyes, by experience. A ship, although the no- 
 blest machine that human art can boast, is far inferior 
 to the eye in (his respect, that it requires art and inge- 
 nuity to navigate her; and a sailor must know what ropes 
 he must pull, and what he must slacken, to fit her to a 
 particular wind : but with such superior wisdom is the 
 fabric of thf eye, and the principles of its motion con- 
 trived. tha< it requires no art nor ingenuity to see by it. 
 Even that part of vision which is got by experience, 
 is attained by idiots. We need not know what muscles 
 we are to contract, and what we are to relax, in order to 
 fit the eye to a particular distance of the object. 
 
 But although we are conscious of the motions we per- 
 form, in order to fit theeyes to the distance of theobject, i 
 we are coascious of the effort employp! in producing these , 
 
392 OV THE HUMAN MINU. 
 
 motions ; and probably have some sensation which accom- 
 panies them, to which we give as little attention as to other 
 sensations. And thus, an effort consciouisly exerted, or a 
 sensation consequent upon that effort, comes to be conjoin- 
 ed with the distance ofthe object which gave occasion to it, 
 and by this conjunction becomes a sign of that distance. 
 Some instances of this will appear in considering the means 
 or signs by which we learn to see the distance of objects 
 from the eye. In the enumeration of these, we agree 
 with Dr. Porterfield, notwithstanding that distance from 
 his eye, in his opinion, is perceived originally, but in our 
 opinion, by experience only. 
 
 In general, when a near object affects the eye in one 
 manner, and the same object, placed at a greater distance, 
 affects it in a different manner ; these various affections 
 ofthe eye become signs of the corresponding distances. 
 The means of perceiving distance by the eye, will there- 
 fore be explained, by shewing in what various ways ob- 
 jects affeet the eye differently, according to their proxim- 
 ity or distance. 
 
 1. It is well known, that to see objects distinctly at va- 
 rious distances, the form of the eye must undergo some 
 change. And nature hath given us the power of adapt- 
 ing it to near objects, by the conl raction of certain muscles, 
 and to distant objects by the contraction of other muscles. 
 
 As to the manner in which this is done, and the mus- 
 cular parts employed, anatomists do not altogether agree. 
 The ingenious Dr. Jurin, in his excellent essay on distinct 
 and indistinct vision, seems to have given the most prob- 
 able account of this matter ; and to him I refer the reader. 
 
 But whatever be the manner in which this change of 
 the form of the eye is effected, it is certain that young 
 people have commonly the power of adapting their eyes 
 to all the distances of the object, from six to seven inches, 
 to fifteen or sixteen feet ; so as to have perfect and dis- 
 tinct vision at any distance within these limits. From 
 this it follows, that the effect we conscionsly employ to 
 adapt the eye to any particular distance of objects within 
 
SEEING. 393 
 
 these limits, will be connected and associated with that 
 distance, and will become a sign of it. When the object 
 is removed beyond the farthest limit of dislinct vision, it 
 will be seen indistinctly ; but more or less so, according 
 as its distance is greater or less : so that the degrees 
 of indistinctness of the object may become the signs of dis- 
 tances considerably beyond the farthest limit of distinct 
 vision. 
 
 If we had no other mean but this, of perceiving dis- 
 tance of visible objects, the most distant would not appear 
 to be above twenty or thirty feet from the eye, and 
 the tops of houses and trees would seem to touch the 
 clouds ; for in that case the signs of all greater distances 
 being the same, they have the same signification, and give 
 the same perception of distance. 
 
 But it is of more importance to observe, that because 
 the nearest limit of distinct vision in the time of youth, 
 when we learn to perceive distance by the eye, is about 
 six or seven inches, no object seen distinctly, ever appears 
 to be nearer than six or seven inches from the eye. We 
 can, by art, make a small object appear distinct, when it 
 is in reality not above half an inch from the eye ; either 
 by using a single microscope, or by looking through a 
 small pinhole in a card. When, by either of these means, 
 an object is made to appear distinct, however small its 
 distance is in reality, it seems to he removed at least to 
 the distance of six or seven inches, that is, within the 
 limits of distinct vision. 
 
 This observation is the more important, because it af- 
 fords the only reason we can give why an object is mag- 
 nified either by a single microscope, or by being seen 
 through a pinhole; and the only mean by which we can 
 ascertain the degree in which the object will he magnified 
 by either. Thus, if the ob^el is really half an inch dis- 
 tant from the eye, and appears to be seven inches distant, 
 its diameter will seem to be enlarged in the same propor- 
 tion as its distance, that is^ fourteen times. 
 
 vol. I. 60 
 
394 OF THE HUMAN MIAO. 
 
 2. In order to direct both eyes to an object, the optie 
 axes must have a greater or less inclination, according 
 as the object is nearer or more distant. And although 
 we are not conscious of this inclination, yet we are con- 
 scions of the effort employed in it. By this mean we per- 
 ceive small distances more accurately than we could do 
 by the conformadon of the eye only. And therefore we 
 find, (hat those who have lost the sight of one eye, are 
 apt, even within arm's length, to make mistakes in the 
 distance of objects, which are easily avoided by those who 
 see with both eyes. Such mistakes are often discovered 
 in snuffing a candle, in threading a needle, or in filling a 
 tea cup. 
 
 When a picture is seen with both eyes, and at no great 
 distance, (he representation appears not so natural as 
 when it is seen only with one. The intention of painting 
 being to deceive the eye, and to make things appear at 
 ditferent distances which in reality are upon the same 
 piece of canvas, this deception is not so easily put upon 
 boih eyes as upon one ; because we perceive the distance 
 of visible objects more exactly and determinately with 
 two eyes than with one. If the shading and relief be ex- 
 ecuted in the best manner, the picture may have almost 
 the same appearance to one eye as the objects themselves 
 would have, but it cannot have the same appearance to 
 both. Tliis is not the fault of the artist, but an unaroid- 
 able imperfection ia the art. And it is owing to what we 
 just now observed, tliat the perception we have of the 
 distance of objects by one eye is more uncertain, and 
 more liable to deception, than that which we have by both. 
 
 The great impediment, and I think the only invincible 
 impediment, to that agreeable deception of the eye which 
 the painter aims at, is the perception which we have of 
 the distance of visible objects from the eye, partly by 
 njeans of (he conformation of the eye, but chiefly by means 
 of (he inclination of the optic axes. If this perception 
 could be removed, I see no reason why a picture might 
 
SEEITTG. 395 
 
 not be made so perfect as to deceive the eye in reality, 
 and to be mistaken for the original object. Therefore, 
 in order to judge of the merit of a picture, we ought, as 
 much as possible, to exclude these two means of perceiv- 
 ing the distance of the several parts of it. 
 
 In order to remove this perception of distance, (he con- 
 noisseurs in painting use a method which is very projier. 
 They look at the picture with one eye, through a lube 
 which excludes the view of all the otlier objects. By this 
 method, the principle mean whereby we perceive the dis- 
 tance of the object, to wit, the inclination of the optie 
 axes, is entirely excluded. I would humbly jjropose, as 
 an improvement of this method of viewing pictures, tliat 
 the, aperture of the tube next to the eye should be very 
 small. If it is as small as a pinhole, so much the belter, 
 providing there be light enough to see the picture clearly. 
 The reason of this proposal is, that when we look at an 
 object through a small aperture, it will be seen distinctly, 
 whether the conformation of the eye be adapted lo its dis- 
 tance or not, and we have no mean left to judge of the 
 distance, but the light and colouring, which are in the 
 painter's power. If, therefore, the artist performs his 
 part properly, the picture will by this method affect the 
 eye in the same manner that the object represented would 
 do ; which is the perfection of this art. 
 
 Although the second mean, of perceiving the distance 
 of visible objects be more determinate and exact than the 
 first, yet it hath its limits, beyond which it can be of no 
 use. For when the optic axes directed to an object are 
 so nearly parallel, that in directing them to an object yet 
 more distant, we are not conscious of any new effort, nor 
 have any different sensation | there our perception of dis- 
 tance stops : and as all more distant objects affect the eye 
 in the same manner, we perceive them to be at the same 
 distance. This is the reason why the sun, moon, planets, 
 and fixed stars, when seen not near the horizon, appear 
 to be all at the same distance, as if they touched the con- 
 cave surface of a great sphere. The surface of this ce- 
 
396 OF THE HUMAN MIND. 
 
 lestial sphere is at that dislance beyond which all objects 
 affect the eye in the same manner. Why this celestial 
 vault appears more distant toward the horizon, than to- 
 ward the zenith, will afterward ap|)ear. 
 
 3. The colours of objects, according as they are more 
 distant, become more faint and languid, and are tinged 
 more with the azure of the intervening atmosphere: to 
 this we may add, that their minute parts become more 
 indistinct, and their outline less accurately defined. It is 
 by these means chiefly, that painters can represent objects 
 at very different distances, upon the same canvas. And 
 the diminution of the magnitude of an object, would not 
 have the effect of making it appear to be at a great dis- 
 tance without this degradation of colour, and indistinct- 
 ness of the outline, and of the minute parts. If a painter 
 should make a human figure ten times less than other 
 human figures that are in the same piece, having the col- 
 ours as bright, and the outline and minute parts as accu- 
 rately defined, it would not have the appearance of a man 
 at a great distance, but of a pigmy or Lilliputian. 
 
 When an object hath a known variety of colours, its dis- 
 tance is more clearly indicated by the gradual dilution of 
 the colours into one another, than when it is of one uni- 
 form colour. In the steeple which stands before me at 
 a small distance, the joinings of the stones are clearly per- 
 ceptible ; the grey colour of the stone, and the white 
 cement, are distinctly limited : when I see at a greater 
 distance, the joinings of the stones are less distinct, and 
 the colours of the stone and of the cement begin to dilute 
 into one another: at a distance still greater, the joinings 
 disappear altogether, and the variety of colour vanishes. 
 
 In an apple-tree which stands at the distance of about 
 twelve feet, covered with flowers, I can perceive the fig- 
 ure and the colour of the leaves and petals ; pieces of 
 branches, some larger, others smaller, peeping through 
 the interval of the leaves, some of them enlightened by 
 the sun's rays, others shaded ; and some openings of the 
 sky are perceived through the whole. When I gradually 
 
SEEING. S97 
 
 vemove from this tree, the appearance, even as to colour, 
 changes every minute. First, the smaller parts, then the 
 larger, are gradually confounded and mixed. The colours 
 of leaves, petals, branches, and sky, are gradually diluted 
 into each other, and the colour of the whole becomes 
 more and more uniform. This change of appearance, 
 corresponding to the several distances, marks the distance 
 more exactly than if the whole object had bec^n of one 
 colour. 
 
 Dr. Smith, in his Optics, gives us a very curious ob- 
 servation made by bishop Berkeley, in his travels through 
 Italy and Sicily. He observed. That in those countries, 
 cities and palaces seen at a great distance, appeared near- 
 er to him by several miles than they really were : and 
 he very judiciously imputed it to this cause. That the 
 purity of the Italian and Sicilian air, gave to very dis- 
 tant objects, that degree of brightness and distinctness, 
 which, in the grosser air of his own country, was to be 
 seen only in those that are near. The purity of the Ital- 
 ian air has been assigned as the reason why the Italian 
 painters commonly give a more lively colour to the sky, 
 than the Flemish. Ought they not, for the same reason, to 
 give less degradation of the colours, and less indistinctness 
 of the minute parts, in the representation of very dis- 
 tant objects ? 
 
 It is very certain, that as, in air uncommonly pure, we 
 are apt to think visible objects nearer, and less than they 
 really are ; so, in air uncommonly foggy, we are apt to 
 think them more distant, and larger than the truth. 
 Walking by the seaside, in a thick fog, I see an object 
 which seems to me to be a man on horseback, and at the 
 distance of about half a mile. My companion, who has 
 better eyes, or is more accustomed to see such objects in 
 such circumstances, assures me, that it is a sea-gull, and 
 not a man on horseback. Upon a second view, I imme- 
 diately assent to his opinion ; and now it appears to me to 
 be a sea-gull, and at the distance of only seventy or eighty 
 yards. The mistake made on this occasion, and the cor- 
 
398 OF THE HUMAN MIND, 
 
 rectioii of it, are both so sudden, that we are at a loss 
 whetliep to call tlicmbjthe name of judgment, or by that 
 of simple perception. 
 
