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THE PHYSICAL SYSTEM 
 
 OF ST. T HOMAS. 
 
BY THE SAME AUTHOR. 
 
 Principles of Political Economy. By Matteo Libeeatoke, 
 S.J. Translated by Edward Heneage Dering, author of 
 "Freville Chase," etc. 8vo, cloth, bevelled, 7s. 6d. 
 
 On Universals. An Exposition of Thomistic Doctrine. By 
 Matteo Libebatore, S.J. Translated by E. H. Debing. 
 In wrapper, 7s. 6d. Bound in vellum, 10s. 6d. 
 
 The Atherstone Novels, by E. H. Dering. 
 The Lady of Raven's Combe. 2 vols. , 7s. 6d. ; in one vol. , 5s. 
 Freville Chase. New Edition. 2 vols., 7s. 6d. : in one vol., 5s. 
 The Ban of Maplethorpe. In the Press. 
 
 Sherborne ; or, The House at the Four Ways. New 
 
 Edition. To follow. 
 
THE 
 
 PHYSICAL SYSTEM 
 
 OF ST. THOMAS 
 
 BY 
 
 FATHER GIOVANNI MARIA CORNOLDI, S.J. 
 
 TRANSLATED BY 
 
 EDWARD HENEAGE DERING 
 
 Translator of " On Uitiversals,'' and "Political Economy ;" 
 
 Author of " Freville Chase," " The Ban of Maplethorpe" "Memoirs 
 
 of Georgiana Lady Chatterton" &^c., ^c. 
 
 LONDON AND LEAMINGTON 
 
 Brt an& Booft Compans 
 
 Nkw Yokk, Cincinnati & Chicago: Benziger Bros. 
 
 1893 
 E.M. 
 

BEFORE the last chapter of this treatise 
 was in print, its lamented author had 
 passed out of this world, in which he had done 
 invaluable service to the Church of God. 
 
 While the present translation was passing 
 through the press, the translator also, Edward 
 Heneage Dering, was suddenly called to his 
 reward. The last composition that he printed 
 (in the Tablet, Nov. 19, 1892), was the following 
 short memoir of his friend and master in 
 Scholastic science, Father Matteo Liberatore : 
 
 ** 3n flDemoriam. 
 
 " Sixty-seven years ago a boy of fifteen, 
 whose book-learning had till then been in 
 abeyance, by reason of his having wonderfully 
 been the mainstay of his widowed mother's 
 house from the age of ten, entered a Jesuit 
 school in Naples, and, rapidly passing all his 
 competitors, was in the following year a novice 
 in the Society of Jesus. He was Professor of 
 Philosophy from 1837 — only twelve years after 
 going to school — till the Revolution of 1848 
 
VI 
 
 forced him into exile, from which he returned 
 at the imminent risk of his life, and was made 
 Professor of Theology at Naples. The risk 
 was evident, because his name was on the list 
 of the proscribed, as intended for the patriot's 
 dagger. In 1850 he co-operated in founding 
 the Civiltdb Cattolica, to defend the Church, 
 the Holy See, and notably the teaching of 
 St. Thomas. Without him that invaluable 
 periodical would have died still-born, instead 
 of doing the great work that it has done and 
 continues to do. But this necessitates a brief 
 retrospect. When he began teaching philo- 
 sophy as a professor, thirteen years before, he 
 found it infected with dangerous errors. We 
 cannot speak of them here for want of space, 
 but certain it is that the Angelic Doctor was 
 generally forgotten, discredited, misrepresented, 
 and that false philosophy was taught even 
 within the Church. He was the first in the 
 field against that, published his Insiitutiones 
 Philosophicoe in 1840, and continued to fight 
 the good fight as long as Almighty God willed 
 that his life should last. That man was 
 Father Matteo Liberatore, who died in Eome 
 on the 18th of last October, eight months after 
 the death of his great co-operator and confrere, 
 Father Giovaxni Maria Cornoldi. When two 
 such men are taken away from the Church 
 militant, one can only turn to Almighty God 
 
Vll 
 
 and say, Fiat voluntas Tua. To myself the 
 loss of Father Liberatore is a personal grief 
 and an irreparable loss. Dominus dedit. . . 
 Dominus ahstulit. . . sit nomen Domini 
 benedictum. — Baddesley Clinton,l^o\. 19, 1892." 
 
 Mr. Daring's life and literary labours had 
 been devoted to the enlightenment and conver- 
 sion of his countrymen. He died, as he had 
 desired to do, in harness; and, lamenting the 
 greatness of his loss, the many who loved him, 
 can only echo his last printed words : Dominus 
 dedit. . . . Dominus ahstulit. . . . sit nomen 
 Domini henedictum. 
 
PREFACE. 
 
 WHY THIS TREATISE WAS WRITTEN. 
 
 TT A V I N G for many years openly defended 
 the Philosophy of St. Thomas, even in 
 what concerns the fundamental doctrines of 
 organic and inorganic nature, we think it time 
 to treat that subject, not merely touching on 
 one or another point, but dealing with those 
 doctrines philosophically. 
 
 [n Italy, where Masonic influence is now 
 felt in every department of Government, no- 
 thing has been omitted by which the minds 
 and hearts of our young men could be turned 
 away, not only from the religious teaching of 
 the Catholic Church, but also from all philoso- 
 phical doctrines that are not against Keligion. 
 The teaching of Metaphysics was made over 
 years ago to professors who only corrupted 
 their pupils by the German transcendentalism 
 of Kant, Hegel, Schelling and others : but, 
 
X PREFACE. 
 
 inasmuch as that philosophy was abstruse, ill- 
 suited to the wicked purpose intended and 
 very apt to produce weariness, Metaphysics, 
 properly so-called, were afterwards proscribed 
 in the schools, to make way for Positivism 
 and Materialism. 
 
 If in our Catholic schools Physical Sciences 
 were rightly and fully taught, the evil would 
 be less. But what we call Government schools 
 are, for the most part, obligatory ; and, by 
 reason of the method prescribed, even for 
 private schools it is impossible to elucidate 
 those doctrines without which the pupils are 
 neither instructed sufl&ciently nor prepared for 
 resisting the temptations of the Universities. 
 
 By this treatise we cannot hope to be of 
 use directly and immediately in the public 
 schools of the Government : but we can hope 
 to do something indirectly and mediately. 
 
 In the second place, many who have a 
 great reverence for the wisdom of the Angelic 
 Doctor, and, in obedience to the Vicar of 
 Jesus Christ, declare their adhesion to his 
 
PEEFACE. XI 
 
 doctriney, know too little of the fundamental 
 questions that belong to Physics. Many have 
 confused ideas about them, and therefore are 
 liable to be taken in by the sophisms and the 
 authority of men who pass as wise and learned 
 in such things. Hence they either give in or 
 vacillate, accepting as probable what is not 
 only improbable, but also absurd and bad. 
 
 These and other reasons have induced us to 
 put before our readers, especially those who 
 are given to the stud)'' of philosophy and 
 natural sciences, that system which we call 
 the Physical System, whose principles were 
 certainly professed by the Angelic Doctor, 
 St. Thomas. It is, or should be, unnecessary 
 to say that we are not going to rake up ex- 
 ploded doctrines of the old physicists. The 
 habit of confusing such opinions with the 
 philosophical principles of rational Physics, 
 ascribing to the latter what belongs to pure 
 experiment, has led many to attack truth 
 with the hatred due to error and to put the 
 wisest in the category of quacks. 
 
CONTENTS. 
 
 Chap. I. the essence and nature of 
 
 CORPOREAL substances 1 
 
 II. MATERIA PRIMA 4 
 
 III. SUBSTANTIAL FORM 12 
 
 IV. NATURE - 21 
 V. CREATION 28 
 
 VI. ATOMS 37 
 
 VII. SEMINAL CAUSES 46 
 
 VIII. QUALITIES 56 
 
 IX. ATTRACTION 69 
 
 X. PHYSICAL LAWS 81 
 
 XL WHY THE PHYSICAL SYSTEM IS 
 
 SO CALLED 90 
 
 XII. THE PHYSICAL SYSTEM WITH 
 RESPECT TO PHYSICS IN 
 GENERAL. ' THE NATURE OF 
 THIS SCIENCE 95 
 
 XIII. MECHANICAL INERTIA AND 
 
 PHYSICAL ACTIVITY OF 
 BODIES 100 
 
 XIV. OBJECTIONS AGAINST THE DOC- 
 
 TRINE PROPOSED 108 
 
XIV 
 
 CONTENTS. 
 
 XV. ACTION AT AN ABSOLUTE DIS- 
 TANCE 117 
 XVI. MOTION 125 
 XVII. THE PRINCIPLE, "quod MOVETUR 
 AB ALIO MOVETUE, ET PRI- 
 MUM ilOVENS EST IMMOBILE" 138 
 XVIII. THE MUTABILITY OF EXTENSION 150 
 XIX. WHY THE PHYSICAL SYSTEM IS 
 SUPPOSED TO BE IN OPPOSI- 
 TION TO PHYSICS 160 
 XX. ON THE DIVISIBILITY OF THE 
 
 CONTINUOUS EXTENDED 163 
 
 XXI. ETHER 170 
 
 XXII. CHEMISTRY- 177 
 
 XXIII. ELEMENTARY ATOMS 180 
 
 XXIV. THE MATTER AND FORM OF 
 ELEMENTARY SUBSTANCES 
 
 ARE REALLY DISTINCT 184 
 
 XXV. AN ELEMENTARY SUBSTANCE IS 
 
 CHEMICALLY SIMPLE- 188 
 
 XXVI. THE " MIXTUM," OR THE CHEMI- 
 CAL COMPOUND. AFFINITY 
 BETWEEN THE ELEMENTS 193 
 
 XXVII. THE " MIXTUM," OR CHEMICAL 
 COMPOUND, HAS A NATURE 
 SPECIFICALLY DIFFERENT 
 
 FROM THAT OF ITS COM- 
 PONENTS 198 
 XXVIII. WHAT IS MEANT BY SUBSTAN- 
 TIAL TRANSFORMATION 201 
 
CONTENTS. XV 
 
 XXIX. THK COMMON SENSE OF MAN- 
 KIND IS IN FAVOUR OF A 
 BELIEF IN THE TRUE SUB- 
 STANTIAL TRANSFORMATION 
 OP THE ELEMENTS 204 
 
 XXX. THE SUBSTANTIAL TRANSFORMA- 
 TION OF THE ELEMENTS IS 
 PROVED BY FACTS 207 
 
 XXXI. OPPOSITION TO THE DOCTRINE 
 OF SUBSTANTIAL TRANSFOR- 
 MATION 211 
 
THE PHYSICAL SYSTEM 
 OF ST. THOMAS. 
 
 I 
 
 THE ESSENCE AND NATURE OF COEPOEEAL 
 SUBSTANCES. 
 
 THERE is nothing perhaps harder to defend 
 and easier to attack than a system not 
 clearly defined, at least in its principal parts. 
 Its defenders waste their time in showing what 
 is either beside the question or only touches 
 the surface, and its adversaries, when they 
 have pointed out the weak points in that 
 which, true or false, has nothing to do with 
 the truth of the system, settle the controversy 
 in their own favour. 
 
 To avoid this, we shall explain without 
 delay the system of which we are going to 
 treat ; and, first of all, we must remark that it 
 differs from the Mechanic and Dynamic systems 
 as to the very essence of corporeal substances. 
 According to the Mechanic system, corporeal 
 substance means inert and resisting atoms 
 aggregated in varying order. The Dynamic 
 
I THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 system recognizes subsisting forces only, as in 
 mathematical points of space. The Physical 
 system supposes that every individual corporeal 
 substance is essentially composed of two prin- 
 ciples really distinct. One is the source of 
 extension, and is called ^materia prima. The 
 other is the source of activity, and is called 
 the substantial form. On the variety of the 
 latter the diversities of nature in every substance 
 depend. The materia prima and the sub- 
 stantial form, being incomplete substances, 
 cannot be apart. God did not create matter 
 quite without form, but endowed it with diverse 
 forms actuated with virtues that may be called 
 seminal, radically containing the whole order 
 and beauty of the sensible universe, which by 
 degrees developed and in the course of time 
 is continually developing. During this continual 
 development we perceive changes in substances, 
 in their qualities and in their accidents, and 
 in their mutual approach and departure. In 
 the former case there is a true change of sub- 
 stantial forms, the matter of one body being 
 transmuted into that of another. In the 
 second there is a change of accidental forms 
 only. In the third, unless there is some 
 mechanical impulse, one body is brought to- 
 wards another by true attraction. From such 
 forms and such properties, impressed on creation, 
 a determinate development of the corporeal 
 
MATERIA PRIMA. 3 
 
 universe necessarily follows ; and in these forms 
 and in these properties we must recognize the 
 existence of physical laws, considered, not as in 
 the Mind or Will of the Creator, but as an effect 
 in the created things themselves. 
 
 But this is too rapid a sketch. We must 
 consider each part of the system in detail. 
 
II. 
 
 MATERIA PEIMA. 
 
 TH E very ancient philosophers, the beginners 
 in philosophy, held that corporeal substances 
 are nothing more than aggregations of atoms, 
 either inert, or, at the most, endowed with attrac- 
 tive and repulsive force, like some sort of sympa- 
 thy and antipathy. Afterwards Plato taught the 
 doctrine of Matter and Form, infected however 
 with grave errors, which Aristotle partly cor- 
 rected, and which the Catholic Doctors, the only 
 philosophers who had a clear and firm conception 
 of God the Creator, afterwards rooted out. 
 " The ancient philosophers," says St. Thomas, 
 " came to the knowledge of truth slowly and 
 by degrees. For at first, as being less cultivated, 
 they recognized no other beings than sensible 
 bodies ; and those among them who acknow- 
 ledged movement in such, admitted that sort 
 of movement only which takes place in some 
 accidents, as in rarity and density, by aggre- 
 gation and disgregation. Afterwards, supposing 
 corporeal substance to be uncreated, they assigned 
 some causes for their accidental changes, as, for 
 
MATERIA PEIMA. 5 
 
 instance, friendship, strife and such like. 
 Thence they went on to distinguish substantial 
 form and matter, which they supposed to be 
 uncreated, and they perceived that substantial 
 transmutations happen in bodies."* 
 
 We shall proceed to enquire how they came to 
 this knowledge. 
 
 Plato in his Timceus remarks that in the 
 sensible universe every being is subject to 
 substantial changes without a continual annihila- 
 tion of previous things and continual creation 
 of succeeding ones. Hence he inferred that 
 in this changing of substance there always 
 remains a substratum, or subject, — a matter 
 which is adapted and transformed successively 
 into various natures. Thus fluids become plants, 
 and plants become the flesh of brutes and even 
 of man. And, since by such transforming of 
 matter the eternal forms or ideas are determined, 
 there must be in the universe a matter that 
 is itself deprived of all determinate nature and 
 is disposed for receiving those species which 
 it derives from the communication or impres- 
 sion of the archetypal ideas. " Three things," 
 he says, " have here to be distinguished : that 
 which is generated (the new nature) ; that in 
 which it is generated (the matter) ; that from 
 which the generated thing gets its proper like- 
 ness (the idea or form). Now, if these things 
 
 * Sttmma, P. i. Q. xliv. a. 2. 
 
b THE PHYSIOAL SYSTEM OF ST. THOMAS. 
 
 be compared, the nature generated resembles 
 an offspring ; the thing in which it is generated 
 resembles a mother ; and that from which 
 it gets its likeness resembles a father. This 
 doctrine must be understood to mean that, 
 as the forms of things are distinguished 
 by every sort of variety, this womb [i.e. 
 matter, thereto compared J could never 
 be well disposed for the formations to be 
 produced in it, unless it were formless, quite 
 void of all forms whatsoever; because, if it 
 already had in itself any of those natures for 
 which it is in a state of potentiality, it would 
 not be capable of receiving a contrary form. 
 Thus, if it were essentially water, how could it 
 be changed into wood ? It would inconceivably 
 be at once water and wood. But, as it is po- 
 tentially all these things, it cannot have the 
 form of any, just as modelling clay has none. 
 As the matter of scented unguents is purposel}^ 
 without scent, and modelling clay has no shape 
 till the artist has modelled it, so the thing 
 that is to be modelled according to the 
 eternal ideas must have no form natural to 
 itself. Therefore the mother, or receptacle of 
 the corporeal universe, is neither earth, nor 
 air, nor fire, nor water, nor that which con- 
 stitutes their nature, nor something else com- 
 posed of them, but rather it is a certain invisible 
 something, a formless womb, potentially every- 
 
MATERIA PEIMA. 7 
 
 thing, incompreiiensibly participating in the 
 Divine nature through the impression that it 
 receives from the archetypal ideas. Such a 
 womb cannot be known as it is, but only as we 
 have explained it." In these words Plato 
 gives us a doctrine almost perfect as to the 
 essence of bodies ; but he spoilt it by 
 his theory of ideas subsisting outside the 
 Divine Mind, and by his belief that the matter 
 which receives the impression of them is 
 eternal. 
 
 St. Augustine, who was a great admirer of 
 Plato, vainly sought from learned men that 
 knowledge of matter which he afterwards gained 
 when he had considered the passing of things 
 from one substantial form to another, and 
 seen that all through the change between two 
 terms there must remain in both something 
 identical and itself indifferent to both. " 
 my God," he said, " if I were to speak or write 
 what Thou hast taught me about this ! When 
 I heard of it from those who understood it 
 not, I heard the name without knowing what 
 it meant, and, thinking of it under innumer- 
 able forms, precisely for that reason thought 
 not of it as it is. Ugly and horrible forms 
 passed in disorder through my mind ; but 
 forms they were all the while. I called them 
 formless, not as being without form, but 
 because they were such that the sight of 
 
8 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 them was too strange and hideous for human 
 infirmity to bear. That of which I thought was 
 not formless by privation of all form, but 
 only in comparison with more beautiful forms ; 
 and right reason showed me that, if I wanted 
 to think of the formless, I must take quite 
 away aU remains whatsoever of form. But/ 
 this I was unable to do ; -for I could think 
 more easily that what has no form is nothing, 
 than think of something between a thing formed 
 of nothing, not formed and not nothing, form- 
 less and therefore near to nothing. Then, 
 instead of continuing to imagine various changes 
 of bodies already formed, I fixed my attention 
 on the bodies themselves, examining more 
 deeply their mutability, how they cease to be 
 what they were, and begin to be what they 
 were not ; and I suspected that such passing 
 on from form to form must be through a 
 something without form, yet not pure nothing. 
 But I wanted to know, not to conjecture. 
 If I could unfold all that in this question 
 Thou hast made clear, who among my readers 
 would be able to understand it ? But my heart 
 will never cease to give thanks and praise 
 for what it cannot express." * 
 
 That St. Thomas foi'med his conception of 
 materia prima in the same way is evident 
 in many passages. Here is one of them : " He 
 
 * Con/ess., 1. xii. c. 6. 
 
MATERIA PKIMA. 9 
 
 [Aristotle] declares the aforesaid principles, 
 and affirms that the nature firstly subject to 
 change, i.e. materia prima, cannot itself be 
 known, inasmuch as things are known through 
 their form, while materia 'prima is the 
 subject of every form. The thing is known 
 by analogy, i.e. according to proportion. Thus 
 we know that wood is something really distinct 
 from the form of a bench or of a bed, because 
 the wood is sometimes under the one form and 
 sometimes under the other. When therefore 
 we see that what was air becomes water, 'we 
 must say that there is something existing 
 beneath the forms of natural substances," (for 
 instance, under the form of water and the form 
 of air,) "just as in artificial ones, wood is some- 
 thing besides the form of a bench or the form of a 
 bed, or copper is something besides the form of 
 a statue. Therefore that which is to natural 
 substances as copper is to a statue and wood is to 
 bed, and every material and formless thing is to 
 its form, that thing we call materia prima."* 
 Materia prima is then the subject of all 
 
 THE SUBSTANTIAL TKANSFORMATIONS OF THE 
 
 CORPOREAL UNIVERSE, which from the beginning 
 of the world, while the various natures of things 
 have perished and are perishing to make way 
 for new ones, has remained and remains always 
 the same. Yet some people believe that St. 
 
 * In I. Phys., lect. xiii. 
 
10 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 Thomas understood materia prima to mean 
 j)ure nothing or the possibility of forms ; and 
 this in defiance of such passages, for instance, 
 as the following in the Summa Theologica, 
 P. i. Q. xiv. a. xi. ad 3, where we read : — 
 Materia, licet recedat a Dei similitudine secun- 
 dum suatn potentialitatem, tamen, in quantum 
 vel sic esse hahet, similitudinem quamdam retinet 
 divini esse. And in the Qiicestiones Disputatce, 
 De Verit. Q. iii. a. v. ad 1, he says: Quamvis 
 materia prima sit informis, tamen inest in ea 
 imitatio primce formce. Quantumcumque dehile 
 esse habeat, illud tamen est imitatio primi entis ; 
 et secundum hoc piotest habere similitudinem in 
 Deo. 
 
 The followers of the Mechanic and Dynamic 
 systems have quite a different conception of 
 materia prima. The former suppose it to be 
 inert atoms, while the latter consider it as a 
 subsisting form in the manner of mathematical 
 points. According to these two theories the 
 atoms and the forces would not be the subject 
 of substance, but true substances. An atom of 
 oxygen, for instance, which with hydrogen 
 forms water, is not merely an atom, but has 
 the nature of oxygen, not that of hydrogen ; 
 whereas, according to the doctrine of Plato, 
 Aristotle, St. Augustine, St. Thomas, and so 
 many other men of noble genius who followed 
 them, the potential entity which was there 
 
MATERIA PRIMA. 11 
 
 constituted in the nature of oxygen, and which 
 afterwards, by union with hydrogen, became 
 water, is materia ■prima. It is called prima 
 to mark it as the first requisite for bodies, 
 in order to constitute their substantial being, 
 which substantial being is first ; and also 
 to distinguish it from that which is called 
 viateria secunda (secondary matter), which 
 becomes the subject of various accidental modi- 
 fications. We must now speak of the form 
 whence that primary constitution proceeds. 
 
12 
 
 III. 
 
 SUBSTANTIAL FORM. 
 
 IN Latin the word forma was used to signify 
 idea, and was applied to the exemplar 
 of a work, whether it be in the mind of the 
 artist or expressed materially. 
 
 Nee vero, says Cicero, ille artifex, cum 
 faceret Jovis formam aut Minervce, contem- 
 plabatur aliquem a quo similitudinem duceret, 
 sed ipsius in mente insidebat species, qiiam 
 contuens in eaque dejixus, ad illius similitudinem 
 
 artem et manum dirigehat Has rerum formas 
 
 appellahat ideas ille, non intelligendi solum, 
 sed etiam dicendi, gravissimus auctor et magister 
 Plato, easque gigni negat, et ait semper esse, a 
 ratione et intelligentia contineri ; cetera nasci, oc- 
 cidere, fiuere, lahi, nee diutius esse uno et eodem 
 statu. 
 
 The substantial form of anything is, philo- 
 sophically speaking, the likeness of a Divine 
 
 IDEA, WHICH BEING EXPRESSED IN MATTER CON- 
 STITUTES IT IN A DETERMINATE SUBSTANCE ; aS, 
 
 for example, the entity whence the matter 
 of gold is constituted in its proper substantial 
 being. 
 
SUBSTANTIAL FORM. 13 
 
 From the variety of these forms results the 
 distinction of Genera and Species. These, adorn- 
 ing the sensible universe, present beautiful images 
 of those exemplars which are in the Divine 
 Mind. Hence Plato and Aristotle with their 
 followers gave to those forms names that in- 
 dicate order and beauty, even calling them 
 a divine thing, a participation of God, the one 
 from which every substance receives unity. 
 And Albert the Great approves of these, adding 
 more of his own, especially where he takes 
 into consideration the names adapted to signify 
 form in its twofold relations, viz. as the term 
 of the artist's action expressed in matter, 
 and as that which constitutes the matter in 
 a determinate being. " The names of form," 
 he says, " are various, inasmuch as it is the 
 end of motion, an4 constitutes in being the 
 thing formed. In the former sense it is said 
 to be something divine, something most ex- 
 cellent, something desirable. ... In the latter 
 sense it is called form, as giving form and 
 as distinguishing formless matter ; and species, 
 as constituting the thing in its being, thus 
 rendering it knowable ; reason, as having in it 
 the definition of the thing ; idea, paradigma^ 
 image, as proceeding from its exemplar, 
 which is in the First Cause, because every 
 form impressed in matter was at first in the 
 First Mover, called by Plato the archetypal 
 
14 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 world, accordins; to the well known words of 
 Boetius : Pidchrum pulcherrimus ipse mun- 
 dum mente gerens, similique ah imagine formans. 
 Form then, as being in the First Exemplar, 
 is called idea ; as expressed in matter it is 
 called paradigma ; and that impression, as 
 imitating the idea, is called an image." * 
 
 From this one sees clearly that the degrees 
 are in the perfection of the forms, according 
 to the various expressions of the Divine Being 
 communicated by these forms to corporeal 
 substances. 
 
 St. Thomas thus distinguishes them in the 
 second article of his Opusculum De Formis, t 
 where the whole doctrine, contained in various 
 parts of his writings, is put together. 
 
 " By means of the form," he says, " things 
 come to participate of the Divine Being, and 
 therefore the form also must be a certain 
 participation and likeness of the First Act or 
 Divine Being. ... So that the nearer 
 this form is in its likeness to the First Act, 
 or the more it participates of His perfections, 
 the more perfect it will be. Therefore the 
 forms that participate of the perfections of 
 the Actus Primus merely as to their being are 
 of the lowest degree. Those that are like- 
 
 * In 11. Phys., 17. 
 t This Opusculum De Formis was formerly printed as an 
 appendix to St. Thomas's Commentary In Libras Physicorum. 
 
SUBSTANTIAL FORM. 15 
 
 nesses of the Actus Primus not only by being, 
 but also by living and being able to give life, 
 have the second rank, under the name of 
 animce vegetativce. The third are those that 
 are likenesses of the Actus Primus not only 
 in having being and life, but also in knowing, 
 though imperfectly ; and these are named 
 animcB sensitivce. These are the first that 
 have any participation of knowledge. Lastly, 
 those that are likenesses of the Actus Primus 
 not only in being and living and having a 
 sort of knowledge, but moreover in knowing 
 with intellective cognition, constitute in nature 
 the highest and noblest grade, though in 
 different ways ; and all of these are called in- 
 tellectual substances." 
 
 One can easily conceive how a greater per- 
 fection takes into itself inferior perfections, or 
 how an act perfect in itself contains the less 
 perfect acts. Therefore Almighty God, Who 
 is the most perfect Act, has in Himself the 
 perfection of all things created and possible. 
 The more perfect substantial form contains 
 virtually the less perfect, till we come down- 
 wards to a form that in its perfection may 
 be called elementary or lowest. So from unity 
 there begins a series, each term of which is > 
 endowed with the perfection of the preceding 
 one and something more ; so that it tends 
 towards the infinite, which it never can reach. 
 
16 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 Thus from the triangle begins a spries of 
 polygons, inclining more and more to a polygon 
 with infinite sides, that gives us the concep- 
 tion of the circle, wherein we may find imaged 
 the various perfections of the forms whence the 
 beings in this visible created world, from 
 elements up to man, have their proper 
 perfection. 
 
 Since then, according to the principles of 
 this system, every individual being is one 
 substance, so the substantial form that makes 
 it one substance must be one. And where 
 it is more perfect, as in man, it must contain 
 in itself all the perfections which, apart from 
 man, are communicated by diverse other forms 
 to beings less perfect. 
 
 Thus in this system the human soul, through 
 being a form superior to all others in the 
 visible creation, contains in itself virtually 
 their perfection, which it therefore can 
 communicate to matter, while, through being 
 spiritual, it is like the separated substances (the 
 angels), but inferior tq all of them, and is as a 
 link that binds the corporeal substances with the 
 incorporeal, the visible with the invisible, a 
 link that joins beings without sense and beings 
 with sense to the order of purely intellectual 
 beings. Therefore it is the most perfect ex- 
 pression made in matter by the First Act, 
 Who is God. It is a divine inspiration, a 
 
SUBSTANTIAL FORM. 17 
 
 principle which, though intellectual, can never- 
 theless transmute the slime of the earth into 
 vegetative and sentient substance. " The soul," 
 says St. Thomas, "is on the confines of the 
 separated substances which are incorporeal, 
 and of the material forms which are corporeal ; 
 for it is the lowest of incorruptible forms, . . . 
 and therefore is partly separated from matter 
 and partly in matter." * 
 
 Hence the essential difference between 
 materia prima and the material form and 
 the subsisting form. Materia prima is the 
 determinable principle of corporeal substances. 
 The substantial form is the determining princi- 
 ple, the act that constitutes matter in a 
 determinate nature. A substantial form is 
 either inseparable from matter, and is called 
 m^aterial, or separable from matter, and is 
 called immaterial. This quality of being 
 separable from matter is called subsistence, 
 and the forms endowed with it are called 
 suhsistent. 
 
 The forms of which we have hitherto spoken 
 are called substantial, in contradistinction to 
 those which are called accidental forms ; for, 
 as the former constitute substances in their 
 first being as such, so do the latter bring to 
 them, without changing their nature, a second 
 and accidental being. 
 
 * Opuso. 45, De Pluralitate, Formar., P. i. 
 
18 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 " Some things that are, not, may be," says 
 St. Thomas, " and some ' already are. That 
 which may be, but is not, is said to be in 
 potentia. That which already is, is said to be 
 in actu. The being of a thing is two-fold, — 
 essential or substantial, such as being a man, 
 which is called Being simpliciter, and acciden- 
 tal being, such as a man being white, which 
 is called Being secundum quid. . . . That 
 which makes the substantial being in actu is 
 called the substantial form, and that which 
 makes accidental being i7i actu is called an 
 accidental form. And, since generation is 
 motion towards a certain form, as there is a 
 twofold form so is there a twofold generation. 
 Generation absolutely [simpliciter'] answers to 
 a substantial form. Generation secundum quid 
 answers to an accidental form. So that the 
 substantial form of a thing is said to make it 
 be simpliciter, as a man comes to be, or is 
 generated ; but the accidental form makes it 
 come to be, not simpliciter, but in this or 
 that way, as a man who is fair is said to 
 have been born fair, in contradistinction to 
 having been born simpliciter. This twofold 
 generation implies a twofold corruption, viz. 
 corruption simpliciter and corruption secundum 
 quid. Simple generation and corruption go 
 not beyond the genus of substance ; but 
 generation and corruption secundum quid 
 
SUBSTANTIAL FORM. 19 
 
 are in all the other genera of accidentals."* 
 Clearly, then, on the death of a man or a 
 brute or a plant, the substance of the man 
 or of the brute or of the plant ceases to be 
 the substance that it was, as water does when 
 decomposed into its elements. These are exam- 
 ples of absolute corruption ; whereas, when a 
 man loses his colour, the brute its healthiness, 
 the plant its vigour, or the hot water its heat, 
 the substances remain while the accidents 
 change, and the corruption therefore is not a 
 corruption of the substance, but of something 
 that is in the substance. 
 
 Hence it follows that matter can pass from 
 one form into another, by reason of not having 
 the form into which it will pass. If the 
 matter, for instance, which now is wheat had 
 already the substantial form of flesh, how could 
 its transformation into flesh be intelligible ? 
 When we think of a substance in its actual 
 being, we have only to look at the two princi- 
 ples of matter and form ; but if we think of 
 it in its production, we must also consider the 
 privation of that form, by which privation the 
 matter is, so to speak, affected. St. Thomas 
 says : "In order that generation may take 
 place, three things are required, viz. a potential 
 being, which is matter (materia prima) ; the 
 want of actual being, which is privation ; 
 
 * Opusc. De Principiis Naturce. 
 
20 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 and that which makes a thing actually to 
 be, which is the form. Thus, for instance, 
 when an image is made of copper, the copper 
 which is in potentia to the form of the image 
 is the matter. The want of figure is pri- 
 vation. The figure that makes it an image 
 is the form. Not, however, a substantial 
 form ; for the copper had an actual being 
 previously as copper, a being not depen- 
 dent on having this or that figure. It 
 is an accidental form ; and so are all artificial 
 forms, because art works at those things only 
 that have their own natural being. There 
 are three principles of nature therefore, viz. 
 matter, form and privation ; the form being that 
 for which generation takes place. The other 
 two belong to the term from which generation 
 is. Hence matter and privation are the same 
 thing in their subject, but differ in our minds ; 
 for the same thing that is copper is unfigured 
 before it receives the form of an image, but 
 in one respect is called copper, and in another 
 respect is called unfigured. Wherefore priva- 
 tion is said to be a principle, not per se hnt per 
 accidens, because it coincides with the matter."* 
 Having now considered separately the two 
 principles of every corporeal substance, we 
 shall pass on to consider the same together, 
 as constituting the nature of such. 
 
 * Ibid. 
 
21 
 
 IV. 
 
 NATUKE. 
 
 TH E definition of the word nature, as 
 used by the Scholastic doctors, is taken 
 from the second book of Aristotle's Physics. 
 " Nature," he says, " is the first principle of 
 MOTION AND OF REST, peQ^ SB, not per accidens." 
 To understand this definition, we must re- 
 member that a substance may be moved by 
 an intrinsic or an extrinsic principle. If it is 
 moved by an extrinsic principle, the motion is 
 forced. If it is moved by an intrinsic principle, 
 the motion is natural. When one billiard ball 
 is sent at another, the impulse is extrinsic 
 and the motion forced ; but when two drops 
 of mercury, placed near each other, approach 
 and meet, their motion is from an intrinsic 
 principle, and is natural. 
 