 It is not worth while to dispute about names ; but it is 
 evident that my belief, both first and last, was pruducid 
 rather by signs than by arguments; and that liie mind 
 proceeded to the conclusion i;i both cases by habit, and 
 not by ratiocination. And the process of the mind seems 
 to have been this. First, not knowing, or not minding, 
 the effect of a foggy air on the visible appearance of ob- 
 jects, the object seems to me to liave tiiat degradation of 
 colour, and that indistinctness of (he outline, wiiieh objects 
 have at the distance of half a mile; therefore, from the 
 visible appearance as a sign, I immediately proceed to the 
 belief, that the object is half a mile distant. Then, this 
 distance, together with the visible magnitude, signify to 
 me the real magnitude; which, supposing (he distance to 
 be half a mile, must be equal to that of a nian on horse- 
 back; and the figure, considering the indi^lirielness of 
 the outline, agrees with that of a man on horseback. Thus 
 the deception is brought about. But when I am assured 
 that it is a sea-gull, the real magnitude of a sea-gull, to- 
 gether with the visible magnitude presented to the eye, 
 immediately suggest the distance, which in this case can- 
 not be above seventy or eighty yards : the indistinctness 
 of the figure likewise suggests the fogginess of the air as 
 its cause : and now the whole chain of signs, and things 
 signified, seems strongerandbetter connected than it was 
 before ; the half mile vanishes to eighty yards; the man 
 on horseback dwindles to a sea-gull ; I get a new percep- 
 tion, and wonder how I got the former, or what is become 
 of it; for it is now so entirely gone, that I cannot re- 
 cover it. 
 
 It ought to be observed, that in order to produce such 
 deceptions from the clearness or fogginess of the air, it 
 must be uncommonly clear or uncommonly foggy ; for 
 we learn from experience, to make allowance for that va- 
 riety of constitutions of the air which we have been ac- 
 
SEEING. 399 
 
 ciistomeil to ohserve, and of which we are aware. Bishop 
 Berkeley, tlierefore, committed a mistake, when he at- 
 tributed the large appearance of the horizontal moon to 
 the faiiitness of her light, occasioned by its passing through 
 a larger tract of atmosphere: for we are so much ac- 
 CMsloined to see the moon in all degrees of faintness and 
 biightness. from the greatest to the least, that we learn 
 to make iillowance for it ; and do not imagine her magni- 
 tude increased by the faintness of her appearance. Be- 
 sides, ii is certain, that (lie hoi izonlal moon, seen through 
 a tube which cuts off (he view of the inteijacent ground, 
 and of all terrestrial objects, loses all that unusual ap- 
 pearance of magnitude. 
 
 4. We frequently perceive the distance of objects, by 
 means of intei'vening or contiguous objects, whose dis- 
 tance or magnitude is otherwise known. When I per- 
 ceive certain fields or tracts of ground to lie between me 
 and an ol»ject, it is evident, that these may become sign* 
 of its distance. And although we have no particular in- 
 formation of the dimensions of such fields or tracts, yet 
 their sintilitude to others which we know, suggests their 
 dimensions. 
 
 We are so much accustomed to measure with our eye 
 the ground which we travel, and to compare the judg- 
 ments of distances formed by sight with our experience or 
 information, that we learn by degrees, in this way, to form 
 a more accurate judgment of the distance of terrestrial 
 objects, than we could do by the means before mentioned. 
 An object placed upon the top of a high building, appears 
 much less than when placed upon the ground at the same 
 distance. When it stands upon the ground, the interven- 
 ing tract of ground serves as a sign of its distance; and 
 the distance, together with the visible magnitude, serves 
 as a sign of its real magnitude. But when the object is 
 placed on high, this sign of its distance is taken away; 
 the remaining signs lead us to place it at a less distance ; 
 and this less distance, together with the visible magni- 
 tude, becomes a sign of a less real magaituder 
 
■iiOO OU THE HITM4N MINO. 
 
 The two first means we have mentioned, would nevei? 
 of themselves make a visible object appear above a hun- 
 dred and fifty, or two hundred feet distant ; because, be- 
 yond that, there is no sensible change, either of the con- 
 formation of the eyes, or of the inclination of their axes : 
 the third mean, is but a vague and indeterminate sign, 
 when applied to distances above two or three hundred 
 feet, unless we know the real colour and figure of the 
 ob'ect : and the fifth mean, to be afterward mentioned, 
 can only be applicable to objects which are familiar, or 
 whose real magnitude is known. Hence it follows, that 
 when unknown objects, upon, or near the surface of the 
 earth, are perceived to be at the distance of some miles, 
 it is always by this fourth mean that we are led to that 
 conclusion. 
 
 Dr. Smith ha<h observed, very justly, that the known 
 distance of the terrestrial objects which terminate our 
 view, makes that part of the sky which is toward the ho- 
 rizon, appear more distant than that which is toward the 
 zenith. Hence it comes to pass, that the apparent figure 
 of the sky is not that of a hemisphere, but rather a less 
 segment of a sphere. And hence likewise it comes to 
 pass, that the diameter of the sun or moon, or the dis- 
 tance between two fixed stars, seen contiguous to a hill, 
 or to any distant terrestrial object, appears much greater 
 than when no such object strikes the e^e at the same 
 time. 
 
 These observations have been sufficiently explained and 
 confirmed by Dr. Smith. I beg leave to add, that when 
 the visible horizon is terminated by very distant objects, 
 the celestial vault seems to be enlarged in all dimensions. 
 When I view it from a confined street or lane, it bears 
 some proportion to the buildings that surround me : but 
 when I view it from a large plain, terminated on all hands 
 by hills which rise one above another, to the distance of 
 twenty miles from the eye, methinks I see a new heaven, 
 whose magnificence declares the greatness of its Author, 
 and puts every human edifice out of couatenance; for 
 
SEEING, 401 
 
 now the lofty spires and the gorgeous palaces shrink in- 
 to nothing before it, and bear no more proportion to the 
 celestial dome, than their makers bear to its Maker. 
 
 S. There remains another mean by which we perceive 
 the distance of visible objects, and that is the diminution 
 of their visible or apparent magnitude. By experience I 
 know what figure a man, or any other known object, makes 
 to my eye, at the distance of ten feet : I perceive the 
 gradual and proportional diminution of this visible figure, 
 at the distance of twenty, forty, a hundred feet, and at 
 greater distances, until it vanish altogether. Hence a 
 certain visible magnitude of a known object, becomes 
 the sign of a certain determinate distance, and carries 
 along with it the conception and belief of that distance. 
 
 In this process of the mind, the sign is not a sensation; 
 it is an original perception. We perceive the visible fig- 
 ure and visible magnitude of the object, by the original 
 powers of vision ; but the visible figure is used only as a 
 sign of the real figure ; and the visible magnitude is used 
 only as a sign either of the distance, or of the real mag- 
 nitude, of the object ; and therefore these original per- 
 ceptions like other mere signs, pass through the mind, 
 without any attention or reflection. 
 
 This last mean of perceiving the distance of known ob- 
 jects, serves to explain some very remarkable phenomena 
 in optics, which would otherwise appear very mysterious. 
 When we view objects of known dimensions through op- 
 tical glasses, there is no other mean left of determining 
 their distance, but this fifth. Hence it follows, that 
 known objects seen through glasses, must seem to be 
 brought nearer, in proportion to the magnifying power of 
 the glass, or to be removed to a greater distance, in pro- 
 portion to the diminishing power of the glass. 
 
 If a man who had never before seen objects through a 
 telescope, were told, that the telescope, which he is about 
 to use, magnifies the diameter of the object ten times ; 
 when he looks through this telescope at a man six feet 
 high, what would he expect to see ? Surely he would very 
 
 vol. I. 51 
 
iOZ OF THE HUMAN MINI). 
 
 naturally expect to see a giant sixty feet high. But 
 he sees no such thing. The man appears no more 
 than six feet high, and consequently no bigger than he 
 really is ; but he appears ten times nearer than he is. The 
 telescope indeed magnifies the image of this man upon 
 the retina ten times in diameter, and must therefore mag- 
 nify his visible figure in the same proportion ; and as we 
 have been accustomed to see him of this visible magni- 
 tude, when he was ten times nearer than he is presently, 
 and in no other ease ; this visible magnitude, therefore, 
 suggests the conception and belief of that distance of the 
 object with which it hath been always connected. We 
 have been accustomed to conceive this amplification of 
 the visible figure of a known object, only as the effect or 
 sign of its being brought nearer : and we have annexed 
 a certain determinate distance to every degree of visible 
 magnitude of the object ; and therefore, any particular 
 degree of visible magnitude, whether seen by the naked 
 eye or by glasses, brings along with it the conception and 
 belief of the distance which corresponds to it. This is 
 the reason why a telescope seems not to magnify known 
 objects, but to bring them nearer to the eye. 
 
 When we look through a pinhole, or a single micro- 
 scope, at an object which is half an inch from the eye, 
 the picture of the object upon the retina is not enlarged, 
 but only rendered distinct j neither is the visible figure 
 enlarged : yet the object appears to the eye twelve or 
 fourteen times more distant, and as many times larger 
 in diameter, than it really is. Such a telescope as we 
 have mentioned amplifies the image on the retina, and 
 the visible figure of the object, ten times in diameter, and 
 yet makes it seem no bigger, but only ten times nearer. 
 These appearances had been long observed by the writers 
 on optics ; they tortured their invention to find the causes 
 of (hem from optical principles ; but in vain : they must 
 be resolved into habits of perception, which are acquir- 
 ed by custom, but are apt to be mistaken for original per- 
 ceptions. The bishop of Cloyne first furnished the world 
 with the proper key for opening up these mysterious ap- 
 
SEEING. 403 
 
 pearances ; but he made considerable mistakes in the ap- 
 plication of it. Dr. Smith, in hiselabora(e and judicious 
 treatise of Optics, hath applied it to the apparent dis- 
 tance of objects seen with glasses, and to the apparent 
 figure of the heavens, with such happj success, that 
 there can be no more doubt about the causes of these phe- 
 nomena. 
 
 SECTION XXI II. 
 of] THE SlGTfS USED IN OTHEE ACQ,UIRED PEKCEPTIONS. 
 
 The distance of objects from the eye, is the most im- 
 portant lesson in vision. Many others are easily learned 
 in consequence of it. The distance of the object, joined j 
 with its visible magnitude, is a sign of its real magnitude : j 
 and the distance of the several parts of an object, joined 
 with its visible figure, becomes a sign of its real figure. 
 Thus, when I look at a globe, which stands before me, by 
 the original powers of sight I perceive only something 
 of a circular form, variously coloured. The visible figure 
 hath no distance from the eye, no convexity, nor hath it , 
 three dimensions : even its length and breadth are inca- 
 pable of being measured by inches, feet, or other linear 
 measures. But when I have learned to perceive the dis- 
 tance of every part of this object from the eye, this per- 
 ception gives it convexity, and a spherical figure ,• and adds 
 a third dimension to that which had but two before. The 
 distance of the whole object makes me likewise perceive 
 the real magnitude ; for being accustomed to observe how 
 an inch or a foot of length atfects the eye at that distance, 
 I plainly perceive by my eye the linear dimensions of (he 
 globe, and can affirm with certainty that its diameter is 
 about one toot and three inches. 
 
 It was shown in the seventh section of this chapter, 
 that the visible figure of a body may, by mathematical 
 reasoning, be inferred from its real figure, distance, and 
 position, with regard to the eye : in like manner, we 
 may, by mathematical reasoning, from the visible figure. 
 
404 OF THE HUMAN MINU. 
 
 together mUIi the distance of the several parts of it, from 
 the eye, infer the real figure and position. But this last 
 inference is not commonly made by mathematical reason- 
 ing, nor indeed by reasoning of any kind, but by custom. 
 
 The original appearance which the colour of an object 
 makes to the eye, is a sensation for which we have no 
 name, because it is used merely as a sign, and is never 
 made an object of attention in common life: but this ap- 
 pearance, according to the different circumstances, sig- 
 nifies various things. If a piece of cloth, of one uniform 
 colour, is laid so that part of it is in the sun, and part in 
 the shade ; the appearance of colour, in these different 
 parts, is very different : yet we perceive the colour to be 
 the same ; we interpret the variety of appearance as a sign 
 of light and shade, and not as a sign of real difference in 
 colour. But if the eye could be so far deceived, as not to 
 perceive the difference of light in the two parts of the 
 cloth, we should, in that case, interpret the variety of 
 of appearance to signify a variety of colour in the parts 
 of the cloth. 
 
 Again, if we suppose a piece of cloth placed as before, 
 but having the shaded part so much brighter in the col- 
 our, that it gives the same appearance to the eye as the 
 more enlightened part j the sameness of appearance will 
 here be interpreted to signify a variety of colour, because 
 we shall make allowance for the effect of light and shade. 
 
 When the real colour of an object is known, the ap- 
 pearance of it indicates in some circumstances, the degree 
 of light or shade ; in others, the colour of the circumam- 
 bient bodies, whose rays are reflected by it ; and in other 
 circumstances, it indicates the distance or proximity of the 
 object, as was observed in the last section ; and by means 
 of these, many other things are suggested to the mind. 
 Thus, an unusual appearance in the colour of familiar 
 objects may be the diagnostic of a disease in the specta- 
 tor. The appearance of things in my room, may indi- 
 cate sunshine or cloudy weather, the earth covered with 
 snow, or blackened with rain. It hath been observed^ 
 
sEEiive. 405 
 
 that the colour of the sky, in a piece of painting, may in- 
 dicate the country of the painter, because the Italian sky 
 is really of a different colour from the Flemish. 
 
 It was already observed, that the original and acquired 
 perceptions which we have by our senses, are the language 
 of nature to man, which, in many respects, hath a great 
 affinity to human languages. The instances which we 
 have given of acquired perceptions, suggest this affinity; 
 that as, in human languages, ambiguities are often fpund, 
 so this language of nature in our acquired perceptions is 
 not exempted from them. We have seen, in vision par- 
 ticularly, that the same appearance to the eye, may, in 
 different circumstances, indicate different things. There- 
 fore, when the circumstances are unknown upon which \ 
 the interpretation of the signs depends, their meaning 
 must be ambiguous; and when the circumstances are 
 mistaken, the meaning of the signs must also be mistaken. 
 
 This is the case in all the phenomena which we call 
 fallacies of the senses ; and particularly in those which are 
 called fallacies in vision. The appearance of things to 
 the eye, always corresponds to the fixed laws of nature; 
 therefore, if we speak properly, there is no fallacy in the 
 senses. Nature always speaketh the same language, and 
 useth the same signs in the same circumstances : but we 
 sometimes mistake the meaning of the signs, either 
 through ignorance of the laws of nature, or through ig- 
 norance of the circumstances which attend the signs. 
 
 To a man, unacquainted with the principles of optics, 
 almost every experiment that is made with the prism, 
 with the magic lantern, with the telescope, with the 
 microscope, seems to produce some fallacy in vision. 
 Even the appearance of a common mirror, to one alto- 
 gether unacquainted with the effects of it, would seem 
 most remarkably fallacious. For how can a man be 
 more imposed upon, tlian in seeing that before him which 
 is really behind him ? How can he be more imposed upon, 
 than in being made to see himself several yards removed 
 from himself ? Yet children, even before they can speak 
 
406 OF THE HUMAN MINIJ. 
 
 their mother tongue, learn not to be deceived by these 
 appearances. These, as well as all other surprising ap- 
 pearances produced by optical glasses, are a part of the 
 visual language ; and, to those who understand the laws 
 of nature concerning light and colours, are in no ways 
 fallacious, but have a distinct and true meaning. 
 
 SECTION XXIV. 
 
 OF THE ANALOGY BETWEEN PERCEPTION, AND THE CREDIT WE GIVE 
 TO HUMAN TESTIMONY. 
 
 The objects of human knowledge are innumerable, but 
 the channels by which it is conveyed to the mind are few. 
 Among these, the perception of external things by our 
 senses, and the informations which we receive upon hu- 
 man testimony, are not the least considerable : and so re- 
 markable is the analogy between these two, and the an- 
 alogy between the principles of the mind, which are sub- 
 servient to the one, and those which are subservient to 
 the other, without further apology we shall consider them 
 together. 
 
 In the testimony of nature given by the senses, as well 
 as in human testimony given by language, things are signi- 
 fied to us by signs : and in one, as well as the other, the 
 mind, either by original principles or by custom, passes 
 from the sign to the conception and belief of the things 
 signified. 
 
 We have distinguished our percepf ions into original and 
 acquired ; and language, into natural and artificial. Be- 
 tween acquired perception, and artificial language, there 
 is a great analogy ; but still a greater between original 
 perception and natural language. 
 
 The signs in original perception are sensations, of which 
 nature hath given us a great variety, suited to the variety 
 of the things signified by them. Nature hath establish- 
 ed a real connection between the signs and the things 
 signified i and nature hath also taught us the interpreta- 
 
sEEiwe. 4,07 
 
 tion of the signs ; so that, previous to experience, the 
 sign suggests the thing signified, and creates the belief 
 of it. 
 
 The signs in natural language are features of the face, 
 gestures of tlie body, and modulations of the voice; the 
 variety of which is suited to the variety of the things 
 signified by them. Nature hath established a real con- 
 nection between these signs, and the thoughts and dispo- 
 sitions of the mind which are signified by them; and na- 
 ture hath taught us the interpretation of tliese signs; so 
 that, previous to experience, the sign suggests the things 
 signified and creates the belief of it. 
 
 A man in company, without doing good or evil, with- 
 out uttering an articulate sound, may behave himself 
 gracefully, civilly, politely ; or, on the contrary, meanly, 
 rudely and impertinently. We see the dispositions of 
 his mind, by their natural signs in his countenance and 
 behaviour, in the same manner as we perceive the figure 
 and other qualities of bodies by the sensations which na- 
 ture hath connected with them. 
 
 Tlie signs in the natural language of the human coun- 
 tenance and behaviour, as well as the signs in our orig- 
 inal perceptions, have the same signification in all climates 
 and in all nations; and the skill of interpreting them is 
 not acquired, but innate. 
 
 In acquired perception, the signs are either sensations^ ji 
 or things which we perceive by means of sensations. The i 
 connection between the sign and the thing signified, isi; 
 established by nature : and we discover this connection by 
 experience ; but not without the aid of our original percep- 
 tions, or of those wliieh we have already acquired. Af- 
 ter this connection is discovered, the sign, in lilic manner 
 as in original perception, always suggests the things sig- 
 nified, and creates the belief of it. 
 
 In artificial language, the signs are articulate sounds, 
 whose connection with the things signified by them is es- 
 tablished by the will of men : and in learning our mother 
 tongue, we discover this connection by experience ; but 
 not without the aid of natural language, or of what w« 
 
408 OF THE HUMAN MINB. 
 
 I had before attained of artificial language. And after 
 this connection is discovered, the sign, as in natural lan- 
 ■ guage, always suggests the thing signified, and creates 
 the belief of it. 
 
 Our original perceptions are few, compared with the 
 acquired ; but without the former, we could not possibly 
 attain the latter. In like manner, natural language is 
 scanty, compared with artificial ; but without the former 
 we could not possibly attain the latter. 
 
 Our original perceptions, as well as the natural Ian- 
 guage of human features and gestures, must be resolved 
 into particular principles of the human constitution. Thus 
 it is by one particular principle of our constitution, that 
 certain features express anger ; and by another particular 
 principle that certain features express benevolence. It is 
 in like manner by one particular principle of our consti- 
 tution, that a certain sensation signifies hardness in the 
 body which I handle ; and it is by another particular prin- 
 ciple, that a certain sensation signifies motion in that body. 
 But our acquired perceptions, and the information we 
 receive by means of artificial language, must be resolved 
 into general principles of the human constitution. When a 
 painter perceives that this picture is the work of Raphael, 
 that the work of Titian : a jeweller, that this is a true 
 diamond, that a counterfeit ; a sailor, that this is a ship of 
 five hundred tons, that of four hundred; these different 
 acquired perceptions are produced by the same general 
 principles of the human mind, which have a different 
 operation in the same person, according as they are va- 
 riously applied, and in different persons, according to the 
 diversify of their education and manner of life. In like 
 manner, when certain articulate sounds convey to my 
 mind the knowledge of the battle of Pharsalia ; and oth- 
 ers, the knowledge of the battle of Poltowa ; when a 
 Frenchman and an Englishman receive the same inform- 
 ation by different articulate sounds 5 the signs used in 
 these different cases, produce the knowledge and belief 
 of the things signified, by means of the same general 
 principles of the human constitution. 
 
SEEING. 409 
 
 Kow, if we compare the general principles of our con- 
 stitution, which fit us for receiving information from our 
 fellow-creatures by language, with the general principles 
 which fit us for acquiring the perception of things by our 
 senses, we shall find them to be very similar in their na- 
 ture and manner of operation. 
 
 When we begin to learn our mother tongue, we per- 
 ceive by the help of natural language, that they who speak 
 to us, use certain sounds to express certain things : we 
 imitate the same sounds when we would express the same 
 things, and find that we are understood. 
 
 But here a difficulty occurs which merits our attention, 
 because the solution of it leads to some original principles 
 of the human mind, which are of great importance, and 
 of very extensive influence. We know by experience, that 
 men have used such words to express such things. But 
 all experience is of the past, and can, of itself, give no 
 notion or belief of what is future^ How come we then to 
 believe, and to rely upon it with assurance, that men who 
 have it in their power to do otherwise, will continue to 
 use the same words when they think the same things ? 
 Whence comes this k-nowledge aud belief, this foresight 
 we ought rather to call it, of the future and voluntary 
 actions of our fellow-creatures ? Have they promised that 
 they will never impose upon us by equivocation or false- 
 hood ? No, they have not. And, if they had, this would 
 not solve the difficulty : for such promise must be ex- 
 pressed by words, or by other signs j and, before we can 
 rely upon it, we must be assured, that they put the usual 
 meaning upon the signs which express thaty)romise. No 
 man of common sense ever thought of taking a man's own 
 word for his honesty ; and it is evident that we take his 
 veracity for granted, when we lay any stress upon his 
 word or promise., I might add, that this reliance upon 
 the declarations and testimony of men, is found in chil- 
 dren long before they know what a promise is. 
 
 There is, therefore, in the human mind an early an- 
 ticipation, neither derived from experience, nor from rea- 
 
 voi. I. 52 
 
MO OF THE HUMAN MIND. 
 
 son, nor from aoy compact or promise, that our fellow- 
 creatures will use the same signs in language, when they 
 have the same sentiments. 
 
 This is, in reality, a kind of prescience of human ac- 
 tions ,• and it seems to me to he an original principle of 
 the human constitution, without which we should be in- 
 capahle of language, and consequently incapable of in- 
 struction. 
 
 The wise and beneficent Author of nature, who intend- 
 ed that we should be social creatures, and that we should 
 receive the greatest and most important part of our 
 knowledge by the information of others, hath, for these 
 purposes implanted in our natures two principles that 
 tally with each other. 
 
 The first of these principles is, a propensity to speak 
 truth, and to use the signs of language, so as to convey 
 our real sentiments. This principle has a powerful ope- 
 ration, even in the greatest liars ; for, where they lie 
 once, they "speak truth a hundred times. Truth is al- 
 ways uppermost, ^nd is the natural issue of the mind. It 
 requires no art or training, no inducement or temptation, 
 but only that we yield to a natural impulse. Lying, on 
 the contrary, is doing violence to our nature ; and is never 
 practised, even by the worst men, without some tempta- 
 tion. Speaking truth is like using our natural food, 
 which we would do from appetite, although it answered 
 no end ; but lying is like taking physic, which is nauseous 
 to the taste, and which no man takes but for some end 
 which he cannot otherwise attain.* 
 
 * All men, from an instinct of the animal nature, eat when they are hun- 
 gry, and were they to he governed by this instinct alone, they would nev- 
 er abstain from eating any thing which they desired and could obtain. 
 When, in obedience to the physician, the person parched with fever re. 
 fuses water, he does violence to that instinct, which, if suffered to govern 
 him, would always induce him to drink when thirsty. 
 
 The human mind, as well as the animal nature, has its instincts, or native 
 propensities. Ope of these induces man to speak the truth ; and, were he 
 to be governed by this alone, he would deceive neither by natural nor by arti- 
 ficial language. Frrm a native propensity to express our feelings, wefrown» 
 smile, sigh, weep, or blush, or groan ; and without artifice, without doing 
 
sEEixe. 411 
 
 If it should be objected, That men may be influenced 
 by moral or political considerations to speak truth, and 
 therefore, that their doing so, is no proof of such an 
 original principle as we have mentioned : I answer, first, 
 That moral or political considerations can have no in- 
 fluence until we arrive at years of understanding and re- 
 flection ; and it is certain, from experience, that chil- 
 dren keep to truth invariably, before they are capable of 
 being influenced by such considerations. Secondly, When 
 we are influenced by moral or political considerations, 
 we must be conscious of that influence, and capable of 
 
 violence to instinct, men would never speak lies by tliese natural signs of 
 thought and feeling. He -who gave man intelligence and sensibility, and 
 placed him in a social state, gave him also language which so naturally indi. 
 cates a person's mental operations, that it requires a made up face and much 
 exertion to conceal them. That artificial language would invariably express 
 what men believe, were they to be entirely governed by their native pro. 
 pensity to truth, is proved by our author ; and may be confirmed by this 
 fact, that those who are accustomed to converse in their sleep never speak 
 lies. A. child of about ten years of age is known to the Editors, who is full of 
 cunning evasion, and rarely acknowledges his faults, when awake ; but when 
 asleep, if any one questions him concerning his past conduct, he reveals the 
 whole truth. Many have heard him repeat in his sleep the answers to forty 
 or fifty questions in the Assembly's Catechism, besides acknowledging the 
 faults which he had committed a few hours before, and had concealed, until 
 he was in a sound slumber Jt is a saying not less true than common, that 
 loverain their sleep divulge the secrets of their hearts, and we believe that 
 the remark will apply to all who talk in their sleep ; for they seem then 
 to be guided wholly by the native principles of the mind. 
 