 This principle is called nature. But, besides 
 being a principle of motion, it must also be 
 a principle of rest ; for nature inclines things 
 to move, not for the sake of moving, but because 
 it tends to a scope, an end, a honum, which 
 being attained, rest supervenes. Without some 
 obstacle or attraction the motion given to the 
 
22 THE PHYSICAL SYSTEM OF ST. THOMAS. ' 
 
 billiard ball would be perpetual, because it 
 was not directed to a term fixed ; whereas the 
 drop of mercury will rest as soon as it has 
 touched the other drop of mercury, to which 
 it is brought by the principle that causes its 
 motion. In this definition of nature, as the 
 principle of motion and of rest, the words 
 prima and per se, contradistinctive to pei' 
 accidens, are put to distinguish the principle 
 whence the motion proceeds (which is nature) 
 from any modification or accidental affection 
 of it, without which it would either not be 
 set in motion towards the object, or inclined 
 with a different intensity — a very valuable 
 distinction in Catholic theology for distinguish- 
 ing nature from grace and the natural from 
 the supernatural. And this much will suffice 
 about the physical meaning of the word nature. 
 Let us now see what constitutes it in a 
 corporeal substance. In this there is matter 
 and form. Matter alone would not be sufficient, 
 because matter (materia prima) remains the 
 same under all substantial forms, and there- 
 fore, were it per se a principle of operation, 
 it would always operate in one way. But 
 that does not happen. Oxygen, for instance, and 
 water are different in their operation, though 
 all the matter (materia jyrima) that is in one 
 is likewise in the other. Does the substantial 
 form, then, constitute the nature of corporeal 
 
NATURE. 23 
 
 substance ? If we consider the matter as per se 
 inert, and the form as the only other thing in 
 corporeal substances, we must say that the form 
 is the principle of operation or of motion. 
 But would it be so, if it were separated from the 
 matter ? No, for it could not exist at all. 
 And therefore, to be the principle of operation 
 and of motion, it must be united with matter. 
 The word nature does indeed principally apply 
 to it, but not with propriety as prescinding 
 from the matter which it informs. Eightlv 
 therefore did Aristotle say in the second book 
 of Physics, that as copper, if we prescind 
 from its figure, cannot be called art, neither 
 can matter (materia prima), when considered 
 apart from the substantial form which deter- 
 mines it to a certain species, be called the 
 nature of a thing ; but that name should rather 
 be given to the form.* " As that may be 
 called art," says St. Thomas, " which belongs to 
 anything that is according to art and artificial, 
 so may that be called nature which belongs 
 to anything that is according to nature and 
 natural. But that which is only in potentia 
 to be made by man's art cannot be said to have 
 anything of art in it, because it has not as yet 
 the nature of (for instance) a bed. Therefore in 
 natural things that which is flesh and bone in 
 potentia has not the nature of flesh and bone 
 
 * Phys., Lib. ii. Cap. i. 
 
24 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 till it has received the form, according to which 
 is the definite nature of the thing, and through 
 which we know what flesh is and what bone 
 is. There is no nature in it till it has 
 its form ; and therefore the form is in a way 
 the nature of natural things that have in 
 them the principle of motion." t 
 
 From this we can easily understand why 
 the Scholastics called matter and form incom- 
 plete substances, and the compositum a complete 
 substance. For that being which naturally is 
 of itself is a substance ; and matter cannot be 
 of itself without the form, nor can a material 
 form (for of that we are here speaking) be 
 without matter. True it is that neither the 
 one nor the other can be called an accident, 
 because each has its own entity ; but 
 when disjoined they are wanting in what is 
 required for the definition of substance, and 
 therefore are incomplete. This they acquire 
 when conjoined ; and then they are a complete 
 substance. "We call a substance physically 
 incomplete," says Suarez in his Metaphysics, 
 "that by its entity has not in itself what is 
 required for the nature of substance taken 
 generically ; and that which has it we call a 
 complete substance. This we express by means 
 of negation, saying that a substance is physi- 
 cally complete which is not ordained per se 
 
 t In II. Phys., lect. 2. 
 
NATURE. 25 
 
 to perfect or to constitute with another sub- 
 stance another being." * 
 
 And Cicero speaks likewise in these words : 
 De natura autem ita dicehant (Aristotle and 
 his followers) ut earn dividerent in res duas, 
 tit altera esset efficiens, altera, quasi huic se 
 prcebens, ea quce efficeretur aliquid. In eo 
 quod efficeret, vim esse censebant : in eo 
 autem quod efficeretur materiam quamdam : 
 in utroque tamen utrumque. Neque enim 
 materiam ipsam cohcerere potuisse, si nulla 
 VI contineretur, neque vim sine aliqua materia. 
 Nihil est enim quod non alicubi esse cogatur. 
 Sed quod ex utroque, id jam corpus nomina- 
 hant. t 
 
 Here it is evident that, since what he calls 
 vim cannot be without matter, nor matter 
 without form, each is an incomplete substance, 
 and the body alone, composed of the two, is 
 a complete substance. 
 
 Moreover, if the substantial form principally 
 constitutes the nature, clear it is that plurality 
 of such forms brings plurality of natures. 
 Hence a body can never be considered as one 
 nature, if it be nothing more than an aggregate 
 of atoms, each furnished with its own sub- 
 stantial form. Even a man could not be said 
 to have one complete nature, if there were in 
 him more than one substantial form ; for with 
 
 * Disp., 3.3, Sect. 1. n. 3. t Acad., i. 6. 
 
26 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 each form he would have a complete nature. 
 And therefore St. Thomas argues thus : " One 
 thing results from many things, firstly accord- 
 ing to order alone, as a city is made of many 
 houses, or an army is made of many soldiers ; 
 and secondly by order and composition, as a 
 house is made by contact and junction of parts. 
 But these two ways do not suffice to constitute 
 out of many things one nature ; and therefore 
 those things that have a common form in order 
 or in composition are not natural things, whose 
 unity can be called the unity of nature."* 
 And therefore, if we suppose a body as formed 
 by mere aggregation of atoms or molecules, we 
 cannot call it one in nature, though all its 
 parts concur in one operation as to the term. 
 One nature implies not only one term, but 
 also one principle of operation, which cannot 
 be where many operating things have a divided 
 being. "It is impossible," says St. Thomas, 
 " that there can be one operation in things 
 which differ in their being, I say one, not on 
 the part of that in which the action terminates, 
 but as it comes from the agent ; for many 
 men dragging a boat do one work as to the 
 thing done, which is one, but on the part of 
 the men who drag it the actions are many, 
 because the impulses that move the boat are 
 many." t 
 
 » Contra Gent., iv. 35. + Contra Gent, ii. 57. 
 
IsATURE. 27 
 
 Nor can it be said that we may suppose 
 each atom to be an incomplete nature which is 
 completed by the aggregation of many atoms ; for 
 from what we have shown about the two natures 
 (the complete and the incomplete), it is evident 
 that each atom would really be a complete 
 substance and nature, and therefore that the 
 whole would only have a collective unity. 
 
 We say this because it is important to make 
 the meaning of the word nature quite clear, 
 seeing that it is not always in these times as 
 clear as in the days of old. Any one may see 
 how necessary it is to be clear about this. 
 If there were no other reason, the Catholic 
 definitions concerning man, and above all, con- 
 cerning the Divine Word Incarnate, ought to be 
 sufficient. 
 
28 
 
 CEEATION. 
 
 TO show the unity, beauty and majesty of 
 the Physical System, we must consider 
 it, as far as the nature of this treatise will 
 allow, in its principal relations ; and creation 
 is certainly one of them. For this purpose 
 we shall here quote the words of a most 
 sublime genius, where he interprets the first 
 chapter of Genesis. What is that void and 
 formless earth, and the darkness, and the 
 abysses, and the waters, and the Spirit of 
 God moving over it, of which we read 
 in that divine book ? " The Spirit of God," 
 says St. Augustine, " moved over the water. 
 It was not yet said that God made the water; 
 nor can we believe that the water was not 
 made by God, nor that it was before He had 
 formed anything. For by Him, through Him 
 and in Him are all things, as the Apostle says. 
 Therefore God did make the water, and we 
 cannot say otherwise without being greatly 
 in error. Why then is it not said that God 
 made the water ? Did He give the name of water 
 to that same matter which He called heaven 
 
CREATION. 29 
 
 and earth, earth invisible and uncomposed, and 
 an abyss ? Why should it not be called water, 
 if it could be called earth, when neither earth 
 nor water nor anything was distinct ? But 
 perhaps, and not incongruously, it was first 
 called heaven and earth, then uncomposed 
 earth, and an abyss without light, and lastly 
 water. Firstly, to indicate, under the name 
 of heaven and earth, the matter of the universe, 
 to form which it was all taken out of nothing. 
 Secondly, to show, under the names of uncom- 
 posed earth, and of an abyss, the nudity of 
 forms [informitas], because the earth is the 
 most unformed and least splendid of those 
 things. Thirdly, to signify under the name of 
 water that matter is obedient to the artificer ; 
 for water is more pliant than earth, and 
 therefore matter, by reason of being pliant, was 
 better expressed by the word ' water ' than by 
 the word ' earth.' . . . This way of signifying 
 matter shows firstly the end, or why it was 
 made, secondly the formlessness, thirdly the 
 dependence on and subjection to the artificer. 
 To the first, then, belong ' heaven and earth,' 
 for which precisely matter was made. To the 
 second belong the words, ' invisible and un- 
 composed earth,' and ' darkness over the abyss,' 
 or formlessness without light, wherefore it was 
 called invisible earth. To the third belongs 
 ' the water subject to the Spirit,' and receiving 
 
30 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 therefrom order and forms. Thus the Spirit 
 of God moved over the waters ; whereby we 
 may understand that the Spirit operated, and 
 that water was the matter of His operation."* 
 We can therefore conceive, in accordance with 
 the saint, an immense ocean, as it were, of 
 we know not what entity, as yet without 
 any definite nature, so that it could be truly 
 called neither water, nor air, nor ether, nor 
 anything that is considered in physics. It 
 was not divided into atoms nor determined 
 in certain figures any more than the darkness 
 that represents it was divided into colours. 
 It only gives us that primitive matter which 
 God created as the indeterminate subject, 
 capable of receiving in itself the images of 
 the divine archetypal ideas, which, as we showed 
 in the third chapter, the substantial forms are. 
 
 This is how the Spirit of God (which means 
 God Himself) applies Himself, as we may say, 
 to this formless water, or rather primitive 
 matter, and infuses into it His own virtue, 
 so that in it and with it in ways innumerable 
 He expresses Himself in more or less perfect 
 degrees, just as a sculptor (to use a weak 
 similitude) might express in modelling clay 
 his own image, not by an instrument, but 
 by the application of himself, that leaves 
 a greater or less impress here and there. 
 
 * De Gen., ad litt. i. c. 2. 
 
CREATION. 31 
 
 God, being infinite, cannot express Himself 
 adequately otherwise than in His Word, Whom 
 He generates, and Who has the same nature. 
 In matter, whether the whole or a part, He 
 cannot be expressed. Hence, though the 
 grades of creatures in the corporeal universe 
 are almost innumerable, according to the various 
 perfections imparted to them by their forms, 
 these creatures reflect only a very feeble ray 
 from that Actus Ptjrissimus which God is ; 
 and so does every other created being, however 
 sublime and perfect. This is expressed by 
 Dante, in the Paradiso : 
 
 Colui che volse il sesto 
 Alio stremo del mondo, e dentvo ad esso 
 Distinse tauto occulto e manifesto, 
 Non potfeo suo valor si fare impresso 
 In tutto rUniverso, che il suo Verbo 
 Non rimanesse in infinite eccesso. 
 * * » * 
 
 E quinci appar ch' ogni minor natura 
 
 E corto recettacolo a quel bene 
 
 Che non ha fine e sfe con sfe misura. * 
 
 And in Canto xxix. he says : 
 
 Vedi 1' ecoelso omai e la larghezza 
 Deir eterno Valor, poseia che tanti 
 Speculi fatti s'ha, in che si spezza, 
 Uno manendo in sfe come davanti. 
 
 St, Augustine goes on to explain the self- 
 application of God in forming matter to His 
 own image. " And the Spirit of God," he 
 
 * II Paradiso, canto xix. 
 
32 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 says, " bore Himself over the water, not as 
 oil floats on water .... but with a certain 
 effective and making virtue [ vi quadavi 
 effectoria et fabricatoria\ by which that over 
 which Hfe bears Himself is made and constructed, 
 as the will of an artificer acts on the wood or 
 other material on which he works, or on the 
 limbs of his own body when he moves them to 
 the work. But this, though the best of cor- 
 poreal similitudes, is poor and almost nothing 
 as intended to make us understand how the 
 Spirit of God bore Himself above the mundane 
 matter subject to His operation. Yet, among 
 those things that may somehow be understood 
 by men, we cannot find a similitude that could 
 be more clearly understood, or more nearly 
 resemble that of which we have spoken." * 
 
 It will be objected that, if materia prima 
 is at first formless and then formed, we must 
 admit an entity which has neither the nature 
 of earth nor of water nor of anything else ; 
 an entity which has no nature at all, or, as 
 they say in the Schools, is not quid ; an entity 
 which has no determinate figure, and therefore is 
 not quantum , sua. entity which has no attributes, 
 no accidents, no quality of any sort, and there- 
 fore is not quale. This, it will be said, is 
 inconceivable. Now, if the doctrine were that 
 God created materia prima first in order of 
 
 * De Gen., ad litt. ibid. 16. 
 
CREATION. 33 
 
 time, and afterwards determined it in various 
 natures by impression of forms, assuredly such 
 a Tiec quid, nee quantum, nee quale, standing 
 by itself, would be inconceivable and extremely 
 unnatural, if not absurd. But, when we are 
 told that in creation materia prima preceded 
 the forms in order of nature only, and not 
 in order of time, the difficulty vanishes, as 
 St. Augustine explains with his usual profound- 
 ness. " Hast Thou not taught me, Lord," 
 he says, " that before this formless matter 
 was formed and distinguished by Thee, there 
 was nothing at all — no colour, no figure, no 
 body, no spirit ? Not however quite nothing, 
 but a certain informity without a species of 
 any sort. . . Nor will this appear inconsis- 
 tent to any one who can distinguish between 
 the precedence of eternity, of time, of election 
 and of origin — between eternal precedence, as 
 God precedes all things ; precedence in time, 
 as the flower precedes its fruit ; precedence 
 by election, as the fruit is preferred to the 
 flower ; and precedence by origin, as the sound 
 precedes the singing. Of these examples the 
 first and last are very difficult to understand ; 
 but the others are very easy. For indeed 
 it is an arduous work, and very rarely done, 
 to raise one's eyes to Thine Eternity, 
 Lord, which, being incommutable, makes the 
 mutable things, and therefore precedes them. 
 
34 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 And then, who is sufficiently acute to discern 
 without much labour how the sound is before 
 the singing, seeing that the singing is the sound 
 formed (distinct in certain forms), and that, 
 although there can be a thing unformed, what 
 is not cannot receive a form ? Thus matter 
 is before that which is made of it, but not 
 first, as the efficient cause ; for it does not 
 make, but rather is made. Nor is it first by 
 an interval of time ; for even in singing we 
 do not first emit unformed sounds, and then 
 give them the order and form of singing, as whten 
 a man makes a casket out of wood or a vase 
 out of silver. The wood and the silver precede 
 in time the form of a casket and of a vase : 
 but in singing it is not so. What we hear 
 is not firstly an unformed sound, that passes 
 away when formed, and leaves nothing behind 
 for art to recover. It is the very sound of 
 the singing itself ; and therefore the singing de- 
 velopes in the sound, which is its own sound, 
 its own matter formed into song. Hence, as 
 I said, the matter of the sound is prior to the 
 form of the song : not prior by efficiency, for 
 the sound does not make the song ; but by being 
 subject to the soul that produces the song. 
 Neither is it prior in time ; for it comes forth 
 together with the song. Nor is it prior by 
 choice ; for sound is not preferable to song, 
 which is a sound and also a beautiful sound. 
 
CREATION. 35 
 
 It is prior by priority of origin ; for the form 
 is not given to make the song a sound, but 
 to make the sound a song. Let this example 
 serve to show, before those who can under- 
 stand, how the matter of things was 
 made first, and called heaven and earth, 
 because heaven and earth were made of it, but 
 not made first in time, because the forms give 
 the order of time, and the matter was 
 unformed."* 
 
 The holy doctor then exclaims : " May Thy 
 works praise Thee, that we may love 
 Thee ; and may we love Thee, that so Thy 
 works may praise Thee— those works which have 
 in time their beginning and end, their rising 
 and setting, their perfection and defect, form 
 and privation. They had therefore successively 
 morning and evening, partly hidden and partly 
 manifest ; for by Thee they were made from 
 nothing, not of Thee, nor of anything not Thine, 
 nor of anything anterior in time, but of matter 
 concreated, by Thee created together with them ; 
 because Thou, without interval of time, didst 
 give form to the formlessness of this matter, 
 the matter of heaven and earth being other 
 than the form of heaven and earth, Thou took- 
 est the matter absolutely from nothing, and 
 from formless matter the form of the world. 
 Yet both didst Thou make together, so that 
 
 * Confess, xii. 3, 40. 
 
36 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 without the interposition of a moment the form 
 followed the matter."* 
 
 But we have said enough about the out- 
 coming of primitive matter by the power of 
 God, and about its distinction in those primitive 
 substantial forms from which the development 
 of the universe came successively. We have 
 now to see what happens in the actuation 
 of this matter in the diverse forms that dis- 
 tinguish it. 
 
 * Ibid. xili. 48 
 
37 
 
 VI. 
 
 ATOMS. 
 
 rp HE word "atom," used by Democritus and 
 -L Epicurus, Descartes and Gassendi, to signify 
 the smallest possible substance, means rather 
 that which is undivided, and cannot while 
 preserving its nature be divided. This defini- 
 tion implies the notion of individuality, as 
 Cicero says ; and, since it prescinds per se 
 from size, a large body might sometimes be 
 called an atom, while a smaller one could not. 
 This being premised, let us consider what an 
 atom is in the system that we are explaining. 
 As a seal can multiply its own image by 
 impressing any sealing-wax whatsoever, so can 
 the divine archetypal idea multiply the divine 
 image in matter according to the number of 
 impressions that God makes on it. From this 
 it clearly appears that universality belongs to 
 the idea, and that singularity and individuality 
 come from the matter on which it is impressed, 
 as St. Thomas lays down in these often re- 
 peated words : Individuatio formcB est ex ma- 
 teria, per quam forma contrahitur ad hoc 
 determinatum. * Now this impression on 
 
 * Quodlib. vii. 3. 
 
38 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 matter is in the manner of a virtue derived 
 from God ; and the substantial form determines 
 an individual being in its nature. Hence it 
 evidently is not and cannot be made in 
 divided and separated matter, because in 
 that case the form would not be one, but as 
 many as the parts of the disjointed matter. 
 Therefore an individual corporeal substance is 
 continuous — ^is an atom. The size of it will 
 depend on the form, which may require more 
 or less extension in the matter, or be itself 
 indifferent as to that. Thus an individual 
 man is a substance in his continuous extension, 
 not an aggregate of minute bodies divided and 
 separated. For otherwise the human soul, which 
 is the substantial form of human beings, would 
 be in itself divided and separated ; and instead 
 of one soul there would in fact be as many 
 souls as there would be little bodies of which 
 we should suppose ourselves to be constituted. 
 The same may be said of an individual brute, 
 and of an individual plant, and of any inani- 
 mate substance that is individual. So that, 
 if the word cdom is to mean an individual 
 corporeal substance, we may call by that name 
 not only a little inanimate substance, but even 
 a plant, a brute or a man. Whence it follows 
 that in the one and the same substance 
 the so-called physical pores, i.e. interstices 
 placed all round each atom, or, as they call 
 
ATOMS. 39 
 
 it, each corporeal substance of the smallest 
 dimensions, cannot be admitted in the physical 
 system, because they would take away the 
 unity of the individual. But the pores that 
 we do find in corporeal substances do not 
 take away the unity of the subject ; and they 
 must be acknowledged, because experience proves 
 that they are. 
 
 An atom, understood in the strict sense of 
 the word, requires also indivisibility, not abso- 
 lute but relative, owing to which the substance 
 called " atom" cannot be divided without ceas- 
 ing to be what it is. This does not prejudice the 
 indefinite divisibility of matter ; for that re- 
 gards extension as considered by reason of the 
 quantity, not by reason of the nature in which 
 it inheres. The relative indivisibility of matter 
 is especially observable in living things, that 
 will not bear division while retaining the nature 
 of their being, because they have a form that 
 requires a certain organism not to be had in 
 every small quantity of matter. Generally all 
 corporeal substances have a minimum, that 
 cannot be less without ceasing to exist, and 
 therefore may deservedly be called an atom 
 according to the strictest meaning of the word. 
 
 But will two individual substances, or atoms, 
 that occupy an equal space, have in themselves 
 an equal quantity of matter? And, without 
 increase of the matter, can the same substance 
 
40 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 occupy more space than before, or occupy less 
 without diminishing it ? This question belongs 
 to the doctrine about the mass and volume 
 of the atom ; the volume meaning the place 
 occupied by the atom, or its extension with re- 
 spect to space, and the said volume being either 
 real or apparent. The place, for instance, which 
 a plant seems to occupy is the apparent, not 
 the real volume ; for, although the plant has 
 in all its living substance a true continuation, 
 it yet contains innumerable interstices or pores, 
 in which the substance is not. If it were 
 there, the volume would be not merely ap- 
 parent, but real. The matter intrinsic to the 
 plant constitutes its mass. 
 
 This being laid down, the followers of the 
 physical system said that two substances occu- 
 pying an equal space can have different masses, 
 or a different mass in equal real volumes, and 
 that the same substance may have, without 
 increase of mass, a real volume sometimes 
 more and sometimes less. We remember show- 
 ing in the year 1878 in the " Civilta Cattolica" 
 (Serie x. vol. vi. p. 73) that an argument of 
 Galileo's, to prove the variability of real volumes, 
 had no force : but disapproving of the argument 
 in favour of a thing is very different from dis- 
 approving of the opinion itself. Epicurus and 
 Descartes did disapprove of it, for they acknow- 
 ledged no other density and rarity than what 
 
ATOMS. 41 
 
 arises from more or less distance between the 
 atoms, and affirmed their extension to be 
 immutable. Cardinal Toledo explains the 
 teaching of Aristotle and of St. Thomas about 
 it in these words : " That which contains little 
 matter in much quantity is called i^re. . . 
 That which contains much matter in little 
 quantity is dense. . . We have to remem- 
 ber that there is a twofold rarefaction and 
 condensation, proper and improper. Improper 
 rarefaction or condensation is what happens 
 by mere approximation or segregation of 
 parts, without any change or , alteration of 
 them, . . .and this [improper rarefaction 
 or condensation] does not take place unless an 
 external body is expelled or introduced. Manj^ 
 among the ancients acknowledged no other 
 than this ; but they supposed quite vacant 
 pores in bodies, while we affirm them to be 
 full of a most subtle corporeal substance. 
 Proper rarefaction and condensation is not pro- 
 duced by expelling or introducing an extraneous 
 body, but by an internal change of the sub- 
 ject." * Here we have a change of extension. 
 The matter remains the same. 
 
 This suggests a natural explanation of the 
 greater or less gravity that substances acquire 
 by change of position. In fact, if part of a 
 solid body be divided and subdivided ever 
 
 * In IV. Phys., C. 9, Q. 11. 
 
42 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 SO much by purely mechanical means, it will 
 not be lighter than before ; but it really would 
 be so, if properly rarified, so that in rising 
 it made room for the other part of the same 
 body, which was not rarified, and which has 
 more matter under an equal real volume. 
 We say " of the same body," because we must 
 admit that a corporeal substance in a liquid 
 state may be more dense and contain more 
 matter than another corporeal substance in a 
 solid state. This variation of gravity is ex- 
 plained by St. Thomas, according to the doctrine 
 of Aristotle, as follows : " The size of a body 
 is extended or simplified in rarefaction, not by 
 the matter receiving into itself any other thing, 
 but because the matter which first was in 
 potentia to be greater or less becomes actually 
 so ; and therefore the substance is not made 
 rare or dense by addition or substraction of 
 extraneous particles, but by the matter itself 
 becoming rare or dense, . . . He [Aristotle] 
 proves his assertion by the effects of the rare 
 and the dense ; for the difierence between the 
 heavy and the light, the hard and the soft, 
 follows the difference between rarity and 
 density. . . He says therefore that the light- 
 ness of bodies is in consequence of their rarity, 
 the heaviness in consequence of their density. 
 And he is right ; for the rarity of a substance 
 comes from the matter receiving greater 
 
ATOMS. 43 
 
 dimensions, and its density is because the matter 
 has less dimensions. Hence, if, of two bodies 
 equal in extension, the one is rare and the 
 other dense, the dense body has the most 
 matter." * These considerations deserve to be 
 weighed and examined, not despised. 
 
 According to this doctrine it follows that 
 corporeal substances, unless impeded by an 
 extrinsic motive power or other obstacle, will 
 be so disposed around centres of gravity that 
 the more dilated bodies will go further and 
 further from them. Therefore, if all round 
 the earth, for instance, various spaces be sup- 
 posed in the manner of concentric spherical 
 strata, each corporeal substance would have 
 its own, in proportion to its density, from 
 the densest even to the most subtle ether, 
 whose density is so slight that we can hardly 
 form a conception of it. 
 
 And consequently we have to admit that 
 an ethereal and most subtle bodily substance 
 is everywhere diffused in the interplanetary 
 spaces, as the vehicle and subject of the re- 
 ciprocal operation of the stars and the planets, 
 though these are placed at such enormous dis- 
 tances from each other. Thus without con- 
 tradicting the indisputable axiom, Non datur 
 actio in distans, we can explain the diffusion 
 of light and heat in agreement with experience. 
 
 * III IV. Phys., lect. 14. 
 
44 THE PHYSICAL SYSTEM OP ST. THOMAS. 
 
 On tlie contrary, they who, following Epicurus 
 and Descartes, affirm the existence of equally 
 impenetrable atoms unalterable in their exten- 
 sion, are compelled thereby to admit in 
 nature much more of absolute void than of 
 space occupied by corporeal substances. They 
 have to suppose ethereal atoms at a great dis- 
 tance from each other, and thus make in- 
 explicable (according to the true system of 
 irradiation) not alone the extreme rapidity 
 of the propagation of light, but even the fact 
 of its propagation. God, however. Who willed 
 order and unity in the corporeal universe, 
 and made substances to act on other substances 
 in the most various and admirable ways, so 
 ordained that there are substances whose nature 
 it is to dilate and rarify in the highest degree 
 and fill the vast spaces of the heavens, passing 
 between the interstices of bodies almost incredi- 
 bly small. This is what is meant by the very 
 old adage, Natura abhorret a vacuo. We 
 should be indulgent to the old physicists who 
 explained by this adage such phenomena as 
 the rising of water in curved tubes, and so 
 on ; but the modern physicists have no right 
 to maintain that the Torricellian • vacuum re- 
 futes the adage. The old adage refers to an 
 absolute vacuum, while the vacuum obtained 
 by art is imperfect and relative. 
 
 We have now to pass on from the 
 
ATOMS. 45 
 
 consideration of corporeal substances, in their 
 individual and absolute being, to consider them 
 in those mutual relations that have their founda- 
 tion and origin in the seminal causes. 
 
46 
 
 VII. 
 
 SEMINAL CAUSES. 
 
 IN creating actuated matter by substantial 
 forms God produced also what may be called 
 the seminal causes of things, which enable sub- 
 stances to produce others like or unlike them- 
 selves. Strictly speaking, however, this term 
 expresses the virtue communicated by God to 
 a living substance, and through it to its seed, 
 by which it generates another substance of 
 the same species. Furthermore it expresses 
 the virtue by which even things without life 
 are the causes of substantial change. " From 
 that which is more perfect," says St. Thomas, 
 " the denominations of things are taken. Now 
 the most perfect of all corporeal substances 
 are living substances . . But evidently the 
 seeds from which they are generated are their 
 active and passive principle ; and therefore 
 all the active and passive virtues that 
 tire principles of generation and of natural 
 changes are suitably called by St. Augustine 
 (3 De Trinitate) seminales rationes. The 
 active and passive virtues may be considered 
 in a manifold order. Firstly, as St. Augustine 
 
SEMINAL CAUSES. 47 
 
 says, * they are principally and originally in 
 tlie very Word of God, as ideal essences. 
 Secondly, they are in the elements of the 
 world, where from the beginning they were 
 produced at once, as universal causes. In a 
 third way they are found in those things that 
 out of universal causes are in course of time 
 produced, for instance, in this plant or that 
 animal, as in particular causes. In a fourth 
 way they are in the seeds produced by animals 
 and plants, t . . . Without these seminal 
 virtues, given by God, the living things first 
 created would have disappeared from the earth, 
 and that continual transformation of substances, 
 which is so necessary for the maintenance of 
 such, would ' have ceased. 
 
 This most wise providence of the Creator 
 is thus described by St. Thomas : " The coming 
 forth of creatures from God is like the coming 
 forth of artistic works from an artist ; and 
 therefore, as artificial forms in matter proceed 
 from the artificer, so do natural forms and 
 virtues descend from the ideas in the Divine 
 Mind. . . . But the works of God differ 
 in two respects from those of the artificer. 
 Firstly, on the part of the matter ; for the 
 artificer does not produce that, but works on 
 it, and never could give to it the power of 
 
 * 6 De Gen., ad litt. t Sttmma, P. i. Q. ex v. a. 2. 
 
48 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 receiving those forms which he communicates 
 thereto ; but God, Who is the cause of all 
 being, not only gave to things their forms 
 and natural being, but also communicated to 
 matter (materia prima) the power of receiving 
 whatever He may please to operate in it. 
 Secondly, on the part of the forms ; for the 
 forms introduced by the artificer are not able 
 to produce a being like themselves. A wooden 
 bed cannot bring forth another wooden bed, 
 though, if reduced to ashes, it may help to form 
 a plant ; but the natural forms can produce 
 the same things, and therefore have the property 
 of seed, in virtue of which they may be called 
 seminal." * 
 
 Having thus given a general sketch of the 
 Physical System as to the generation of things, 
 we must now descend to the particular, and 
 apply it to the various kinds of corporeal 
 substances. Some living things have only 
 vegetative life, and others have sensitive 
 life also. The former are called plants, the 
 latter animals. G-od gave to the primitive 
 animals the above mentioned seminal virtue, but 
 so that in the one sex it should be an active 
 principle, in the other passive, and that the 
 seminal substance communicated by the ge- 
 nitors should have life, not actually, but 
 virtually, as having the power to produce, 
 
 * III II. Sent., Dist. xviii. 1, 2. 
 
SEMINAL CAUSES. 49 
 
 under requisite circumstances, a living thing. 
 In such generation therefore there is no 
 creation, properly so called ; for the anima 
 sensitiva is caused by the originating seminal 
 virtue, which, though simple in itself, is yet 
 material, as being so tied to matter that it 
 can neither operate nor exist separate there- 
 from. Of course we are prescinding from man, 
 because the human soul is immaterial, and there- 
 fore, even when separated, can exist and operate. 
 " God has not given to corporeal substances," 
 says St. Thomas, " by means of the seminal 
 virtues, the means of producing a human soul ; 
 but He has given to brutes the power of so 
 producing the anima sensitiva. And this," he 
 adds, " the Sacred Scripture seems to indicate 
 in the book of Genesis. There, speaking of 
 the origin of other animals, it ascribes their 
 souls to other causes, saying Producant aqucB 
 reptile animce viventis, &c. * But, when 
 speaking of man, it shows that his soul was 
 immediately created by God ; for it says 
 that God formed man of the slime of the 
 earth, and breathed into his face the breath 
 of life." t And here we must remark that 
 the conjunction of the two seminal principles 
 in every living thing is called conception, 
 and is prior in time to the production and 
 existence of the vital principle or soul, which 
 
 * Gen., i. 20. t Met, vii. 
 
50 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 is called animation. It is absurd and against 
 facts to suppose that the conception and the 
 animation are simultaneous. 
 
 The same thing is to be said of plants ; 
 for God conferred on them similar virtues, 
 and they confer those virtues on the seminal 
 substances, so that the one gives the active, and 
 the other the passive seminal principle, which, 
 being conjoined, give the completed seed, not 
 living actually, but having efficient power of 
 life. When there is no distinction of sex 
 one part of the same plant gives the active 
 principle, and the other the passive. " Those 
 [animals]," St. Thomas says, " that have perfect 
 life have also a perfect generation, and there- 
 fore are distinguished as active and passive. 
 But it is not so in the imperfect life that 
 plants have ; for in the same plant there 
 is the twofold virtue, active and passive, though 
 sometimes the active is found in one, and the 
 passive in another, so that the one plant is 
 said to be masculine and the other feminine." 
 
 Clearly then the distinction of sex in plants 
 is not a recent discovery of modern science, 
 as some people would have it to be. Here 
 we must remark, by the way, that, if any 
 human being could by chemical art determine 
 with certainty the elements of which the seminal 
 substance of living beings is composed, and 
 
 * Comm. in III. Sent., Dist.iii. Q. ii. a. 1. 
 
SEMINAL CAUSES. 51 
 
 combine them so as to make of it a substance 
 quite similar materially to the completed seed, 
 the substance would nevertheless have no semi- 
 nal virtue, because it would not proceed from 
 living parents. And therefore if, per impossihile, 
 it were possible for any man to produce by 
 art the organism of a plant or of a brute, he 
 could never produce a live brute or a live 
 plant. 
 
 The two principles of seminal virtue for the 
 generation of animals and plants may, by ana- 
 logy, be said to be required for the production 
 of a new substance in beings without life. 
 Oxygen and hydrogen will not produce water, 
 although put together ia the right proportions, 
 unless there is some extrinsic cause to modify 
 their virtue, so that their mutual action may 
 produce a change of one relative principle into 
 another, thereby constituting the nature of 
 water. Evidently these elementary substances 
 are different from non-elementary or mixed 
 substances. The elementary substances do not 
 result from the union of two other substances ; 
 but by physically uniting they produce a new 
 substance in a different nature, yiz. mixed 
 substances. But why do we call these mixed, 
 when in natural sciences now they are called 
 composite, and the word mixed is used to signify 
 a mixture 1 The reason is, that since every 
 corporeal substance is composed of matter and 
 
52. THE PHYSICAL SYSTEM OF ST, THOMAS. 
 
 form, tlie name of composite belongs as much 
 to the elementary as to the non-elementary ; 
 so that a mixed substance cannot properly be 
 called a mixture, but only two or more sub- 
 stances locally mingled by aggregation, each 
 keeping its primary nature. The word onixed 
 belongs of right to that only which is produced 
 by physical union, so that from two or more 
 substances there results one substance only. 
 
 And, since anything may be resolved into 
 the elements of which it is constituted, any 
 mixed substance (say water) may be resolved 
 into its component parts. Aristotle, explaining 
 as a philosopher the inmost nature of elements, 
 tells us* that an element of bodies is that 
 substance which is obtained by resolution of 
 others, and which cannot be resolved into 
 another of a diflferent species. St. Thomas, 
 commenting on him, says : "An element of 
 other bodies is that into which those other 
 bodies are decomposed or resolved ; for not 
 every cause may be called an element, but 
 only that which enters into the composition 
 of a thing." t Again he says: "In natural 
 corporeal substances, those into which all mixed 
 bodies resolve themselves are called elements 
 of bodies ; and consequently they are those 
 from which the mixed bodies result. And 
 the bodies called elements are not divided into 
 
 * iii. De Coelo et MuMo. + Lect. viii. 
 