 When our learned author says that lying is doing violence to our nature, 
 he intends that it is doing violence to this native propensity to speak. the 
 truth ; for it is not true that lying is opposed to that complex thing, which 
 h commoaly deDOiainated depraved human nature, anymore than abiti- 
 nence from cold water is opposed to the compound nature of that man, in 
 a fever, who is actuated by reason, the desire of restoration to health, and 
 the love of life, as well as anima! instincts. Lying does violence to one 
 original principle of that mind, which God made, and the person, who prac. 
 tises it, must struggle against the dictates of his conscience ; but selfishness, 
 and the perception of some personal advantage, which will apparently ac- 
 crue from falsehood, have such influence upon all men, in their natural 
 estate, that most children, and all savages lie, whenever they think decep. 
 tion will be gain. The sinful, moral propensities of man, and the illusions 
 otthe father of lies, not the original faculties of the human soul, have given 
 rise to that figurative, but humbling assertion, " they go astray as soon as 
 they be born, speaking lies." American Editor. 
 
412 OF THE HUMAN MIND. 
 
 perceiving it upon reflection. Now, when I reflect up- 
 on ni^ actions most atteniively, I am not conscious, that, 
 in speaking truth, I am influenced on ordinary occasions, 
 by any motive moral or political. I find, that truth is 
 always at the door of my lips, and goes forth spontaneous- 
 ly, if not held back. It requires neither good nor bad 
 intention to bring it forth, but only that I be artless and 
 undesigning. There may, indeed, be temptations to 
 falsehood, which would be too strong for the natural 
 principle of veracity, unaided by principles of honour or 
 virtue ,• but where there is no such temptation, we speak 
 truth by instinct ; and this instinct is the principle I have 
 been explaining. 
 
 By this instinct, a real connection is formed between 
 our words and our thoughts, and thereby the former be- 
 come fit to be signs of the latter, which, they could not 
 otherwise be. And although this connection is broken 
 in every instance of lying and equivocation, yet these in- 
 stances being comparatively few, the authority of humaii 
 testimony is only weakened by them, but not destroyed. 
 
 Another original principle implanted in us by the Su- 
 preme Being, is a disposition to confide in the veracity of 
 others, and to believe what they tell us. This is the 
 counter part to the former; and as that maybe called 
 the principle of veracity, we shall, for want of a more 
 pi'oper name, call this the principle of credulity. It is 
 unlimited in children, until they meet with instances of 
 deceit and falsehood : and it retains a very considerable 
 degree of strength through life. 
 
 If nature had left t!ie mind of the speaker in equilibriot 
 without any inclination to the side of truth more than to 
 that of falsehood ; children wouldlie as often as they speak 
 truth, until reason was so far ripened, as to suggest the 
 imprudence of lying, or conscience, a^ to suggest its im- 
 mortality. And if nature had left the mind of the hearer 
 in equilibria, without any inclination to the side of belief 
 more than to that of disbelief, we should take no man's 
 word until we had positive evidence that he spoke truth. 
 
S£BIN6. 4il3 
 
 His testimony would, in this case, have no more authori- 
 ty tlian his dreams ; which may be true or false, but no 
 man is disposed to believe them, on this account, that 
 they were dreamed. It is evident, that, in the matter of 
 testimony, the balance of human judgment is by nature in- 
 clined to the side of belief; and turns to that side of itself, 
 when there is nothing put into the opposite scale. If it 
 was not so, no proposition that is uttered in discourse 
 would be believed, until it was examined and tried by 
 reason ; and most men would be unable to find reasons 
 for believing the thousandth part of what is told them. 
 Such distrust and incredulity would deprive us of the 
 greatest benefits of society, and place us in a worse con- 
 dition than that of savages. 
 
 Children, on this supposition, would be absolutely in- 
 credulous ; and therefore absolutely incapable of instruc- 
 tion : those who had little knowledge of human life, and 
 of the manners and characters of men, would be in the 
 next degree incredulous: and the most credulous men 
 would be those of greatest experience, and of the deep- 
 est penetration ; because, in many cases, they would be 
 able to find good reasons for believing the testimony, which 
 the weak and the ignorant could not discover. 
 
 In a word, if credulity were the effect of reasoning and 
 experience, it must grow up and gatljer strength, in 
 the same proportion as reason and experience do. But 
 if it is the gift of nature, it will be strongest in childhood, 
 and limited and restrained by experience j and the most 
 superficial view of human life shows, that the last is really 
 the case, and not the first. 
 
 It is the intention of nature, that we should be carried 
 in arms before we are able to walk upon our legs j and it 
 is likewise the intention of nature, that our belief should 
 be guided by the authority and reason of others, before 
 it can be guided by our own reason. The weakness 
 of the infant, and the natural affection of the mother, 
 plainly indicate the former ; and the natural credulity of 
 youth, and authority of age, as plainly indicate the lat- 
 
414 or THE HUMAN MIND. 
 
 ter. The iofant, by proper nursing and care, acquires 
 strength to walk witiiout support. Reason hatii likewise 
 her infancy, when she must be carried in arms : then 
 she leans entirely upon authority, by natural instinct, as 
 if she was conscious of lier own weakness ; and without 
 this support, she becomes vertiginous. When brought 
 to maturity by proper culture, she begins to feel her own 
 strength, and leans less upon the reason of others ; she 
 learns to suspect testimony i!i some eases, and to disbe- 
 lieve it in others ; and sets bounds to that authority to 
 which she was at first entirely subject. But still, to the 
 end of life, she finds a necessity of borrowing light from 
 testimony, where she has none within herself, and of 
 leaning in some degree upon the reason of others, where 
 she is conscious of her own imbecility. 
 
 And as in many instances, Reason, even in her maturity, 
 borrows aid from testimony ; so in others she mutually 
 gives aid to it, and strengthens its authority. For as we 
 find good reason to reject testimony in some cases, so 
 in others we find good reason to rely upon it with per- 
 fect security, in our most important concerns. The 
 character, the number, and the disinterestedness of wit- 
 nesses, the impossibility of collusion, and the incredibility 
 of their concurring in their testimony without collusion, 
 may give an irresistible strength to testimony, compared 
 to which, its native and intrinsic authority is very incon- 
 siderable. 
 
 Having now considered the general principles of the 
 human mind which fit us for receiving information from 
 our fellow -creatures, by (he means of language : let us 
 next consider tlie general principles which fit us for re- 
 ceiving the informationof nature by our acquired percep- 
 tions. 
 
 It is undeniable, and indeed is acknowledged by all, that 
 when we have found two things to have been constantly 
 conjoined in the course of nature, the appearance of one 
 of them is immediately followed by the conception and 
 belief of the other. The former becomes a natural sign 
 
SEEIIVG. 41a 
 
 of the latter ; and the knowledge of their constant con- 
 junction in time past, whether got by experience or oth- 
 erwise, is sufficient lo make us rely with assurance upon 
 the continuance of that conjunction. ' 
 
 This process of the human mind is so familiar, that we 
 never (hink of inquiring into the principles upon which it 
 is founded. We are apt to conceive it as a self-evident 
 truth, (hat wha< is to come must be similar to what is past. 
 Thus if a certain degree of cold freezes water today, and 
 has been known <o do so in all time past, we have no doubt 
 but the same degree of cold will freeze water tomorrow, or 
 a year hence. That this is a truth which all men believe 
 as soon as they understand it, I readily admit, but the 
 question is, Whence does its evidence arise ? Not from 
 comparing the ideas, surely. For when I compare the 
 idea of cold with that of water hardened into a transpa- 
 rent solid body, I can perceive no connection between them : 
 no man can show the one to be the necessary effect of the,! 
 other : no man can give a shadow of reason why nature 
 hath conjoined them. But do we not learn their conjunct 
 tion from experience ? True : experience informs us that 
 they have been conjoined in time past: but no man evet 
 had any experience of what is future : and this is the very 
 question to be resolved, How we come to believe that the 
 future will be like the past ? Hath the Author of nature 
 promised this ? Or were we admitted to bis council, when 
 he established the present laws of nature, and determined 
 the time of their continuance ? No, surely. Indeed, if 
 we believe that there is a wise and good Author of nature, 
 we may see a good reason, why he should continue the 
 same laws of nature, and the same connections of things, 
 for a long time ; because, if he did otherwise, we dould 
 learn nothing from what is past, and all our experience 
 would be of no use to us. But though this consideration, 
 when >ve come to the use of reason, may confirm our be- 
 lief of the continuance of the present course of nature, it 
 is certain that it did not give rise to this belief | for chil- 
 
416 OJT THE HUMAN MIND. 
 
 dren and idiots have this belief as soon as they know 
 that fire will burn them. It must therefore be the ef- 
 fect of instinct, not of reason. 
 
 The wise Author of our nature intended, that a great 
 and necessary part of our knowledge should be derived 
 from experience, before we are capable of reasoning, and 
 he hath provided means perfectly adequate to this inten- 
 tion. For, first. He governs nature by fixed laws, so that 
 we find innumerable connections of things which continue 
 from age to age. Without this stability of the course of 
 nature, there could be no experience ; or, it would be a 
 false guide, and lead us into error and mischief. If there 
 were not a principle of veracity in the human mind, 
 men's words would not be signs of their thoughts : and if 
 there were no regularity in the course of nature, no one 
 thing could be a natural sign of another. Secondly, He 
 hath implanted in human minds an original principle by 
 which we believe and expect the eoolinuance of the course 
 of nature, and the continuance of those connections which 
 we have observed in time past. It is by this general 
 principle of our nature, that when two things have been 
 found connected in time past, the appearance of the one 
 produces the belief of the other. 
 
 I think the ingenious author of the Treatise of Human 
 Nature first observed, Thatour belief of (he continuance 
 of the laws of nature cannot be founded either upon knowl- 
 edge or probability ; but, far from conceiving it to be an 
 original principle of the mind, he endeavours to account 
 for it from his favourite hypothesis. That belief is noth. 
 ing but a certain degree of vivacity in the idea of the thing 
 believed. I made a remark upon this curious hypothesis 
 in the second chapter, and shall now make another. 
 
 The belief which we have in perception, is a belief of 
 the present existence of the object | that which we have 
 in memory, is a belief of its past existence ; the belief of 
 which we are now speaking, is a belief of its future ex- 
 istence, and in imagination there is no belief at all. Now, 
 I would gladly know of this author, how one degree of 
 
SEEING. 417 
 
 vivacity fixes the existence of the object to the present 
 moment; another carries it back to time past; a third, 
 taking a contrary direction, carries it into futurity ; and 
 a fourth carries it out of existence altogether. Suppose, 
 for instance, that I see the sun rising out of the sea; I 
 remember to have seen him rise yesterday ; I believe he 
 will rise tomorrow near the same place ; I can likewise 
 imagine him rising in that place, without any belief at 
 all. Now, according to this skeptical hypothesis, this 
 perception, this memory, this foreknowledge, and this im- 
 agination, are all (he same idea, diversified only by differ- 
 ent degrees of vivacity. The perception of the sun rising, 
 is the most lively idea; the memory of his rising yester- 
 day, is the same idea a little more'faint ; the belief of his 
 rising tomorrow, is the same idea yet fainter ; and the 
 imagination of his rising, is still the same idea, but 
 faintest of all. One is apt to think, that this idea might 
 gradually pass through all possible degrees of vivaci- 
 ty, without stirring out of its place. But if we think 
 so, we deceive ourselves ; for no sooner does it begin to 
 grow languid, than it moves backward into time past. 
 Supposing this to be granted, we expect at least that as 
 it moves backward by the decay of its vivacity, the more 
 that vivacity decays, it will go back the farther, until it 
 remove quite out of sight. But here we are deceived 
 again ; for there is a certain period of this declining 
 vivacity, when, as if it had met an elastic obstacle 
 in its motion backward, it suddenly rebounds from the 
 past to the future, without taking tJie present in its way. 
 And now having got into the regions of futurity, we are 
 apt to think, that it has room enough to spend all its re- 
 maining vigour : but still we are deceived ; for, by anoth- 
 er sprightly bound, it mounts up into the airy region of 
 imagination. So that ideas, in the gradual declension of; 
 their vivacity, seem to imitate the inflection of verbs in\ 
 grammar. They begin with the present, and proceed in 
 order to the preterite, the future, and the indefinite. This 
 vol. I. BS 
 
MS O^ TUB HUMAN MIND. 
 
 article of the skeptical creed is indeed so full of mystery, 
 on whatever side we view it, that they who hold that 
 ereed, are very injuriously chargied with incredulity : for 
 to rae it appears to require as much faith as that of St. 
 Athanasius. 
 
 However, we agree with the author of the Treatise of 
 Human Nature in this, That our belief of the continuance 
 of nature's laws is not derived from reason. It is an in- 
 stinctive prescience of the operations of nature, very 
 like to that prescience of hiiman actions which makes us 
 rely upon the testimony of our fellow creatures ; and as, 
 without the latter, we should be incapable of receiving 
 information from men by language, so, without the for- 
 mer, we should be incapable of receiving the information 
 of nature by means of experience. 
 
 All our knowledge of nature beyond our original per- 
 ceptions, is got by experience, and consists in the inter- 
 pretation of natural signs. The constancy of nature's 
 laws connects the sign with the thing signified, and, by 
 the natural principle just now explained, we rely upon 
 the continuance of the connections which experience hath 
 discovered ; and thus the appearance of the sign, is fol- 
 lowed by thebelief of the thing signified. 
 
 Upon this principle of our constitution, not only ac- 
 quired perception, but all inductive reasoning, and all our 
 reasoning from analogy, is grounded : and therefore, for 
 want of another name, we shall beg leave to call it the 
 inductive principle. It is from the force of this principle, 
 that we immediately assent to that axiom, upon which 
 all <.ur know'edge of nature is built, that effects of the 
 same kind must have the same cause. For effects and 
 causes, in the operations of nature, mean nothing but signs 
 and the things signified by them. We perceive no proper 
 casualty or efficiency in any natural cause; but only a 
 connection established by the course of nature between it 
 and what is called its effect. Antecedently to all reason- 
 ing, we have, by our constitution, an anticipation, that 
 there is a fixed and steady course of nature; and we have 
 
s£Ki\e. 4,19 
 
 an eager desire to discover this course of nature. We 
 attend to every conjunction of things which presents it- 
 self, and expect the continuance of that conjunction. And 
 when such a conjunction has been often observed, we con- 
 ceive the things to be naturally eonnected, and the ap- 
 pearance of one, without any reasoning or reflection, car- 
 ries along with it the belief of the other. 
 
 If any reader should imagine that the inductive prin- 
 ciple may be resolved into what philosophers usually call 
 the association of ideas, let him observe, that, by this 
 pi'inciple, natural signs are not associated with the idea 
 only, butwiththe belief of the things signified. Now, this 
 can with no propriety be called an association of ideas, 
 unless ideas and belief be one and the same thing. A child 
 has found the prick of a pin conjoined with pain ; hence 
 he believes and knows that these things are naturally 
 connected; he knows that the one will always follow the 
 other. If any man will call this only an association of ideas, 
 I dispute not about words, but I think he speaks very im- 
 properly. For if we express it in plain English, it is a 
 prescience, that things which he hath found conjoined in 
 time past, will be conjoined in time to come. And this 
 prescience is not the effect of reasoning, but of an orig- 
 inal principle of human nature, which I have called the 
 inductive principle. 
 
 This principle, like that of credulity, is unlimited in 
 infancy, and gradually restrained and regulated as we 
 grow up. It leads us often into mistakes, but is of in- 
 finite advantage- upon the whole. By it the child once 
 burnt shuns the fire ; by it, he likewise runs away from 
 the surgeon, by whom he was inoculated. It is better 
 that he should do the last, than that he should not do 
 the first. 
 
 But the mistakes we are led into by these two natural 
 principles, are of a different kind. Men sometimes lead 
 us into mistakes, when we perfectly understand their 
 language, by speaking lies. But nature never misleads 
 us in this way ; her language is always true ; and it is 
 
420 OF THE HUMAN MIND. 
 
 only by misinterpreting it that we fall into error. There 
 must be many accidental conjunctions of things, as well 
 as natural connections; and the former are apt to be mis- 
 taken forthe latter. Thus in theiiistance above mentioned; 
 the child connected the pain of inoculation with the sur- 
 ge6n ; whereas it was really connected with the incision on- 
 ly. Philosophers, and men of science, are not exempted 
 from such mistakes ; indeed all false reasoning in philoso- 
 phyis owing to them : it is drawn from experience and an- 
 alogy, as well as just reasoning, otherwise, it could have no 
 verisimilitude : but the one is an unskilful and rash, the 
 other a just and legitimate, interpretation of natural 
 signs. If a child, or a man of common understanding, 
 were put to interpret a book of science, written in his 
 mother tongue, how many blunders and mistakes would 
 he be apt to fall into ? Yet he knows as much of this lan- 
 guage as is necessary for his manner of life. 
 
 The language of nature is the universal study; and the 
 students are of different classes. Brutes, idiots, and chil- 
 dren, employ themselves in this study, and owe to it all 
 their acquired perceptions. Men of common understand- 
 ing make a greater progress, and learn, by a small de- 
 gree of reflection, many things of which children are ig- 
 norant. 
 
 Philosophers fill up the highest form in this school, 
 and are critics in the language of nature. All these dif- 
 ferent classes have one teacher. Experience, enlightened 
 by the inductive principle. Take away the light of this 
 inductive principle, and Experience is asblind as a mole : 
 she may indeed feel what is present, and what immedi- 
 ately touches her j bat she sees nothing that is either be- 
 fore or behind, upon the right hand or upon the leftj fu- 
 ture or past. 
 
 The rules of inductive reasoning, op of a just interpreta- 
 tion of nature, as well as the fallacies by which we are 
 apt to misinterpret her language, have been, with won- 
 derful sagacity, delineated by the great genius of lord 
 Bacon : so that his Novum organum may justly be called 
 
SEEIBTG. 421 
 
 a grammar of the language of nature. It adds greatly 
 to the merit of this work, and atones for its defects, that 
 at the time it was written, the world had not seen any 
 tolerable model of inductive reasoning, from which the 
 rules of it might be copied. The arts of poetry and elo- 
 quence were grown up to perfection when Aristotle de- 
 scribed them ; but the art of interpreting nature was yet 
 in embryo when Bacon delineated its manly features and 
 proportions. Aristotle drew his rules from the best 
 models of those arts that have yet appeared j but the best 
 models of inductive reasoning that have yet appeared, 
 which I take to be the third book of the Principia and 
 the Optics of Newton, were drawn from Bacon's rules. 
 The purpose of all those rules, is to teach us to distin- 
 guish seeming or apparent connections of things in the 
 course of nature, from such as are real. 
 
 They that are unskilful in inductive reasoning are 
 more apt to fall into error in their reasonings from the 
 phenomena of nature, than in their acquired perceptions; I 
 because we often reason from a few instances, and there- 
 by are apt to mistake accidental conjunctions of things for 
 natural connections : but that habit of passing, without 
 reasoning, from the sign to the thing signified, which 
 constitutes acquired perception, must be learned by ma- 
 ny instances or experiments ; and the number of experi-,! 
 ments serves to disjoin those things which have been acci-; 
 dentally conjoined, as well as to confirm our belief of nat-- 
 ural connections. 
 
 From the time that children begin to use their hands, 
 nature directs them to handle every thing over and over, 
 to look at it while they handle it, and to put it in various 
 positions, and at various distances from the eye. We are 
 apt to excuse this as a childish diversion, because they 
 must be doing something, and have not reason to enter- 
 tain themselves in a more manly way. But if we think 
 more justly, we shall find, that they are engaged in the 
 most serious and important study ,■ and if they had all the 
 reason of a philosopher, they could not be more properly 
 
422 Of THE HUMAN MINB. 
 
 employed. For it is this childish employment that en- 
 ables them to make the proper use of their eyes. They 
 are thereby every day acquiring habits of perception, 
 vhich are of greater importance than any thing we can 
 teach them. The original perceptions which nature gave 
 them are few, and insuflicient for the purposes of life ; 
 and therefore she made them capable of acquiring many 
 more perceptions by habit. And, to complete her work, 
 she hath given them an unwearied assiduity in applying 
 to the exercises by which those perceptions are acquired. 
 This is the education which nature gives to her chil- 
 dren. And since we have fallen upon this subject, we 
 may add, that another part of nature's education is, that, 
 by the course of things, children must often exert all 
 their muscular force, and employ all their ingenuity, in 
 order to gratify their curiosity, and satisfy their little ap- 
 petites. What they desire is only to be obtained at the 
 expense of labour and patience, and many disappointments. 
 By the exercise of body and mind necessary for satisfying 
 their desires, they acquire agility, strength, and dexterity 
 in their motions, as well as health and vigour to their 
 constitutions j they learn patience and perseverance ; they 
 learn to bear pain without dejection, and disappointment 
 without despondence. The education of nature is most per- 
 fect in savages, who have no other tutor : and we see, that, 
 in the quickness of all their senses, in the agility of their 
 motions, in the hardiness of their constitutions, and in the 
 strength of their minds to bear hunger, thirst, pain, and 
 disappointment, they commonly far exceed the civilized. 
 A most ingenious writer, on this account, seems to prefer 
 the savage life to that of society. But the education of na- 
 ture could never of itself produce a Bousseau. It is the in- 
 tention of nature, that human education should be joined 
 ! to her institution, in order to form the man. And she hath 
 fitted us for human education, by the natural principles of 
 imitation and credulity, which discover themselves almost 
 in infancy, as well as by others which are of later growth. 
 
SEEIN*. *23 
 
 Wlien the edacation which we receive from men, does 
 not give scope to the education of nature, it is wrong di- 
 rected ; it tends to hurt our faculties of perception, and 
 to enervate both the body and mind. Nature hath her 
 way of rearing men, as she hath of curing their diseases. 
 The art of medicine is to follow nature, to imitate and to 
 assist her in the cure of diseases; and the art of educa- 
 tion is to follow nature, and to assist and to imitate her 
 in her way of rearing men. The ancient inhabitants 
 of the Baleares followed nature in the manner of teach- 
 ing their children to be good archers, when they hung 
 their dinner aloft by a thread, and left the younkers to 
 bring it down by their skill in archery. 
 
 The education of nature, without any more human care 
 than is necessary to preserve life, makes a perfect savage. 
 Human education, joined to that of nature, may make a 
 good citizen, a skilful artisan, or a well bred man. But 
 reason and reflection must superadd their tutory, in order 
 to produce a Rousseau, a Bacon, or a Newton. 
 
 Notwithstanding the innumerable errors committed in 
 human education, there is hardly any education so bad, 
 as to be worse than none. And I apprehend, that if 
 even Rousseau were to choose whether to educate a son 
 among the French, the Italians, the Chinese, or among 
 the Eskimaux, he would not give the preference to the 
 last. 
 
 When reason is proijcrly employed, she will confirm 
 the documents of nature, which are always true and whole- 
 some ; she will distinguish, in the documents of human 
 education, the good from the bad, rejecting the last with 
 modesty, and adhering to the first with reverence. 
 
 Most men continue all their days to be just what na- 
 ture and human education made them. Their manners, 
 their opinions, their virtues, and their vices, are all got 
 by habit, imitation, and instruction ; and reason has little 
 or no share in forming them. 
 
42* OF THE HUMAN MINB. 
 
 CHAP. VII. 
 CONCLUSION. 
 
 CONTAINING REFLECTIONS UPON THE OPINIONS OF PHI- 
 XOSOPHEBS ON THIS SUBJECT. 
 
 There are two ways in which men may form their no- 
 tions and opinions concerning the mind, and concerning its 
 powers and operations. The first is the only way that 
 leads to truth ; but it is narrow and rugged, and few have 
 entered upon it. The second is broad and smooth, and 
 hath been much beaten, not only by the vulgar, but even 
 by philosophers ; it is sufficient for common life, and is 
 well adapted to the purposes of the poet and orator : but 
 in philosophical disquisitions concerning the mind, it leads 
 to error and delusion. 
 
 We may call the first of these ways, the way of rejke- 
 tioii. When the operations of the mind are exerted, we 
 are conscious of them ; and it is in our power to attend to 
 them, and to reflect upon them, until they become famil- 
 iar objects of thought. This is the only way in which 
 we can form just and accurate notions of those opera- 
 tions. But this attention and reflection is so difficult to 
 man, surrounded on all hands by external objects, which 
 constantly solicit his attention, that it has been very little 
 practised, even by philosophers. In the course of this 
 Inquiry, we have had many occasions to show how little 
 attention hath been given to the most familiar operations 
 of the senses. 
 