SEMINAL CAUSES. 53 
 
 others differing from each other in species, 
 but into similar parts."* Hence he calls 
 elementary bodies " simple." " Elementary- 
 bodies," he says " are simple, and there is no 
 composition in them except that of matter 
 and form."t Following this doctrine, Toledo 
 says : "In two ways we may conclude that 
 elementary substances are. Firstly, from the 
 dissolution of bodies ; it being a fact that some 
 decompose into bodies of a different nature, 
 and others into bodies of the same nature. 
 The resolved parts are evidently composed of 
 those into which they do resolve ; and an 
 infinite process of resolving is repugnant to 
 reason. Therefore, there must be bodies that 
 are not resolved into others, or, in other words, 
 elementary bodies. Secondly, we may conclude 
 this likewise from composition. For we know 
 that many bodies are made by mixture (now 
 called chemical combination) ; but elementary 
 bodies cannot be so made. Therefore those 
 really are simple bodies, which do not result 
 from composition of others." J 
 
 Such is the doctrine professed in the system 
 before us ; but it does not claim to determine 
 how many and which the elementary bodies 
 are. These have been supposed to be four, 
 and thought to be twenty or fifty, and now 
 
 * In V. Ma., 3. f Contra Gent., iii. 23. 
 
 t Lib. ii. De Generat. et corrupt. , Q. 4. 
 
54 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 the amount is over eighty ; nor can any one say 
 how many they may be found to be. By 
 means of reasoning we can only affirm with 
 Toledo that " the elements are more than one." * 
 That much we can affirm ; for otherwise the 
 production of new natures would be impossible, 
 because the union of two equal things cannot 
 constitute something of a different species. 
 The atomic theory, therefore, cannot be true ; 
 because, according to that doctrine, thq atoms 
 are all of the same nature. Experiment, hot 
 reason, determines which and how many ele- 
 mentary substances cooperate in forming this 
 or that mixed body ; and even experiment 
 does not, after so many centuries, give with 
 certainty a final settlement of that question. 
 
 In defending the old teachers from unjust 
 attacks, men of high ability and great learn- 
 ing, such as the distinguished philosopher, 
 Cardinal Battaglini, and the famous Professor 
 Lorenzelli, have in their philosophical courses 
 given another meaning to the word " elements ;" 
 but we prefer to avoid troublesome and un- 
 necessary disputation. We simply say that 
 since the old teachers, when teaching as 
 philosophers, tell us that elements or elemen- 
 tary bodies are those bodies of which mixed 
 bodies are composed, and which result from 
 the decomposition of the latter, we have a 
 
 * Ibid., iii. 
 
SEMINAL CAUSES. 55 
 
 right to use the same correct definition in ex- 
 perimental physics, for the purpose of seeing 
 what bodies are such — whether solid, liquid, 
 fluid, or aerial. Modern chemists cannot deny 
 that ; for with them the element is the first 
 in chemical synthesis and the last in chemical 
 analysis. 
 
56 
 
 VIII. 
 
 QUALITIES. 
 
 OF these very little is said in modern schools 
 of physics or of philosophy ; and yet the 
 doctrine about it is so important, that without 
 it the physical system would be untenable, and 
 all nature would appear to the mind to be full, 
 not only of inexplicable puzzles, but also of 
 evident contradictions. Let us begin by asking 
 this question : Suppose that we acknowledge the 
 complete and highest Being of God, yet deny His 
 operation. What could we then say about His 
 knowing, loving, creating ? What sort of con- 
 ception could we form of that most perfect 
 Nature ? Either none at all, or the conception 
 of an absurdity. 
 
 ' As God is the complete and most perfect 
 Being (esse), so in Him there is not any real 
 difference between being and the power to do 
 and the action itself. He is the One most pure, 
 most simple, most complete, most perfect Act. 
 But it is not so with created substances, especial- 
 ly corporeal ones, with which we are now more 
 particularly concerned. They have indeed a 
 likeness to God, inasmuch as they have being, 
 and have power to act, and do act ; but, by 
 
QUALITIES. 57 
 
 reason of their imperfection, there necessarily is 
 a real distinction between their being, their 
 power to act and their action. Moreover, since 
 God is most perfect and the source of all being. 
 He never can receive from His creatures any- 
 thing intrinsic to Himself, nor can they take 
 from Him anything of His own. In other 
 words, He cannot receive that inner mutation 
 which is philosophically called passio, and 
 which in its general meaning denotes a change 
 made in a substance by the action of some 
 being. 
 
 This being premised as the basis of the fol- 
 lowing dissertation, let us consider any finite 
 substance : and since it is easier to descend 
 from the more perfect to the less, when the 
 more perfect is known to us, we shall begin 
 with man. Now by mentally abstracting 
 from man all action, all passion, every faculty, 
 what remains of him ? The bare essence of 
 the human individual, as constituted by the 
 soul substantially informing the corporeal mat- 
 ter. Whatever therefore we may conceive as 
 happening to him when thus constituted and 
 determined, will not be a substantial form that 
 determines his nature, but an accidental form, 
 which adds nothing more than quality. There- 
 fore, remembering that besides human nature 
 with its natural faculties, man has dispositions 
 that adorn it and make it fitter for action. 
 
58 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 we must acknowledge that these are true 
 qualities. 
 
 When a man acts either with his intellect 
 or with his will, or with any other power that 
 he has, there certainly happens to him a modi- 
 fication that before was not ; and this is a 
 quality. And, when at the sight of an object, 
 pleasing or otherwise, he receives in his senses 
 and in his soul an impression that was not 
 there before, this, too, is a quality. Lastly, 
 the human soul, as the substantial form, is 
 the determining principle of the substances 
 that nourish man to become part of his nature ; 
 and thus it gives in various ways to the body 
 a certain extension, quantity and figure. Here 
 again there is quality. We can therefore 
 ' distinguish four species of quality, of which 
 the first belongs to Being ; the second to action ; 
 the third to passion ; the fourth to quantity. 
 " Properly speaking," says St. Thomas, " quality 
 means a certain mode of substance. . . . 
 Now the mode, or the determination of the 
 subject, according to accidental Being, may be 
 understood either according to the nature of 
 the subject, or in reference to action, or to passion, 
 (these proceed from the principles of nature which 
 arc matter and form,) or according to quantity. 
 If we take the mode or determination of the 
 subject according to quantity, we have the 
 fourth species of quality. . . . The mode 
 
QUALITIES. 5.9 
 
 or determination of the subject according 
 to action and passion gives the second and 
 third species of quality. . . . But the 
 mode or determination of the subject according 
 to the nature of the thing belongs to the first 
 species of quality. * . . . This does not 
 contradict what he lays down in his commen- 
 tary on the Sentences, where he says that the 
 compositum does not operate in virtue of 
 the matter, but of the form, which is its actus 
 and principle of action. " The quantity," he 
 says, "belongs to matter, the quality to 
 Form."t For it is not afiirmed that the said 
 species of quality is quantity itself. It is 
 the determination that is in the composite being 
 under this or that quantity ; and though the 
 quantity belongs to matter, the determination 
 is by virtue of the form. 
 
 Of the species inferior to man, whether they 
 have life or have not, we must consider firstly 
 their substantial being : secondly, what is acci- 
 dental in them, constituted by the four different 
 species of quality before mentioned. If an 
 atom of oxygen, for instance, receives into 
 itself a disposition which it previously had 
 not, it will have a quality of the first species : 
 and being in fact able to operate on another 
 by attracting or altering, it will have a 
 modification that contains the quality of the 
 
 * Summa, la. 2ee. Q. xlix. 2. t Bk. xii. iv. Q. 1. 
 
60 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 second species. If instead of that, it receives 
 into itself the operation of another, it will ac- 
 quire through the change undergone a quality 
 of the third species. Lastly, if by virtue of 
 an extrinsic cause, its proper quantity comes 
 to be so determined that it acquires a different 
 conformation of parts, that quality will belong 
 to the fourth species. 
 
 We must observe that all the corporeal sub- 
 stances of equal matter have substantial forms, 
 which, though differing from each other in per- 
 fection, have something in common, as we have 
 seen by the comparison that Aristotle and St. 
 Thomas took from geometricalj figures and num- 
 bers. As in every polygon there is the triangle, 
 and in every number there is unity, so in every 
 substantial form there is an inferior or ele- 
 mentary form, not formally but virtually. This 
 applies to qualities also, which, as we have 
 said, are in being by reason of form. Hence 
 the lowest qualities of the lowest elementary 
 substance are common to all the superior sub- 
 stances. Thus, for instance, we find that 
 attraction and gravitation, subjection to heat, 
 expansion and the rest, are common to all 
 corporeal substances. Since then a more per- 
 fect being has a substantial form that contains 
 the perfections of the inferior forms, it must 
 also possess their qualities. But as in a one 
 being all must be in harmony and order, so 
 
QUALITIES. 61 
 
 even in the qualities, there is a certain law 
 by which, where the inferior qualities would 
 clash with the superior, the inferior are there 
 in a remitted degree, or, in modern language, 
 diminished or neutralized. " We must hold 
 with the philosopher (Aristotle), " says St. 
 Thomas, " that the forms of the elements re- 
 main in the mixture, not actually, but virtually. 
 The qualities of the elements properly remain, 
 though remitted ; and in them appears the 
 virtue of the elementary forms." * 
 
 And now, to make the whole theory of the 
 system clear as to the gradation in the 
 modes operating and the qualities of all beings, 
 we cannot do better than quote another grand 
 passage from the Angelic Doctor, where he 
 reduces it to order and unity, giving us a sure 
 foundation of rational physics. 
 
 " There is nothing," he says, " that more im- 
 mediately and intimately belongs to things 
 than Being ; and therefore, since matter is 
 actuated by form, the form that gives being 
 to the matter must be conceived as coming to 
 it first of all things, and most intimately 
 Now it is a property of the substantial form 
 that it gives being absolutely to matter ; for 
 
 THE SUBSTANTIAL FORM IS THAT BY WHICH A 
 
 THING IS WHAT IT IS. The accidental forms 
 do not give being absolutely, but in one 
 
 • Summa, P. i. Q. Ixxvi. a. 4 ad 4. 
 
62 THE PHYSICAL SYSTEM OF ST. THOMAS, 
 
 respect, such as being great, or coloured, etc. 
 Hence, if there is a form that does not give 
 being to matter absolutely, but comes to matter 
 already actuated by some form, it will not be 
 substantial. Hence it is evident that between 
 substantial form and matter there cannot be 
 any intermediate substantial form (as some will 
 have it) supposing that, according to the order 
 of genera, of which one is under the other, 
 there is an order of diverse forms in matter : 
 as, for instance, that matter has the being 
 of actual substance from one form, the being 
 of corporeal substance from another, the being 
 of an animated body from another, and so on. 
 But according to that position the first form 
 only, by which the actual being of substance 
 was given, would be substantial. All the 
 others would be accidental ; for the substantial 
 form, as we have already said, is that which 
 constitutes the determinate being, (quce facit 
 hoc aliquid.) ' We must therefore say that one 
 and the same form is that by which a thing is 
 a determinate substance and by which it is 
 determined in its ultimate species (specialissima), 
 and in all the intermediate genera," (by which, 
 for example, a man is a man and an animal and 
 a living creature and a corporeal substance). 
 " Consequently, since the forms of natural things 
 are like numbers, in which the addition and sub- 
 traction of a unit makes a difi'erent species. 
 
QUALITIES. 63 
 
 we must understand that the diversity of 
 natural forms, according to which the matter 
 is constituted in different species, is because 
 one form adds a greater perfection. For in- 
 stance, one form constitutes a substance in 
 corporeal being only. . . . Another and 
 more perfect form constitutes matter in 
 vital as well as in corporeal being. And then 
 another form gives to it not only corporeal 
 and vital being, but also sensitive being, and 
 so forth. We must see therefore that the 
 more perfect form, inasmuch as simultaneously 
 with the matter it constitutes the compositum 
 in the perfection of an inferior grade, must 
 be understood as material with respect to an 
 ulterior perfection, and so on. Thus materia 
 prima, as constituted in corporeal being, is 
 matter with respect to the ulterior perfection 
 of that which has life. Hence (logically) the 
 body is the genus of the living body, and its 
 being animated or living is the differentia. 
 For the genus is as the matter, the differentia 
 is as the form ; and thus in a manner one 
 and the same form, as actuating matter in a 
 lower grade, is midway between the matter 
 and itself as actuating it in a higher grade. 
 Matter understood as constituted in substantial 
 being according to the perfection of an inferior 
 grade, must consequently be supposed as 
 subject to accidents. For a substance in that 
 
64 THE PHYSICAL -SYSTEM OF ST. THOMAS. 
 
 lower grade of perfection must have certain 
 accidents proper to itself.*' .... 
 
 " Thus, when we say that man is a corporeal 
 substance, living, sensitive and rational, we do 
 not mean that he is constituted in these di- 
 verse grades by diverse forms. We mean that 
 the perfect form, the soul, which makes him 
 rational, makes him a sensitive substance also, 
 and a living substance and a corporeal sub- 
 stance ; for since every superior grade pre- 
 supposes the inferior, the human soul as con- 
 stituting the rational grade, presupposes itself 
 as constituting the sensitive grade, or sensitive 
 being (esse) with its accidents and qualities ; 
 and so on." 
 
 St. Thomas goes on to say : " Since then 
 the soul is the substantial form, as constituting 
 man in a determinate species of substance, there 
 is no substantial form between the soul and 
 'materia prima: but man is perfected by his 
 rational soul according to the different degrees 
 of perfection, so as to be a body and an animated 
 body and a rational animal. But matter, under- 
 stood as receiving from the rational soul the 
 perfections of a lower grade — suppose it to 
 be a body and an animated body and an animal 
 — must be understood as suitably disposed 
 for the rational soul that gives the ultimate 
 perfection. Thus the soul, as the form that 
 gives being, has nothing between itself and 
 
QUALITIES. 65 
 
 materia prima. Now, since the same form that 
 gives being to matter is also the principle of 
 operation, and because everything acts accord- 
 ing to what it actually is, the soul like every 
 other form must be a principle of operation. 
 But we must consider that according to the 
 grades of the forms with respect to the perfec- 
 tion of Being, there is also a grade in their 
 virtue of operating, because that which operates 
 has already an actual existence. Therefore, 
 the more perfect a form is in giving being, 
 the greater is its virtue in operating ; and the 
 more perfect forms operate more and with greater 
 diversity than the less perfect. Hence it is that 
 in the less perfect things diversity of accidents is 
 sufficient for diversity of operation, while the 
 more perfect require diversity of parts also, more 
 or less, according to the perfection of the form. 
 Thus we see that fire operates in diverse ways 
 according to the diversity of accidents, such 
 as rising by reason of its lightness, warming 
 by its heat, and so on : yet each of these 
 operations belongs to the fire as a whole. But 
 in animated bodies, which have nobler forms, 
 difierent parts are assigned for difiierent opera- 
 tions, as in plants the operation of the root 
 is difi'erent from that of the boughs or of the 
 trunk ; and the more perfect an animated body 
 is, the more does it require, by reason of 
 its greater perfection, a greater diversity in 
 
66 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 its parts. Therefore, since the rational soul 
 is the most perfect of natural forms, in man 
 do we find the greatest distinction of parts 
 owing to the diversity of his operations ; and 
 the soul gives to each of them substantial being 
 in the manner that is suitable to its operations. 
 This is marked by the fact that, when the soul 
 is separated, the flesh or the eye remains only 
 equivoce. Now, since the order of instruments 
 must accord with the order of the operations, 
 and, of the diverse operations that are from the 
 soul, one naturally precedes another, so one part 
 of the body must be moved by another to do 
 its own work. Thus then, between the soul as 
 the mover and the principle of operation, and 
 the whole body, there is some medium ; for by 
 means of some part first moved it moves the 
 other parts to their work, as by means of the 
 heart it moves the other members to their vital 
 operations. But when it gives being to the body, 
 it immediately gives to every part substantial 
 and specific being. And this is why many 
 people say that the soul, as being_thfi_form 
 of the body, is united to the body with- 
 out a medjlim, but, as being Jhe mover of 
 the body, is united thereto through a me- 
 dium, : which accords with the opinion of 
 Aristotle, who aflSrms the soul to be the sub- 
 stantial form of the body. But some people, 
 supposing with Plato that the soul is united 
 
QUALITIES. 67 
 
 to the body as one substance to another sub- 
 stance " (that is, one complete substance not 
 resulting therefrom), " had to suppose media 
 through which the soul could be united to 
 the body, because diverse and distant substances 
 are not united unless there is something to 
 unite them. And so some of them supposed 
 that a fluid or humour is the medium between 
 the soul and the body, while some supposed 
 it to be light, and others believed it to be 
 the powers of the soul, or something of the 
 sort. * But none of these things are necessary, 
 if the soul is the form of the body. For a 
 thing, whatever it may be, is one because it 
 is an ens, and therefore, since the form by 
 itself gives being to matter, by itself is it united 
 to materia prima, and not by anything else." t 
 
 Here ends our long quotation from the An- 
 gelic Doctor. It went beyond the question 
 before us by speaking of animated beings and 
 of human beings ; but that is not altogether 
 out of place, as we shall see further on. 
 
 And now, having discoursed on the mutual 
 operation of the corporeal substances, according to 
 the perfection of their being, we have to see how 
 this can happen between substances far apart. 
 These, as St. Thomas says, must approach 
 
 * And all they who suppose that the soul is united to the hody 
 by means of the biotic fluid, or by ether, or by physical influx, fall 
 into this error. 
 
 t De anima, art. 9. 
 
68 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 in order to operate. " Alteration," he says, 
 " cannot happen without a previous change 
 of place ; foi- in order that the alteration 
 may take place, the alterant must be nearer 
 than before to the altered."* And since this 
 approach may be either by internal attraction 
 or by external impulse, we had better speak of 
 the former as being more difficult. 
 
 * Contra Gent., iii. 82. 
 
69 
 
 IX. 
 
 ATTRACTION. 
 
 THAT bodies move towards other bodies, 
 to unite with them, is a fact shown con- 
 tinually by experience. But what is the principle 
 of such movement 1 It certainly is often ex- 
 trinsic ; and when it is so, its motion is 
 mechanical or forced. But often we find it 
 to be intrinsic, and then the motion is physical 
 or natural, i.e. by true attraction. Now what 
 is this mysterious attraction ? How does one 
 body attract another from a distance ? Where 
 are the means of (so to speak) pulling it ? Are 
 these attracting forces invented for the pur- 
 pose of hiding our own ignorance ? 
 
 For the sake of clearness, let us begin with 
 a comparison, and suppose that a cow in a field 
 is attracted by some better grass. The grass, 
 by means of light that makes it visible and the 
 exhalation that carries the scent, is made an 
 object for the cow ; and the cow, moved by 
 its presence, goes to it. In this fact we have 
 to distinguish firstly the principle of attraction, 
 which is in the grass : secondly the means by 
 which the attraction is communicated, i.e. light 
 
70 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 and air : thirdly the manner of attracting, which 
 is by acting on the sensible appetite of the 
 cow through the senses and the imagination : 
 fourthly the principle of motion, by which the 
 cow is moved and goes; which is the cow's nature 
 determined actually to go, instead of being merely 
 in potentia to do so. But we must remember, 
 that inasmuch as the substantial form or anima 
 of the cow is the principle of its every operation, 
 the said nature is its principle of motion in 
 virtue of the substantial form. We must re- 
 member also that, in order to be such, it 
 must be endowed with some qualities. For 
 the cow would not go after the grass without 
 having first received an impression from it : 
 nor would the impression suffice without the 
 actual going ; nor would the cow actually go, 
 if she had not an antecedent disposition to 
 choose the better grass. 
 
 This much is clear in living and sensible 
 creatures : but we may speak analagously of 
 inanimate things also. " "We find," says St. 
 Thomas, " a certain operation that in one way 
 is common to the animate and the inanimate 
 things, but in another is proper to the animate, 
 such as motion and generation. For spiritual 
 things absolutely have such a nature that they 
 can move but cannot be moved. Bodies indeed 
 move ; but, though one of them can move another 
 none can move itself ; for, as Aristotle proves in 
 
ATTEACTION. 71 
 
 VIII. Phys., those things that move themselves 
 have two parts, of which one is the mover 
 and the other is the moved. But in things 
 purely corporeal this cannot be ; for their forms 
 cannot be movers, though they can be a prin- 
 ciple of motion by which a thing is moved 
 (uT quo aliquid movetur), as, in the motion of 
 the earth, gravity is the principle by which it is 
 moved (quo movetur J, but is not the mover." * 
 To understand this doctrine then we must 
 remember that, if a substance is to move itself, 
 it must have in it two different parts, one 
 the mover and the other the moved. And 
 this is evident, for in that which moves itself 
 there must be the principle and the term of 
 the motion ; and if its parts were quite alike, 
 there would be no sufficient reason why the 
 one should be the mover instead of the moved. 
 Hence living things only, as being composed 
 of various parts differently inclined, can move 
 themselves : and this motion within themselves 
 is called an immanent action. It is not so 
 with inanimate things. These, not having in 
 their parts any diversity of organism, have no 
 immanent action, but only the action that is 
 called in Latin transient : and herein living 
 bodies differ from those without life. Thus 
 we see that, whenever an inanimate body goes 
 to another, it cannot do so by moving itself 
 
 '. Disp., De Veritate, Q. xxii. a. 3. 
 
72 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 as above mentioned, but only by transporting 
 its whole self. The attraction then of inani- 
 mate things is in this way: First of all, the 
 body attracted will be disposed for going to 
 one body rather than to another. Secondly, the 
 attracting body must act on the attracted 
 through a medium, and, making itself, so to 
 speak, present to it, become its object. Thirdly, 
 the attracted body must receive an impression 
 (in scholastic language passio) sent by virtue 
 of the said medium. Fourthly, having re- 
 ceived this, the attracted body must tend 
 actually towards the attractor. And here a 
 question may arise about the attracted body 
 going whole and entire without one part moving 
 the other. To make it clear, we had better 
 begin with an example. 
 
 The human soul, being the substantial form 
 of man, does not by one act move the whole 
 body, but, by informing one part, moves 
 another ; so that the soul, which informs the 
 whole hiiman body, being the form of a 
 part, is the mover of the other parts. And 
 thus it seems that the motive power originates 
 from the brain and the heart; so that the soul, 
 which informs both, gives by their means move- 
 ment to the other moveable parts. We may 
 consider the moving part then as a body that 
 gives motion to the contiguous part by trans- 
 porting its whole self, and thus pressing the 
 
ATTRACTION. 73 
 
 part immediately moved by it ; for, if we sup- 
 pose that of tlie same part one side is tlie 
 mover and the other the moved, we only re- 
 move the question a little, or admit an infinite 
 process repugnant to reason. Here we have 
 the example therefore of a body that in its 
 motion transports its whole self by virtue of 
 the soul, its true substantial form ; and there- 
 fore it is easy to conceive how a body, even 
 though inorganic, can in virtue of its own 
 substantial form be transported from one place 
 to another. 
 
 The Angelic Doctor, speaking of the order 
 and variety of the corporeal universe, finds 
 therein, not a fortuitous collection of many 
 substances, but true dispositions of each for 
 tending mutually to the wondrous formation 
 of the* sensible universe. 
 
 " All things," he says, " seek a bonum, whether 
 they have knowledge or have not. To make 
 this clear, we must know that some ancient 
 philosophers supposed the effects of nature to 
 arise from necessity of preceding causes, and 
 not because the natural causes had a proper 
 disposition for producing such effects. This 
 the Philosopher condemns in the second book 
 of Physics, where he shows that, if the relation 
 and mutual utility of things were not in 
 some way intended, they would happen by 
 chance, and therefore would not happen in the 
 
74 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 greater part, but in the less, like all other things 
 that proceed from chance. We must there- 
 fore say that all natural things are ordered 
 and disposed for their proper eflFects. But a 
 thing may be ordered and directed to another 
 as an end in two ways, viz., either by itself, 
 as when a man directs himself to the place 
 whither he means to go, or by something else, 
 as an arrow is directed to a given place by 
 . an archer. Now a thing cannot be directed 
 to an end, unless the director knows the end. 
 For that which directs must have knowledge of 
 that to which it directs ; but things that know 
 not the end may be directed to a given end. 
 And this happens in two ways. For sometimes 
 that which is directed to an end is only impelledj 
 without receiving from its director any form to 
 adapt it for this or that direction or inclination ; 
 and such inclination is forced, as an arrow aimed 
 at a mark by an archer. But sometimes the 
 directed or inclined thing has from its director or 
 mover some form by which it is adapted for that 
 inclination ; and therefore such inclination will 
 be natural, as from a natural principle, Thus 
 He Who gave gravity to stones inclined them 
 to fall naturally downward ; and therefore it 
 is said [VIII. Physics] that the Maker of heavy 
 and light things is also their Mover. In this 
 way all natural things have an inclination to 
 others that are adapted for them, having in 
 
ATTRACTION. 75 
 
 themselves a certain principle of inclination, 
 by reason of which their inclination is natural, 
 so that these in a manner go of themselves, 
 and are not merely led to their proper end 
 (ita ut quodammodo ipsa vadant, et non solum 
 ducantur in fines debitos.) But in forced move- 
 ment things are only led or pushed, not co- 
 operating themselves at all with the mover ; 
 but in natural movement things go to their 
 end, inasmuch as they cooperate with the in- 
 cliner and director by a principle given to them."* 
 In accordance with this doctrine Dante wrote : 
 
 Ond' ella (Beatrice) appresso d'un pio sospiro 
 
 Gli occhi diizzb ver me con quel sembiante 
 
 Che madre fa sopra figUuol deliro. 
 E comiucib : Le cose tutte quants 
 
 Hann' ordine tra loro ; e questo i forma 
 
 Che r universe a Dio fa simigliante. 
 Qui veggion I'alte creature I'orma 
 
 Dell' eterno valore, il quale h fine 
 
 Al quale fe fatta la toccata norma. 
 Nell' ordine ch' io dico sono accline 
 
 Tutte nature, per diverse sorti 
 
 Pih al principio loro e men vicine ; 
 Onde si muovono a diversi porti 
 
 Per lo gran mar dell' essere, e ciascuna 
 
 Con istinto a lei data che la porti. 
 
 Farad., I. 
 
 What has been said shows clearly the meaning 
 of the triple appetitus, so often spoken of by 
 St. Thomas. For, setting aside the forced 
 
 * Quaest. Disp., De Veritate, Q. xxii. a. 1. 
 
76 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 motion of things, and considering their natural 
 motion only, we find in the first place that 
 man petit aliquem terminum by freely moving 
 himself, because there is in him — that is, in his 
 intellectual knowledge — the known honum that 
 inclines him. Secondly, we find that a brute 
 petit aliquem terminum, not freely, and learns 
 by sensitive knowledge the honum that inclines 
 him. Thirdly, we find that an inanimate body, 
 whatever it may be, petit aliquem, terminum, 
 not by moving itself — because in it there is not 
 a part that moves and a part that is moved — 
 but by an inner principle of motion transport- 
 ing itself to the term. From this we infer 
 that, as principles of motion, there is a rational 
 appetite in man, a sensitive appetite in brutes, 
 and a natural appetite in substances without 
 life. 
 
 " As the sensitive appetite," says St. Thomas, 
 " is distinguished from the natural by its more 
 perfect manner of seeking, so is the rational 
 appetite distinguishable from the sensitive ; 
 for the nearer a nature is to God, the more 
 is the Divine dignity expressed in it." 
 
 " Now it belongs to the Divine dignity that 
 God should move, incline and direct all things. 
 He being neither moved nor inclined nor 
 directed by anyone. Hence the nearer a na- 
 ture is to Him, the less is it by Him inclined, 
 and the more is it adapted to incline itself. 
 
ATTRACTION. 77 
 
 Insensible nature, therefore, being, by reason 
 of its materiality, the furthest removed from 
 God, is inclined indeed to some end, but 
 has not in itself anything to incline itself. It 
 has only the principle of inclination, as is evi- 
 dent from what has been said. Now, though a 
 sensitive nature, as being nearer to God, has in 
 itself something that inclines, viz., the appe- 
 tihile apprehended, yet the inclination itself is 
 not in the power of the animal inclined, but 
 is determined from without, (i.e. by God). 
 Animals, when they see a desirable thing, 
 cannot help wishing for it, because they 
 have no dominion over their own inclination. 
 Wherefore they may be said to be drawn, 
 rather than to draw themselves, as St. John 
 Damascene says : which is because the sen- 
 sible appetitive power has a corporeal organ, 
 and therefore is near to the dispositions 
 of matter and of things corporeal, so as to be 
 moved rather than move. But the rational nature, 
 which is the nearest to God, not only has an 
 inclination to something, as inanimate things 
 have, nor does it only move this inclination 
 by mere extrinsic determination, as sensitive 
 natures do. Over and above that, it has the 
 inclination itself in its own power, so that it 
 does not necessarily incline towards the appeti- 
 hile apprehended, but may either incline or not 
 
78 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 incline : so that its inclination is not deter- 
 mined for it by another, but by itself. * And 
 this belongs to it not because it uses no cor- 
 poreal organ, but because, withdrawing from the 
 nature of a moveable thing, it approaches the na- 
 ture of a mover and operator. Nothing can 
 determine its own inclination to an end without 
 knowing the end and the aptitude of the means 
 to attain it (habitudinem finis in ea quae sunt 
 ad finem) ; which reason alone can do. And 
 therefore this appetite, being not determined 
 necessarily by others, follows the apprehen- 
 sion of reason ; wherefore the rational appetite, 
 which is called the will, is different from the 
 sensitive appetite." t 
 
 From this evidence we gather the noblest 
 conceptions about the wondrous unity of cor- 
 poreal substances, which in their multiplex 
 tendencies imitate variously the Divine perfect- 
 ions ; but we must content ourselves now 
 with noting some deductions that serve our 
 present purpose. 
 
 Since the order and beauty of the corporeal 
 universe depends on the reciprocal operations 
 of corporeal substances, and these cannot 
 
 * Hence whilst human will is evidently determined by God to 
 the universal bonum, it is equally clear that the will freely 
 determines itself to the particular objects in which the mind 
 recognizes a participation of that universal bonum. And this 
 reconciles the Divine impulse with human freedom as taught 
 by St. Thomas. 
 
 t Qucest, Disp., De Veritate, Q. xxii. a. 4. 
 
ATTRACTION. 79 
 
 operate without approaching, therefore to all 
 of them an inner inclination is given, called 
 itniversal gravitation, by which they tend towards 
 each other. As this inclination is solicited 
 (through some medium) by the interchanging 
 action of corporeal substances, so this solicitation 
 receives the name of universal attraction. Thus 
 these substances have a principle by which 
 (quo) they attract, and a principle by which 
 they go to the attracting body, and an inner 
 disposition suited for that effect. 
 
 But if there were no other than universal 
 gravitation, those substances, though tending 
 by mutual approach to form an aggregate 
 in the universe, would be wanting in that 
 distinction and order from which the beauty 
 of each part results. Moreover the formation 
 of new substances requires that substances 
 should unite and be transformed into other 
 substances of a determinate nature, and that 
 these be disposed for mutual attraction, so as 
 to operate specially on each other. Universal 
 attraction and gravitation would not be suffi- 
 cient in the universe. Particular attractions 
 and particular gravitations are required, which, 
 though reducible to the same genus, constitute 
 different species. From this chemical affini- 
 ties arise, and the inclining of certain sub- 
 stances to be united with other determinate 
 substances. Such affinities and inclinations 
 
80 THE PHYSICAL SYSTEM OP ST. THOMAS. 
 
 must also have a true cause in the inner 
 disposition of substances, which are therefore 
 said to have affinity to each other, like what 
 we have seen in universal gravitation — -like, 
 but not equal, because we cannot speak of 
 species identically, as we speak of a genus. 
 As these dispositions, by the bye, are qualities, 
 no wonder if they diminish or fail without a 
 change of the whole substance into another 
 substance. Lastly, it follows, from what 
 we have said, that universal attraction and 
 gravitation being generic and therefore common 
 to all corporeal substances as such, it will 
 outlast their transformation. So that, as the 
 weight of bodies results from gravitation, the 
 weight of the elements will remain in the com- 
 pound that results, and the weight of the 
 compound will remain in the elements into 
 which it is resolved. Here we must be under- 
 stood to mean the absolute weight ; for we 
 should have to speak otherwise of the specific 
 weight, which is also in proportion to the 
 real volume. Hence, if the specific weight is 
 greater or less in the compound than the 
 absolute weight that was in the elements, 
 greater or less will the absolute weight be ; 
 e converso. We have now to speak of physical 
 laws, which may be considered as a corollary 
 of the doctrines hitherto explained. 
 
X. 
 
 PHYSICAL LAWS. 
 
 THIS is a name commonly given : but the 
 conception of it is not always just and 
 distinct, because the philosophers of these days 
 differ much in their doctrine about corporeal 
 natures, and not a few of them, as if in despair 
 of getting at the truth on that point, oscillate 
 between different systems. 
 
 Law is a rule and measure of operations ; 
 and law must proceed from reason, because 
 reason alone can properly be a rule and 
 measure. But that alone is not sufficient. 
 Eeason must have from Will the power of 
 putting in motion ; and therefore Law, which 
 is commanded by Eeason, presupposes Will. 
 " Commanding," says St. Thomas, " is an act 
 of reason, presupposing, however, an act of 
 the will." * How the command is expressed 
 he explains thus : " Commanding is essentially 
 an act of reason : for when he who commands 
 orders the commanded to do something, he 
 intimates or threatens." t 
 
 *!»■ 2»- Q. xvii. 1. t Ibid. 
 
82 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 Now ordering in the manner of intimation 
 belongs to reason, whicli can intimate or de- 
 nounce in two ways. It may intimate in the 
 indicative mood, as when a man says to another, 
 " You ought to do this : " or it may intimate 
 by moving him to do the thing, saying in 
 the imperative mood, " Do this." If it be asked 
 what Eeason it is that we may call the rule 
 and measure of all created things, unquestion- 
 ably the answer must be that it is the Divine 
 Reason, which in union with the Divine Will 
 is the rule and exemplar of the whole order 
 of the Universe. The Divine Eeason therefore 
 must be considered as universal Law ; and as 
 It is Eternal, so must this law be eternal. 
 " Granted that the world is ruled by divine 
 providence," says St. Thomas, ..." clearl}- 
 the whole Universe is ruled by Divine Reason : 
 and therefore that rule of government in God 
 as in the supreme governor of the Universe, 
 has the ratio of law. And since the Divine 
 Reason conceives nothing in time, but has an 
 eternal conception, we must therefore say that 
 such law is eternal." * We have, therefore, 
 the eternal divine law which directs with 
 supreme power the order of all created things, 
 that by tending to their different ends the}- 
 may be the created expression of the Divine 
 goodness, not only in being but also in operating ; 
 
 * Summa, !"• '2*- Q. xci. a. 1. 
 
PHYSICAL LAWS. 83 
 
 and thus there shines forth in the Universe 
 the image of the Divine perfections, or that 
 extrinsic glory for which the Creator ordered 
 the created universe. 
 