 The second, and the most common way, in which men 
 form their opinions concerning the mind and its opera- 
 lions, we may call the way of analogy. There is nothing 
 in the course of nature so singular, but we can find some 
 resemblance, or at least some analogy, between it and 
 other things with which we are acquainted. The mind 
 
coNciusioir. 485 
 
 naturally delights in hunting after such analogies, and 
 attends to them with pleasure. From them, poetry and 
 wit derive a great part of their charms | and eloquence, 
 not a little of its persuasive force. 
 
 Besides the pleasure we receive from analogies, they 
 are of very considerable use, both to facilitate the concep- 
 tion of things, when they are not easily apprehended with- 
 out such a handle, and to lead us to probable conjectures 
 about their nature and qualities, when we want the means 
 of more direct and immediate knowledge. When I con- 
 sider that the planet Jupiter, in like manner as the earih, 
 rolls round his own axis, and revolves round the sun, and 
 that he is enlightened by several secondary planets, as 
 the earth is enlightened by the moon ; I am apt to con- 
 jecture from analogy, that as the earth by these means 
 is fitted to be the habitation of various orders of animals, 
 so the planet Jupiter is, by the like means, fitted for the 
 same purpose: and having no argument more direct and 
 conclusive to determine me in this point, I yield, to this 
 analogical reasoning, a degree of assent proportioned to 
 its strength. When I observe that the potatoe plant very 
 much resembles the solanum in its flower and fructifica- 
 tion, and am informed, that the last is poisonous, I am 
 apt from analogy to have some suspicion of the former : 
 but in this case, I have access to more direct and certain 
 evidence; and therefore ought not to trust to analogy, 
 which would lead me into an error. 
 
 Arguments from analogy are always at hand, and grow 
 up spontaneously in a fruitful imagination, while argu- 
 ments that are more direct, and more conclusive, often 
 require painful attention and application : and therefore, 
 mankind in general have been very much disposed to trust 
 to the former. If one attentively examines the systems 
 of the ancient philosophers, either concerning the mate- 
 rial world, or concerning the mind, he will find them to 
 be built solely upon the foundation of analogy. Lord Ba- 
 con first delineated the strict and severe method of induc- 
 tion ; since his time it has been applied with very happy 
 
 vol. I. 54 
 
426 or THE HUMAN MINU. 
 
 success in some parts of natural philosophy ; and bardir 
 in any thing else. But there is no subject in which man- 
 kind are so much disposed to trust to the analogical way 
 of thinking and reasoning, as in what concerns the mind 
 and its operations ; because, to form clear and distinct 
 notions of those operations in the direct and proper way, 
 and to reason about them, requires a habit of attentive 
 reflection, of which few are capable, and which, even by 
 those few, cannot be attained without much pains and 
 labour. 
 
 Every man'is apt to form his notions of things difficult 
 to be apprehended, or less familiar, from their analogy 
 to things which are more familiar. Thus, if a man bred 
 to the seafaring life, and accustomed to think and talk 
 only of matters relating to navigation, enters into dis- 
 course upon any other subject ; it is well known, that the 
 language and the notions proper to his own profession are 
 infused into every subject, and all things are measured by 
 the rules of navigation : and if he should take it into his 
 head to philosophize concerning the faculties of the mind, 
 it cannot be doubted, but he would draw his notions from 
 the fabric of his ship, and would find in the mind, saik, 
 masts, rudder, and compass. 
 
 Sensible objects of one kind or other, do no less occupy 
 and engross the rest of mankind, than things relating to 
 navigation, the seafaring man. For a considerable part 
 of life, we can think of nothing but the objects of sense j 
 and to attend to objects of another nature, so as to form 
 clear and distinct notions of them, is no easy matter, even 
 after we come to years of reflection. The condition of 
 mankind, therefore, affords good reason to apprehend, 
 that their language, and their common notions, concern- 
 ing the mind and its operations, will be analogical, and 
 derived from the objects of sense 5 and that these analo- 
 gies will be apt to impose upon philosophers, as well as 
 upon the vulgar, and to lead them to materialize the mind 
 and its faculties,- and experience abundantly confirms the 
 truth of this. 
 
CONClUSIOTf. 427 
 
 How generally men of all nations, and in all ages of 
 the world, have conceived the soul, or thinking principle 
 in man, to be some subtile matter, like breath or wind, 
 the names given to it almost in all languages sufficiently 
 testify. "We have words which are proper, and not an- 
 alogical, to express the various ways in which we per- 
 ceive external objects by the senses; such as feeiing, 
 sight, taste: but we are often obliged to use these words 
 analogically, to express other powers of the mind which, 
 are of a very different nature. And the powers which;' 
 imply some degree of reflection, have generally no names; 
 but such as are analogical. The objects of thought are'j 
 said to be in the mind, to be apprehended, comprehended,] 
 conceived, imagined, retained, weighed, ruminated. I 
 
 It does not appear that the notions of the ancient phi- 
 losophers, with regard to the nature of the soul, were ■ 
 much more refined than those of the vulgar, or that they t 
 were formed in any other way. We shall distinguish , 
 the pliilosophy that regards our subject into the old 
 and the new. The old reached down to Des Cartes, 
 who gave it a fatal blow, of which it has been grad- 
 ually expiring ever since, and is now almost extinct. 
 Des Cartes is the father of the new philosophy that re- 
 lates to this subject; but it hath been gradually improv- 
 ing since his time, upon the principles laid down by him. 
 The old philosophy seems to have been purely analogi- 
 cal : the new is more derived from reflection, but still 
 with a very considerable mixture of the old analogical 
 notions. 
 
 Because the objects of sense consist of matter audform, 
 the ancient philosophers conceived every thing to belong! 
 to one of these, or to be made up of both. Some there-; 
 fore thought, that the soul is a particular kind of subtilel 
 matter, separable from our gross bodies ; others thought 
 that it is only a particular form of the body, and insep- 
 arable from it. Fop there seem to have been some among 
 the ancients, as well as among the moderns, who conceiv- 
 ed that a certain structure or organization of the body, 
 
428 or THE HUMAN MINB. 
 
 is all that is necessary to render it sensible and intelli' 
 gent. The different powers of the mind were, accord- 
 ingly, by the last sect of philosophers, conceived to be- 
 long to different parts of the body, as the heart, the brain, 
 the liver, the stomach, the blood. 
 
 I'hey vfho thought that the soul is a subtile matter 
 separable from the body, disputed to which of the four 
 elements it belongs, whether to earth, water, air, or 
 fire. Of the three last, each had its particular advocates. 
 But some were of opinion, that it partakes of all the ele- 
 ments ; that it must have something in its composition 
 similar to every thing we perceive; and that we perceive 
 earth by the earthly part ; water, by the watery part ; and 
 fire, by the fiery part of the soul. Some philosophers, not 
 satisfied with determining of what kind of matter the soul 
 is made, inquired likewise into its figure, which they de- 
 termined to be spherical, that it might be the more iit 
 for motion. The most spiritual and sublime notion con. 
 cerning the nature of the soul, to be met with among the 
 ancient philosophers, I conceive to be that of the Plato- 
 nists, who held, that it is made of that celestial and in- 
 corrruptible matter of which the fixed stars were made, 
 and therefore has a natural tendency to rejoin its proper 
 element. I am at a loss to say, in which of these classes 
 of philosophers Aristotle ought to be placed. He defines 
 the soul to be. The first h-vthty^iKx, of a natural body which 
 has potential life. I beg to be excused from translating 
 the Greek word, because I know not the meaning of it. 
 
 The notions of the ancient philosophers with regard to 
 the operations of the mind, particularly with regard to 
 perceptions and ideas, seem likewise to have been formed 
 by the same kind of analogy, 
 
 Plato, of the writers that are extant, first introduced 
 ;the word idea into philosophy; but his doctrine upon this 
 subject had somewhat peculiar. He agreed with the 
 rest of the ancient philosophers in this, that all things 
 consist of matter and form ; and that the matter of which 
 all things were made, existed from eternity, without form : 
 
CONCmsiON. 439 
 
 but he likewise believed, that there are eternal forms of 
 all possible things which exist, without matter ; and to 
 these eternal and immaterial forms he gave the name of 
 ideas ; maintaining, that they are the only object of true 
 knowledge. It is of no great moment to us, whether he 
 borrowed these notions fromParmenides, or whether they 
 were the issue of his own creative imagination. The 
 later Platonists seem to have improved upon them, in 
 conceiving those ideas, or eternal forms of things, to 
 exist, not of themselves, but in the Divine Mind, and to 
 be the models and patterns according to which all things 
 were made : 
 
 Then lived the Eternal One, then, deep retired 
 In his unfathomed essence, viewed at large 
 The uncreated images of things. 
 
 To these Platonic notions, that of Malebranche is 
 very nearly allied. This author seems, more than any; 
 other, to have been aware of the difSculties attending the 
 common hypothesis concerning ideas, to wit. That ideas 
 of all objects of thought are in the human mind ; and 
 therefore, in order to avoid those difficulties, makes the 
 ideas, which arc the immediate objects of liuman thought, 
 to be the ideas of things in the Divine Mind ; who being 
 intimately present to every human mind, may discover 
 his ideas to it, as far as pleaseth him. 
 
 The Platonists and Malebranclie excepted, all other 
 philosophers, as far as I know, have conceived that there 
 are ideas or images of every object of thought in the 
 human mind, or at least in some part of the brain, where 
 the mind is supposed to have its residence. 
 
 Aristotle had no good affection to the word idea, and 
 seldom or never uses it but in refuting Plato's notions 
 about ideas. He thought that matter may exist without 
 form ; but that forms cannot exist without matter. But 
 at the same time he taught, That there can be no sensa- 
 tion, no imagination, nor intellection, without forms, 
 phantasms, or species in the mind ; and that things sen- 
 sible are perceived by sensible species, and things intelli- 
 gible by intelligible species. His followers taught more 
 
•iSO OF THE HUMAN MIND. 
 
 explicitly, that those sensible and intelligible species are 
 sent forth bj the objects, and make their impressions upon 
 the passive intellect ; and that the active intellect pei'ceives 
 them in the passive intellect. And this seems to have 
 been the common opinion while the Peripatetic philosophy 
 retained its authority.** 
 
 The Epicurean doctrine, as explained by Lucretius, 
 though widely different from the Peripatetic in many 
 things, is almost the same in this. He affirms, that slen- 
 der films or ghosts, tenuia rerum simulacra, are still go- 
 ing off from all things and flying about ; and that these be- 
 ing extremely subtile, easily penetrate our gross bodies, and 
 striking upon the mind, cause thought and imagination. 
 
 After the Peripatetic system had reigned above a thou- 
 sand years in the schools of Europe, almost without a 
 rival, it sunk before that of Des Cartes ; the perspicuity 
 of whose writings and notions, contrasted with the ob- 
 scurity of Aristotle and his commentators, created a strong 
 prejudice in favour of this new philosophy. The charac- 
 teristic of Plato's genius was sublimity, that of Aristotle's 
 subtilty ; but Des Cartes far excelled both in perspicuity, 
 and bequeathed this spirit to his successors. The sys- 
 tem which is now generally received, with regard to the 
 mind and its operations, derives not only its spirit from 
 Des Cartes, but its fundamental principles ; and after all 
 the improvements made by Malebranche, Locke, Berke- 
 ley, and Hume, may still be called the Cartesian system: 
 we shall therefore make some remarks upon its spirit and 
 tendency in general, and upon its doctrine concerning 
 ideas in particular. 
 
 1. It may be observed. That the method which Des 
 Cartes pursued, naturally led him to attend more to the 
 operations of the mind by accurate reflection, and to trust 
 less to analogical reasoning upon this subject, than any 
 philosopher had done before him. Intending to build a 
 system upon a new foundation, he began with a resolu- 
 tion to admit nothing but what was absolutely certain 
 and evident. He supposed that his senses, his memory, 
 
CONCXUSIOIT. iSl 
 
 his reason, and every other faculty to which we trust in 
 common life, might be fallacious; and resolved to disbe- 
 lieve every thing, until he was compelled by irresistible 
 evidence to yield assent. 
 
 In this method of proceeding, what appeared to him, 
 first of all, certain and evident, was, That he thought, 
 that he doubted, that he deliberated. In a word, the opera- 
 tions of his own mind, of which he was conscious, must be 
 real, and no delusion ; and though all his other faculties i 
 should deceive him, his consciousness could not. This! 
 therefore he looked upon as the first of all truths. This 
 was the first firm ground upon which he set his foot, af- 
 ter being tossed in the ocean of skepticism ; and he resolv- 
 ed to build all knowledge upon it, without seeking after 
 any more first principles. 
 
 As every other truth, therefore, and particularly the 
 existence of the objects of sense, was to be deduced by a 
 train of strict argumentation from what he knew by con- 
 sciousness, he was naturally led to give attention to the 
 operations of which he was conscious, without borrowing 
 his notions of them from external things. 
 
 It was not in the way of analogy, but of attentive re- 
 flection, that he was led to observe. That thought, volition, 
 remembrance, and the other attributes of the mind, are 
 altogether unlike to extension, to figure, and to all the 
 attributes of body ; that we have no reason, therefore, ta 
 conceive thinking substances to have, any resemblance 
 to extended substances; and that as the attributes of the 
 thinking substance are things of which we are conscious, 
 we may have a more certain and immediate knowledge of | 
 them by reflection, than we can have of external objects 
 by our senses. 
 
 These observations, as far as I know, were first made 
 by Des Cartes; and they are of more importance, and 
 throw more light upon the subject, than all that had been 
 said upon it before. They ought to make us diffident [ 
 and jealous of every notion concerning the mind and its 
 operations, which is drawn from sensible objects in the 
 
*S2 or THE HUMAN MIND. 
 
 way of analogy, and to make us rely only upon accu' 
 rate reflection, as the source of all real knowledge upon 
 this subject. 
 
 2. I observe, that as the Peripatetic system has a ten- 
 dency to materialize the mind, and its operations ; so the 
 Cartesian has a tendency to spiritualize body, and its qual- 
 ities. One error, common to both systems, leads to the 
 first of these extremes in the way of analogy, and to the 
 last, in the way of reflection. The error I mean is. That 
 we can know nothing about body, or its qualities, but as 
 far as we have sensations, which resemble those qualities. 
 Both systems agreed in this ; but according to their dif- 
 ferent methods of reasoning, they drew very difierent 
 conclusions from it ; the Peripatetic drawing his notions 
 of sensation from the qualities of body ; the Cartesian, on 
 the contrary, drawing his notions of the qualities of 
 body from his sensations. 
 
 The Peripatetic, taking it for granted that bodies and 
 their qualities do really exist, and are such as we com- 
 monly take them to be, inferred from them the nature of 
 his sensations, and reasoned in this manner: Our sensa- 
 tions are the impressions which sensible objects make 
 upon the mind, and may be compared to the impression 
 of a seal upon wax ; the impression is the image or form 
 of the seal, without the matter of it: in like manner, 
 every sensation is the image or form of some sensible 
 quality of the object. This is the reasoning of Aristotle, 
 and it has an evident tendency to materialize the mind 
 and its sensations. 
 
 The Cartesian, on the contrary, thinks, that the exist- 
 ence of body, or of any of its qualities, is not to be taken as 
 a first principle 5 and that we ought to admit nothing con- 
 cerning it, but what, by just reasoning, can be deduced 
 from our sensations ; and he knows, that by reflection, 
 we can form clear and distinct notions of our sensa- 
 tions, without borrowing our notions of them by analo- 
 gy from the objects of sense. The Cartesians, therefore,, 
 beginning to give attention to their sensations, first dis- 
 covered that the sensations corresponding to secondary 
 
coNcxrsiON, 433 
 
 qualities, cannot resemble any quality of body. Henee, 
 Des Cartes and Locke inferred, tfiat sound, taste, smell, 
 colour, heat, and cold, ^vhich the vulgar took to be cjual- 
 ities of body, were not qualities of body, but mere 
 sensations of the mind. Afterward (be ingenious Berke- 
 ley, considering more attentively the nature of sen- 
 sation in general, discovered, and demonslraled, that 
 no sensation whatever could possibly resemble any 
 quality of an insentient being, such as body is sup. 
 posed to be : and hence he inferred, very justly, that 
 there is the same reason to hold extension, figure, and all 
 the primary qualities, to be mere sensations, as there is 
 to hold the secondary qualities to be mere sensations. 
 Thus, by just reasoning upon the Cartesian principles, 
 matter was stripped of all its qualities : the new system, by 
 a kind of metaphysical sublimation, converted all the 
 qualities of matter into sensations, and spiritualized body, 
 as the old bad materialized spirit. 
 
 The way to avoid both these extremes, is. to admit the 
 existence of what we see and feel as a first principle, 
 as well as the existence of things whereof we are eon- 
 scious; and to take our notions of the qualities of body, 
 from the testimony of our senses, with the Peripatetics; 
 and our notions of our sensations, from the testimony of 
 consciousness, with the Cartesians. 
 
 3. I observe, That the modern skepticism is the nat- 
 ural issue of the new system; and that, although it did 
 not bring forth this monster until the year 1739. it may 
 be said to have carried it in its womb from the beginning.'.. 
 
 The old system admitted all the principles of common 
 sense as first principles, without requiring any proof of 
 them ; and therefore, though its reasoning was commonly 
 vague, analogical, and dark, yet it was built upon abroad 
 foundation, and had no tendency to skepticism. We do 
 not find that any Peripatetic thought it incumbent upon 
 him to prove the existence of a material world ; but every 
 writer upon the Cartesian system attempted this, until 
 Berkeley clearly demonstrated the futility of their argu- 
 
 ToX. I. 55 
 
434 pv THE HUMAN MIND. 
 
 ments ; and thence concluded, that there was no such 
 thing as a material world ; and that the belief of it ought 
 to be rejected as a vulgar error. 
 
 The new system admits only one of the principles of 
 common sense, as a first principle ; and pretends, by 
 strict argumentation, to deduce all the rest from it. That 
 our thoughts, our sensations, and every thing of which 
 we are conscious, hath a real existence, is admitted in 
 this system as a first principle ^ but every thing else must 
 be made evident by the light of reason. Reason must 
 rear the whole fabric of knowledge upon this single prin- 
 ciple of consciousness. 
 
 There is a disposition in human nature to reduce things 
 to as few principles as possible ; and this, without doubt, 
 adds to the beauty of a system, if the principles are able to 
 support what rests upon them. The mathematicians glo- 
 ry, very justly, in having raised so noble and magnificent 
 a system of science, upon the foundation of a few axioms 
 and definitions. Thisloveof simplicity, of reducing things 
 to few principles, hath produced many a false system; 
 but there never was any system in which it appears so 
 remarkably as that of Des Cartes. His whole system 
 concerning matter and spirit is built upon one axiom, ex- 
 pressed in one word, Cogito. Upon the foundation of con- 
 scious thought, with ideas for his materials, he builds his 
 system of the human understanding, and attempts to ac- 
 count for all its phenomena : and having, as he imagined, 
 from his consciousness, proved the existence of matter, 
 and of a certain quantity of motion originally impressed 
 upon it, he builds his system of the material world, and 
 attempts to account for all its phenomena. 
 
 These principles, with regard to the material system, 
 have been found insufiicient ; and it has been made evi- 
 dent, that besides matter and motion, we must admit 
 gravitation, cohesion, corpuscular attraction, magnetism, 
 and other centripetal and centrifugal forces, by which 
 the particles of matter attract and repel each other. 
 Newton, having discovered this, and demonstrated that 
 these principles cannot be resolved into matter and mo- 
 
coNCiusioJf. 4)35 
 
 tion, was led by analogy, and the love of simplicity, to 
 conjecture, but with a modesty and caution peculiar to 
 him, that all the phenomena of the material world de- 
 pended upon attracting and repelling forces in the par- 
 ticles of matter. But we may now venture to say, that 
 this conjecture fell short of the mark. For, even in the 
 unorganized kingdom, the powers by which salts, crystals, 
 spars, and many other bodies, concrete into regular forms, 
 can never be accounted for by attracting and repelling 
 forces in the particles of matter. And in the vegetable 
 and animal kingdoms, there are strong indications of pow- 
 ers of a different nature from all the powers of unorgan- 
 ized bodies. We see then, that although in the structure 
 of the material world, there is, without doubt, all the 
 beautiful simplicity consistent with the purposes for 
 which it was made, it is not so simple as the great Des 
 Cartes determined it to be : nay, it is not so simple as 
 the greater Newton modestly conjectured it to be. Both 
 were misled by analogy, and the love of simplicity. One 
 bad been much conversant about extension, figure, and 
 motion j the other had enlarged his views to attracting 
 and repelling forces j and both formed their notions of the 
 unknown parts of nature, from those with which they 
 were acquainted, as the shepherd Tityrus formed his 
 notion of the city of Rome from his country village : 
 
 Urbem quam dicunt Romam, Melibcee, putavi 
 Stultas ego, huic nostr^B similem, quo saspe solemus 
 Pastores ovium teneros depellere fetus. 
 Sic canibus catulos similes, sic matribus hcsdos 
 Noram ; sic parvis componere magna solebam. 
 
 This is a just picture of the analogical way of thinking. 
 
 But to come to the system of Des Cartes, concerning ; 
 the human understanding ; it was built, as we have ob- , 
 served, upon consciousness as its sole foundation, and 
 with ideas as its materials ; and all his followers have ^ 
 built upon the same foundation, and with the same mate- 
 erials. They acknowledge that nature hath given us va- 
 rious simple ideas. These are analogous to the matter 
 
*36 or THE HUMAN MIND. 
 
 of Ties Cartes's physical system. Tliey acknowledge 
 likewise a natural power by which ideas arc compounded 
 disjoined, associated, compared. This is analogous to the 
 original quantify of motion in Des Cartes's physical sys- 
 tem. From these principles they attempt to explain the 
 phenomena of the human understanding, just as in the 
 physical system the phenomena of nature were to be ex- 
 plained by matter and motion. It must indeed he ac- 
 knowledged, that there is great simplicity in this sys- 
 tem as well as in the other. There is such a similitude 
 between the two, as may be expected between children 
 of the same father : but as the one has been found to be 
 the child of Des Cartes, and not of nature, there is gt'ound 
 to think that the other is so likewise. 
 
 '^I'hat the natural issue of this system is skepticism with 
 regard to every thing except the existence of our ideas, 
 and of their necessary relations which appear upon com- 
 paring them, is evident : for ideas being the only objects 
 of thought, and having no existence but when we are 
 conscious of them, it necessarily follows, that there is no 
 object of our thought which can have a continued and per- 
 Tnanent existence. Body and spirit, cause and effect, 
 time and s "dce. to which we were wont to ascribe an ex- 
 istence independent of our thought, are all turned out of 
 existence by this short dilemma : Either these things are 
 ideas of sensation or reflection, or they are not : if they v 
 are ideas of sensation or reflection, they can have no ex- 
 ist(n<< but when we are conscious of them ; if they are 
 not ideas of sensation or rehection, they are words with- 
 out, any meaning. 
 
 Jfeither Des Cartes nor Locke perceived this conse- 
 quence of their sj stem concerning ideas. Bishop Berke- 
 ley was the first who discovered it. And what followed 
 upon this discovery? Why. with regard to the material 
 'world, and with regard to space and time, he admits the 
 consequence. That these things are mere ideas, and have 
 no existence but in our minds : hut with regard to the 
 existence of spirits or minds, he does not admit the con< 
 
CONCtlTSION. 437 
 
 sequence; and if he hail admitted it. he must have been 
 an -absolute skeptic. But huw does he evade this conse- 
 quence with regard to the existence of spirits? The ex- 
 pedient which the good bishop uses on this occasion is 
 very remarkable, and shows his great aversion to skepti- 
 cism. He maintains, that we have no ideas of spirits ; 
 and that we can think, and speak, and reason about them, 
 and about I heir attributes, without having any ideas of 
 them. If this is so, my lord, what should hinder us 
 from thinking and reasoning about bodies, and their 
 qualities, without having ideas of them ? The bishop 
 either did not think of this question, or did not think fit 
 to give any answer to it. However, we may observe, 
 that in order to avoid skepticism, he fairly starts out of 
 the Cartesian system, without giving any reason why he 
 did so in this instance, and in no other. This indeed is 
 the only instance of a deviation from Cartesian principles ; 
 •which I have met with in the successors of Des Cartes ; 
 and it seems to have been only a sudden start, occasioned 
 by the terror of skepticism ; for in all other things Berke- 
 ley's system is founded upon Cartesian principles. 
 
 Thus we see, that Des Cartes and Locke take the 
 road that leads to skepticism, without knowing the 
 end of it ; but they stop short for want of light to 
 carry them farther. Berkeley, frighted at the appear- 
 ance of the dreadful abyss, starts aside, and avoids it. 
 But the author of the Treatise of Human Nature, more 
 daring and intrepid, without turning aside to the right 
 hand or to the left, like Virgil's Alecto, shoots directly 
 into the gulf : 
 
 Hie specus horrendum, et ssvi spiracala Ditis 
 Monstrantur : ruptoque ingens Achcronte vorago 
 Festiferas aperit fauces. 
 