 The law, being the rule and measure of 
 the operations, must be applied to those beings 
 that have to operate ; for if it merely remained 
 in the mind of the legislator, it would be to 
 no purpose. " Law," says the Angelic Doctor, 
 " is imposed as a rule and measure. Now the 
 rule and measure is imposed by its application 
 to the things regulated and measured." * This 
 application varies according to the variety of 
 things, which, if rational, participate of the 
 eternal law through the light of reason, which 
 reflecting naturally as a mirror, the very prin- 
 ciples of that law, have therefore the proper 
 name of natural law. If they are no more 
 than sensitive, they participate of the eternal 
 law, through the instincts impressed on their 
 nature, which only amount to a knowledge of 
 a term by imagination and a necessary tendency 
 to reach it. If they are without any knowledge 
 at all, they participate of the Eternal Law by 
 means of a disposition in their nature which 
 inclines them to a certain end. " Law, being 
 a rule and measure," says St. Thomas, " may be 
 found in two ways, viz., either in the regulator 
 and measurer or in the regulated or measured. 
 
 * Ibid. P- 2»- Q. xp. a. 4. 
 
84 THE PHYSICAL SYSTEM OP ST, THOMAS. 
 
 For that whicli participates of tlie law and 
 measure is ruled and measured ; and therefore^ 
 since all things, being subject to Divine Provi- 
 dence, are regulated and measured by eternal 
 law, as is evident from what has been said 
 (Art. I.), it is evident that all participate some- 
 how of the eternal law, seeing that from the 
 impression of it they have their inclinations 
 to their proper acts and ends. But rational 
 creatures are in a more excellent way under 
 Divine Providence, as being a participant of 
 Providence by providing for themselves and 
 others. Wherefore in them there is parti- 
 cipation of the Eternal Eeason, through which 
 they have a natural inclination to their proper 
 act and end : and such participation of 
 the eternal law in rational creatures is called 
 natural law. Hence the Psalmist, after saying 
 (Ps. 4), Sacrificate sacrificium justitice, answers 
 the question, Quis ostendit nobis bona ? saying, 
 Signatum est super nos lumen vultus tui, 
 Domine; as if he had said that the natural 
 light by which we discern what is good from 
 what is bad, which belongs to the natural 
 law, is nothing else than an impression of the 
 Divine light in us. Hence it is evident that 
 the natural law is nothing else than a par- 
 ticipation of the Eternal Law in rational 
 creatures." * And speaking of brutes, he 
 
 * IlDid. Q. xci. a. 2. 
 
PHYSICAL LAWS. 85 
 
 remarks, that their participation, not being by the 
 way of reason, cannot properly be called natural 
 law. " Even irrational animals," he says, " par- 
 ticipate of the Eternal Eeason in their own 
 way ; but since rational creatures participate 
 intellectually and rationally, therefore their 
 participation is properly called law, because law 
 is a thing that belongs to reason, as above 
 stated.* But irrational creatures do not partici- 
 pate of it rationally ; and therefore it is not 
 called law, except by a similitude." t 
 
 And here we must notice particularly what 
 the holy Doctor says about the participation 
 of the Eternal Law in inanimate beings. 
 
 " It seems," he objects, " that contingent 
 natural things (i.e., corporeal things without 
 sense) are not under the Eternal Law : for 
 promulgation belongs to law, as was said 
 above : | (but promulgation can only be for 
 rational creatures, to whom something may be 
 announced.) Therefore rational creatures only 
 are under the Eternal Law, and contingent 
 natural things are not under it." But this, 
 he replies, is contrary to what is said in the 
 Book of Proverbs, viii. 29 : Quando circum- 
 dabat mari terminum suum, et legem ponebat 
 aquis, ne transirent fines suos. And he says 
 (in corp. artic.) : " We must give one answer 
 about the law of man, and another about the 
 
 * Ibid., ad 3. t Ibid., ad 3. t Q. xo. a. 4. 
 
86 THE PHYSICAL SYSTEM OP ST. THOMAS. 
 
 eternal law, which is the law of God ; for the 
 law of man does not extend beyond the rational 
 creatures subject to man. The reason of this 
 is, that law is directive of actions adapted to 
 those who are under some one else ; so that, 
 properly speaking, no one gives law to his 
 own actions. Whatever things are done about 
 the use of irrational things that are subject 
 to man, are done by the act of the man him- 
 self who moves them, because such things do 
 not move themselves, but are moved, as we 
 said.* Therefore man cannot impose a law on 
 irrational creatures, however much they are 
 subject to him, but on rational creatures sub- 
 ject to him he can, inasmuch as by precept 
 or proclamation he impresses on their minds 
 a certain rule which is a principle of action. 
 And as man impresses by proclamation a cer- 
 tain interior principle of action on others who 
 are subject to him, so does God impress on all 
 nature its principles of action (imprimit toti 
 naturce principia propriorum actuum) ; and 
 therefore God is said to command all nature ; 
 as is said in the Psalms (cxlviii. 6 ) : Prceceptum 
 posmt, et non prceteribit ; and thus every motion 
 and every action of all nature is under the 
 eternal law. Wherefore irrational creatures are 
 under the eternal law in another way " (not 
 as rational creatures are) ; " for they are 
 
 * Q. i. a. 2. 
 
PHYSICAL LAWS. 87 
 
 moved by Divine Providence, but not through 
 understanding the Divine Precept as rational 
 creatures do." And, in the answer ad primum, 
 he ssijs that " the impression of the intrinsic 
 active principle on natural things is like the 
 promulgation of law to man, for through the 
 promulgation of the law a certain directive 
 principle of human action is impressed on men, 
 as was said." (in corp. art.) * 
 
 From this we can see clearly what is meant 
 by Physical Laws. For a law may be con- 
 sidered either as in the legislator, who is the 
 measure and rule, or in the things measured 
 and ruled by him. Considered in the legislator, 
 the eternal law, as prescribing the order to 
 be followed by rational creatures in their opera- 
 tions, directing them towards their due proxi- 
 mate ends, and through these to their ultimate 
 end, is called Moral Law. As prescribing the 
 order to be followed by irrational creatures, ani- 
 mate or otherwise, in the operations by which 
 they arrive at certain terms and certain direct 
 ends, it is called Physical Law. Considered 
 in the things measured and ruled, the Eternal 
 Law, as Moral Law, is the impress of the 
 Eternal Eea,son made by mental light on 
 rational creatures, so that in them are the 
 principles of practical truth, as expressions of 
 eternal principles in the Divine Mind : and 
 
 * Ibid., xciii. a. 5. ' 
 
88 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 according to whether those principles are 
 derived from the essence of the things or from- 
 the free will of the legislator, that law is called 
 natural or positive. As Physical Law it is 
 the impress made by God on all irrational 
 things, that these may tend in their operations 
 to the ends intended by the Eternal Law : 
 and this impress is found in the disposition, 
 instincts and qualities given them by Grod, by 
 Whose power they are inclined and determined 
 to operate in this or that way rather than in 
 another. 
 
 This is what Physical Laws were universally 
 understood to mean ; and if the said principles 
 of operation in irrational creatures are to be 
 denied, one fails to see how we can do other- 
 wise than deny the existence of any physical 
 laws, unless we apply the name without any 
 real meaning. As the moral order consists in 
 disposing human actions by the rule of Moral 
 Law existing in human reason, so does the 
 physical order consist in disposing the opera- 
 tions of all irrational creatures by the rule of 
 physical law found in the principles of opera- 
 tion that God communicates to them : and 
 therefore, since moral order cannot be without 
 moral law, neither can physical order be without 
 physical laws. Thus, if we reject the above- 
 stated doctrines, we shall be led by logical 
 necessity either to deny the physical order and 
 
PHYSICAL LAWS. ' 89 
 
 harmony manifested in the triple kingdom of 
 nature and in each individual thing therein, 
 or, admitting it, ascribe the same to blind 
 chance, or assert that God is not only the 
 First Supreme and Universal Cause, but also 
 the secondary, immediate and total cause. 
 This last conclusion would involve the risk 
 of falling into the error of those ancient 
 philosophers who said that God is the soul of 
 the Universe ; unless, being driven further, we 
 madly affirm, as in fact many do in these days, 
 that God is everything, and everything is God. 
 And here let us make an end of the general 
 exposition, wherein much will be found wanting 
 as to the various natures of the corporeal 
 universe, their proportions and operations and 
 the many and different phenomena resulting 
 from them. But our purpose is to make evi- 
 dent the constitution of inorganic substances. 
 We have touched on some of their principal 
 and universal properties, now and then speaking 
 of animate creatures, so as to make the rest 
 clearer, and shew the unity and beauty of 
 the system that we call the Physical System. 
 We shall now say why it is called so. 
 
90 
 
 XL 
 
 WHY THE PHYSICAL SYSTEM IS SO CALLED. 
 
 WH Y (it may be asked) is this system 
 to be called the Physical System, and 
 not the Scholastic System, or the System of 
 Matter and Form ? 
 
 We cannot call it Scholastic. In the first 
 place that name would not indicate its nature, 
 but only its history ; and historically it should 
 rather be called Aristotelian or Peripatetic. 
 Secondly it is well known that, although the 
 Scholastics, generally speaking, agreed about 
 the principal points of philosophy, they diflfered 
 not a little on other points, especially after 
 Luther had brought into contempt, with the 
 teaching of St. Thomas and Aristotle, not only 
 scholastic Theology but scholastic philosophy 
 also : and Descartes had set himself, by means 
 of a little mechanical motion, to infuse new 
 life into the dead and forgotten system of 
 Epicurus. A man professing himself to be a 
 scholastic may be accused of all the opinions 
 put forth as scholastic of any sort, even in 
 the experimental order, for the purpose of 
 
WHY THE PHYSICAL SYSTEM IS SO CALLED. 91 
 
 refuting and ridiculing and raising wearisome 
 controversies. Thirdly, some people would 
 carry the dispute from philosophy into history, 
 trying to show that the system here defended 
 was wrongly ascribed to the scholastics. Alto- 
 gether the name would be unadviseable. 
 
 Shall we call it then the system of Matter 
 and Form, or of Materialism and Formalism, 
 as including the Mechanic and Dynamic systems, 
 to each of which belongs one of those names ? 
 Hy no means. The Mechanic System is not 
 strictly a system of Materialism ; for that con- 
 sists in negation of Forms, and has as many 
 degrees' as there are degrees of forms. In 
 the first degree form is denied of inanimate 
 substances. In the second it is denied of 
 vegetating things. In the third it is denied 
 of brutes. In the fourth it is denied of man. 
 That system only which admits in all nature 
 nothing more than matter and mechanical 
 motion is absolute Materialism : but a very 
 great number of those who profess the Mechanic 
 system are a long way from that, though the 
 passage from one degree to the other is not 
 difficult. 
 
 Descartes himself and his most faithful 
 disciples never went beyond the third degree, 
 turning brutes into machines. His recent 
 followers restrict their denial of form to plants, 
 which they take to be machines, and to things 
 
92 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 without life, which they suppose to consist in 
 a collection of inert atoms. Moreover materia 
 2)rima, as we have shown, is quite diflferent 
 from the said atoms. As to the dynamic 
 system, what have its forces to do with sub- 
 stantial forms ■? Those forces are supposed to 
 subsist in mathematical points, whereas sub- 
 stantial forms make corporeal substances, repre- 
 senting, in various ways, the Divine archetypal 
 ideas ; and are not in mathematical points, but 
 in extended matter informed. Since then 
 materia prima is not a principle admitted by 
 the Mechanic system, nor is Form admitted 
 by the Dynamic system, consequently the 
 Physical system cannot be the union of the 
 two. Some have said, when treating of the 
 Physical system, that the Physical Sciences, not 
 satisfied with what is given to them by the one 
 or the other of the above mentioned systems, 
 require what is given by both together. But 
 this they said, considering the thing in the 
 abstract and by analogy, not in the concrete 
 and properly : for the physical sciences, demand- 
 ing a principle of extension and a principle of 
 activity, are not to be satisfied with inert 
 atoms and mere forces. Therefore the Physical 
 system, as here explained, cannot be called a 
 system of either Materialism or Formalism, 
 but requires a more appropriate name of its own. 
 " Anyhow," it will be said, " you have no 
 
WHY THE PHYSICAL SYSTEM IS SO CALLED. 93 
 
 right to call it Physical. By giving it that' 
 name you affirm it to be requisite for the 
 natural sciences commonly called physical, 
 and you exclude all the others invented and 
 defended by philosophers." But we cannot 
 help excluding them. We have shown that 
 Mechanic and Dynamic are names not suitable 
 to the Physical Sciences; and therefore, since 
 all the other systems are reducible to the 
 Mechanic and Dynamic, the system that we 
 are defending has a right to be called the 
 Physical system. 
 
 Moreover that name marks the essence of 
 the thing meant, and thus distinguishes it 
 clearly from every other. For the word ^voikoq 
 means natural : and the word nature means 
 the sum of corporeal substances as having an 
 inner principle of operation. Therefore those 
 inner principles, which the corporeal substances 
 have, are called physical or natural laws. But, 
 as we said before, a corporeal substance is called 
 a nature, because matter is therein united to a 
 substantial form which is its first principle of 
 operation : and therefore the name of " Physical" 
 serves to point out that the system, so called, 
 requires in substances the two-fold principle, 
 material and formal, which constitutes the 
 essence of the same. 
 
 " According to the Philosopher," (V. Metaph.) 
 says St. Thomas, " the word nature was first 
 
94 THE PHySICAL SYSTEM OF ST. THOMAS. 
 
 given to signify the generation of living things, 
 which, is called hirth. And, because such gene- 
 ration is from an intrinsic principle, the name 
 was further understood to mean the inner 
 principle of every motion whatsoever. And 
 so is nature defined in the second Book of 
 Physics. And because this principle is both 
 formal and material, both the matter and the 
 form are commonly called the nature of the 
 thing. And because the essence of everything 
 whatsoever is completed by the form, the 
 essence, which is signified by the definition, 
 is commonly called its nature." * 
 
 The word Physical then, marks what is 
 proper to the system before us, distinguishing 
 it essentially from every other : and therefore 
 that name is appropriately given to it. In 
 the next chapter we shall have to consider 
 the system relatively. 
 
 * P. i. Q. xxix. a. 1 ad i. 
 
95 
 
 XII. 
 
 THE PHYSICAL SYSTEM WITH RESPECT TO PHYSICS 
 IN GENERAL. THE NATURE OF THIS SCIENCE. 
 
 IN the division of sciences, whether specula- 
 tive or practical, we have to consider the 
 proper object of each, not in itself, but as 
 treated by them ; and this constitutes the 
 formal object. There are three classes of things 
 that may be the object of speculative science : 
 Firstly, those that are in matter and are con- 
 sidered as in matter ; secondly, those that are 
 considered as without matter, but cannot be 
 otherwise than in matter ; thirdly, those that 
 transcend matter, either because they cannot 
 be in matter, or because, though they are in 
 matter, they may be separated from it. The 
 first of these three classes gives the object of 
 Physics, for that science deals with sensible 
 things that are in matter and are contemplated 
 as in matter. They are these : 1°. corporeal 
 substances without life ; 2°. those that merely 
 vegetate; 3°. those that are animate and 
 sensitive, but not rational ; 4°. those that are 
 sensitive, animate and rational. The second 
 class gives us the object of Mathematics, a 
 
96 THE PHYSICAL SYSTEM OF ST, THOMAS. 
 
 science tliat treats of quantity, either continuous, 
 as it is in geometry, or discrete, as in arithmetic 
 and algebra ; for although quantity cannot 
 naturally be without matter, nevertheless in 
 those sciences, matter is considered by abstrac- 
 tion as apart from quantity. The third class 
 (i.e., that which transcends matter, etc.) gives 
 us the object of metaphysics, which treat 
 of substances separated from matter, as God 
 and spirits, or of things that may belong to 
 matter, but are also found without it, such as 
 the essence of Being, Substance, Actus, Potentia, 
 Cause, effect, &c. Thus the three speculative 
 sciences are Physics, Mathematics, and Meta- 
 physics. 
 
 St. Thomas teaches this as follows : " Be- 
 cause," he says, " the first book of Physics, 
 which we purpose to expound, is the first book 
 of natural science, we must first determine what 
 is the matter and the subject of natural science. 
 It must therefore be understood that, since all 
 science is in the intellect, and things become 
 actually intelligible by being in a certain 
 manner abstracted from matter, things belong 
 to different sciences in accordance with their 
 different relations to matter. Again, since 
 every science is acquired through demonstra- 
 tion, and the medium of demonstration is 
 definition, it necessarily follows that sciences 
 differ according to the diversity of their 
 
ITS RELATION TO PHYSICAL SCIENCE. 97 
 
 definitions. Be it known then, that there are 
 some things whose being depends on matter, 
 and which without matter cannot be defined. 
 There are others that cannot be except in 
 sensible matter ; yet sensible matter does not 
 come into their definition." ... Of the 
 former sort, he says, are all natural things, as 
 man, for instance, or a stone. Of the latter 
 are all mathematics — as numbers, magnitude, 
 figure. " But there are some things," he goes 
 on to say, " that are independent of matter 
 not only as to their being, but also in our 
 conception of them, either because they never 
 are in matter, as God and other separated 
 substances, or because they are not always in 
 matter, as substance, potentia, actus and Being, 
 (Ens). Metaphysics treat of these ; mathema- 
 tics of those that depend on matter for their 
 being, but not in the manner of conceiving 
 them. Natural science, which is called physical, 
 treats of those things that depend on sensible 
 matter both in their being and in the manner 
 of conceiving them. And since all that has 
 matter is moveable, the consequence is that 
 ens mobile is the subject of natural philosophy. 
 For natural philosophy treats of natural things : 
 and natural things are those whose principle 
 is nature : and nature is the principle of motion 
 and of rest in that wherein it is. Natural 
 science therefore treats of those things that 
 
98 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 have iu themselves a principle of motion." * 
 The holy Doctor requires us to recognize in 
 the object of Physics two properties. The 
 former is that it can neither be nor be defined 
 without matter. The latter (which belongs 
 to the former) is its being endowed with an 
 inner principle of activity or of nature. Hence 
 the name of Physics, as we said before. 
 
 This will serve to show how vast is the 
 domain of physics, embracing as its proper 
 object every corporeal substance, or, in other 
 words, the whole visible universe. Many, how- 
 ever, give to metaphysics that part which 
 concerns living substances, viz., plants, brutes 
 and man. According to this division, physical 
 science is restricted to things without life, 
 and is called general when treating of them 
 as a whole, special as discussing the various 
 species ; chief among which are chemical 
 physics, mechanical physics and astronomic 
 physics. To go into all these would lengthen 
 our work enormously without serving its 
 purpose : and therefore we restrict ourselves 
 to General Physics. Of the others, which are 
 subordinate thereto, we shall show that their 
 fundamental principles are not in opposition 
 to the discoveries of modern science. And 
 here we distinguish between science and scien- 
 tists : for scientists often disagree among 
 
 * Comm. Phys. Aris., Lib. i. Leet. i. 
 
ITS EELATION TO PHYSICAL SCIENCE. 99 
 
 themselves on many important points, or con- 
 fine themselves to exposition of facts, setting 
 aside philosophical principles ; or explain those 
 facts by hypotheses that fit into their systems 
 but are not grounded on certainty. 
 
100 
 
 XIII. 
 
 MECHANICAL INERTIA AND PHYSICAL ACTIVITY 
 OF BODIES. 
 
 IN its primary signification inertia means 
 want of art, and in that sense a thing 
 that operates without art would be called 
 inert. But afterwards it was extended to mean 
 inactivity or even laziness. Lustremus animo 
 has artes, says Cicero, quibus qui carebant 
 inertes nominabantur. Postea taonen consue- 
 tudo obtinuit, ut pro ignavo potius et deside 
 accipiatur. * Lastly it was employed to mean 
 the want of an inner principle of activity. 
 And in this sense bodies are called inert. The 
 question of whether they are so, or not, is 
 differently solved, and, according to the solu- 
 tion of it, men philosophize variously about 
 corporeal things. 
 
 The followers of the Mechanic system say 
 that bodies have no principle of physical 
 activity, and reduce all natural phenomena to 
 shocks mutually given and received by atoms. 
 Hence their principle : " There is nothing in 
 
 * III. de Fin. 
 
INERTIA AND ACTIVITY. 101 
 
 nature but matter and motion : and motion 
 proceeds from motion alone." Some of the 
 Dynamic school come near to this opinion : 
 which at first sight seems very strange and 
 contradictory. But they soften it off in a way, 
 assigning to all corporeal beings not an in- 
 trinsic, but an extrinsic inertness : and so they 
 say that forces per se subsisting can operate 
 on themselves, but not reciprocally, because 
 they are distant from each other. Hence they 
 fall back on pre-established harmony or occa- 
 sionalism, laying down that two forces show a 
 mutual operation because they are inly deter- 
 mined by God to operate, or because God 
 alone operates in both. Others admit action 
 in distans and reciprocal activity of forces. 
 All these hypotheses are in contradiction to the 
 Physical system. 
 
 The Physical system acknowledges mechani- 
 cal inertness, as common to all corporeal 
 substances without life, and physical activity 
 as common to them all in different ways. 
 And in the first place, when we speak of 
 mechanical inertia, we must understand it to 
 mean that a body is capable of passing, by 
 extrinsic impulse, from rest into motion, and 
 incapable of changing by itself either the 
 direction or the velocity of the motion. Both 
 reason and experience will show that bodies 
 are of themselves moveable, not requiring to 
 
102 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 occupy this or that portion of space more than 
 another, and therefore that, when there is space 
 and a cause able to give a suitable impulse, 
 there is no sufficient reason why a body 
 should not leave the place where it was. If 
 the body is an atom, it cannot operate on 
 itself, because immanent action is not proper 
 to it, but only transient action, inasmuch as 
 it acts on other bodies, but not on itself 
 Not operating on itself, it cannot free itself, 
 so to speak, from the impulse received, nor 
 increase it, nor change its direction. Reason 
 then demonstrates mechanical inertia : and 
 experience is continually proving that, when 
 there are no impediments nor attraction and no 
 repulsion of other bodies, an inanimate body 
 goes by the impulse received, without ever 
 changing its direction or otherwise modifying 
 its motion. 
 
 But if bodies are mechanically inert, they 
 are not physically so. Why, as the Angelic 
 Doctor says, may we not allow all created 
 substances to have a true physical efficiency 
 and causality ? To suppose that we may not 
 would never occur to anyone capable of con- 
 templating God's Infinite Goodness. The crea- 
 tive j^a^ brought all things out of nothing, and 
 God saw that they were good, as participating 
 of His own Goodness. Now the Divine Good- 
 ness not only requires perfection of being, but 
 
INERTIA AND ACTIVITY. 103 
 
 tends also to diffuse itself, because honum est 
 diffusivum sui. Therefore, since God created 
 all things good, He imparts to them not only- 
 Being, but also that property of Good which 
 consists in diffusing itself by operation. Like 
 St. Dionysius and St. Augustine, the holy 
 Doctor teaches that the Divine Goodness was 
 the Cause of all things. " For God willed," 
 said St. Thomas, " to communicate to creatures, 
 as much as possible, the perfection of His 
 goodness. Now the Divine Goodness has a 
 twofold perfection : firstly, in respect of Him- 
 self as eminently containing every perfection ; 
 secondly, in respect of His operating on things, 
 inasmuch as He is their Cause. Wherefore, it 
 accorded with the Divine Goodness that this 
 double perfection should be communicated to 
 creatures, so that every created thing should, 
 by the Divine Goodness, be made not only to 
 be good, but also to give being and goodness 
 to others, as the sun by diffusion of its rays 
 makes bodies not only illuminated but 
 luminous." * 
 
 He remarks moreover that the faculty of 
 operating is a natural consequence of being ; 
 so that whenever God gives being to a thing. 
 He must enable it naturally to be a cause by 
 its own operation. " That which gives the 
 principal thing to something," says St. Thomas, 
 
 * QuKst. Disp., Q. de Veritate, V. De Pro v. 8. 
 
104 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 " gives to the same all things that are a con- 
 sequence of it. . . . Now doing in actu is a 
 consequence of being in actu.; as is evident 
 in God, Who is the Actus Purus and the first 
 Cause of the being of all things. ... If there- 
 fore He communicated His likeness to things 
 by making them be, it follows that He com- 
 municated His likeness to them by enabling 
 them to act, so that each creature should have 
 its proper operation." * 
 
 And the holy Doctor shows that, if the true 
 efficiency of creatures be denied, the order of 
 the universe, with its beauty and perfection, 
 disappears. " To take away order from created 
 things," he says, " is to take away what is 
 best in them ; for the individual things are 
 good in themselves ; but all of them together 
 are best because of the order of the Universe ; 
 for the whole is always better than the parts, 
 and is the end for which they are. But if 
 their power of acting be taken away, the mutual 
 interchanging order of things is taken away 
 also. In fact things different in their natures 
 cannot be bound together in the unity of 
 order unless some are acting and others acted 
 upon. It is therefore wrong to say that things 
 have not their proper operations." t Passing 
 over many other reasons which he brings 
 forward to prove a true efficiency in all 
 
 * Contra Gent., iii. 69. + Ibid. 
 
INERTIA AND ACTIVITY. 105 
 
 corporeal substances, we need only quote what 
 he says in another part of the same chapter at 
 the conclusion of an argument : " To deny, 
 therefore," he says, " that created things have 
 their proper operations, is to derogate from 
 the Divine Goodness." * 
 
 But why should we look for philosophical 
 arguments, when all nature speaks to us, 
 persuades us, compels us to confess the truth 
 about this ? If we raise our eyes towards 
 Heaven, we find it in the gravitation of the 
 heavenly bodies and the marvellous laws of 
 their revolutions. If we look on the earth, 
 we have it in the fertilization of seeds, the 
 formation of embryos, the increase of all living 
 beings, the transformation of elements into 
 compounds. If you acknowledge true activity, 
 you can find your way in the labyrinth of 
 your researches about light, heat, electricity, 
 •magnetism. Deny it, and you have to grope 
 about without any guide at all. With the 
 doctrine that acknowledges the efiiciency of 
 all secondary causes, that vary more or less 
 by the rule of their comparative perfection, 
 the whole universe becomes one harmonious 
 chorus that sings the glories of its Maker. 
 The contrary doctrine makes the universe mute. 
 All is mystery — not such a mystery as raises 
 and sublimates the intellect of the believer, 
 
 * Ibid. 
 
106 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 but a mystery that abases, depresses, destroys. 
 We need not give other proofs here of such 
 physical activity and efficiency in each of the 
 substances. We shall only remark that, in 
 this its fundamental doctrine, the Physical 
 system agrees completely with the teaching of 
 the Catholic Church. The greatest theologians 
 have not hesitated to affirm that we cannot 
 deny it without incurring the taint of rashness. 
 " We must say," writes the great Suarez, 
 " that created agents work, truly and properly, 
 effects connatural and proportional to them- 
 selves. And I believe that this truth is not 
 only most evident to sense and reason, but 
 also most certain according to Catholic doc- 
 trine. Therefore, as for the former reason, 
 St. Thomas called the contrary opinion foolish, 
 so for the latter reason we may call it rash 
 and erroneous, and, as such, deservedly rejected 
 by all philosophers and theologians. . . Not 
 immaterial substances only, but also material 
 substances have a physical and true efficiency. 
 This follows from the preceding doctrine with 
 almost equal demonstration and certainty ; for 
 experience, reason and evidence speak as 
 strongly in favour of natural and material 
 causes as of immaterial causes." * And Euvio 
 says plainly that : Tollere efficientiam ab omnibus 
 causis, vel etiam corporeis, error est non solum 
 
 * Met. Disp., 18, Sect. 1. 
 
INERTIA AND ACTIVITY. 107 
 
 in fide catholica, sed in vera philosophia. * 
 Cardinal Toledo speaks in like manner : Auferre 
 efficientiam, he says, ab iis causis particulari- 
 hus, nee est sacrce doctrince, nee doctorihus 
 Sanctis, nee vercB philosophice consonum. t We 
 are not bringing a theological doctrine to bear 
 on our contradictors, for that in a philosophical 
 treatise would not be allowable. But we have 
 a right to say that those who would not reason 
 on created things under the guidance of true 
 philosophy destroyed science, and substituting 
 their own wild imaginings, incurred the danger 
 of that punishment with which God Himself 
 has threatened them : Quoniam non inteUex- 
 erunt opera Domini, et in opera manuum ejus, 
 destrues illos, et non cedificabis eos. J 
 
 * In II. Phys., Tract. 2, Q. 2. t In II. Phys., 3. % Ps. xxvii. 5 
 
108 
 
 XIV. 
 
 OBJECTIONS AGAINST THE DOCTRHSTE PROPOSED. 
 
 DIFFICULTIES direct and indirect are 
 put forward against the true physical 
 activity of bodies. The indirect difficulties 
 are put forward by the followers of the 
 Mechanical system, in a vague and abstract 
 manner, to support their own opinion: and 
 these we have sufficiently refuted. We shall 
 now answer the direct arguments against the 
 doctrine itself, and begin by quoting from 
 Malebranche. 
 
 " If," he says, " anyone supposes that there 
 are in bodies entities distinct from matter, 
 and has not a distinct idea of matter, he will 
 easily be led to imagine that these bodies 
 are the true and chief causes of those effects 
 which are seen to happen. Nay, that is the 
 opinion of ordinary philosophers, who, to ex- 
 plain these effects, argue that there are 
 substantial forms, real qualities and other like 
 entities. But if we set ourselves to consider 
 the idea of the cause or the power of operating, 
 we cannot doubt that it represents a something 
 
OBJECTIONS. 109 
 
 divine. For the idea of a sovereign power is 
 the idea of a sovereign divinity, and the 
 idea of a subject power is the idea of 
 an inferior divinity, but still a true divi- 
 nity, at least according to the judgment 
 of the pagans, always supposing it to be the 
 idea of a true power or a true cause. One 
 admits then, something divine in all the bodies 
 around us, when one admits forms, faculties, 
 qualities, virtues, or real beings capable of 
 producing 'certain effects by force of their 
 nature ; and thus, one is insensibly brought 
 into agreement with the pagans, by reason 
 of respecting their philosophy. True it is that 
 faith recalls us to our duty : but perhaps it may 
 be rightly said that in this, if the heart is 
 Christian, the mind is fundamentally pagan. . . . 
 " Moreover it is difficult to persuade ourselves 
 that we ought neither to fear nor love true 
 forces, beings that have the faculty of operating 
 on us, of punishing us by pain and rewarding 
 us by pleasure. And since true adoration 
 is in love and fear, it furthermore becomes 
 difficult to persuade ourselves that we ought 
 not to adore them. . . . The feeling that 
 we ought to love or fear where there is a 
 true cause of good or evil, seems to be so 
 natural and just, that on no account ought 
 we to throw it off. Therefore, given that 
 false philosophical opinion which we are 
 
110 THE PHYSICAIi SYSTEM OF ST. THOMAS. 
 
 endeavouring to destroy, viz., that the bodies 
 around us are true causes of the good and evil 
 experienced by us, reason would seem to justify 
 a religion like that of the pagans, and ap- 
 prove of universal dissoluteness of manners. 
 It is true that reason teaches us not to adore 
 leeks and onions, for instance, as the Supreme 
 Divinity, because we are not made completely 
 happy by having them, nor completelj'- un- 
 happy by not having them ; and therefore 
 the pagans never rendered the same honour 
 to them as to the Supreme Jove, on whom 
 all this divinity depended. . . . But though 
 we should not be justified in rendering supreme 
 honour to leeks and onions, we may always 
 give to them some particular adoration. I 
 mean that we may have a regard for them, 
 and somehow love them, if it is true that 
 somehow they can do us good, in proportion 
 to which they should be honoured." * Alarmed 
 at the sight of so frightful a precipice, he 
 uttered a cry of warning to the scholastics, 
 ^nd, imploring them to have pity on them- 
 selves, proposed, as the only means of escape 
 and security, his Mechanical system. 
 
 Were his accusations true, we should have 
 to shed bitter tears over the memory not only 
 of Aristotle and Plato, but also of St. Augustine 
 and the other Fathers and Doctors of the 
 
 * Rech. de la Ver., I. vi. p. ii. 
 
OBJECTIONS. Ill 
 
 Church, who would, all of them, have been 
 deluded by pagan philosophy, and have, all 
 of them, taught idolatry. 
 
 Strange it is that Malebranche should have 
 made those charges against experience of facts, 
 against reason, against the authority of so 
 many great men, illustrious by their wisdom 
 as by their holiness, and strangely too, (con- 
 sidering that he was a Catholic) against the 
 teaching of the Catholic schools, which the 
 Church, as the greatest theologians testify, 
 has so approved as to make it her own. What 
 can we say about him ? Certain it is that, 
 owing to his antipathy to matter and form, 
 he looked upon everything else as unimportant, 
 and spoke like a madman ; so that answering 
 him is a sheer waste of time. 
 
 Our acknowledging a principle of physical 
 activity in corporeal substances will not make 
 us idolaters, as long as we admire in the 
 creatures endowed with it the goodness of God, 
 Who gave and preserves their Being and their 
 power of operating, and cooperates with the 
 operator. There is no danger of our falling 
 into idolatry while, by the order, beauty, variety 
 and magnificence of those things, and by all 
 that strictly proceeds from their activity, our 
 minds are raised up to the infinite perfection 
 of the Cause Who produced them and made 
 them operate. You would never dream of 
 
112 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 saying that because the sun's rays are not 
 the sun, they are not bright. Eather would 
 their beauty invite you to contemplate that 
 ocean of light from which they come. 
 
 But the sun diffuses its rays by necessity 
 of nature, whereas God, of His own most free 
 and bounteous Will, imparts a likeness of Him- 
 self to the secondary causes, that operate 
 according to that Will. Of His pure goodness, 
 as the Angelic Doctor says, He, Who has no need 
 of anything, (because His perfection does not 
 depend on anything external,) has communi- 
 cated to other beings also the dignity of being 
 a cause. As to the only proof put forward 
 by Malebranche in support of his charges, viz., 
 that if created substances operated physically, 
 they would do good or harm to us and be 
 worthy of love, in which the adoration due 
 exclusively to God consists, our answer is that 
 it proves nothing, unless we wish to maintain 
 that loving parents, relations and friends is 
 giving them divine adoration. What he meant 
 by saying that, if we believe in substantial 
 forms and therefore in physical activity, we 
 might love leeks and onions, we cannot under- 
 stand. He ought to have known that love, 
 as here understood, is a rational, not a sensitive 
 affection, and therefore is only for those who 
 have the dignity of a person, which irrational 
 creatures have not. 
 
OBJECTIONS. 113 
 
 Modern teachers bring forward another objec- 
 tion, by which many are deceived. " Who," 
 they say, " can form a conception of this form, 
 this principle of physical activity ? Is it a 
 body or a soul ? You will not allow it to be 
 a body, therefore it must be a soul : and thus 
 the world would be populated with souls, as 
 many souls as there are atoms." This objec- 
 tion, though obtruded on us now, is of an 
 earlier date, having been used by more than 
 one Cartesian as a valid argument against 
 scholastic philosophy. Descartes, as is well 
 known, laid down a criterion of truth, viz. : 
 " That which is contained in a clear and dis- 
 tinct idea is true." From which we pass on 
 quickly to this other : " That which is not a 
 clear and distinct idea is false." But this, if 
 admitted with all its consequences, is as 
 destructive to faith as to science. Destructive 
 it is to faith ; for we should have to reject 
 as lies all the mysteries of faith, because we 
 cannot have a clear and distinct idea of them. 
 Of its being destructive to science we have a 
 proof before us. They began by asking what 
 these forms and principles of activity are. 
 We cannot have a clear and distinct idea of 
 them ; and therefore according to them, they 
 do not exist. We cannot have a clear and 
 distinct idea of one principle of life in 
 plants : and therefore plants are a clashing 
 
114 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 together of inert atoms. But we cannot have 
 a clear and distinct idea of the anima of 
 brutes, which is neither a spirit nor a body. 
 Therefore they are machines artificially put 
 together, and all their movements are mechani- 
 cal. And what can we say about the union 
 of the human soul with the body ? However 
 much we may try, we cannot succeed in 
 forming a clear and distinct idea of that. 
 We must therefore say that the human soul 
 is only present to the body, or at most directs 
 it, like the engine-driver of a locomotive, 
 without communicating to it any true force. 
 And who can form a clear and distinct idea 
 of the human soul itself, as a spirit quite 
 without form and figure ? We should have to 
 say that it is the phosphorus of the brain, and 
 that its movements are our acts of reasoning 
 and will. And how can we have a clear and 
 distinct idea of the origin of things, of their 
 mutual action, of the order and the laws to 
 which they are subject ? It is much more 
 convenient to get rid of the difficulty by 
 reducing all this to human ways of thinking. 
 And then, who can venture to say that he 
 has a clear and distinct idea of God— a Beine 
 spiritual and immense, free and immutable, 
 most simple and infinite ? It is easier to 
 acknowledge no God other than the world 
 itself, and leave the world without God. 
 
OBJECTIONS. 115 
 
 What else ? The very idea of Being is then 
 so thickly veiled, that its essence, modes, 
 origin and properties become impenetrable : and 
 yet Being cannot be altogether denied. And 
 so we come to universal doubt, as the first 
 step in philosophical discovery, or rather to 
 Hegel's principle that Being is Non-Being; 
 which crowns the edifice, and has the one 
 good effect of making it no longer possible for 
 the opponents of the old philosophy to under- 
 stand each other. 
 
 We cannot, in fairness, be expected to say 
 anything in reply to men who stigmatize as 
 false everything of which, by reason of not 
 ascending from effects to causes, from opera- 
 tions to operators, they cannot in their own 
 mind form a clear and distinct idea. As to 
 the particular difficulty alleged, it is a curious 
 thing to hear people repeat that we cannot 
 possibly have a clear idea of physical activity, 
 of substantial forms, of attraction, and there- 
 fore that all this must be voted to be a 
 chimera (or, as some say, fictitious, abstract 
 beings, or realized abstractions) ; when for so 
 many centuries the brightest geniuses have attes- 
 ted the contrary, and even now, so many noble 
 thinkers find therein the foundation of that 
 one philosophy which, besides being the hand- 
 maid of theology, can be fruitfully applied to 
 explaining the phenomena of nature. What 
 
116 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 shall we say in particular to the followers of 
 the Dynamic system, who cry up the clear- 
 ness of their forces, which are qualities without 
 a subject ? Or what shall we say to the 
 Mechanic school with its inert atoms, from 
 whose incomprehensible whirlings come forth 
 wholly and in its parts, the nature, order and 
 beauty of the Universe ? 
 
 The general objections brought against the 
 forms and physical activity of substances are 
 reducible to the two above mentioned. Of 
 the special objections to this or that mrode of 
 activity we shall treat in their proper places, 
 when we come to speak of the various forms 
 under which that activity shows itself. 
 
117 
 
 XV. 
 
 ACTION AT AN ABSOLUTE DISTANCE. 
 
 IT is a fixed principle in St. Thomas's 
 physical system that the agent and the 
 patient must be conjoined, and therefore that 
 action at an absolute distance is impossible 
 and absurd : but the agent may be substantially 
 distant from the patient, if the two are con- 
 joined by virtue of a medium. The Scholastics, 
 therefore, said that the immediatio suppositi 
 is not always necessary, the immediatio virtutis 
 being sufficient in finite causes. " However 
 great the virtue of the agent may be," says 
 St. Thomas, " it cannot act on anything dis- 
 tant, except through a medium," * and because 
 the virtue of God is not really distinguishable 
 from His essence, the holy Doctor adds that, 
 " To act immediately on all things belongs to 
 the most great virtue of God. Wherefore no- 
 thing is so distant that God is not in it." 
 And he exemplifies this with regard to finite 
 agents by saying that he who operates, being 
 absent, is not the proximate cause of the thing 
 
 * Sumina, P. i. Q. viii. 1 ad 3. 
 
118 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 done, but its remote cause, as the sun's virtue 
 is first impressed on a body conjoined to it, 
 and so on successively; whicb virtue, as 
 Avicenna says, is its light, by which it acts 
 on inferior things. There is more sense in this 
 than in the sayings of modern scientists, who 
 talk about ethereal atoms very far apart, and 
 oscillations of light parallel to each other, so 
 that the ethereal atoms never can meet ; while 
 the sun nevertheless communicates its virtue 
 by atomic ethereal motion to all things, and 
 by illuminating, fructifies them. 
 
 When we consider the facts of nature, we 
 always find valid arguments for a general 
 induction that created causes never operate 
 at a distance : and philosophical reasoning 
 makes us draw the same conclusion. For if 
 we admit that a substance can operate on 
 another, in spite of an absolute void between, 
 we must admit an efi"ect without a cause. In 
 fact, if there are two substances, A and V, 
 separated by an absolute void, and A is to 
 operate a change, X, on V, between these there 
 must be a virtue, a force, a cause, productive 
 of that change. Now this virtue and the 
 substance whence it proceeds are either con- 
 joined or not conjoined. If they are conjoined, 
 A must be in true contact with V, and that 
 upsets the hjrpothesis of absolute distance. If 
 they are not conjoined, that virtue must either 
 
ACTION AT AN ABSOLUTE DISTANCE. 119 
 
 depend on another substance, to which it was 
 transmitted from A, or it must subsist of itself- 
 In the former case the hypothesis of action 
 absolutely at a distance would vanish : in the 
 second we should be affirming what is contrary 
 to nature. Substance alone can subsist of 
 itself. Every virtue or force or quality or 
 accident must be inherent in a substance as 
 in its proper subject. Therefore that virtue or 
 force of A cannot detach itself and fly alone 
 to V ; but, in order to arrive there, must be 
 consigned, so to speak, first to B, then from 
 B to C, and from C to D, and from D to E, 
 and so on, through a series of intermediate 
 substances, till it comes to that which is in 
 immediate contact with V, like the mechanical 
 movement communicated from the first to the 
 last in a series of balls apart from each other. 
 Hence the Scholastic principle, that the operator 
 and the thing operated on must be conjoined, 
 either immediatione suppositi or immediatione 
 virtutis. 
 
 The illustrious Cardinal Toledo says in his 
 Commentaries on Aristotle : " Substance that 
 moves anything or is the cause of some change 
 therein, is twofold, viz., either mediate and 
 remote, or immediate and proximate. It is 
 immediate when there is no mover between 
 it and the thing that it moves, as fire burns 
 the wood to which it is conjoined. It is 
 
120 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 mediate when between it and the thing that 
 it moves there is some other substance, as 
 fire warms distant objects through the medium 
 of air. . . . Moreover, when any sub- 
 stance operates between, and thereby produces 
 an efi'ect at a distance, that effect is not always 
 the same in the medium and in the distant 
 object. Fire, through the medium of glass, 
 liquifies wax, not the glass: and the reason 
 is, that one and the same accident received 
 in various subjects produces in them different 
 effects according to their various dispositions ; 
 and thus heat makes one subject white, another 
 black. . . . Therefore, though the same 
 accident be received in the medium and in 
 the remote object, the effect in them is not 
 always equal. ..." Hence we may lay down 
 this first conclusion, that if there is not some 
 immediate mover, no true change can take 
 place. This is an axiom of the Peripatetics. 
 In fact it is inconceivable that one substance 
 could produce a change in another without 
 it, either immediately or through the medium 
 of something else : for the operation and the 
 being are conjoined, and therefore where a 
 substance is not, its operation will not be. 
 Thus, when a substance does not operate on 
 another at a distance by communicating its 
 own operation to a medium, it cannot by any 
 means be found operating in that substance. 
 
ACTION AT AN ABSOI-UTE DISTANCE. 121 
 
 Hence theologians validly argue that God is 
 present everywhere, precisely because He 
 operates everywhere. . . . And now let 
 us lay down a second conclusion, that the 
 proximate mover and the moved are always 
 together, and immediately together. For though 
 the former is far off in its suppositum, its 
 virtue is always immediate. And thus we 
 must understand Aristotle to mean that no 
 change, of any sort, can take place unless the 
 mover and the moved are together. We must 
 not suppose him to have believed that all the 
 movers are contemporaneous." * 
 
 The Conimbricant commentators of the 
 Stagirite furnish us with another argument 
 on the question, and one that is not to be 
 despised. Every substance, they say, has a 
 sphere of action, beyond which it cannot pro- 
 duce any sensible effect : but if it could operate 
 from an absolute distance, it could also extend 
 its virtue to any degree of remoteness. There- 
 fore, operating at a truly absolute distance 
 cannot be admitted. The minor proposition 
 is certain : for supposing an operation at an 
 absolute distance, the more or less of distance 
 gives no reason for limiting the extent of the 
 operating power. The precise words of the 
 authors are as follows : " If a thing can, without 
 a medium, operate on another at a distance, 
 
 * In VII. Phye., Q. 2. t Coimbrian, antico Conimbrioan. 
 
122 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 philosophers have no reason to say that every 
 agent has its determined sphere of action r 
 for the agent could not diffuse its action to 
 any given distance, if its virtue did not pass 
 through a medium in which it is gradually 
 spent and weakened." * 
 
 It is not worth while to put forward 
 other reasons. Common sense tells us that, 
 as nothing can act before it exists, no cause 
 can operate in a place where as yet it is not in 
 any way, either by itself (immediatione suppositi) 
 or by its virtue (immediatione virtutisj : for 
 that would imply an effect without a cause. 
 
 It will not be amiss to speak of some 
 doctrines that were afl&rmed and are affirmed 
 even now. Firstly then, it is false that the 
 agent A can operate an effect on V without 
 communicating its whole virtue to the medium 
 between, but only causing some change in 
 the substance immediate to itself. This is 
 evidently false, because in that case there would 
 be, for a moment at least, action truly at 
 a distance. Secondly, it is false that any 
 medium whatsoever is sufficient between A 
 and V, for the one to operate on the other. 
 Not every substance is adapted to receive in 
 the same way the qualities of another. We 
 can see this in bodies that transmit badly 
 either light or heat or electricity or magnetic 
 
 , * In VII. Phys., Q. i. a. 2. 
 
ACTION AT AN ABSOLUTE DISTANCE. 123 
 
 virtue, and therefore are called bad conductors. 
 For if a medium is necessary to transport 
 the action of A into V, an insufficient medium 
 would mean action truly at a distance. Hence 
 it follows, thirdly, that merely operating on V, 
 anyhow, would not be sufficient. A must operate 
 in a manner adapted for transmitting its action 
 into V : for the change in V would equally 
 be an effect without a cause, whether we sup- 
 posed it to proceed from A without a medium, 
 or whether we supposed it to be caused by 
 A with a medium, but without communicating 
 anything proportionate to that change. Thus 
 we find that many substances conduct certain 
 operations of other substances well, others badly, 
 as in the phenomena of light, heat, electricity 
 and magnetism. 
 
 It is puerile to say that the absolute distance 
 between the agent and the patient is too 
 small to be worth considering : for action 
 at an absolute distance is essentially repug- 
 nant to reason. The more and the less have no 
 place in what concerns the essence of things. 
 
 This alone would show the falseness of the 
 Mechanic and Dynamic systems, that oppose 
 the Physical system : for they who profess them 
 cannot avoid admitting action at a distance. 
 
 With this criterion we can also refute certain 
 modern doctrines that find support from the 
 science of the day, such as modern magnetism 
 
124 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 and hypnotism : for the very singular phe- 
 nomena put forward in support of these 
 doctrines are attributed by some people not 
 to good spirits, because that would be re- 
 pugnant to the holiness of such, nor to evil 
 spirits, lest consciences should be disturbed, but 
 to the operations of nature. Now, in the first 
 place, the human soul with its intellect and 
 will cannot immediately join itself to the 
 intellect and will of other human beings, nor 
 to any external bodily thing. Secondly, to 
 enter into communication with other men, it 
 must compose sensible signs of its own acts, 
 as, for instance, words or other external signs, 
 and then the other people to whom the signs 
 are directed, must have previously known the 
 value of them : for otherwise they might feel 
 the impressions, but would not understand the 
 meaning of them. Moreover we should require 
 some suitable medium for sending to others 
 the signs of our thoughts and wishes ; for 
 otherwise we should have recourse to axitio 
 in distans, which we have shown to be absurd. 
 To fall back on our ignorance about the reach of 
 physical forces is not reasonable : and still less is 
 it philosophical. True it is that we often do not 
 know the value of those forces : but we certainly 
 do know that they never can make an absurdity, 
 and that it is an absurdity to suppose action at 
 a distance, however small, — as above shown. 
 
125 
 
 XVI. 
 
 MOTION. 
 
 IN general all change whatsoever is motion. 
 One Being only is in rest. That Being 
 is God, Who is immutable. All created things 
 may be said to be more or less in a state of 
 change and motion, especially corporeal things, 
 whose nature and operations have to be con- 
 sidered by the physical philosopher. Let us 
 begin therefore by giving Aristotle's definition 
 of motion : " Motion is the act of Being that 
 is in potentia as such." 
 
 This at first sight may seem somewhat 
 obscure, especially to anyone who, having accus- 
 tomed himself to be satisfied with descriptive 
 and superficial definitions, cares little or nothing 
 for those that penetrate and explain the essence 
 of things. But let us see what St. Thomas 
 says about it in his commentary on Aristotle's 
 Physics. " We must know," he says, " that some 
 have defined motion as the non-instantaneous 
 coming forth of the actual from the potential : 
 but this definition is erroneous, because they 
 put into it that which presupposes motion. 
 
126 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 Coming forth is a species of motion : and the 
 word instantaneous regards time, instantaneous 
 being that which happens in an indivisible 
 point of time, and time being defined by motion. 
 Hence it is impossible to define motion by 
 previous notions better known (per priora et 
 notiora), except as the Philosopher defines it. 
 For, as we have said, everything is divided 
 into the potential and the actual. But potentia 
 and actus, being among the first difi'erences 
 of being, are naturally prior to motion : and 
 the Philosopher uses them in defining motion. 
 We must consider therefore that some things 
 are actual only, and others potential only, and 
 others midway between the potential and the 
 actual. Now that which is in potentia is not 
 yet moved. That which already is in actu 
 perfecto is not moved, but has been moved. 
 That which is being moved is midway between 
 the potential and the actual, being partly in 
 potentia and partly in actu : and this is evident 
 in alteration. For water, when hot in potentia 
 only, is not yet moved or changed. When 
 already hot, the movement of heating is ended. 
 But if it participate of heat imperfectly, it 
 is then moving towards being hot ; for that 
 which is becoming hot participates of heat 
 gradually by little and little. Therefore that 
 imperfect act of heat in the thing that is being 
 heated is motion, not as actual only, but 
 
MOTION. 127 
 
 inasmucli as, being an act, it has a disposition 
 for a further act, because, if that disposition 
 were taken away, the act, however imperfect, 
 would terminate the motion, instead of being 
 motion, as when anything is incompletely 
 heated. But the disposition for a further act 
 belongs to what is potentially that further act. 
 In like manner, if the imperfect act be con- 
 sidered merely in order to the further act, 
 according to which it means a potentia, it has 
 not the essence of motion, but of a principle 
 of motion, for heating may begin from what 
 is tepid, as well as from what is cold. Thus 
 therefore the imperfect act has the essence of 
 motion, as a potentia, in comparison with an 
 ulterior act, and as an act, in comparison with 
 something more imperfect. Wherefore motion 
 is neither the potentia of that which is potenti- 
 ally, nor the act of that which is actually. 
 It is the act of what is in potentia, the word 
 act referring to an anterior potentia, and the 
 word potentia referring to an ulterior act. 
 Most suitably therefore did Aristotle define 
 motion to be the evreXixci-a, i.e. the act of 
 Being existing in potentia, has such : Motus 
 est actus existentis in potentia secundum quod 
 hujusmodi. * 
 
 Evidently this definition of motion is general, 
 defining the genus, not the species. So 
 
 * St. Thomas, III. Physic, Lect. 2. 
 
128 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 considered, motion requires two terms, and, like 
 a tide, ebbs and flows between tbem. One 
 term is the terminus a quo, and is tlie principle 
 of motion. The other is the terminus ad quern, 
 and is the end of motion, viz., rest. The 
 thing in motion cannot have reached the 
 terminus ad quem, or it would be at rest; 
 nor can it be in the terminus a quo, or it 
 would not yet be in motion. It must be 
 between the one and the other, leaving the 
 former and tending towards the latter. Every 
 change is precisely the transit from the one 
 term to the other. In the former case the 
 thing may change. In the latter it has 
 changed. Between them it is changing : and 
 precisely between these two every change is 
 motion. Therefore God, Who is the most 
 perfect and immutable Act, has no perfection 
 potentially, cannot pass from not possessing 
 to possessing, so as to rest in a terminus ad 
 quem. Hence in God all motion whatsoever 
 is impossible. But in all creatures there is, 
 firstly, potentia, secondly, an imperfect act, 
 lastly, a complete act : and therefore that 
 between the two terms a quo and ad quem, 
 has the true essence of motion. Hence in the 
 created intellect, in the will^ in the sensitive 
 and vegetative faculties, and in every alteration, 
 there is the generic essence of motion : but 
 in each of these the specific essence evidently 
 
MOTION. 129 
 
 varies. And since all creatures, by the necessity 
 of their contingent being, are in potentia — 
 therefore are imperfect and perfectible — so in 
 them there is essentially the principle of motion, 
 which, as was said elsewhere, is called nature. 
 
 Hence, as St. Thomas remarlfs with Aristotle, 
 he who has not a true knowledge of what 
 motion is can never have a true notion of 
 nature, and therefore cannot reason rightly 
 about natural things. Natura, he says, est 
 j)rincipium motus. . . . Et sic patet quod, 
 ignorato motu, ignoratur natura, quum in ejus 
 definitione ponatur. Quum ergo nos intendamus 
 tradere scientiam de natura, necesse est noti- 
 ficare motum. * And here we cannot help 
 noticing, by the way, the wisdom with which 
 in that philosophy the First Cause, the First 
 Mover, Almighty God, was called the Immove- 
 able Being, and all created beings were called 
 moveable. The Essence of God is incompatible 
 with motion. The essence of created beings 
 is, of its own necessity, ordered for motion. 
 Hence, the word nature is, in its proper sense, 
 applicable to created essences, but to the Divine 
 Essence in an analogical sense only. 
 
 With regard to the species of motion we 
 may remark firstly that motion, if it means 
 the quality, is called alteration ; but if it means 
 the quantity, it is called increase or decrease. 
 
 * Ibid. In III. Phys. Lect. 1. 
 
130 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 Thus through a change of quality a liquid 
 is altered, or an animal through illness, while 
 a plant or animal has a movement of increase 
 if growing, or contrariwise of decrease. Local 
 movement, i.e. the passing of a corporeal 
 substance from one place to another, is called 
 translocation, or change of place. 
 
 Here it must be remarked that in physics 
 we have to consider the motion of material 
 beings only. In them the motion, whatever 
 it may be, is genericaUy different from what 
 it is in immaterial beings, as the angels are, 
 and human souls when separated from the 
 bodies which they had informed. In such 
 immaterial beings motion is a non-material 
 change. 
 
 And now let us go a little further in con- 
 sidering the said motion of physical things. 
 The first of all motions in order of time is 
 local motion, because the others presuppose 
 it, as the Angelic Doctor, in accordance with 
 Aristotle, tells ns in these words : 
 
 " He (Aristotle) begins by laying down what 
 he means to show : and he says that, of the 
 three species of motion — one according to 
 quantity, which is called increase and decrease, 
 another according to quality, which is called 
 alteration, and another according to place, which 
 is called change of place — the last-named must 
 be the first of all. And secondly, he proves 
 
MOTION. 131 
 
 this by the fact of its being impossible that 
 increase can be the first of motions, because it 
 cannot take place without a previous alteration. 
 For that by which anything is increased is in 
 a way similar and in another way dissimilar. 
 It is evidently dissimilar : for that by which 
 anything is increased is nourishment, which 
 at first is different from what it nourishes ; 
 but when it does nourish, it must be similar. 
 Now it cannot pass from dissimilarity to 
 similarity without alteration. Increase, there- 
 fore, must be preceded by alteration, through 
 which the nourishment passes from one dis- 
 position into another. Thirdly, he shows that 
 every alteration is preceded by local motion. 
 When anything is altered, there must be some- 
 thing that alters it, making (for instance) 
 actually hot that which before was potentially 
 so. But if that which causes the alteration 
 were always equally near to the altered thing, 
 it would not cause the heat now rather than 
 sooner. Evidently therefore the mover of the 
 alteration is not always at the same distance 
 from that which is altered, but sometimes 
 nearer and sometimes further. This cannot 
 happen without change of place." * 
 
 A little further on the holy Doctor speaks 
 of the generation of substances. Without 
 quoting the passage, it will suffice to say that 
 
 * Ibid. In VIII. Phys. Lect. 14. 
 
132 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 generation cannot happen without the altera- 
 tion and concurrence of the generators where 
 it should take place. Now all this supposes 
 local motion : and therefore local motion 
 precedes every other motion of corporeal sub- 
 stances. 
 
 And now, to examine from a more philosophic 
 and important point of view the doctrine 
 explained, let us consider how some created 
 causes are immaterial and others material. 
 An immaterial cause is a cause that does not 
 in its own being and operation depend on 
 matter ; so that matter does not co-operate 
 in the operation as a principle, though it may 
 do so as a term. 
 
 Every angel (to say nothing of God) is a 
 cause that can operate on corporeal and 
 material beings ; but matter does not co-operate 
 at all therein as a principle of the operation. 
 Hence an angel may in substance and by 
 operation be where a corporeal substance is, 
 and operate on it, and operate at the same 
 time at which the corporeal substance operates : 
 but it cannot constitute therewith one principle 
 of operation. This is philosophically expressed 
 by the saying, that an angel can be the forma 
 assistens of a body, but not its forma in- 
 formans. A material cause is that which in 
 its being and operation so depends on matter, 
 that matter is a co-principle of operation ; as 
 
MOTION. 133 
 
 for instance, the principle of activity in any 
 elementary atom, or the vital principle of 
 plants, or the sensitive principle of brutes. 
 These principles cannot of themselves either 
 be or operate : and therefore, to sustain them, 
 they require a subject with which they can 
 operate as a co-principle. Hence the adequate 
 subject of the operations of things inanimate, 
 of plants, and of brutes, is not the principle 
 of activity alone, nor the substantial form only, 
 but, more correctly, the form and the matter 
 together. Therefore these principles and their 
 relative powers are called organic. Now man 
 is the link that unites in himself this twofold 
 causality, material and immaterial ; for his 
 spiritual soul is the substantial form of matter, 
 as the anima of the brute is. As being spiri^ 
 tual, it has powers or faculties and operations 
 that are proper to. itself and inorganic. Such 
 are the faculties of understanding and of 
 willing. As the substantial form of matter, 
 it has powers or faculties and operations 
 that depend on matter, as those of a brute 
 do. Hence the essential diflference between 
 the vegetative or the sensitive powers and 
 those that are intellective lies in this : that 
 the latter are inorganic, and the former organic. 
 If then the being and operating of an imma- 
 terial cause is without matter, it cannot when 
 operating, admit in itself local motion, though 
 
134 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 able to effect it at the term of action : 
 whereas, contrariwise, a material cause always 
 operates with local motion. Hence every 
 operation of organic things, of plants, or of 
 brutes, is done with such local motion. 
 
 But then in man we must distinguish the 
 operations. Those that proceed from spiritual 
 or inorganic faculties are not done with local 
 motion : but those that proceed from organic 
 faculties, such as the acts of vegetative life, 
 of animal appetites and of imagination, &c., 
 are done with local motion. And since, as 
 philosophy shows, the acts of the spiritual or 
 inorganic faculties presuppose or draw with 
 them those of the material faculties, therefore 
 in man every act of the former is succeeded 
 by a true local motion through the operating 
 of the latter : and evidently this motion, 
 wherever it may take place, will vary accord- 
 ing to the variation of the powers and acts 
 by which it is produced. Thus, for' instance, 
 it will be different in the imaginative power 
 and in the imagination from what it is in the 
 animal appetitiva and its tendencies ; different 
 again in the faculty of sight and the act of 
 seeing ; different in the faculty of hearing and 
 the act of hearing ; different in the vegetativa 
 and the act of assimilating ; and so on, in 
 every operation derived from material power. 
 
 It must therefore be maintained, firstlj', 
 
MOTION. 135 
 
 that a material or corporeal substance operates 
 with local motion : secondly, that such motion 
 will vary according to the operation. Thirdly, 
 therefore, the motion will be immanent where 
 the operation is immanent, i.e. one that has 
 its proper term within the same individual, 
 as it does in living things. Fourthly, it will 
 be transient ftransiens) * where the operation 
 is so, as it is in living things and in things 
 without life, when the substance, that is the 
 cause, operates outside itself. Fifthly, every 
 passion or modification in a material substance 
 that receives the action of another will be 
 done with local motion, which local motion 
 will vary according to the passion or modifica- 
 tion. 
 
 Anyone who will think a little about these 
 things will easily see how far from the truth 
 are those who, not caring to penetrate to the 
 diversity of essence and of operations in im- 
 material and material causes, confuse the opera- 
 tions of the latter with local motion, because 
 they always find it accompanied by local 
 motion. They conclude therefore that " in 
 
 * I.e. in the sense of going beyond itself. How can one 
 translate transiens into the anti-philosophic language of Protestant 
 England, where "immaterial" is understood to mean unim- 
 portant, ' ' formal " to mean absurdly ceremonious, and the two are 
 marvellously jumbled in " a matter of form " ? " Transient " is 
 supposed to mean something not permanent, and " transitive " is 
 applied to nothing but verbs. Will any good Christian oblige me 
 with a valid translation of the word ? — Trans. 
 
136 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 nature there is only local motion," on the 
 principle that hoc est cum illo, ergo est hoc. 
 This is giving all to the senses and nothing 
 to the intellect. By rule of reasoning our 
 conclusion can only be this : If in all the 
 operations of corporeal substances we find, as 
 in fact we do, a true local motion, various 
 according to their variations, we have no right 
 to infer therefrom that in nature there is 
 nothing but matter and motion — thus exclud- 
 ing every principle of physical activity that 
 causes motion — but only that the principles 
 of activity, in corporeal substances and in 
 material powers, operate with motion on matter, 
 and variously according to their various modes 
 of operation. 
 
 If the so-called Positivists of modern times, 
 who acknowledge no reality beyond that which 
 is perceived by the senses, had known St. 
 Thomas's sound and true principles of physics, 
 they would not have identified the actions 
 and passions of the sensitive and intelligent 
 human soul with local motion. And those 
 modern physicians, called Psychiatrians, who 
 follow the foolish doctrines of the Positivists, 
 would not have confused that which precedes 
 madness, as a condition, with the disordered 
 reason of a rational soul, and would not, by 
 reducing all to mere motion, deserve to be 
 thought mad themselves as well as mad-makers. 
 
MOTION. 137 
 
 But the folly of modern science consists in 
 admitting seiisible facts only and condemning 
 as an abuse the use of reason about those 
 facts. This is destructive. 
 
138 
 
 XVII. 
 
 THE PEINCIPLE, " QUOD MOVETUR AB ALIO MOVE- 
 TUR, ET PRIMUM MOVENS EST IMMOBILE." 
 
 THIS principle of St. Thomas's school is 
 of high importance and pregnant with 
 the most momentous consequences. The scien- 
 tists and philosophers of the modern sort do 
 not even deign to notice it, but set it aside 
 as an antiquated axiom of Peripatetic philo- 
 sophy : and therefore they often fall into 
 gross errors. Here we must remark that by 
 the word movetur we mean, not only all bodies 
 that are in local motion, but also every being 
 whatsoever that by its motion, whatever it 
 may be, passes from a potential to an actual 
 state : for, as we have said, every change is 
 motion. 
 
 In fact, when anything passes from potential 
 being to actual being, its actual being is con- 
 tingent, and might not have been. It there- 
 fore is a thing begun, an effect. But anything 
 begun must have in its principle a sufficient 
 reason of its being, as every effect has in its 
 cause. This act therefore cannot have in 
 
THE PEINCIPLB, QUOD MOVETUE. 139 
 
 itself the reason of its being, because if it 
 could, the act, which as yet is not, would be 
 its own cause. But that is impossible : there- 
 fore the cause of the act must be sought 
 outside the act. That which moves the acting 
 thing from being potential to being actual is 
 hoc ipso not in potentia but in actu. But, if 
 this mover were first potentially so, and then 
 actually, it would hoc ipso require a sufficient 
 reason of its own act, prior to that act in 
 time, or at least in nature. This therefore 
 can be repeated each time ; and unless we stop 
 at one that moves without passing ■ from the 
 potential to the actual, we shall have to admit 
 an infinite series of movers and moved, because 
 all these movers were potential before they 
 were actual. But this infinite series is non- 
 sense ; firstly, because it would constitute in 
 the concrete an infinite number, which is in- 
 trinsically absurd, and secondly because the 
 whole series would be a thing reasoned on 
 without a sufficient reason, and an efiiect without 
 a cause. Therefore we must admit the exis- 
 tence of a First Mover Who is immoveable, i.e. 
 immutable. 
 
 This is the Aristotelian argument by which 
 we may rise to a knowledge of God, the 
 Infinite, Necessary and therefore Immoveable 
 or Immutable Being, Whose most beautiful 
 definition, Actus Purus, given by Aristotle, 
 
140 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 was indicated by God Himself to Moses in the 
 words, Ego sum qui sum, thereby excluding 
 all potentiality ; because that which is in 
 potentia to be, cannot be said to be, simpliciter, 
 but will be what it will be by passing from 
 potentially being to being actually. 
 
 If we consider existing things, we find that 
 all are mutable because they are contingent, 
 and therefore that all of them, in order to 
 23ass from potentially being to actually being, 
 need to be moved by God, the Immoveable 
 First Mover. 
 
 But created things, it may be said, are 
 animate and inanimate. Inanimate things, that 
 cannot move themselves, evidently, as you say, 
 depend on something else to be moved or 
 changed by : and unless we go on ad infinitum 
 with a fantastic series of movers and moved, 
 we must come at last to a supreme immove- 
 able Mover, who is God. But living creatures 
 move themselves, and therefore do not require 
 to be moved by another, having in themselves 
 the principle of their motion. 
 
 But we say in reply that a living creature 
 does not move itself secundum se totum. One 
 part moves the other, or one faculty is moved 
 by another. Hence in the living creature 
 there is the moved and there is the mover. 
 But how about that which in the livins 
 creature is the mover ? Is that immoveable ? 
 
THE PRINCIPLE, QUOD MOVETUR. 141 
 
 Or is it first a mover in potentia and then 
 an actual mover ? Evidently the latter ; 
 and therefore the motion of living creatures is 
 primarily caused by the Immoveable First 
 Mover, God. 
 
 God moves everything according to its 
 nature. Irrational things He moves by deter- 
 mining them to particular objects ; either 
 because they are quite without knowledge, or 
 because they have only a sensitive knowledge 
 of particulars. In these therefore God. deter- 
 mines the potentia to the act. Moreover He 
 moves, and by causing determines, the will of 
 rational creatures to the good which is their 
 specific object, and which the intellect knows 
 in the Universal. The will therefore cannot 
 in its acts tend otherwise than to that which 
 has in itself some reason of being good in a 
 universal sense. Now since Almighty God, 
 by causing, determines the will to the universal 
 ratio of Good, the will would in fact be quite 
 determined by God, if the object that ade- 
 quately and fully contains the universal ratio 
 of the Good were manifested to the intellect ; 
 but when the object manifested to the intellect 
 presents a limited participation of Good, the 
 will is not then determined by Him. It then 
 is free. It may either not choose the particular 
 good, or (inasmuch as it is not determined by 
 God to that limitation of Good which it knows 
 
142 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 in the particular) it may determine itself to 
 clioose that limitation of good. Therefore, 
 when the will chooses a finite honum, it must 
 always be said to have been moved by God, 
 because moved it was by Him to the Universal 
 Bonum without determination to the particular. 
 We must observe, however, that since the 
 will can never, in its acts, go beyond its own 
 specific object, which is the Good to which 
 it is determined by God, it never can reject 
 a particular good as a good, but only as 
 limited and therefore deprived of greater good ; 
 thus by reason of this privation, being an evil, 
 and therefore not within the sphere of its 
 formal and specific object, which is the Good. 
 In rejecting evil, the will inclines to its con- 
 trary — good, whereto it is moved by God, 
 Who, as its Mover, inclines it always to the 
 Good, which more or less is to be found in 
 every particular object whatsoever. When a 
 man sins, he wills the sin by reason of its 
 being an apparent good, which he apprehends 
 therein ; and God moves him to this ratio of 
 good, while the disordered will freely wills 
 the bad object that participates of it. Thus 
 it is that God, as the first Immoveable Mover, 
 moves and determines the will to its specific 
 object — the universal Good, apprehended in 
 every particular object, — but does not deter- 
 mine it to sin. 
 
THE PRINCIPLE, QUOD MOVETXJR. 143 
 
 From this we can see that, although the 
 inclination or motion towards the Universal 
 Good never can be repudiated by the will, 
 because without that it cannot will anything, 
 nevertheless this inclination and motion is not 
 in fact necessitated or determined at the pre- 
 sence of any finite good, (as it is at the 
 presence of the Infinite Good, in which the 
 whole ratio of good is contained,) but is in 
 proportion to that limited ratio of good which 
 the particular object presents. Therefore the 
 Angelic Doctor writes as follows : He says 
 firstly : Deus movet voluntatem hominis, sicut 
 universalis motor, ad universale objectum volun- 
 tatis, quod est bonum ; et sine hoc universali 
 motione homo non potest aliquid velle, sed homo 
 'per rationem determinat se ad volendum hoc, 
 vel illud, quod est vere bonum, vel apparens 
 honum. * 1'his motion cannot be called uni- 
 versal except so far as it regards all the 
 motions that God gives to all the singular 
 acts. The universal bonum is the 7'atio boni 
 to which the will must tend in every particular 
 act. By sine hoc, &c., he points out, not that 
 it must precede in time every act whatsoever 
 of the will, but that it necessarily is to be 
 found in every act of the will. Determinat 
 se, &c., &c., means, that with this in sensu 
 composto, Divine motion moving it, the will 
 
 * 1" 2« Q. ix. a. 6 ad 3. 
 