 •4. "We may observe, That the account given by the 
 new system, of that furniture of the human understand- 
 ing which is the gift of nature, and not the acquisition of 
 our own reasoning faculty, is extremely lame aud imper- 
 fect. 
 
438 or THE HUMAN MIND. 
 
 The natural furniture of the human understanding is of 
 two kinds ; first, The notions or simple apprehensions 
 which we have of things: and, secondly, Ti^he judgments 
 or the belief which we have concerning them. As to our 
 notions, the new system reduces them to two classes; 
 ideas of sensation and ideas of reflection : the first are 
 conceived to be copies of our sensations, retained in tlie 
 memory or imagination ; the second, to be copies of the 
 operations of our minds whereof we are conscious, in 
 like manner retained in the memory or imagination : and 
 we are taught, that these two comprehend all the mate- 
 rials about which the human understanding is, or can be, 
 employed. As to our judgment of things, or the belief 
 which we have concerning them, the new system allows 
 no part of it to be the gift of nature, but holds it to be 
 the acquisition of reason, and to be got by comparing our 
 ideas, and perceiving their agreements or disagreements. 
 Now I take this account, both of our notions, and of our 
 judgments or belief, to be extremely imperfect ; and I 
 shall briefly point out some of its capital defects. 
 
 The division of our notions into ideas of sensation, and 
 ideas of reflection, is contrary to all rules of logic ; because 
 the second member of the division includes the first. For, 
 can we form clear and just notions of our sensations any 
 other way than by reflection ? Surely we cannot. Sen- 
 sation is an operation of the mind of which we are con- 
 scious ; and we get the notion of sensation, by reflecting 
 upon that which we are conscious of. In like manner, 
 doubting and believing are operations of the mind where- 
 of we are conscious; and we get the notion of them by 
 reflecting upon what we are conscious of. The ideas of 
 sensation, therefore, are ideas of reflection, as much as 
 the ideas of doubting or believing, or any other ideas 
 whatsoever. 
 
 But to pass over the inaccuracy of this division, it is 
 extremely incomplete. For, since sensation is an opera- 
 tion of the mind, as well as all the other things of which 
 we form our notions by reflection, when it is asserted, that 
 
coNCirsioir. 439 
 
 all our notions are either ideas of sensation, or ideas of 
 reflection, the plain English of this is, That mankind 
 neither do, nor can think of any thing but of the opera- 
 tions of their own minds. Nothing can be more contrary 
 to truth, or more contrary to the experience of mankind. 
 I know that Locke, while he maintained this doctrine, 
 believed the notions which we have of body and of its 
 qualities, and the notions which we have of motion and of 
 space, to be ideas of sensation. But why did he believe 
 this ? Because he believed those notions to be nothing else 
 but images of our sensations. If therefore the notions of 
 body and its qualities, of motion and space, be not images 
 of our sensations, will it not follow that those notions are 
 not ideas of sensation? Most certainly. 
 
 There is no doctrine in the new system which more 
 directly leads to skepticism than this. And the author 
 of the Treatise of Human Nature knew very well how to 
 use it for that purpose : for, if you maintain that there 
 is any such existence as body or sjririt, time or place, 
 cause or effect, he immediately catches you between the 
 horns of this dilemma; your notions of these existences 
 are either ideas of sensation, or ideas of reflection j if of 
 sensation, from what sensation are they copied ? if of re- 
 rieflection, from what operations of the mind are they 
 copied ? 
 
 It is indeed to be wished, that those who have writ- 
 ten much about sensation, and^outthe other operations 
 of the mind, had likewise thought and reflected much, 
 and with great care, upon those operations : but is it not 
 very strange, that they will not allow it to be possible for 
 mankind to think of any thing else ? 
 
 The account which this system gives Of our judgment 
 and belief concerning things, is as far from the truth as 
 the account it gives of our notions or simple apprehen- 
 sions. It represents our senses as having no other of- 
 fice, but that of furnishing the mind with notions or sim-; 
 pie apprehensions of things ; and makes our judgment 
 and belief concerning those things to be acquired by com- 
 
440 8F THB HUMAN MINB. 
 
 paring our notions Jogether, and perceiving their agree' 
 ments or disagreements. 
 
 We have shown, on the contrary, that every operation 
 of the senses, in its very nature, implies judgirienl or be- 
 lief, as well as simple apprehension. Tims, when I feel 
 the pain of <he goiil in my toe, 1 have not only a notion 
 of pain, but a belief of i(s existence, and a belief of some 
 disorder in my toe which occasions il ; and (his belief is 
 not produced by comparing ideas, and perceiving (heir 
 agreements and disagreements ? ii is included in the very 
 nature of the sensation. When I perceive a tree before 
 me, ray faculty of seeing gives me not only a notion or 
 simple apprehension of (he tree, but a belief of its exist- 
 ence, and of its figure, distance, and magnitude ; and this 
 judgment or belief is not got by comparing ideas, it is in- 
 eluded in the very nature of the perception. We have 
 taken notice of several original principles of belief in the 
 course of this Inquiry ; and when other facnllies of the 
 mind are examined, we shall find more, which have not 
 occurred in the examination of the five senses. 
 
 Such original and natural judgments are therefore a 
 part of that furniture which nature hath given tothehumati 
 understanding. Theyare (heinspiraiionof (he Almighty, 
 no less than our notions of simple appreheuKinns. They 
 serve to direct us in the common afl^airs of life, where 
 our reasoning faculty would leave us in (he dark. They 
 are a part of our constitution, and all the discoveries of 
 our reason are grounded upon them. They make up what 
 is called the common sense of mankind; and what is man- 
 ifestly contrary to any of (hose first principles, is what 
 we call absurd. The s(reng(h of them is gooA sense, 
 which is often found in those who are not acute in rea- 
 soning. A remarkable deviation from them, arising 
 from adisorderin the constitution, is what wecall lunacy; 
 as when a man believes that he is made of glass. When 
 a man suffers himself (o be reasoned out of (he principles 
 of common sense, by metaphysical arguments, we may 
 call this metaphysieal lunacy; which differs from the 
 
CONCiUSIOKT. Hi 
 
 other species of the distemper in this, that it is not contin- 
 ued, but intermittent : it is apt to seize the patient in soli- 
 tary and speculative moments ; but when he enters into 
 society. Common Sense recovers her authority. A clear 
 explication and enumeration of the principles of common 
 sense, is one of the chief desiderata in logic. We have 
 only considered such of them as occurred in the examina- 
 tion of the five senses. 
 
 S. The last observation that I shall make upon the 
 new system is. That although it professes to set out in the 
 way of reflection, and not of analogy, it hath retained 
 some of the old analogical notions concerning the opera- 
 tions of the mind ; particularly. That things which do not 
 now exist in the mind itself, can only be perceived, re- 
 membered, or imagined, by means of ideas or images of 
 them in the mind, which are the immediate objects of 
 perception, remembrance, and imagination. This doc- 
 trine appears evidently to be borrowed from the old sys- 
 tem ; whicli taught, that external things make impres- 
 sions upon the mind, like the impressions of a seal upon 
 wax ; that it is by means of those impressions that we 
 perceive, remember, or imagine them ; and that those im* 
 pressions must resemble the things from which they are 
 taken. When we form our notions of the operations of 
 the mind by analogy, this way of conceiving them seems to 
 be very natural, and offers itself to our thoughts : for as 
 evei-y thing which is felt must make some impression 
 upon the body, we are apt to think, that every thing 
 which is understood must make some impression upon the 
 mind. 
 
 From such analogical reasoning, this opinion of the 
 existence of ideas or images of things in the mind, seems 
 to have taken its rise, and to have been so universal- 
 ly received among philosophers. It was observed al- 
 ready, that Berkeley, in one instance, apostatizes from 
 this principle of the new system, by affirming that we 
 have no ideas of spirits, and that we can think of them 
 immediately, without ideas. But I know not whether in 
 
 T»L. I. 56 
 
442 OF THE HUMAX MINB. 
 
 this he has had any followers. Tliere is some ditferenee 
 likewise among modern philosophers, with regard to the 
 ideas or images by which we perceive, rememher, or im- 
 agine sensihie things. For, though all agree in the ex- 
 istence of such images, they differ about their place; 
 some placing them in a particular part of the brain, where 
 the soul is thought to have her residence, and o(hers 
 placing them in the mind itself. Des Cartes held the 
 first of these opinions; to which Newton seems likewise 
 to have inclined ; for he proposes this query in his Op- 
 tics : *»Annon sensorium animaiium est locus cui sub- 
 stantia sentiens adest, et in quern sensihiles rernin s|)e- 
 eies per nervos et cerebrum deferuntur, ut ibi prsesentcs 
 a priesenle sentiri possinl ?" But Locke seems (o place 
 the ideas of sensible things in the mind : and that Berke- 
 ley, and the author of (he Treatise of Human Nature, 
 were of (he same opinion, is evident. The last makes a 
 very curious application of this doctrine, by endeavour- 
 ing to prove from it. That the mind either is no substance, 
 or that it is an extended and divisible substance ; because 
 the ideas of extension cannot be in a subject which is in- 
 divisible and unextended. 
 
 I confess I think his reasoning in this, as in most cases, 
 is clear and strong. For whether the idea of extension 
 be only ano(her name for extension itself, as Berkeley 
 and his author assert; or whetlier (he idea of extension 
 be an image and resemblance of extension, as Locke con- 
 ceived ; I appeal to any man of common sense, whether 
 extension, or any image of extension, can be in an unex- 
 tended and indivisible subject. But while I agree with 
 him in his reasoning, I would make a different application 
 of it. He takes it for granted, that there are ideas of 
 extension in the mind; and thence infers, that if it is at 
 all a substance, it must be an extended and divisible sub- 
 stance. On the contrary, I take it for granted, upon the 
 testiinony of common sense, that my mind is a substance, 
 that is, a permanent subject of thought ; and my reason 
 couvinces me, that it is an unextended and indivisible 
 
80NC1USI0N. 443 
 
 substance ; and hence I infer, tliat (here cannot be in it 
 any thing that reseiubles extension. If (his reKsuning 
 had occurred to Beikeley, it would |irobabl^ have led 
 him to aciinowledge, that we may think and reason con- 
 cerning bodies, without having ideas of them in the mind, 
 as well as concerning spirils. 
 
 I intended to have examined more particularly and 
 fully this doctrine of the exi-(enee of ideas or images of 
 things in the mind ; and likewise another docii'ine, wliieli 
 is founded upon it, to wit. That judgment or belief is 
 nothing but a perception of the agreement or disagreement 
 of our ideas : but having already shewn, through the 
 course of this inquiry, that the operations of the mind 
 which we have examined, give no countenance to eilher 
 of these doctrines, and in many things contradict them, I 
 have thought it proper to drop this part of my design. It 
 maybe executed with more advantage, if it is at all nec- 
 essary, after inquiring into some other powers of the 
 human understanding. 
 
 Although we have examined only the five senses, and 
 the principles of the human mind which are employed 
 about them, or such as have fallen in our way in the 
 course of this examination ; we shall leave the further 
 prosecution of this inquiry to future deliberation. The 
 powers of memory, of imagination, of taste, of reasoning, 
 of moral perception, the will, the passions, the affections, 
 and all the active powers of the soul, present a vast and 
 boundless field of philosophical disquisition, which the 
 author of this inquiry is fai- from thinking himself able 
 to survey with accuracy. Many authors of ingenuity, 
 ancient and modern, have made excursions into this vast 
 territory, and have communicated useful observations: 
 but there is reason to believe, that those who have pre- 
 tended to gire us a map of the whole, have satisfied 
 themselves with a very inaccurate and incomplete sur- 
 vey. If Galileo had attempted a complete system of nat- 
 ural philosophy, he had, probably, done little service to 
 mankind: but by confining himself to what was mthia 
 
444 OY THE HUMAN MIJVD. 
 
 his comprehension, he laid the foundation of a system of 
 knowledge, which rises hy degrees, and does honour to 
 the human understanding. Newton, building upon this 
 foundation, and in like manner confining his inquiries to 
 the law of gravitation and the properties of light, per- 
 formed wonders. If he had attempted a great deal more, 
 he had done a great deal less, and perhaps nothing at all. 
 Ambitious of following such great examples, with une- 
 qual steps, alas ! and unequal force, we have attempted 
 an inquiry only into one little corner of the Iiuman mind | 
 that corner wliich seems to be most exposed to vulgar 
 observation, and to be most easily comprehended; and 
 yet, if we have delineated it justly, it must be acknowl- 
 edged, that the accounts heretofore given of it, were very 
 lame, and wide of the truth. 
 
 END OF THE FIRST VOIUME. 
 
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