144 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 determines itself to each particular bonum, and 
 therefore that the Divine Motion is not the 
 determinator. 
 
 In the QucBStiones Disputatce * St. Thomas 
 expresses the same conception thus : Natura 
 rationalis, quce est Deo vicinissima, non solum 
 habet inclinationem in aliquid sicut habent 
 inanimata, nee solum movens hanc inclina- 
 tionem quasi aliunde eis determinatam, sicut 
 natura sensibilis ; sed ultra hoc habet in potes- 
 tate ipsam inclinationem, ut non sit ei neces- 
 sarium inclinari ad appetibile apprehensum, 
 
 SED POSSIT INCLINARI VEL NON INCLINARI ; et 
 
 sic ipsa inclinatio non determinatur ei ab 
 ALIO, SED A SEIPSA. This means that when 
 the intellect apprehends a particular and sees 
 in it a ratio boni, (to which God moves us, 
 the ratio boni being the formal and specific 
 object of the will,) then the will is inclined 
 thereby to the participated good in the par- 
 ticular object ; but such inclining does not 
 determine the will to the said particular 
 object. The intellect may think of something 
 else that has some ratio boni, and experiencing 
 in the will the Divine inclining, choose the 
 same : or it may think of other things. 
 
 Hence, on this most important point, St. 
 Thomas tells us that, when the will is in 
 potentia to act, i.e., is not acting, it cannot 
 
 * Q. xxii. De Veritafe, De appetitu boni et voluntate, a. 4. 
 
THE PRINCIPLE, QUOD MOVETUR. 145 
 
 be moved by itself alone. God, the First 
 immoveable Mover, moves it, not as He moves 
 irrational beings, but, as its rational nature 
 requires, determining it to its universal or 
 formal object, the Good, i.e. the ratio honi ; but 
 not determining it to those finite participations 
 of Good, or of the ratio honi, which are found 
 in particulars. 
 
 After this exposition of the great principle 
 that quod movetur, i.e., what passes from the 
 potential to the actual, ab alio movetur, and 
 that the primum movens, i.e. God, est immohile, 
 we can appreciate that wonderful saying of 
 the Angelic Doctor, that all created nature is 
 the instrument of God. Instrumentum enim est 
 causa quodainmodo effectus principalis causce, 
 nan per formam vel virtutem propriam, sed in 
 quantum participat aliquid de virtute principalis 
 causceper motum ejus, sicut dolahra non est causa 
 rei artijiciatce per formam vel virtutem pro- 
 priam, sed per virtutem artificis a quo movetur 
 et earn quoquomodo participat* But though 
 the principal cause moves the instrumental, the 
 latter does something in accordance with its 
 own nature. Nisi res naturales aliquid 
 agerent, frustra essent eis formcB et virtutes 
 naturales collatce; sicut si cultellus non in- 
 cideret, frustra haberet acumen, t 
 
 While showing that all creatures are 
 
 iii., De Pot., a. 9. + Ibid. 
 
 K 
 
146 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 instruments of God, though they operate accord- 
 ing to their own virtues, we must carefully 
 consider how God operates in all things and 
 applies them to their operations. St. Thomas, 
 with an angelic penetration, teaches us that 
 God is the cause of all Being, and that 
 creatures determine the mode of the Divine 
 Causality. Secundum ordinem causarum, he 
 says, est ordo effectuum. Primum autem in 
 omnibus effectibus est esse ; nam, omnia alia 
 sunt determinationes ipsius. Igitur esse est 
 proprius effectus primi agentis, et omnia alia 
 agunt ipsum in quantum agunt in virtute primi 
 agentis ; secunda autem agentia, quae sunt 
 quasi particidantia et determinantia actionem 
 primi agentis, agunt sicut proprios effectus alias 
 perfectiones quce determinant esse* The attri- 
 butes of Being are the True and the Good : 
 and because omne ens est verum, et omne esse 
 est bonum, these are the two transcendental 
 attributes of Being. Hence when any intellect 
 tends to the true, that tendency is the effect 
 of the first Mover, God, and is particularized 
 and determined by the intellect embracing 
 this or that truth : and when any appetite — 
 intellective, sensitive, or natural — tends to the 
 Good, this tendency will be an eff"ect of the 
 first Agent, God, which is particularized and 
 determined to this or that bonum. The first 
 
 * Contra Gent, iii. 66. 
 
THE PRINCIPLE, QUOD MOVETUR, 147 
 
 Mover will always be the immediate cause of 
 the tendency to Being, which is true and 
 good. Therefore, while the secondary agent 
 particularizes and determines that tendency, 
 God applies it to the True and the Good. 
 
 But this particularizing or determining will 
 be necessary in some cases, free in others. 
 When the particularizing must be one, it will 
 be necessary. When it may be manifold, it 
 will not be necessary. If the form with which 
 the object is apprehended is of one particular 
 object only, there cannot be a choice of more: and 
 therefore there is a necessary actuation to that 
 particular object whereto the First Mover moves 
 it : but if the form by which the object is 
 presented is the Bonum Universale, clearly 
 the agent cannot be necessitated to a particular 
 honuTn, because that form may answer to an 
 indefinite number of things. Now, whenever 
 a man uses his reason, a corporeal singular 
 honum is presented in sense or in imagination. 
 But then, together with that, the reason of 
 the Universal Bonum is apprehended by the 
 intellect, because the singular is known in- 
 directly by a sort of reflection, and in it is 
 known a limited participation of Good uni- 
 versally, of which the intellect has the idea. 
 Therefore, since the will follows the intellect, 
 which would be determined per se and necessi- 
 tated, if the total ratio honi were presented 
 
148 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 in the concrete boniim, the will must remain 
 not determined, but free, — free to determine 
 itself to any object whatsoever that may pre- 
 sent itself as having some participation of Good. 
 Therefore, as the fact that Grod is the Infinite 
 Being and the First Being does not exclude 
 created beings, who participate of Being, from 
 existing in their singularity, neither does the 
 fact of His being the first and universal Cause 
 prevent the existence of secondary causes di- 
 versely participating of the first and universal 
 Causality. Hence in a recent work, Concordia 
 tra la UberiA e la divina mozione, the author, 
 following St. Thomas, laid down the Divine 
 Moving towards the Universal Bonum as the 
 specific and universal object of the human will ; 
 and he proved that the will freely particularizes 
 and determines the Divine motion itself to 
 particular objects or hona, so that the tendency 
 impressed by God to the Universal ratio boni 
 is the same tendency with which the will 
 freely determines itself to the participated ratio, 
 limited to the particular object. St. Thomas, 
 as the above-quoted author shows, admits 
 that God may also move us in a particular 
 manner to a particular bonum : but this is an 
 exception. God does not, in that case, act as 
 Motor Universalis. * This much, I think, is 
 
 * Giovanni Maria Cornoldi, S.J., Quale secondo San Tommaso, 
 sia la Concordia della Mozione Divina colla libertd umana. 
 
THK PRINCIPLE, QUOD MOVETUE. 149 
 
 sufficient in explanation of the principle that 
 whatever is moved is moved by something else, 
 and that the first Mover is immoveable. 
 
 Roma, 1890. Against this demonstration we have not as yet 
 heard any important objection. 
 
150 
 
 XVIII. 
 
 THE MUTABILITY OP EXTENSION. 
 
 DESCAETES asserted that the exten- 
 sion of corporeal substances is per se 
 immutable ; nor could he say otherwise after 
 denying substantial forms, in which there is the 
 principle or sufficient reason of the changes of 
 that extension. Now, if we admit the muta- 
 bility of extension, many facts in nature can be 
 explained, which if it be denied, can only be cut 
 like the Gordian knot. This has, in fact, been 
 experienced by his followers. They could not 
 explain nature consistently with the principle 
 of reasoning ; and therefore they must either 
 content themselves with a merely historic or 
 empirical description of nature, or else ignore 
 the principles of reasoning, sometimes admit- 
 ting action truly at a distance, and sometimes 
 putting forward effects of which, in that system, 
 no proportionate cause could be assigned ; which 
 comes to the same thing as denying it. Thus 
 we find that, in the explanation of certain 
 phenomena belonging to proper expansion, some 
 
THE MUTABILITY OF EXTENSION. 151 
 
 modern scientists, who insist on explaining 
 them by improper expansion only and deny 
 the variability of real volumes, fall back pitiably 
 on ridiculous hypotheses. 
 
 Let us here examine the arguments used 
 against us. The first and strongest is a ques- 
 tion of reasoning. " Compenetration of corpo- 
 real substances," they say, "is repugnant to 
 reason : but without that there cannot be such 
 a thing as proper mutability of extension in 
 a corporeal substance. Therefore, such muta- 
 bility is repugnant to reason." 
 
 In reply we must begin by referring back 
 to what we said * about the real and 
 apparent volume of corporeal substances, and 
 why, when treating of the mutabihty of 
 extension, we must have regard to the former, 
 not to the latter. Even our adversaries admit 
 that a porous body can expand or contract by 
 increase or diminution of its pores, in number 
 or in size : but they deny that a corporeal 
 substance, individual and therefore continuous, 
 can, without having pores, dilate, and whUe 
 retaining the continuity, become more extended. 
 Thus the question before us is about continuous 
 substances, and not about aggregates of substances. 
 
 Having premised thus much, let us come to 
 the major of their, argument, viz., that com- 
 penetration of corporeal substances is repugnant 
 
 « Chapter VI. 
 
152 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 to reason. What, we ask, do you mean by 
 compenetration ? " It means," they say, " that 
 one corporeal substance is occupying the same 
 place actually occupied by another." Granted, 
 but we deny its being repugnant to reason. 
 The contradictory alone — viz., its being and 
 not being at the same time — is repugnant to 
 reason, because negation only is irreconcilable 
 with affirmation. If therefore compenetration 
 of corporeal substances is repugnant to reason, 
 we should have to say that, in consequence of 
 the compenetration, the substance loses its 
 own essence and ceases to be. Now this 
 cannot be shown, for the essence of a body 
 does not require for itself only a determinate 
 place. The body requires that by reason of 
 its local quantity : and local quantity is an 
 accident not essential to the body but merely 
 natural, and therefore may, by the omnipo- 
 tence of God, be taken away in a particular 
 case. This is demonstrated by those philoso- 
 phers who, keeping to the true principles of 
 reasoning, instead of being led by fancy, do 
 not suppose that nothing is true except what 
 is perceived by the senses. 
 
 Two bodies therefore can be in the same 
 place, provided that both, or at least one of 
 them, be deprived of local quantity, which 
 has an extrinsic regard to excluding from its 
 own place any other substance that has local 
 
THE MUTABILITY OF EXTENSION. 153 
 
 quantity. Hence a philosopher may say that 
 compenetration of corporeal substances is not 
 natural, but he cannot say that it is absurd. 
 
 It is no answer to say, " I can't conceive 
 such a thing," for a personal want of power 
 to understand can never be a criterion of 
 what is intrinsically repugnant or not repug- 
 nant to reason. If so, we should have to reject 
 many indubitable truths as repugnant . to 
 reason. The human mind cannot create. It 
 only copies. This means that it cannot well 
 conceive things of which nature does not furnish 
 the species. Therefore of all those things that 
 are beyond or outside the order fixed in 
 nature, and are called supernatural or preter- 
 natural, it has but weak and ill-proportioned 
 conceptions, formed almost always by mere 
 analogy. However much we may show by 
 force of argument, that true compenetration is 
 not repugnant to reason, it nevertheless is 
 beyond the order fixed in nature : and there- 
 fore it is difiicult for the mind of man to 
 form a clear conception of it. 
 
 Let us now come to the minor, in which 
 the weak part of the objection is. 
 
 "There cannot be such a thing," they say, 
 " as mutability of extension without compene- 
 tration." This is false. Compenetration means 
 the simultaneous occupation of one place by 
 more than one body, each of which occupies 
 
154 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 the whole of it. The mutability implies con- 
 traction, which merely requires that one point 
 in the mutable thing should happen to occupy 
 the space left free by another that occupied 
 it before. Thus compenetration differs from 
 contraction as the simultaneous from the succes- 
 sive : and therefore if contraction takes place 
 where there is mutability, compenetration does 
 not. Let us make the conclusion clearer to 
 sense by considering two points, a and h, of 
 one continuous individual substance, as near 
 to each other as you like. 
 
 a b 
 
 a V 
 
 a" h" 
 
 a'" V" 
 
 P 
 
 Given the gradual contraction of the sub- 
 stance, a and h will tend continually to 
 approach each other : but will they ever 
 compenetrate ? Certainly not, unless we say 
 that the extension of the substance is not 
 merely diminished by condensing, but quite 
 lost by reducing itself to a mathematical point. 
 Therefore a and h will never compenetrate in p : 
 but the distance between them will diminish as 
 
 a' b', a" b", a'" b'", 
 
 according to the measure of its contraction, the 
 distance becoming continually less. This is 
 founded on the principle that, inasmuch as we 
 can conceive a quantity always increasing, 
 
THE MUTABILITY OF EXTEKSION. 155 
 
 though never becoming infinite, so can we con- 
 ceive a quantity always diminishing but never 
 quite destroyed by mere diminution. What we 
 have said about the substance between these 
 points, a and 6, applies equally to any other 
 particle of a continuous substance, and shows that 
 contraction can take place without compenetration. 
 It is easy therefore to perceive why our 
 opponents persist in saying that mutability of 
 extension implies compenetration. They can- 
 not conceive contraction first, and then local 
 transposition, but only think of the transpo- 
 sition. Thus, for instance, they imagine a 
 continuous spherical substance, which condenses 
 in such a manner that each of its least particles, 
 while remaining as it was, approaches the 
 centre where, with the others, it agglomerates. 
 According to this hypothesis there would be 
 no real contraction of the spherical substance, 
 but only a transposition of each part ; which 
 assuredly could not take place without a true 
 compenetration. We say advisedly, " real con- 
 traction ; " for though the substance would 
 then seem to be more restricted than before, 
 its entity would not be really condensed, but 
 only transposed, as the real surface of a piece 
 of paper is (to make use of a similitude) not 
 diminished by being folded up into a smaller 
 visible size. A particle therefore of the 
 spherical substance cannot, while preserving 
 
156 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 its former extension, be transferred into the 
 centre without occupying the place of what 
 was there before — in other words, not without 
 compenetration. But such is not true con- 
 densation as taught in the Physical system. 
 According to that each particle of the sub- 
 stance contracts within itself entitatively ; so 
 that its whole entity is contracted in one way ; 
 and the act of contraction does not require 
 that any particle placed on the surface should 
 break off and transfer itself elsewhere. Nay, 
 as a part of one and the same substance, it 
 will always be conjoined thereto, continuing 
 to form with the whole a continuous sub- 
 stance in its decreasing extension : and thus 
 only it does not keep the space first occupied, 
 but approaches the centre. Therefore, if we 
 conceive in this manner, firstly contraction in 
 the entity itself and then translocation of all 
 the particles that compose it, there is no 
 danger of having to admit true compenetra- 
 tion. If likeness will clear the conception, 
 we can find it in any object that, when seen 
 through a more or less powerful microscope, 
 shows its mass, either more extended without 
 disjunction of parts, or more' restricted without 
 compenetration of the parts. Thus the minor 
 proposition of our adversary's argument will 
 not stand, and therefore its conclusion falls 
 to the ground. 
 
THE MUTABILITY OF EXTENSION. 157 
 
 And now we come to another difficulty 
 objected against us — a question of fact, put 
 in this way : " All bodies are porous ; and 
 therefore the mutability of extension cannot 
 be admitted. The antecedens is proved from 
 innumerable experiences. The consequens can- 
 not be denied, because in that case all con- 
 densation of substance would be effected by 
 diminution of pores, all rarefaction from their 
 becoming enlarged : so that we must reject 
 all mutability of extension as useless." 
 
 This argument is clear. Let us examine it. 
 The antecedens may be conceded : for though 
 it is not the result of an adequate deduction, 
 the proofs in favour of all bodies being porous 
 are such and so many, that it may be pru- 
 dently affirmed as a universal proposition. Not 
 however as it seems to be understood by the 
 followers of the Mechanic system, in which 
 each atom is so isolated that it comes not in 
 contact with its neighbouring atoms at any 
 part. Setting aside other reasons, one fails to 
 see how, according to that opinion, we could 
 possibly affirm and explain the entitative unity 
 of individual substances, especially the ani- 
 mated, which are not mere aggregates. 
 
 As to the consequens — viz., " All bodies 
 are porous, and therefore true mutability of 
 extension must be excluded " — it will not pass 
 muster in good logic. Granted that by mere 
 
158 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 mutation of pores the bodies furnished with 
 them can be rarefied or condensed, it does 
 not legitimately follow that all condensation 
 and rarefaction must depend on mutation of 
 pores. In the exposition of the Physical 
 system we admitted that, besides the proper 
 condensation and rarefaction produced by true 
 change of extension, there is the improper, 
 which is produced by a change in the inter- 
 stices called pores. This distinction was well 
 known among the Scholastics : and thereby, 
 as Toledo remarks, the followers of Aristotle 
 were distinguished from those of Democritus 
 and Epicurus. Antiqui non cognoscebant nisi 
 hanc solam fsc. impropriam), cum hoc dis- 
 vrimine, quod illi p>onebant intra corpora poros, 
 nos vero plenos suhtiliore corpore. Alia est 
 condensatio et rarefactio propria, et hcec non 
 Jit corporis alterius expulsione vel receptione, 
 sed mutatione ipsius subjecti* 
 
 " But there is an axiom," it will be said, 
 " that we must not multiply beings (entiaj 
 without' necessity : therefore since pores will 
 sufficiently explain the whole thing, away with 
 the mutability of extension." Our answer is 
 this : 
 
 Firstly, the argument may be turned against 
 the objector. Griven the mutability of exten- 
 sion, the whole thing can be explained, and 
 
 * In IV. Ph., c. 9, Q. xi. 
 
THE MUTABILITY OF EXTENSION, 159 
 
 much better. Therefore, what is the use of 
 supposing such and so many discontinuing pores 
 everywhere ? Secondly, our opponent proceeds 
 a posse ad esse, and therefore non valet illatio. 
 It comes to this : " We can explain everything 
 by the theory of pores. Therefore that theory 
 is the orHy true one, and all others are false." 
 
 Nego. There are many phenomena that may 
 be explained in various ways. What right there- 
 fore has anyone to insist on one only in this 
 case, excluding mutability of extension, though 
 it serves its purpose well ? Thirdly, the axiom 
 quoted against the mutability of extension is 
 not applicable, unless the objector had first 
 proved that Almighty God could not have a 
 suitable end for so endowing corporeal sub- 
 stances. This he would find very hard to do. 
 Fourthly, the pores do not explain everything. 
 This I conclusively proved in another work. * 
 
 We may therefore legitimately conclude, I 
 think, that the objections cited are not valid. 
 I have not met with others of any weight. 
 
 * Filosofia Scolastica ; Fisica Kazionale particolare, Parte i. 
 Lezioni xli. xlii. 
 
160 
 
 XIX. 
 
 WHY THE PHYSICAL SYSTEM IS SUPPOSED TO BE 
 IN OPPOSITION TO PHYSIOS. 
 
 SOME people will have it that the Physical 
 system is opposed to physics, because the 
 principles of geometry had been believed to 
 show that no body is continuous, each being 
 composed of mathematical points and therefore 
 quite indivisible. This opinion was refuted by 
 Aristotle. The supporters of it said, " What 
 is a solid ? The sum of the superficies. And 
 what is the superficies ? The sum of lines. 
 And what is the line ? The sum of many 
 points. Therefore a solid is constituted by 
 points, and is not continuous." 
 
 But the falseness of this reasoning is evident. 
 In geometry a line is not considered as an 
 aggregate of points, which, unless they touched 
 one another, would not form it, and if they 
 did touch, would coincide in one point only ; 
 for indivisibilia aut non se tangunt, aut se 
 tangunt juxta se tota. A line is conceived ut 
 excursio puncti, as an imaginary track leaving 
 
ALLEGED OPPOSITION TO PHYSICS. 161 
 
 nothing of itself except the point that slips 
 away. Thus we may suppose geometrically 
 that a superficies is derived from excursion 
 of lines, and a solid from excursion of super- 
 ficies. But though we may consider a mathe- 
 matical point as a limit of a line, we may not 
 say that it can exist by itself. . These are 
 fictions of the imagination : but solid bodies 
 are real, and therefore cannot be constituted 
 by indivisible points. 
 
 Hence it is evident that, since the Dynamic 
 system, which supposes the extended and the 
 solid to be constituted by unextended forces 
 in mathematical points, is repugnant to reason: 
 the Physical system, which admits the extended 
 and the real continuous, accords with the 
 sure testimony of the senses, by which we 
 perceive things that are extended, and that, 
 as such, must have a certain continuity. 
 
 In attacking the Physical system, the adver- 
 saries of St. Thomas and of the Scholastics 
 put forth a specious but sophistical argument. 
 "If," they say, "we grant that a body is 
 extended and continuous, we cannot avoid 
 admitting that a particle of it is infinite ; 
 which cannot be maintained without an evi- 
 dent contradiction. The real extended, if there 
 is such a thing, must be divisible into the 
 extended whose extension ever decreases. 
 Therefore a small part has an infinite number 
 
162 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 of parts : and so that small part will be 
 infinite, because an extended thing that in- 
 cludes an infinite number of extended things 
 cannot be said to be finite." 
 
 To make this question clear we must clearly 
 understand the divisibility of the continuous 
 extended. 
 
163 
 
 XX. 
 
 ON THE DIVISIBILITY OF THE CONTINUOUS 
 EXTENDED. 
 
 FIRST of all we must know the difference 
 between an entitative or real distinction 
 and a mere distinction of reason. When two 
 entities can really be divided from each other, 
 or so separated that one or both continue to 
 exist, we certainly must affirm that there is 
 a real distinction between them, and not a 
 mere distinction of reason. There cannot be 
 any question about that ; for if it were 
 only a distinction of reason, there would be 
 a real identity, the one would really be the 
 other. Both would be the idem. But the 
 idem cannot really be divided into parts that 
 continue to exist independently of each other ; 
 just as a mathematical point cannot be divided 
 into two points. That division therefore is a 
 sure sign of real distinction. 
 
 But though this real divisibility shows a 
 previously real distinction between the divisi- 
 bles, it is not the only sign. We can deduce 
 
164 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 the real distinction otherwise. Now because 
 what is here indicated is a true criterion, we 
 say firstly, that the parts of an extended 
 substance are really distinct, because by a 
 finite or infinite virtue they are really 
 divisible ; secondly, that the potentia is really 
 distinct from its actus, because it may be 
 separated therefrom. The matter, for instance, 
 may be separated from the form, the intellect 
 from the determinate act of understanding, 
 the will from the volition, the soul from 
 virtue and grace, a substance from its acci- 
 dents. But we must bear in mind that, 
 although the divisibility of two things essen- 
 tially supposes a real distinction between them, 
 nevertheless the conception of the real distinc- 
 tion is essentially diff"erent from the conception 
 of the divisibility, and a fortiori difi'erent from 
 the conception of the division. To confound 
 them together and identify them would be 
 absurd. 
 
 Certainly then, in the continuous, the parts 
 are really but indeterminately distinct, and 
 so long as the parts are not divided, either 
 really or in the mind, it is not a dis- 
 crete quantity. Whence it follows that the 
 parts of the continuous have in reality no 
 number ; therefore it is absurd to speak of 
 the continuous as having an infinite number 
 of parts, though we can conceive it as infinitely 
 
THE CONTINUOUS EXTENDED. 165 
 
 divisible, and mentally imagine it as divided 
 into numerable and numbered parts. 
 
 To make our meaning clear, we must 
 distinguish the mathematical continuity from 
 physical continuity. In mathematics the con- 
 tinuous is the continuous quantity mentally 
 abstracted from the real substance or body 
 which is the subject of the same. In physics 
 the continuous is this or that substance or 
 body with the quantity whose subject it is. 
 Have both or has either infinite parts ? 
 
 To this we reply that in the mathematical 
 continuous, just because it is not a discrete 
 quantity, there are no parts, finite or infinite, 
 in actu, but there are infinite parts in potentia. 
 In the physical continuous there are no parts, 
 finite or infinite, in actu, but there are finite, 
 not infinite, parts in potentia. 
 
 That in the mathematical continuous there 
 are no parts in actu, either finite or infinite, 
 but only finite parts in potentia, is evident. 
 A small quantity, being essentially extended, 
 can never be reduced to such a, state by division 
 that at one part it should be an extended 
 thing, and at the other a mathematical point, 
 or that an extended thing should be divisible 
 into two mathematical points. The continuous 
 quantity therefore will be essentially divisible 
 into extended parts ever divisible: so that 
 we never can consider as impossible a further 
 
166 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 division. Thus the mathematical continuous is 
 in potentia essentially divisible ad infinitum. 
 The infinite is the goal or term that we never 
 can reach. In that term each part would be 
 unextended : — = 0. 
 
 cc 
 
 The physical continuous is not mere quantity. 
 It is the solid substance in which, as in a 
 subject, the quantity is ; and therefore the 
 quantity cannot be divided without dividing 
 the substance. If we consider the mere quan- 
 tity, we find the continuous divisible ad 
 infinitum potentially and not actually ; but 
 having to consider the substance also, we must 
 say that the physical continuous is neither 
 actually nor potentially divisible ad infinitum. 
 Some people tell us that a division ad infini- 
 tum is impossible because a substance, unless 
 it were infinite, could not be capable of such 
 a division. Others think that this is a para- 
 dox ; for they cannot understand how in the 
 continuous the division can stop, seeing that 
 the continuous is quantum, and that quantity 
 is per se divisible ad infinitum. But we have 
 to see whether this impossibility of dividing 
 the physical continuous ad infinitum, which 
 cannot be derived from the ratio of quantity, 
 can be derived from the ratio of substance, 
 or of the concrete nature of divisible being. 
 The Angelic Doctor tells us that it is so 
 derived. 
 
THE CONTINUOUS EXTENDED. 167 
 
 For every corporeal nature must be con- 
 sidered, firstly, in its intrinsic essence, and 
 secondly in what we may call its extrinsication, 
 by which it stretches out to occupy a place 
 and impede occupation of the same place by 
 any other body. This latter property origi- 
 nates from the substance itself as a force or 
 virtue of it. We can easily conceive a mini- 
 mum of extension, at which a corporeal 
 substance is no longer able to extend itself, 
 occupy a place and resist the occupation of 
 the same place by other substances. " It must 
 be understood," says St. Thomas, " that a 
 body, which is complete in size, is to be con- 
 sidered in two ways, i.e. mathematically, or 
 according to the quantity alone, and naturally, 
 hj considering in it the matter and the form. 
 It is evident that a natural body cannot be 
 infinite in actu. For every natural body has 
 some determinate substantial form : and there- 
 fore, since accidents follow the substantial 
 form, determinate accidents, one of which is 
 quantity, must follow a determinate substantial 
 form. Therefore every natural body has a 
 determinate quantity for the greater and for 
 the less." * Hence he quotes elsewhere (Comm. 
 in II. Sent., Distinct, xxx. Q. ii. a. 2) those 
 words of Aristotle : Ideo est invenire minimam 
 aquam et minimam carnem, quce si dividatur, 
 
 * Summa, P. i. Q. vil. a. 3. 
 
168 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 non erit ulterius aqua et caro. Therefore, 
 whether the body be elementary, e.g., gold, 
 oxygen and the rest, or a compound of ele- 
 mentary substances, e.g. water, wood, marble, 
 &c., we shall come, in thought at least, to a 
 limit at which it could not be divided again 
 without ceasing to have force or virtue sufl&cient 
 for co-extending and for resisting the occupa- 
 tion of its place by any other body. In other 
 words, it would cease to have quantity, and 
 reonota quantitate, substantia omnis indivisihilis 
 est. * 
 
 According to this doctrine we have, both 
 in elementary and composite bodies, true atoms, 
 i.e. the smallest that can be ; and we may 
 fairly suppose that not mere mixtures, but 
 true chemical combinations, in which the nature 
 of the substance is changed, are made with 
 the smallest corporeal substances. Now these 
 minima, which, if again divided, would cease 
 to have quantity and no longer be divisible, 
 must have volume and weight, and be in a 
 certain number, and occupy certain relative 
 positions. Surely then it cannot be said that 
 we Thomists are far from agreeing to those 
 laws of chemistry which lay down that chemi- 
 cal combinations require the elementary sub- 
 stances to be in a certain number, in a certain 
 volume, in a certain weight, and that, in 
 
 * Contra Gent., iv. 65. 
 
THE CONTINUOUS EXTENDED. 169 
 
 combining, they must have a previously deter- 
 mined relative position according to the nature 
 of each. But these laws must not be arbitrarily 
 presupposed. They must be founded on facts 
 or on well proved reasoning, or not be pre- 
 supposed. 
 
170 
 
 XXI. 
 
 ETHEE. 
 
 WHAT we have said about corporeal 
 substance divisible into particles that 
 are most minute, substantially indivisible, and 
 therefore real atoms, reminds us of what is 
 said and what was said about ether. The 
 most common opinion among the scientists 
 of our time is, firstly, that in the inter- 
 planetary spaces there is a corporeal substance 
 extremely rarified : secondly, that this rare- 
 faction consists in the mutual distance of the 
 atoms from each other, which distance, com- 
 pared with the length of the diameters of 
 these atoms, is so great that (proportions 
 considered) it is as the distance of the stars 
 and the planets from each other : lastly, that 
 the nature of these ethereal atoms is the same 
 in all, and is not difi'erent from that of the 
 corporeal atoms in this world ; so that the 
 ethereal atoms may be said to be the terres- 
 trial atoms themselves extremely diminished 
 and very far from each other. They say too 
 
ETHER. 171 
 
 that this ethereal substance is the subject 
 whence light, electricity and heat are diffused. 
 One of the defects observable in modern 
 scientists is their ignorance of many doctrines, 
 often true and important, which the old scien- 
 tists knew. Hence it is not surprising to hear 
 them say that the conception of ether is 
 modern. In the Cosmos, a French periodical, * 
 Courbet says : " La conception d'une substance 
 transmettant la lumifere et remplissant I'espace 
 a 4te introduite pour la premiere fois dans la 
 science moderne par Hugghens." This pour la 
 premiere fois is historically a blunder. We had 
 better point out the discrepancy between the 
 ancient and modern scientists about the ether. 
 1°. The modern scientists acknowledge the 
 existence of ether in the interplanetary spaces 
 for the purpose of giving a subject to light 
 and heat ; but for the very same reason the 
 old scientists acknowledged the necessity of 
 an ethereal substance. " Aristotle," says St. 
 Thomas, "rejected that error (which denied 
 the existence of ether, and admitted a void), 
 but said that Democritus was wrong in affirm- 
 ing that, if the space between the eye and 
 the object were quite void, we should be able 
 to see the smallest object at an immeasurable 
 distance, — for instance, an ant in the sky. 
 This is totally impossible. 
 
 * An. 1890, xvi. p. 154, &c. 
 
172 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 "We cannot see, unless the organ of sight 
 receives an impression from a visible object : 
 but it has been shown that this impression 
 is not received immediately from the visible 
 external objects ; and therefore that there must 
 be a medium substance between the sight and 
 the visible thing. If there were a void, there 
 would be no medium capable of being im- 
 muted and immuting : so that, if there were 
 an absolute void, we should not see. Demo- 
 critus fell into the mistake, because he believed 
 that distance impedes our sight of an object 
 just so much as that which is between 
 impedes the operation of the visible thing : 
 but this is false. The reason why distance 
 impedes the sight is this : All bodies are seen 
 under a certain angle of some triangle, or 
 rather of a pyramid, whose base is in the seen 
 object, and the angle is in the eye of the 
 seer. {Omne corpus videtur sub quodam angulo 
 cujusdam trianguli, vel magis pyramidis, cujus 
 basis est in re visa, et angulus est in oculo 
 videntis.) Therefore the greater the object is, 
 compared with the size of the pupil, the more 
 diminished proportionately must the immuta- 
 tion of that visible object be when it comes 
 to the sight. It is evident then that the 
 longer the sides of the triangle or of the 
 pyramid are, the size of the base remaining 
 fixed, the less will the angle be. Therefore 
 
ETHER. 173 
 
 the further the object is, the less do we see ; 
 and the distance may be so great that we 
 cannot see it at all." * 
 
 From this it is evident that the old scien- 
 tists admitted interplanetary ethereal substance ; 
 that they did not admit the system of emission 
 of light; that they judged light to be not a 
 substance ; that they believed it to be a 
 quality derived from a luminous body in the 
 ether, a quality that makes an impression on 
 the pupil, which is enabled thereby to see the 
 object from which that quality is derived by 
 means of the ether, and that the ethereal 
 medium is necessary for seeing, whether the 
 object be far or near. The Angelic Doctor 
 said that omnis lux est effectiva caloris, etiam 
 lux lunce, t some centuries before Melloni 
 said so. Evidently therefore it was admitted 
 then that the ethereal substance transmitted 
 heat and was the subject of the medium of 
 heat. 
 
 2°. The modern scientists commonly admit, 
 as we pointed out before, that the ethereal 
 substance is an aggregation of atoms very 
 distant from each other, if the distance be 
 compared with their diameter : but they main- 
 tain the system of undulations, according to 
 which these atoms oscillate in lines parallel to 
 
 * De anima, II. Leot. 15. 
 t In II, Sent., Dist. xv. Q. 1. a. 2 ad 5, 
 
174 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 each other and vertical to the luminous ray. 
 There is a difficulty in this that seems to us 
 insuperable : for if the atoms oscillated, they 
 could never come in contact with each other 
 and determine in the others the motion sup- 
 posed to be given by the luminous object. 
 Hence we should not be able to explain the 
 illumination without the absurdity of admit- 
 ting collision at a true distance. The 
 Scholastics, as we said, acknowledged a true 
 and proper dilation of the corporeal substances, 
 and not merely the improper : so they never 
 fell into the absurdity of admitting action of 
 ethereal atoms at a true distance. They were 
 indeed very far from having certain experiences 
 that modern scientists have : but the latter 
 are very far from having a perfect knowledge 
 of the nature of things, from which facts 
 ought to be derived. 
 
 3°. Many modern scientists hold that the 
 ethereal substance is the very substance of 
 the earth and of the air extremely rarefied 
 by the distance between the atoms : and 
 therefore action at a distance is not the only 
 difficulty to be objected against them. There 
 are others, for such an ethereal substance ought 
 to have the principal properties of the other 
 corporeal substances — that of resisting other 
 bodies — retarding motion, coming into combina- 
 , tion with them, &c. , Hence, the modern 
 
ETHER. 175 
 
 author whom we quoted from The Cosmos, is 
 much embarrassed, and believing himself to 
 have shown that the ethereal substance cannot 
 be at all suspected of the least resistance to 
 the planetary bodies, concludes thus : " Nous 
 sommes en presence de deux affirmations ab- 
 solument opposdes. II n'y a pas de milieu 
 materiel dans I'espace (Hirn, Faye). II est shx 
 que I'espace est rempli d'un milieu capable d'etre 
 en vibration, I'^ther (Hertz)." Hence Courbet, 
 strangely and without sufficient reason, would 
 introduce into science an opinion taken from 
 Theology, where it teaches that the glorified 
 bodies have the gift of being subtle or pene- 
 trable, not resisting earthly bodies nor resisted 
 by them. He says that, if it be necessary, 
 science may without discredit get light from 
 faith, to solve insuperable difficulties in ques- 
 tions of nature. 
 
 In the olden time they did not ask whether 
 the ethereal substance resisted the stars and 
 retarded their course, because the conceptions 
 about that were not those of the vulgar. 
 They did not believe it to have the nature 
 of earthly bodies, solid or aerial : did not be- 
 lieve in the possibility of its combining with 
 such and changing its nature. Therefore it 
 was said to be unalterable. The ethereal 
 substance was the firmament. It was not 
 the stars, but that in which the stars are 
 
176 THE PHYSICAL SYSTEM OF ST. THOMAS, 
 
 placed, according to the first chapter of Genesis : 
 Fecitque Deus duo luminaria magna. . . . et 
 Stellas, et posuit eas in Jirmamento cceli. 
 
 St. Thomas, in answer to the question, 
 Utrum firmamentum sit de natura inferiorum 
 corporum, replies that before Aristotle all the 
 philosophers believed the firmament or heaven 
 to be a substance like in nature to the ele- 
 mentary bodies of this world. Aristotle, he 
 says, proved that the firmament or heaven 
 has not a nature common to other bodies, but 
 has a proper essence : and the later philoso- 
 phers, persuaded by his reasoning, admitted 
 his doctrine. According to this doctrine the 
 substance of the firmament, in which the 
 stars are, is not heavy, does not alter nor 
 corrupt : and since it has not even a common 
 matter with the other bodies, we cannot, he 
 says (De natura generis), form a conception 
 of it univocally with other bodies, but only 
 an analagous conception. In these days, as 
 in those, we are a long way from having a 
 sure knowledge of the essence of the ethereal 
 substance or firmament ; and though we can 
 afiirm in accordance with the doctrine above 
 mentioned, that it is the medium and the 
 subject whence light and heat come (as is 
 hinted in the Book of Genesis), we still 
 hesitate, incapable of solving the grave diffi- 
 culties put forward by Courbet in The Cosmos. 
 
177 
 
 XXII. 
 
 CHEMISTRY. 
 
 THIS is a most important and arduous 
 question, owing to its intrinsic difficulty 
 and the discrepancy of opinion about it. So 
 long as chemistry remains within the limits 
 of its own natural boundaries, collecting facts 
 and registering phenomena, the learned cannot 
 really be at variance with each other, though 
 there may be more or less exactness in explain- 
 ing and more or less faithful accounts of 
 things : but when, passing these limits, it 
 takes to deciding philosophically about the 
 nature and essence of things, then it is that 
 discrepancies arise. This happens, in some 
 cases, through deficient knowledge of philo- 
 sophy and a want of sound logic, while in 
 others it proceeds from the modern fashion of 
 following experience only, and confusing the 
 senses with reason. We must therefore be 
 very cautious, ready to receive all facts that 
 are clearly proved, to admit the principles that 
 are absolutely connected with those facts, and 
 
178 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 then enquire whether such are the principles 
 accepted in the philosophy of St. Thomas. 
 
 Chemistry is the science that treats of the 
 substantial changes in bodies. A substantial 
 change means that which happens when a 
 substance is changed, not by mere variation 
 of temperature, nor by the fleeting influence 
 of extrinsic agents, but by a change in its 
 inmost being, so that it changes its nature, 
 and, instead of being what it was, becomes 
 another substance. Such mutation takes place 
 in corporeal substances only, because they 
 alone have a composite essence : and since 
 our minds have no immediate intuition of 
 substances,, but know them through their opera- 
 tions, the diversity or contrariety of these 
 operations will guide us to discern whether 
 or no their substantial being is changed. This 
 does not require a change in all the operations. 
 It is enough to know that the specific opera- 
 tions have changed : for since the genus 
 remains in the substantial mutations of corpo- 
 real things, the operations or passions belonging 
 to the genus itself must remain. Hence a 
 substance may change into another and yet 
 have the same gravity, the same weight, the 
 same solidity or liquidness, &c. It is very 
 difficult sometimes to be sure of a substantial 
 change, but we often can be sure of it. 
 Knowing, for instance, that substances without 
 
CHEMISTRY. 179 
 
 life are different from living substances, we 
 cannot doubt that inorganic minerals, when 
 changed into plants or into sentient things, 
 are substantially changed. This may, some- 
 times at least, be extended beyond the living, 
 without fear of falling into error. 
 
 The proper and principal object, therefore, 
 of chemistry is to be found, in those sub- 
 stantial changes, obtained by combination of 
 elements, which all modern scientists call 
 chemical combination. The accideiital changes 
 of substances, called alterations, are but a 
 secondary object accidentally treated of in 
 chemistry. Herein -there seems to be no essen- 
 tial discrepancy between the doctrine of St. 
 Thomas and the true principles of modern 
 science, together with the facts that chemists 
 have shown to be certain. But the modern 
 doctrine is in disagreement with that of many 
 old physicists, and also of some modern ones, 
 who put forward, without any sound reason, 
 principles founded on their own fancy, or facts 
 that do not exist. We must therefore discuss 
 elementary substances according to our own 
 doctrines distinctly. 
 
180 
 
 XXIII. 
 
 ELEMENTARY ATOMS. 
 
 AN elementary substance is an atom which, 
 essentially composed of materia prima 
 and substantial form, is simple, inasmuch as 
 it does not result from a chemical combination 
 of different substances. The word " atom " does 
 not in itself indicate a smallest and indivisible 
 substance, but a substance not constituted by 
 aggregation of substances. This meaning is 
 evidently right. An aggregate, though speci- 
 fically one, cannot be called individually one, 
 because it results from the union of many 
 substances, whether their nature be the same, 
 ■or not. By thus using the word " atom," we 
 are in no danger of falling into what is called 
 the atomic theory ; for in that system, strictly 
 speaking, the atoms are inert, of equal 
 nature, essentially extended, only capable of 
 moving and being moved, and quantitatively 
 indivisible. But they are not so in the Physical 
 system. 
 
 Applying then to elementary substances the 
 
ELEMENTARY ATOMS. 181 
 
 known principles that we have pointed out, 
 we must say that it is essentially composed 
 of materia prima and substantial form. Being 
 essentially extended, it must have the principle 
 of extension ; and the principle of extension 
 is what we call materia prima. The substan- 
 tial form is the principle of that virtue or activity 
 which determines the specific nature of the 
 substance, which principle cannot be essentially 
 wanting in that elementary substance. Sup- 
 pose, for instance, that oxygen, sulphur, 
 hydrogen and carbon are, as we now believe 
 them to be, elementary substances, specifically 
 different. We learn their specific diversity 
 from the divers and constant virtues, observ- 
 able in their mutual operations, that chemistry 
 shows plainly by facts within our reach : and 
 we should look for them in vain elsewhere. 
 Since therefore a specific activity is evident in 
 these atoms, there must be a principle of that 
 activity. But this is precisely what places 
 them in different species, making the nature 
 of hydrogen to be the nature of hydrogen, 
 and not the nature of gold or of something 
 else. There being then, in such atoms a 
 principle of activity, we must admit a substan- 
 tial form ; that is, the said principle. 
 
 In discussing the principle of activity we 
 have placed the elements in mutual relation : 
 but that was for the purpose of making the 
 
182 THE PHYSICAL. SYSTEM OF ST. THOMAS. 
 
 a!fgument more easily intelligible. If Oxygen 
 were the only thing in the corporeal world, 
 it would have its materia prima and substan- 
 tial form just as it has now when existing 
 among other elementary substances ; for with 
 its extension it would have the principle of 
 extension, and with its activity, (existing in 
 poteiitia, at least,) it would have the principle 
 of. activity, i.e. the substantial form. We 
 say in potentia, because, being inorganic, it 
 could not operate on itself, so that if no other 
 body of a different nature existed in the world, 
 there would be no subject in which the poten- 
 tial activity could be brought into action. 
 
 The matter and form of the elements cannot 
 be mingled in one principle. They are essen- 
 tially two principles, really distinct. In this 
 question we have to steer between two 
 extremes, one of them sinning by excess, the 
 other, by defect. We should go into excess 
 by imagining that materia prima is a sub- 
 stance constituted per se in its own being, 
 and that every substantial form is a simple 
 being, subsistent per se, and only operating 
 on materia prima. Were it so, the form 
 would not be substantial and informant, be- 
 cause it would not constitute the matter in 
 substantial being. It would only be a forma 
 assistens, not being by its own essence united 
 to the matter, but only by the operation. 
 
ELEMENTARY ATOMS. 183 
 
 In short, there the atom would have two 
 complete substances in its own being, instead 
 of being, as it is, one substance. 
 
 To consider the principles of extension and 
 of activity as one being, in the absurd guise 
 of a matter per se active or a force per se 
 extended, would be sinning by defect. 
 
 Consequently we must afl&rm that in the 
 elementary substances materia prima, though 
 really distinct from the substantial form, is 
 not separate from it. The true and philoso- 
 phic meaning of these two expressions is well 
 known. Two things are really separate when 
 each has its complete being, and is the 
 principle of its own operation. They are really 
 distinct when each has a being per se incom- 
 plete, and each is not per se a principle of 
 operation. Suppose, for instance, a waxen 
 image of Caesar. The image is not separate 
 from the wax, for the very wax is the image : 
 but distinct it is, because otherwise the wax 
 could not be fashioned into any other image. 
 But, between the pen that writes and the 
 hand that holds it, there is something more 
 than a real distinction ; because the pen, though 
 moved as an instrument by the hand, has a 
 substantial and complete being, diiferent from 
 that of the hand. Here there is not a real 
 distinction only. The pen is the separate 
 instrument of the hand. 
 
184 
 
 XXIV. 
 
 THE MATTER AND FOEM OF ELEMENTARY SUB- 
 STANCES ARE REALLY DISTINCT. 
 
 TH E E E is not mucli difficulty in proving 
 that between the materia prima and the 
 substantial form of an atom there truly is a 
 real distinction. Matter is in its essence 
 passive ; while the principle of activity, which 
 the form is, is active. But the relation of 
 the active to the passive is contradictory. 
 Therefore they cannot meet in one being by 
 virtue of one same principle. Hence an atom, 
 being constituted of matter and form, has two 
 principles really distinct from each other. 
 
 Secondly, all existing bodies must have 
 density and a determinate figure. The theoiy 
 of crystallization is founded on that. Now 
 what is the intrinsic cause by which a body, 
 and likewise an atom, has this or that density 
 instead of another ? Matter is not the cause 
 of it, being of itself undetermined. Therefore 
 the form is the cause of it. Hence the form 
 is the determining principle, and the matter 
 
MATTER AND FORM OF ELEMENTS. 185 
 
 is the determined principle. This necessarily 
 implies a real distinction. St. Thomas remarks 
 that matter without a form could not be con- 
 stituted into an atom, i.e. into an indivisible 
 substance, in which the parts, though not 
 divided, are really distinct. Omne corpus 
 divisihile est, he says. Omne autem divisihile 
 indiget aliquo continente et uniente partes ejus. 
 To make this clear, we have only to observe 
 what takes place in plants, in brutes and in 
 man. Whence does their structure, order, and 
 density proceed ? Not from matter ; for 
 without the vital principle by which it is 
 informed, and from which it is really distinct, 
 materia prima is indiiFerent to every structure, 
 order and density, and when deprived of the 
 vital principle, loses the density, order and 
 figure that it had. Therefore all this proceeds 
 from the same principle that informs the body 
 of the living being. The same reasoning holds 
 good about the forms of the elements in rela- 
 tion to the matter which they inform, viz., 
 that the form and the matter of each element 
 are really distinct. 
 
 Thirdly, extension and quantity, like activity 
 and force, are a mode of the elementary atom's 
 being. Now the mode must be in proportion 
 to the modified principle ; and therefore the 
 principle of extension is extended, the principle 
 of activity active. 
 
186 THE PHYSICAL SYSTEM OF ST. THOMAS, 
 
 But there is a real distinction between 
 extension and force. Therefore there is a 
 real distinction between the principle of exten- 
 sion, which is matter, and the principle of force, 
 which is form. This is always the way of 
 arguing in philosophy, when treating of acts 
 and of the principles from which they are 
 derived : for, whenever we perceive diversity 
 of acts, we infer diversity of the immediate 
 potenticB, which are their proximate principles. 
 
 Here again a comparison will be useful. 
 Suppose that you are pushing some sort of 
 body with 3^our whole hand. In doing so 
 you feel a force that presses and operates on 
 an extended thing, because that which pushes 
 is not a mathematical point, but the whole 
 hand : and hence we deduce with certainty 
 that in the hand there must be, besides the 
 extended matter, a principle of force by which 
 the matter presses that body. Again, when 
 we feel heat, our sensation is evidently a 
 mode of two principles really distinct, from 
 one of which, i.e. the matter, we have exten- 
 ded being, and from the other, i.e. the anima, 
 we have the vital afi'ection. In like manner 
 the force manifested by an elementary atom 
 is not in a mathematical point, but in an 
 extended thing : and therefore if the force 
 demonstrates to you a principle of activity, 
 its being in an extended thing shows you the 
 
MATTER AND FORM OF ELEMENTS. 187 
 
 principle of extension really distinct from the 
 principle of activity. 
 
 Fourthly, we can find in the natural disposi- 
 tion of simple bodies a proof not without its 
 value. In fact a substance that in its com- 
 pleted essence is simple will certainl)?^ not have 
 parts outside of parts. Wherever it is, the 
 whole of it will be ; or to use a well-known 
 adage, the whole will be in the whole and in 
 each part. Now this simple substance is pei' 
 se subsi stent and therefore per se not divisible : 
 but that which is per se not divisible cannot 
 be per se extended. Therefore a substance 
 that is 256r se simple and subsistent cannot 
 be per se extended. So that, unless we deny 
 the real extension of corporeal substances, we 
 must admit that the princijDles of activity, 
 which the forms are — or as some people call 
 them, forces — receive their being, as extended 
 and divisible things, from another and a 
 different principle, which, being the principle 
 of extension, is matter precisely. 
 
XXV. 
 
 AN ELEMENTARY SUBSTANCE IS CHEMICALLY 
 SIMPLE. 
 
 I HAVE proved then that an elementary 
 substance is not a simple substance, and 
 is composed of two really distinct principles. 
 
 But, though elementary substances are not 
 simple in their essence, they are chemically 
 simple as not being generated by two ele- 
 mentary substances of different natures. All 
 chemists agree in this : that substances obtained 
 by union of substances differing in their 
 nature, are not elementary substances. They 
 are called chemical compounds : and though 
 at one time they were not called so, they 
 were not said to be elementary. But the 
 practical question, " Which of them are ele- 
 mentary ? " is not a question for philosophers 
 as such to answer. It belongs to the experi- 
 mental physicists, w^ho by little and little, and 
 after centuries of study, have corrected many 
 errors in purely experimental science. 
 
 The proof of this is indisputably evident. 
 
SIMPLICITY OF ELEMENTAKY SUBSTANCES. 189 
 
 In the corporeal universe there certainly are 
 many substances that differ in their nature 
 specifically, as the specific diversity of their 
 operations plainlj'' shows. These either do or 
 do not result from the union of others. Non 
 datur medium, because the opposition is con- 
 tradictory. If they do not result from the 
 union of substances, thej' are chemically simple. 
 If they do, we must either admit an endless 
 series of combinations and unions, which is 
 against reason, or come at last to substances 
 chemically simple. In fact the substances 
 that result from the combination of other sub- 
 stances are like numbers, and those that do 
 not like units. However great a number may 
 be, it always consists of units, and proceeds 
 from a unit as from its principle. Thus com- 
 pound substances are such in relation to their 
 components : and therefore we must acknow- 
 ledge the components, unless we are prepared 
 to suppose the Begun without a beginning, 
 and the Eeasoned without a sufficient reason. 
 But to declare which are simple substances 
 and which are not, belongs to experimental 
 science, and would be foreign to the purpose 
 of a treatise, in which the rational principles 
 only of St. Thomas's Physical system are 
 explained. 
 
 Let it suffice for us to infer by reasoning 
 that elementary substances must be of more 
 
190 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 than one species. I know very well -that 
 many scientists would have all elementary 
 substances to be of one specific nature. Why 
 they do so I know not. Perhaps it comes 
 from a natural tendency to suppose in all 
 substances one and the same matter, as the 
 common principle that subjects them to the 
 various transformations on which the unity, 
 order and beauty of the universe depend. But 
 since it is not easy to form a just conception 
 of such matter, those who hardly give aglancfe 
 at the inmost essence of things may be led to 
 imagine it to be a set of atoms, each having 
 the same nature. Hence the well-known hypo- 
 theses of the Epicureans, Cartesians and the 
 modern followers of the Mechanic system. 
 Some few there have been, who, while dis- • 
 owning these theories, and inclining to the 
 Physical system, admitted the double principle 
 of extension and activity, but stood out for 
 the one species of elementary substance, fancy- 
 ing that, as all colours may be had from one 
 light, so may all corporeal substances be con- 
 stituted from one species of elements. But 
 is that probable ? 
 
 Most certainly the progress of science has 
 not shown that the elements are of one species. 
 They were at one time reduced by Physicists 
 to a few species : but gradually, as empirical 
 teaching advanced, the species increased, and 
 
SIMPLICITY OF ELEMENTARY SUBSTANCES. 191 
 
 now there are a great many. This cannot 
 be said to show that the elements are of one 
 species, but contrariwise would lead us infer 
 from experiment what Cardinal Toledo said 
 as a philosopher, viz., that the elements 
 are of more than one species. And in 
 fact, how can they be not of more than one 
 species ? The mixtum resulting from the ele- 
 ments has a nature different from theirs : but 
 this could not be, if the elements themselves 
 had the same nature. Therefore they differ 
 in nature and consequently in species. If 
 hydrogen and oxygen were the same, the 
 quantity could indeed be increased by aggrega- 
 tion : but not the nature changed belonging 
 thereto. 
 
 Anyone seeking to weaken the force of this 
 argument by saying that these, even though 
 of different species, are not chemically simple, 
 because they may be composed of others equal 
 in species, would greatly deceive himself. The 
 proof is of such a sort that its conclusion is 
 universal for chemically simple elements, 
 whatsoever and wheresoever they may be — 
 elements to which we must come in the last 
 resort, unless we like to loiter in the region 
 of the absurd. 
 
 There is another objection which at first 
 sight may seem to have some importance : i.e. 
 that a specific diversity in the elements is not 
 
192 THE PHYSICAL SYSTEM OF ST, THOMAS. 
 
 required, because an accidental diversity is 
 sufficient. The answer is that it would be 
 sufficient, if the diversity of the mixta or 
 compounds were accidental, but not otherwise. 
 Now chemistry shows them to be substantial. 
 
 In conclusion, therefore, we say that ele- 
 mentary substances are of different species — 
 are atoms composed of materia prima and 
 substantial form — two principles really distinct 
 — -and that these elementary substances are 
 simple, being free from chemical composition. 
 This we have defined and proved. 
 
 From the elementary we pass on to the 
 mixed or composite. 
 
193 
 
 XXVI. 
 
 THE " MIXTUM " OE THE CHEMICAL COMPOUND. 
 AFFINITY BETWEEN THE ELEMENTS. 
 
 T N explaining the Physical system we pointed 
 -^ out that, besides the natural tendency or 
 natural appetite which corporeal substances 
 mutually have, as such, we must admit certain 
 particular tendencies whereby some adhere to 
 others and unite with them, to constitute when 
 united diverse other substances which are 
 called mixta, or chemical compounds. These 
 particular tendencies are known by the name 
 of chemical affinities : and we may discuss 
 either their existence or their nature. As to 
 their existence the fact is certain, and so uni- 
 versally admitted, that even those who deny 
 it in theory have to admit it, in fact, at every 
 step, when they mean to discourse, and not 
 talk nonsense, about the changes of corporeal 
 substances. We shall not waste words about 
 that, but say something about their natures. 
 And here it is well to remember what was 
 said before about mechanical motion, which is 
 
 N 
 
194 THE PHYSICAL SySTEM OF ST. THOMAS. 
 
 forced, because extrinsically produced, and 
 therefore has no natural direction or term fixed 
 at which the motion would cease. No one 
 will deny the. fact that every corporeal sub- 
 stance may be subjected to mechanical impulses, 
 and then moved ab extrinseco : but to suppose 
 that chemical affinities originate from them 
 would be utterly unreasonable and not worth 
 a serious argument. G-od willed that in cor- 
 poreal nature there should be a various and 
 continual succession, in which, as St. Augustine 
 says, " the morning of things always comes after 
 the evening." Therefore He gave to the ele- 
 mentary substances that active principle by 
 which they are constituted in their specific 
 being, and from which those particular ten- 
 dencies follow that go by the name of affinities. 
 Moreover, as if to assure us of the fact that 
 even beings without knowledge have these 
 particular tendencies, He willed that in beings 
 there should be a gradual descent from the 
 most perfect animal down to inorganic sub- 
 stance, not only without knowledge but also 
 without life. Common sense tells us that the 
 movement of a horse or of a lion to a certain 
 spot is by an inner principle of nature : but 
 when, in the order of sensitive beings, we come 
 to the lowest species, such as zoophytes, many 
 people find it hard to see how certain motions 
 can be accounted for on the same principle. 
 
THE CHEMICAL COMPOUND. 195 
 
 Nevertheless analogy alone ought to persuade 
 us of the fact, and make us listen to the 
 suggestions of reason, instead of being carried 
 away by the allurements of imagination. But 
 if this applies to zoophytes, it also applies 
 to inorganic substances tending towards a cer- 
 tain determinate end ; so that sound reasoning 
 rejects the mere external principles of mechani- 
 cal motion as quite improbable. If it be 
 absurd, as in fact it is, to say that a stone 
 pitched at a man is attracted by the man hit, 
 equally absurd is it to assert, as some chemists 
 do, that the elementary atoms are moved and 
 directed to unite by external impulses, aud 
 yet have a mutual affinity. 
 
 We must remark that chemical affinities 
 take place between those substances only 
 which, when afterwards combined, give, as 
 the result of the combination, another substance, 
 whose nature differs from theirs. And since, 
 <xs we have said, the components also must 
 therefore be of diverse natures, chemical 
 <i,ffinities therefote cannot take place otherwise 
 than between elementary substances diifering 
 from each other. 
 
 'i'his affinity may be subject to accidental 
 modifications : for if plants, brutes, men and 
 angels are subject to accidental changes while 
 retaining their own nature, how can we except 
 elementary atoms, placed in the lowest grade 
 
196 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 of being 1 The Physical system says that we 
 cannot. Eeason and experience give the same 
 answer. For in an elementary atom there is 
 extension and the principle of activity or force : 
 and the former can undergo changes in the 
 more or less, while the latter can be altered 
 by contrary force. Thus we can see clearly 
 that elements operate under some circum- 
 stances, and under others do not, or that, if 
 they do, their operation is weak, though not 
 specifically different. No wonder then if the 
 different states, if the different modifications 
 to which the atoms are subject, either impede 
 or promote the appearance of chemical affini- 
 ties : for this is quite natural, as we may 
 judge by the analogy between the proper 
 tendencies of living beings and the affinities 
 of things without life. Hence the common 
 saying of chemists that affinity varies very 
 much, according to the various dispositions in 
 which bodies are found. In fact the elements 
 that have affinity to each other cannot com- 
 bine otherwise than by mutual operation, to 
 which they either are, or are not disposed in 
 themselves. If they are so, proximity and 
 contact will suffice to set going their reciprocal 
 action. If not, they must be disposed from 
 without. Hence the necessity of an extrinsic 
 agent, to operate on them and alter them, as 
 heat and electricity are known to do. Some, 
 
THE CHEMICAL COMPOUND. 197 
 
 it is true, have asserted that the mere 
 presence of some determinate substance is 
 sufficient to make the elements operate : but 
 if this is to be understood strictly, so as not 
 to imply true action, it is trifling and false. 
 What is it present for, if it does nothing ? 
 To introduce that in chemical combinations 
 for the purpose of awakening affinity, is out 
 of the question, and multiplies beings without 
 necessity, against the well known axiom, Entia 
 non sunt multiplicanda sine necessitate. 
 
 And let this be sufficient about affinity, 
 according to the principles of the Physical 
 system : for we have shown that system to 
 be in conformity with science and explanatory 
 of the facts that science undertakes to investi- 
 gate therein. 
 
198 
 
 XXVII. 
 
 THE "MIXTUM," or CHEMICAL COMPOUND, HAS A 
 NATURE SPECIFICALLY DIFFERENT FROM 
 THAT OF ITS COMPONENTS. 
 
 A SUB STANCE that proceeds from the 
 coupling together or combination of ele- 
 ments is called a mixtum, or more commonly 
 a chemical compound. Such for instance is 
 cuniaber, or water — the one resulting from 
 sulphur and quicksilver, the other from hydro- 
 gen and oxygen. The species of the elements 
 of corporeal substances are very few in num- 
 ber, when compared with those of the mixta 
 derived from them, as the letters of the 
 alphabet are very few in comparison with the 
 innumerable words which they compose. , We 
 willingly acknowledge that in these days, by 
 means of diligent and repeated experiments, 
 wonderful discoveries have been made about 
 the manifold formation of the mixta: but 
 their essence is passed over very lightly, 
 though deserving particular study. 
 
 The mixtum or true chemical compound has 
 
THE MIXTUM AND ITS COMPONENTS. 19^9 
 
 a. nature specifically different from that of each 
 element of which it is composed ; and when 
 this is not verified, the elements cannot bfe 
 chemically combined, nor can the body resulting 
 from the combination be a mixtum, but may 
 be called an aggregate or a mingled massv 
 The specific diversity is manifested to us by 
 the constant diversity of their operation, be- 
 cause operari sequitur esse : and this is the 
 only but certain means by which we are 
 able to infer the diversity of the active 
 principle that informs them. 
 
 Suppose, for instance, that into an empty 
 vase of glass with the metallic wire in it 
 you introduce oxygen and hydrogen in pro- 
 portion of volume as one to two, and by the 
 help of the metallic wire strike out the electric 
 spark. There is an instantaneous combustion. 
 The fluids disappear, and little drops of water 
 appear, occupying a space two thousand times 
 less than what was occupied by the oxygen 
 and hydrogen. Now let us consider the mutual 
 relations of these elements to each other and 
 to the water generated from them. 
 
 The specific weight of the oxygen is eight 
 times that of the hydrogen at the samie 
 temperature. Oxygen will burn, hydrogen will 
 not. Animals inhale oxygen, and not hydro- 
 gen. All the specific properties of the one 
 are different from those of the other : and 
 
200 THE PHYSICAL SYSTEM OF ST, THOMAS. 
 
 though they have generic properties in common, 
 such as that of being extended, heavy, resis- 
 tent, the one has positive while the other has 
 negative electricity, and their capacity of heat 
 differs. Their diversity of nature, therefore, 
 could not be more evident. And yet that 
 spark makes all these differences disappear. 
 Instead of the fluids there is one liquid — 
 water, whose properties have nothing to do 
 with the vanished elements. The specific 
 weight is different and so is the capacity of 
 heat. Though generated from oxygen as much 
 as from hydrogen, it extinguishes fire instead 
 of feeding it. Formed from oxygen and 
 hydrogen, its operation in inorganic things 
 differs widely from theirs, and is different 
 again in plants, in brutes, in man : so that 
 in the operation of water we no more recog- 
 nize that of oxygen and hydrogen than we 
 recognize the operation of clay in that of 
 gold or 'silver. Evidently therefore the nature 
 of water differs from that of oxygen and of 
 hydrogen just as the nature of clay ' differs 
 from the nature of gold or of silver : and 
 therefore the nature of water is specifically 
 different from the nature of the oxygen and 
 of the hydrogen from which it was generated. 
 This holds good of every true mixtum, or 
 chemical compound, in relation to its com- 
 ponents. 
 
201 
 
 XXVIII. 
 
 WHAT IS MEANT BY SUBSTANTIAL 
 TRANSFORMATION. 
 
 SOME people seem to think that substan- 
 tial transformation, as understood accord- 
 ing to the Physical system, means annihilation 
 of the elements, or at least of their substantial 
 forms, and the production of a new form to 
 be the specific principle of the chemical 
 compound's activity. If so, we should not 
 have a chemical composition, but annihilation 
 and creation. Mixtio, says Aristotle, est alter- 
 atorum unio. * It therefore consists in this : 
 When, e.g. oxygen and hydrogen combine, 
 there remains, 1". the matter (materia prima) 
 of both ; 2°. in each the principle of activity 
 undergoes a change ; 3°. by virtue of this 
 change every atomic part of the compound 
 molecule has in itself the nature of the 
 mixtum ; so that every atomic part of the 
 water has the nature of water, and the 
 qualities of the previous elements (oxygen 
 
 * De Ge.ner., i. 
 
202 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 and hydrogen) are hidden. All this implies, 
 a substantial transformation of the elements. 
 That, in virtue of this, the mixtuni is a whole,, 
 of a new and homogeneous nature in every 
 part, is taught by Aristotle. He says : "Is 
 a mixtum nothing else than minute particles 
 varying in their nature, but so confused that, 
 although retaining their former nature, they 
 seem a homogeneous , whole ? No : for in the 
 mixtum every part must have the nature of 
 the whole, as each part of water has the 
 nature of water." This principle of his is- 
 quite in accordance with the division of ele- 
 ments into atoms and the disposal of the 
 mixtum into molecules of a certain dimen- 
 sion and a certain figure. 
 
 People are so afraid of this in our times,, 
 that a few words about it may not be amiss.. 
 We said before that every substantial form 
 requires determinate matter, and must natu- 
 rally have also, according to its various states, 
 a determinate figure. Oportet ut determinatce- 
 formce determinata Jigura debeatur* In that 
 which has life the substantial form requires a 
 determinate organism : and thus the soul, which 
 is the substantial form of the human body, 
 could not be adapted to the organism of an eagle, 
 nor the substantial form of a stag to that 
 of a fish, nor the substantial form of a peach- 
 
 * Gomm. in Sent,, ii. Dist. xix, 1, 1. 
 
SUBSTANTIAL TRANSFORMATION. 203 
 
 tree to that of a camellia or of a tulip. Now 
 this doctrine must be equally true of the 
 inorganic : so that, in virtue of a substantial 
 form, an atom of gold has not under the 
 same temperature the same figure as an atom 
 of phosphorus, nor has a molecule of a mixed 
 body the same figure as that of another 
 mixed body. True it is that there are bodies, 
 both elementary and mixed, whose atoms or 
 molecules, in a solid state, show equal figures, 
 and therefore may be called isomorphous : but 
 that is not in contradiction with the doctrine. 
 Rather does it lead thereto by a sort of 
 analogy ; for in the different species the 
 likeness between the external form or figures 
 of bodies becomes greater as the species 
 descend from Man, the noblest of the animates, 
 towards the lowest species of corporeal sub- 
 stances. Anyone may see that what we have 
 said about the atoms of the simple bodies 
 and the molecules of the mixed is in no way 
 against those beautiful theories about crystals, 
 which are so deservedly honoured in physics. 
 
204 
 
 XXIX. 
 
 THE COMMON SENSE OF MANKIND IS IN FAVOUR 
 OF A BELIEF IN THE TRUE SUBSTANTIAL 
 TRANSFORMATION OF THE ELEMENTS. 
 
 THAT in mixed or composite bodies the 
 transformation produces another nature 
 totally different from the nature of its com- 
 ponents, is so evident to the senses that it 
 has no need of further proof. Hence it is a 
 universal and rooted belief. A man of plain 
 common sense would laugh if you said to him, 
 " You must know that which you suppose to 
 be water is nothing of the sort, but only 
 what two other substances, quite different, 
 seem to be, just as a circular piece of wood 
 with seven colours painted on it seems white, 
 if you turn it round very fast." Nature tells 
 us the contrary, and language, that faithfully 
 interprets the common sentiments of mankind, 
 confirms the same truth. It has always been 
 said, and is said by learned and ignorant, that 
 the chemical compound has a new nature, a 
 nature different from that of its elements. 
 
SUBSTANTIAL TEANSFORMATION. 205 
 
 The chemists also say the same, even those 
 who deny it theoretically and think that in 
 the mixtum or compound the elements remain 
 just as they were before the combination. 
 Moreover, the words " unity of nature " mean 
 unity of the active principle, not a co-operation 
 of different operators for one and the same 
 end. 
 
 To this common language St. Thomas ap- 
 pealed when showing, against Eutyches, that 
 in Christ there cannot be one nature only, 
 because the divine and the human nature 
 are permanent in Him. A one results from 
 many, he says, firstly in virtue of order only, 
 as one city is composed of many houses, and 
 one army out of many soldiers. Secondly, 
 in virtue of order and composition ; as one 
 house is made of many parts by mutual con- 
 tact and joining. But these ways, he says, 
 " will not suffice to make one nature from 
 many : and therefore those things whose form 
 is only order and composition are not natural 
 in such a way that their unity may be called 
 unity of nature." He goes on to say : "Never 
 is it found that one nature comes to be, out 
 of two natures remaining such, because each 
 nature is a whole, and those things out of 
 which anything is constituted have the relation 
 of parts. Wherefore, since the result of the 
 soul's union with the body is one individual. 
 
206 THK PHYSICAL SYSTEM OF ST. THOMAS. 
 
 neither the body nor the soul can be said 
 to be a nature in the sense in which we are 
 now using the word, because neither the one 
 nor the other has a complete species, but each 
 is a part of one nature. Therefore, since 
 human nature and the Divine Nature are each 
 a complete nature, it is impossible for them 
 to concur in making one nature, without one 
 •or both ceasing to be : which is not possible, 
 because it is evident from what has been 
 said that one Christ is true God and true 
 man. It is therefore impossible that in Christ 
 there can be one nature only." * 
 
 Here we can see incidentally what mischief 
 may be done by an easy twisting of words 
 from the sense in which they are commonly 
 understood, for the purpose of furthering par- 
 ticular opinions. Those therefore who will 
 not allow that the nature of the elements is 
 changed in the mixtum or compound, should 
 call the compound an aggregate or a mingling 
 together or anything they j^lease, but not a 
 new nature ; or they will not only come into 
 collision with words that are used and must 
 be used in Theology, but also be at variance 
 with the common language of mankind. 
 
 * Contra Gent., iv. 35. 
 
207 
 
 XXX. 
 
 THE SUBSTANTIAL TRANSFORMATION OF THP] 
 ELEMENTS IS PROVED BY FACTS. 
 
 T N fact the mixtum or chemical compound 
 '^ is a substance that has properties and 
 operations invariably different from those of 
 the elements of which it is composed : but the 
 principle of activity, or substantial form, is the 
 source of the properties and of the operations. 
 'Therefore the substantial form of the elements, 
 which is really distinct from their matter, is 
 •different from the substantial form of the 
 mixtum ; and so, in that passing from the 
 state of being elements to the state of being 
 ^ chemical compound, there was a true sub- 
 stantial change. Now what is there to be 
 said against this argument ? Can the elements 
 ■co-operate to the same term of operations, 
 and thus operate in specifically different ways, 
 retaining their own proper principles as before ? 
 This cannot be. The operations resulting from 
 ■co-operation of separate principles must reveal 
 
208 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 the disposition of these principles, either in 
 an equal degree, or as shewing what more 
 belongs to the stronger. Thus, for instance, 
 if the two elements disjoined attract a sub- 
 stance, together they will attract it more 
 strongly : and if one of them attracts while 
 the other repels, the attraction and repulsion 
 will be according to the difference of their 
 contrary forces. Can it be said that the ele- 
 ments themselves by virtue of their union, 
 not only co-operate to a term of operation, 
 but give besides one sole principle of it ? 
 This would suppose the impossibility, that each 
 a.tom remains in the mixtum as a true 
 individual in its own nature. St. Thomas 
 therefore says : 
 
 "It is impossible that of things different 
 in being there should be oug operation. I 
 say ' one,' not speaking of the term, but of 
 its proceeding from the operator. For many 
 men pulling a ship do one action as to the 
 thing operated on, which is one : but on the 
 part of the pullers there are many operations, 
 because there are diverse impulses moving it." * 
 
 Moreover, all that under the opposite hypo- 
 theses is inexplicable, has, at least, a satis- 
 factorj' explanation in the thesis that we are 
 defending : and therefore for that reason alone, 
 
 * Contra Gent., ii. 57. 
 
TRANSFORMATION OF THE ELEMENTS. 209 
 
 if there were no other, it ought to be pre- 
 ferred. In fact, if anyone asks why in 
 chemical combination there is often a species 
 of agitation or conflict or confusion between 
 the combining substances, while everything 
 goes peacefully, so to speak, in perfect 
 crystallization, the reason is this : In chemical 
 combination, the elements operate on each 
 other with a force that ever changes their 
 principle of activity. In crystallization the 
 atoms or molecules have only to dispose 
 themselves conformably with their angles and 
 facets in a determinate, symmetrical order ; to 
 which accurate disposition of parts the impetus 
 and violence often noticed in chemical com- 
 bination would be hurtful. And if it be 
 asked why a crystal may have its forms totally 
 ruined by mechanical means, whilst a mixtum 
 or compound never can be decomposed in that 
 way, the answer is evident in the fact that 
 in a crystal the atoms or molecules are 
 suitably disposed, but not transformed. A 
 merely mechanical cause, therefore, suffices to 
 break them apart and spoU their symmetry ; 
 whereas in a mixtum or compound the ele- 
 ments are not only disposed in a certain 
 manner, but also have their nature changed. 
 To re-establish these in their former substan- 
 tial being requires a cause contrary in effec- 
 tiveness to that which transformed them. So 
 
 
 
210 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 can heat decompose a mixtum or compound, 
 when it has force enough to take away in the 
 principles of activity the change that happened 
 at the moment of combination. So can another 
 element do, with the concurrence of heat, and 
 combine with an element that was with another 
 or with others in the mixtum. In this way 
 we can give a suitable reason for the facts : 
 but to say that electricity, heat and other 
 causes, which extrinsically concur in chemical 
 combinations, can only shove atoms and make 
 them group themselves by twos and threes, 
 giving place to some and resisting others, is 
 inexplicable and against experience. 
 
211 
 
 XXXI. 
 
 CONCERNING THE OPPOSITION TO THE DOCTRINE 
 OF SUBSTANTIAL TRANSFORMATION. 
 
 IN science as in politics innovation is now 
 the rule. The supporters of error do 
 their utmost to hide away by means of silence 
 the demonstrations of truth, which would con- 
 tradict their theories, endeavouring to make 
 the friends of truth contemptible and odious 
 by attributing to them strange and absurd 
 doctrines which they never dreamt of advoca- 
 ting. So it is in the present controversy. 
 According to our opponents the philosophy of 
 St. Thomas is against the progress of physical 
 science, and his modern disciples are supposed 
 either to ignore or deny facts that are certain 
 in modern chemistry. But will they be so 
 good as to tell us what these facts are ? 
 
 We say that a substantial transformation of 
 the components in a mixtum, i.e. in a chemical 
 compound, requires the components to be of 
 different natures, with affinity to each other. 
 
212 THE PHYSICAL SYSTEM OP ST, THOMAS. 
 
 as before stated. But this is an assured fact, 
 and generally accepted as such by the chemists 
 themselves. We say moreover that the ele- 
 mentary substances which compose the mixtum 
 must be in truly physical contact, and if 
 chemists forget to affirm this, reason will 
 remind them. For, if the elements remained 
 at a distance from each other, they could not 
 possibly form one compound substance, and 
 therefore could not operate as such. If the 
 distance between them, however small, were 
 absolute, they could not operate on each other 
 at all, because, as we have clearly shewn, obctio 
 in distans repugnat. 
 
 Since then they must come into contact, 
 their dimensions must be of the smallest. 
 Hence the well known axiom : Corpora non 
 agunt nisi soluta. For if there sometimes is 
 a chemical combination between bodies that are 
 not so small, then that chemical combination 
 is on the surface ; as when, for instance, a 
 thick bar of iron is by exposure to damp 
 gradually changed into rust, i.e. hydrate of 
 sesqui-oxide of iron. 
 
 In reply we are told that, according to 
 the chemists, the elementary substances, be- 
 sides differing in nature, are reduced to the 
 condition of atoms, which have a determinate 
 volume and weight and are placed in a cer- 
 tain position relatively to each other. But 
 
TRANSFORMATION OF THE ELEMENTS. 213 
 
 we have nothing to say against that. Why 
 should we, when it agrees quite well with the 
 principles of St. Thomas ? But the elements, 
 they say, must be atoms in order to combine 
 chemically. Very well, but we have a clear 
 and precise conception of an atom, and the 
 modern writers on chemistry have not. What 
 do they mean by an atom ? According to 
 its etymology it means that which, whatever 
 its size may be, is not divided, and therefore 
 among the Greeks we find the word used of 
 a beard, or of grass, to signify being uncut. 
 But if you take it to mean a very small sub- 
 stance, you wiU find that in modern use the 
 smallness is arbitrary and indeterminate. 
 Moreover in the division of bodies modern, 
 writers consider the quantity alone : and we 
 clearly shewed, * when treating of the divisi- 
 bility of bodies, that, so considered, all bodies 
 must be conceived as divisible ad infinitum. 
 A true atom is indivisible, being the minimum 
 in its own nature. It cannot, remaining what 
 it is, be divided any more. The modern men 
 cannot give any reason for this : but St. 
 Thomas has taught us that quantity is an 
 accident of bodies, and, that if you divide a 
 body till the substance can no longer produce 
 this accident, the substance, no longer having 
 quantity, will be indivisible. We, having 
 
 * Chapter XX. 
 
214 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 already explaiaed this doctrine of the Angelic 
 Doctor, can say, in accordance with his 
 principles, that every species of elementary 
 substance has its atoms, each of which must 
 be a minimum: so that we have no difficulty 
 about admitting elementary atoms in the 
 generation of mixta, i.e. chemical compounds. 
 
 Consequently, we can admit without any 
 difficulty that the number of these atoms or 
 elementary minima is by nature determined 
 for making this or that combination, from 
 which one or another compound substance is 
 generated. If they say that it requires two 
 atoms of X and one of y to make the com- 
 pound substance a, we have nothing to object. 
 If they tell us that with the variation of 
 numerical proportions the substances will vary, 
 so be it, provided that the assertion be justi- 
 fied by fact. 
 
 Clearly these elements, though they are 
 atoms or minima, i.e. reduced to the smallest 
 possible quantity, are extended, are true bodies, 
 are subject to universal attraction, have a deter- 
 minate weight. Therefore we can admit the 
 theory respecting the atomic weight of the 
 aforesaid elements. 
 
 Also, by reason of their being truly extended 
 bodies, they must unite not only in deter- 
 minate atomic weight, but in determinate 
 proportional volumes. 
 
TRANSFORMATION OF THE ELEMENTS. 215 
 
 If these elementary minima occupy space, 
 as they certainly do, each of them will be in 
 a certain position with respect to the others. 
 Therefore, when certain chemists propose cer- 
 tain symbolical figures, to indicate the place 
 where, in order that the chemical combination 
 may take place, the elementary atoms have 
 to be, we do not say that such figures are in 
 themselves absurd, though they cannot be 
 proved by experiments. 
 
 Now, seeing that we accept these theories 
 and all the chemical laws founded On facts, 
 by what right can we be- accused of being in 
 opposition to chemistry and the progress of 
 science 1 
 
 But the adversaries of St, Thomas and of 
 his followers put forward a most important 
 point of disagreement, on which modern 
 chemistry quite condemns the physics of the 
 Angelic Doctor. I allude to the substantial 
 transformation of the mixtum or chemical com- 
 pound, generated from elements. 
 
 To penetrate the meaning of St. Thomas, 
 we must think philosophically : but the em- 
 pirical mind is offended at being required to 
 do that, and follows the easy teaching of 
 Epicurus, which amounts to this : That the 
 world is an innumerable quantity of atoms, 
 gifted somehow with extension and capable 
 of knocking against other atoms, or of being 
 
216 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 knocked against by them. The only difference 
 between these atoms is that some are smooth, 
 some pointed : yet their agglomeration in a 
 certain number gives us all the diiFerent sub- 
 stances that are. This is quite clear, but 
 certainly not reasonable : and Cicero, following 
 the principles of Plato and of Aristotle, 
 ridicules it in the person of a certain Ama- 
 fanius. Tarn vero physica, he says, si 
 JEpicurum et Democritum probarem, possem 
 scribere ita plane ut Amafanius (in company 
 with the modern Epicureans, who make all 
 inorganic things and all living things, in- 
 cluding men, come out of atomic aggrega- 
 tions.) Quid est enim magnum, quum causas 
 rerum efficientes sustuleris, de corpusculorum, 
 ita enim appellant atomos, concussione fortuita 
 loqui ? Nostra tu physica nosti, quce con- 
 tinentur ex ej^ectione et ex materia ea quam 
 format et Jingit effectio. [Acad., ii.) In these 
 last words the Physical system of matter 
 and form is clearly meant. Moreover he says 
 further on : De natura rerum ita dicehant 
 (Plato and Aristotle), ut earn dividerent in res 
 duas, ut altera esset efficiens (in other words, 
 the form :) altera quasi huic se prcebens (i.e. 
 the matter), ea quce efficeretur aliquid. In 
 eo quod efficeret, vim esse censebant ; in eo 
 autem quod efficeretur, materiam quamdam ; 
 in utroque tamen utrumque. Neque enim 
 
TRANSFORMATION OF THE EI-EMENTS. 217 
 
 materia ipsa coalescere potuisset, si nulla vi 
 contineretur, neque vis sine aliqua materia. 
 Nihil est enim quod alicuhi esse cogatur. Sed 
 quod EX XJTROQUE id jam corpus nominabant. 
 {Acad., vi.) Here he clearly acknowledges 
 the fact that all bodies are constituted of two 
 principles really distinct, viz., matter and form. 
 Anyone who can read Latin and understand 
 the meaning of words must see that. The 
 conclusion is that, like Cicero, we must reckon 
 this Epicurean chemistry among the chatterings 
 of quacks, as also the Darwinian system, which 
 is founded on it. 
 
 When we affirm the fact that a true chemical 
 compound is a body generated by the chemi- 
 cal combination of elements differing from 
 each other in their nature and that the body 
 generated therefrom differs from its elements, 
 do we not say what is said expressis terminis 
 by every modern chemist, seeing that all of 
 them find therein precisely the difference be- 
 tween chemical compounds and mere mingling 
 of things ? Moreover we express an incon- 
 trovertible fact, inasmuch as the nature of a 
 body is the principle of operation that deter- 
 mines its species. 
 
 " True," they say, " elements of different 
 natures are required for the generation of a 
 chemical compound : but chemical compounds 
 decompose into their own elements. This 
 
218 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 upsets your formula that compounds differ in 
 nature from their elementary compounds." 
 
 Yes, we do say that the elements are of 
 different natures, and that the mixtum or 
 chemical compound decomposes into its ele- 
 ments — e.g. that water when decomposed 
 becomes oxygen and hydrogen, that in the 
 water there is no trace of the elements 
 oxygen and hydrogen. Therefore we have to 
 say that in the water the oxygen and hydrogen 
 exist, but not as such. But then, how do 
 they exist ? 
 
 There are three ways in which a thing may 
 exist in another thing: viz., formaliter,- in 
 potentia, virtualiter. It exists in another 
 thing formally (formaliter), when it exists 
 there in its own form. The likeness of St. 
 Thomas, for instance, exists formally in the 
 block of marble out of which it was sculp- 
 tured, and a chicken exists formally within 
 the shell of a fertilized egg after incubation. 
 If, that block of marble has not yet been 
 sculptured, the likeness is only in potentia, 
 because the artist may sculpture it into the 
 likeness of St. Thomas or of any one else ; 
 and if the egg were not fertilized, the chicken 
 ■would remain in potentia. A thing exists 
 in another in virtute, when it is there neither 
 formally nor merely in potentia, but has in 
 itself an inner virtue by which ■ it, and nothing 
 
TRANSFQEMATION OF THE ELEMENTS. 219 
 
 else, can or should proceed therefrom ; as, 
 for instance, in a fertilized egg there is an 
 inward virtue by which, given the requisite 
 conditions, a chicken is formed of the same, 
 species as that whence the seminal virtue was 
 derived. 
 
 We say then, first of all, that the elements 
 of a chemical body are not formally in it, 
 because if they were so, the chemical body 
 would be nothing more than an aggregate of 
 different substances ; which is contradicted by 
 fact. Secondly, we say that they are not there 
 merely in potentia, because the said chernical 
 body cannot decompose into any other ele- 
 ments. It follows then that the elements 
 are in the mixtum in virtute, because the 
 mixtum has an inward disposition to decom- 
 pose, under certain circumstances, into those 
 elements, and not into any others. 
 
 Therefore they who accuse us of believing 
 that a mixtum cannot be generated without 
 the annihilation of its, elements, or that nothing 
 but materia prima remains in it, speak 
 ignorautly, because the re-appearance of the ele- 
 ments by resolution of the mixtum clearly 
 shews that somehow they had remained. The 
 illustrious Cardinal Toledo (Lib. 11. De Gen. 
 et Corr.) deduces the existence of the elements 
 precisely from the fact that the mixtum, is 
 resolved into them. Patet, he says, quod 
 
220 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 quae resolvuntur componuntur ex illis in quae 
 resolvunttir. Quumque in resolutionibus non sit 
 ^processus injinitus, oportet fateri esse corpora 
 non resolubilia in alia corpora. Talia igitur 
 erunt elementa. Not only must the compound 
 be capable of resolving into its elements, but 
 the elements must be found in the mixtum, 
 for at Chap. I. he says, Tres conditiones 
 
 DEBEEE INESSE ELEMENTO. PrIMA Ut eX 60 oli- 
 
 quid fiat. . . Secunda, ut insit in re quae fit. 
 
 . . Tertia, ut sit primum ex quo fit 
 res, et ultimum in quod dividitur. Adverte 
 autem, quod debet esse elementum simplex, id 
 est non resolubile in partes differentes specie : 
 non enim repugnat elemento dividi in partes 
 quantitatis, ut literce elementa sunt dictionum, 
 et partes habent Uteres ipsce. 
 
 Certain it is then that the elements do exist 
 in the mixtum, and equally certain that things 
 exist in it, as we have said, neither formaliter, 
 nor merely in potentia, but in viriute. That 
 they are virtually there is proved by the 
 fact that something within disposes the com- 
 pound for decomposing into the elements from 
 which it was generated, and not into any 
 others. Formce elementorum, says St. Thomas,* 
 m/xnent in mixto non actu, sed virtute : manent 
 enim qualitates proprice elementorum, licet 
 remissce, in quibus est virtus forTnarum 
 
 * Summa, P. i. Q. Ixxvi. a. 4 ad 4. 
 
TRANSFORMATION OF THE ELEMENTS. 221 
 
 elementarium. Et hujusmodi qualitas mixtionis 
 est propria dispositio ad formam substantialem 
 corporis mixti ; puta formam lapidis, vel 
 animati cujuscumque. 
 
 Thus does the Angelic Doctor shew that 
 the nature of the component elements is 
 changed into the nature of the mixtum : but 
 let us go a little further into his meaning. 
 
 What is meant by the substantial form of 
 the elements and of the mixtum ? The sub- 
 stantial form is the active principle that 
 specificates a material being [esse], and it 
 difi"ers in the different beings \e,ntid\ that have 
 different natures. This substantial form, speci- 
 ficating the being [ens], is not immutable, but 
 can be changed by a proportionate external 
 agent. When the specificating principle has 
 changed, the being [ens] cannot remain un- 
 changed : and therefore when the substantial 
 form of the elements is specifically changed, 
 so as to become the form of a mixtum, changed 
 must the elements be into the nature of that 
 mixtum. 
 
 These substantial forms are not subsistent 
 forces, neither are they made identical with 
 the matter which they inform : but each of 
 them, with the matter which it informs, con- 
 stitutes one ens. 
 
 Each ens (as we have shewn when speaking 
 of qualities) has certain qualities, generic or 
 
222 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 specific, rooted in its substantial form. There- 
 fore every element has its qualities, according 
 to the nature of its substantial form, and 
 every mixtum has its qualities according to 
 its form. 
 
 Now the internal disposition of a subject to 
 be actuated through extrinsic action by one 
 form, rather than by another, is reducible 
 to the genus of quality. Quidquid recipitur, 
 says an old and wise adage, ^9er moduTn 
 recipientis recipitur ; and hence an external 
 agent operating on an ens will, as to its form, 
 produce a change in proportion to its qualities. 
 But when one ens changes into another, the 
 qualities that preceded the change are 7iot 
 isolated and without a foundation in any sub- 
 stantial form. The new form beginning be- 
 comes the foundation of those qualities that 
 were in the preceding form ; and the pre- 
 ceding form ceases to be when the new form 
 begins, because it is not conceivable that, even 
 for a moment, there should be neither the 
 old form nor the new — no form at all. As 
 the weight of a waggon presses continually on 
 its wheels, and is never without a fulcrum, 
 though the spokes are moving in succession, 
 so do the qualities of an ens continue to exist 
 in a succession of diflferent substantial forms : 
 and the fact is clearly shown in the generation 
 and corruption of inorganic bodies, of plants, 
 
TRANSFORMATION OF THE ELEMENTS. 223 
 
 of animals, and even of man. Eightly tlien 
 was it said that the qualities of the elements 
 are the disposition to the form of the mixtum 
 or compound, and that such qualities remain 
 after the generation of the mixtum : and there- 
 fore that they are the inner cause by which, 
 under the action of a cause that destroys the 
 substantial form of the mixtum, the elements 
 of which it was constituted reappear. But 
 these qualities cannot reappear with their 
 primal energy ; for they are no longer the 
 elements in their own natures, but qualities 
 relaxed or neutralized. 
 
 Synthetically then, we say this : 1°. The 
 concurrence of various elements in the genera- 
 tion of a chemical compound is undeniable. 
 2°. Undeniable is it that in the compound 
 there exists a principle of activity different 
 from that which was in each element. 3°. It 
 is a fact that, by reason of this change of the 
 principle of activity, the nature and substance 
 of the mixtum are different from the nature 
 and substance of the elements, and are said 
 to be so by the chemists, who therein precisely 
 find the difference between a chemical com- 
 bination and a mere mingling of different 
 things. Let us accept these facts then as 
 reasonable, and endeavour to explain reason- 
 ably the phenomenon of substantial change in 
 the elements, however difficult it may be. 
 
224 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 Certain men, however, wishing to follow the 
 variable opinion of so-called scientists, admit 
 the facts, yet with a strange incoherence deny 
 the substantial change, because they cannot 
 explain it, though, as we have seen, it is 
 essentially connected with those facts. " Had 
 it been known," says a modern writer, " that 
 we can obtain safe and sound from the new 
 body, by chemical analysis, the two or more 
 substances in whose combination it originated," 
 {here ' he cooly ignores the fact that the 
 Scholastics did know it), " they would have 
 said, as we say now, that it is not easy to 
 explain how and why the intimate union of 
 two substances gives to the total thereby pro- 
 duced qualities so very diiFerent from those 
 of the component substances ; but that does 
 not confer on us the right to suppose a change 
 of nature and essence in those substances." 
 
 This is nonsense. He might indeed tell us 
 that the fact is difl&cult to explain, but it is 
 irrational to contradict oneself by affirming a 
 fact and then denying it in other words. 
 
 Some will say that we are insisting too 
 stiffly on the importance of substantial changes. 
 But, indeed, the question is of the greatest 
 moment. It is disgraceful to profess error in 
 science, especially when it opens the door to 
 errors universal and most pernicious. He 
 who errs about the essence must err about 
 
TRAKSfORMATION OF THE ELEMENTS. 225 
 
 the powers and operations, because the powers 
 and operations of things are derived from 
 their essence. 
 
 By reason of having denied that the essence 
 of bodies is composed of matter and form, a 
 considerable number among the cultivators of 
 the physical sciences rushed into atomism and 
 evolutionism and that monistic theory which 
 is downright materialism, in which they are 
 already admitting that all is matter and 
 motion, from which, after accepting the famous 
 principle of " stored motion " in organic and 
 inorganic things, they fall so low as to agree, 
 with the physicist Voght, that thoughts are 
 to the brain as the bile is to the liver. " In 
 that struggle of the spirit which is now going 
 on," says Hseckel, in his autobiography, "the 
 war-trumpet announces the dawn of a new 
 day that will end the conflicts of the middle 
 ages. In the war, undertaken in the name 
 of truth " (which is extinguished now in almost 
 all the universities), " the theory of evolution 
 takes the part of heavy artillery. Before the 
 heavy blows of this monistic artillery the' 
 tents of the dualistic sophisms (i.e. soul and 
 body, form and matter) tumble down. The 
 proud edifice of the hierarchy and the rock 
 of the Infallibility-dogma shake and fall like 
 houses of cards. All the libraries of ecclesi- 
 astical , science and retrograde philosophy 
 
226 THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 vanish before the enlightening theory of 
 evolution.* Bois-Raymond, denying the com- 
 position of matter and form, body and soul, 
 discourses in the following fashion : " Suppose 
 that all the atoms which constituted Csesar 
 were by mechanical art put in their proper 
 places (this, according to atomists would be 
 a substantial composition) and that on them 
 were impressed their velocity and their direc- 
 tion. We say that Csesar would then reappear 
 in body and soul. The artificial Csesar would 
 at once have the same sensations, the same 
 desires, the same thoughts that its model had 
 when he stood by the Eubicon. Its memory 
 would be fuU of the same images. It would 
 have the same faculties, inherited and acquired. 
 Suppose that, at the same instant, the same 
 mechanical work were done in several places 
 by the same atoms of carbon, hydrogen, &c., 
 how could so many Caesars be distinguished 
 from each other except by reason of the place 
 in which they were made and equalized? "t 
 
 The professor and senator Moleschott, who 
 is nowij: grieving over the deaths of his wife 
 and daughter, does not call this hypothesis 
 absurd, nor does he object to the theory of 
 
 * This inflated abuse of matter and form will serve to shew 
 what he, et hoc genus omne, think about the importance of the 
 doctrine. Verbvm, sapienti. 
 
 t Les Bornes de la Philosophie Naturelle. 
 
 t I.e., when Father Cornoldi was writing this chapter.— IVawa. 
 
TEANSFOKMATION OF THE ELEMENTS, 227 
 
 thus making up an animated Csesar, but he 
 cannot see his way to find the means of doing 
 so. Such are the illustrious men who now 
 fill our professorial chairs. If such principles 
 were universally admitted, there would of 
 course be no religion ; for there would be no 
 reason, and without reason religion is impossible. 
 Such are the weapons used by these teachers 
 against the Holy See, against the Church, 
 against religion, against God. They put non- 
 sense in the place of truth, and then say 
 that religion and faith are irreconcilable with 
 science. Who can fail to see that these ques- 
 tions are of the greatest moment ? On them 
 depends, not merely the progress of science, 
 but even its very existence. 
 
 In this treatise on the Physical system of 
 St. Thomas we have explained those doctrines 
 only of the Angelic Doctor that were less 
 known, most important and that closely con- 
 cern biology and anthropology, on which we 
 had enlarged before. We might have touched 
 upon a fundamental point respecting the dis- 
 tinction between essence and existence : but 
 inasmuch as this requires to be discussed well — 
 has difiiculties in it more than a few, chiefly 
 owing to the cavils of objectors, and has been 
 sufl&ciently explained by us in the Civiltd 
 CattoUca (Serie xii. Vol. vi. p. 305), we refer 
 the reader thereto. And so we stop here. 
 
228' THE PHYSICAL SYSTEM OF ST. THOMAS. 
 
 hoping that what we have written will serve, 
 not only to remove many inveterate prejudices 
 against the ill-known Scholastic doctrine, but 
 also to make scientists pause on the edge of 
 the abyss and reconsider their teaching,- which 
 indeed is so bad that the errors taught in 
 former times are comparatively unimportant. 
 
 THE END. 
 
 Art and Book Company, Printers, London and IjGaminoton. 
 
OTHER WORKS BY THE SAME AUTHOR. 
 
 In printed wrapper, 7s. 6d. 
 Bound in Vellum, bevelled boards, 10s. 6d. 
 
 ON UNIVERSALS, 
 
 AN EXPOSITION OS' 
 
 THOMISTIC DOCTRINE. 
 
 BY 
 
 FATHER MATTEO LIBERATORE, S.J., 
 
 TRANSLATED BY 
 
 EDWARD HENEAGE DERING. 
 
 o 
 
 OPINIONS OF THE PRESS. 
 
 CIVIZTA CATTOLICA, October, 1889.— This is an elegant 
 translation of the seven opuscula. ... in [them] we find a 
 complete refutation of Kosminianism ; and indeed they may be 
 said to serve as a commentary on the condemnation of the Forty 
 Rosminian Propositions by the Sacred Congregation of the Holy 
 Office. Mr. Bering, who in various writings has shown himself 
 to be fully acquainted with the doctrine of St. Thomas and 
 with that of Rosmini, has done a very praise- worthy work by this 
 translation, and deserves well of his countrymen for thus helping 
 them to see how irreconcilably opposed the one is to the other. 
 
 The MONTH, December, 1889—" We have perused the whole 
 of the 336 octavo pages his book contains, with care and 
 interest, and we are of opinion that they throw a flood of light 
 both upon the relation of St. Thomas to Rosmini, and upon 
 the relation of the proscribed propositions of Rosmini to the 
 system of Catholic doctrine. Many difficult points of the teaching 
 of St. Thomas on most important matters have been made very 
 clear. 
 
 "Mr. Bering's book will enable our readers to get an idea of 
 the rich store of doctrine, which he has made accessible to 
 English readers by the translation of the On Universals. 
 
 " The impression of the whole book upon our mind is in full 
 agreement with the hope expressed by Mr. Bering in the Preface, 
 that "those who have not gone through a course of Thomistic 
 philosophy or, owing to the pressure of other occupations, have 
 not kept it up, will find in these seven opuscula an extraordinary 
 amount of inrormation on most important doctrines." 
 
 The TABLET, October 19th, 1889.— "Fathei Liberatore's work 
 seems to us to deserve the encomium pronounced on it by Mr. 
 Bering, as representing an amount of trained intellectual power 
 such as one rarely meets with in writers of these days .... Mr. 
 Bering has done his work singularly well, when one takes into 
 account the difficulties which must always attend the transla- 
 tion of an Italian metaphysical work into readable English." 
 
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OTHER WORKS BY THE SAME AUTHOR. 
 
 PRINCIPLES OF POLITICAL ECONOMY. 
 
 BY 
 
 FATHER MATTEO LIBERATORE, S.J. 
 
 TRANSLATED BY 
 
 EDWARD HENEAGE DERING. 
 
 Demy 8vo, cloth, bevelled boards, 7s. 6d. 
 
 A most valuable book, — a treatise valuable in itself, and useful as a 
 commentary on the encyclical On the Condition of Labour, with which 
 it is in complete accordance. — Caxton Review. 
 
 The work, as a whole, will prove most welcome to English-speaking 
 students of Political Economy. We may accordingly congratulate 
 Mr. Dering on having added to our English Catholic literature a useful 
 volume. — Tablet. 
 
 We have great pleasure in according a most sincere welcome to Mr. 
 Dering's venture in translating Father Liberatore's splendid manual of 
 Political Economy. We trust the undertaking will meet adequate 
 support at the hands of Catholic professors and students of this science. 
 We can cordially recommend [it] to any student anxious to get a 
 foundation of knowledge of political economy, from which he may view 
 and criticise the views of recent economists. He cannot anywhere find 
 a better epitome of the subject than in this work, which, by the way, is 
 very ably translated. — Freeman's Journal. 
 
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 THE LADY OF RAVEN S COMBE. 
 
 2 vols., CrowB 8vo, 7s. 6d. 
 
 Mr. Dering is a graceful story-teller with a good eye for character 
 and an eflfective style. . . , The romantic interest of the story is very 
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THE ATHERSTONE SERIES, No. II. 
 
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 The following Extracts, from two letters written to the author by the late 
 venerated Archbishop of Cabasa, then Bishop of Birmingham, and 
 printed by his permission, are here inserted by the Publishers. 
 My Dear Mr. Bering, 
 
 Let me thank you for your book Freville Chase. 
 I have carefully read most of the theological parts of it, 'and I 
 say, at once, that they are sound and prudent. 
 
 Having said this, I will go on to say that, what I like in your 
 way of putting points as well to the Catholic as to the non-Catholic 
 mind, is the clear, sharp ring of the spirit of Faith— .£.;t imo pectore. 
 There is not a single quaver of human respect to enfeeble, in the least 
 degree, the conviction of the mind of the reader, that the man who thus 
 speaks, speaks what his soul most clearly sees. 
 
 . The shallow weakness of half Catholicity is brought out by the con- 
 trast with the utter worldliness with which it is linked, and under 
 which it succumbs. There are many tones and tints through the book 
 of character and manners, which bespeak a close observation of human 
 life and ways. It is strong from its sharp incisiveness. It is no book, 
 however, and, consequently, for sentimentalists ; nor for those who like 
 something soft to weep over and then forget. 
 
 I pray God to bless you, and remain my dear Mi. Dering, 
 always your faithful and affectionate friend, 
 
 4. W. B. ULLATHORNE. 
 In another letter the Archbishop writes : — 
 Having now read the whole of your book, I pronounce it to 
 be strong and beautiful, and very pregnant with pointed instruction. , . 
 The pathos of the concluding chapters is exquisite. 
 
 " Considered merely as an intellectual achievement, Freville 
 Chase is remarkable. The narrator is very masterful indeed in his 
 capacity 'o enthral our attention. But profoundly interesting as a work 
 of fiction, its charm, as a novel is as nothing compared with its 
 enchanting effect throughout, as a persuasive appeal to the reader's 
 heart, mind, soul and conscience, in testimony of the truth and 
 imperishable beauty of religion. . , . The two volumes should be read 
 consecutively from the first page to the last, and read thus, they will 
 leave an exquisite and long-enduring impression." — tVeekly Register. 
 
 "You have done untold good by writing. . . . Freville Chase. 
 We have had it in our lending library for many years." Sister M, A., 
 Convent of Mercy, W . . . Sept. 8, iSgo. 
 
 "It is not easy to give a fair idea of this remarkable novel." — 
 Liverpool Weekly Albion. 
 
 " The writer of Freville Chase is evidently an able man. He 
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 Second Edition, 2 Vols., 7s. 6d. 
 
 This is a remarkable book in more ways than one. It takes, to 
 begin with, somewhat of a fresh line in our fictional literature, and 
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 truths put in a strong light, and urged in the most fearless and 
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 religious truth, there is little of what is usually called "controversy," 
 or of the dwelling upon doctrinal points, which overweights the 
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 of the citadel ; the fact of the foundation of some church, and the 
 broad certainty of where it is to be found. Lastly, not to multiply 
 characteristics which we hope many readers will find out for themselves, 
 Mr. bering uses his honest weapons as honestly against the follies of 
 Catholics as against Protestant errors, and boldly holds up the looking- 
 glass all round for all who are wise enough to profit by the glance at 
 their own identity.^Z>ai5/j« Review, January, 1876. 
 
 We cannot in justice do less than speak in terms of very high praise 
 of this new work by Mr. Bering, not only on account of its literary 
 merit, which is considerable, but also, and chiefly, because we think it 
 singularly adapted to the present state of things in the religious world of 
 England. . . . We venture to say that while as a tale it is most inter- 
 esting and entertaining, it is at the same time a real study in mental 
 and moral science. In no other work that we are acquainted with 
 have the workings of the human mind in its struggles between prejudice 
 and conviction, worldly interest and the voice of conscience — between 
 light and darkness in fact — been analysed and depicted with greater 
 ^\\\.—The Tablet. 
 
 A noteworthy book . . . exceedingly well written and replete with 
 interest, having a good and well-managed plot and plenty of excellent 
 delineation of character. . . . Written by a Catholic purely from the 
 Catholic point of view, and apparently in order to show cause for 
 recent conversions, and yet being of sufficient interest as a novel. , . . 
 People w'll gladly study this subject, not in a polemical book, not in a 
 jiere trashy little goody story all full of sentiment and twaddle, but' 
 In a thoughtful, carefully considered, and eminently realistic tale. ... 
 The tale is in itself clever, and written with so much power of 
 analysis, such quaint reflectibns upon men and things, and such, 
 excellent common sense, that it is impossible not to read it with 
 lively interest. — T/ie Morning Foil. 
 
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07CC TiT^'^?^-*i' University Library 
 B765.T54 C81 1893 
 
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