Commentaria in Summam contra Gentiles, Liber III

After St. Thomas showed that God is the cause of operating for all operating things, he now wishes to exclude a certain error that arose from the premises ^{1 2}. For some took occasion, from what was said—that God is the cause of operating for all operating things, and that he operates in all things—to say that no creature has any action in the production of natural effects: so that, namely, fire does not heat, but God causes heat in the presence of fire.

Concerning this error, however, he does two things: first, he excludes it; second, he removes certain doubts, in the following chapter.

Concerning the first, he does three things: first, he sets forth the followers of this error, along with their grounds; second, he confutes the error itself ³; third, he answers the grounds of those who err ⁴.

I. As to the first: — Some, namely the Saracens, as the Commentator recounts in XII Metaph., text 18, and IX Metaph., comment 7, held this error on this ground: that forms cannot be produced except through creation, since they cannot be made from matter, because they do not have matter as a part of themselves; but creating belongs to God alone.

2. Certain others, however, positing that the forms which are in matter come from forms which are per se without matter, agree with the aforesaid opinion. For Plato posited that ideas are the causes of being for these sensible things. — Avicenna, on the other hand, posited that substantial forms flow forth from a separate intelligence. But he turned aside from the former foolishness in this: that he posited accidental forms to be dispositions of matter, and to proceed from natural agents.

Now, they were moved, first, because everything that is not per se comes from that which is per se. — Second, because no active power is found to be in these lower things except accidental form. — Third, because animals generated from putrefaction are not generated from things similar to themselves.

3. Certain ones, however—such as Avicebron, in the book on Matter and Form (as is found in Albert, I Phys. ⁵), which he called the Book of the Fountain of Life, because from it, as from a fountain, life of intellect and of science flows—positing that no body is active, but that the power of a spiritual substance passing through bodies performs the actions that seem to be done through bodies, added these reasons ⁶.

First. Because every form of a body is conjoined to quantity. But quantity impedes action and motion. Which is clear, because through the addition of quantity a body becomes heavier, and its motion is slowed.

Second. Because no substance is lower than bodily substance. But every agent, except the first, that causes requires a subject lower than itself.

Third. Because bodily substance is at the ultimate distance from the first agent.

4. Certain ones in the law of the Moors, however, as Rabbi Moses recounts ⁷, saying that all accidents are created by God, added this reason: because an accident does not pass from subject to subject ⁸.

II. As to the second ⁹, he argues against the aforesaid positions. First thus. If no lower cause, and especially a bodily one, operates anything, but God alone, a diverse effect would not follow from the diversity of the things in which God operates; since God himself is not varied by the fact that he operates in diverse things. But this appears to the senses to be false. Therefore etc.

Note that, if any cause operates through the application and presence of something else, diverse effects cannot proceed from the application of diverse things except either on account of the diverse action of the things that are applied, insofar as the action of the first agent is limited in them; or on account of some mutation and variation of the cause from the fact that it operates through the application of diverse things. If, therefore, it be posited that diverse things applied act nothing in the action of God, and that God is not varied from the application of diverse things in which he operates as in a thing present to his action, and through which his action passes: it will not be possible to preserve how from the application of diverse things diverse effects follow from God; for example, how from the application of what is hot heating follows and not cooling (unless perhaps per accidens); and from the applied seed of a man the generation of a man follows; and so of the others. And this is the ground of this reason.

2. Because, however, it could be said that this diversity of effects proceeds from the application of diverse things, not because these applied things act anything, nor because God is varied from the application of diverse things, but because God established that by applying fire he would heat, and that he would generate a man by applying the seed of a man: therefore, to remove this, St. Thomas adds a second reason, and argues in the second place thus. If God alone operated all things immediately, other things would be applied by him in vain for producing effects. But it is against the nature of wisdom that anything should be in vain in the works of one who is wise. Therefore etc.

3. Third. God communicated to others his likeness with respect to being. Therefore he communicated to them his likeness with respect to acting. Therefore so that created things would also have their proper operations. — The consequence is proved. Because to make something in act follows upon being in act, as is clear in God. But he who gives the principal thing to something gives to the same all things that follow upon that thing, namely, either necessarily, or according to suitability and fittingness. This is shown in the one who gives gravity, who also gives downward motion.

III. Fourth. If no creature has an action for producing any effect, much is subtracted from the perfection of the creature; since it belongs to the abundance of perfection that it can communicate to another the perfection it has. Therefore it is subtracted from the perfection of the divine power. — The consequence is proved. Because, since the perfection of the effect determines ¹⁰ the perfection of the cause, creatures must attain perfection from God, who is the most perfect agent. And thus, while it is subtracted from the perfection of the creature, it is also subtracted from the perfection of God.

2. Concerning this proposition, The perfection of the effect determines the perfection of the cause, it must be considered that it can have a twofold sense. In one way, so that it is understood according to real efficiency. And thus it is not taken here, since it is manifestly false. For it is agreed that the perfection of the effect acts nothing upon the cause, so as to be able to cause the determination of its perfection; but rather the perfection of the cause sets a limit to the perfection of the effect. Whence it is said here, for the manifestation of the said proposition, that a greater power introduces a more perfect effect. — In another way, so that it is understood argumentatively, and according to a certain inference and consequence. And in this way it is taken here. For since a greater power causes a more perfect effect, the perfection of the cause can be inferred a posteriori from the perfection of the effect; and where there is greater perfection in the effect, it can be inferred that there is greater perfection in the cause.

3. But then a doubt occurs. For although, where a cause acts from the necessity of nature, one who derogates from the perfection of the effect also derogates from the perfection of the cause, because where the perfection of the effect is less, it is necessary that the perfection of such a cause be less; nevertheless, where a cause does not act according to the necessity of nature, but according to its own determination and the purpose of its will, in derogating from the effect it is not necessary that there be derogation from the cause; since it is consistent that a voluntarily acting cause be most perfect in itself, and yet will to give little perfection to its effect. But God is a voluntary cause of creatures, not a cause acting from the necessity of nature. Therefore, although it be posited that some perfection is lacking to a creature, from this it is not derogated from the divine power so that it is not most perfect.

4. It is answered, and it is said first, that certainly this reason does not seem to be introduced by St. Thomas as demonstrative, but as probable and persuasive.

It is said secondly, that we can speak of the divine power in a twofold way: in one way, according to what it is in itself; in another way, according as it is communicated to creatures, and is manifested to us from its effects. If it is considered in the first way, thus, while there is derogation from the perfection of the effect, there does not have to be derogation from the perfection of the cause. And according to this sense the objection proceeds. — If, however, it is considered in the second way, thus, in derogating from the perfection of the creature, it is derogated from the perfection of the divine power. For the less perfection there is in creatures, the less will the divine goodness and power be communicated to them; and the less perfection we know in creatures, the less and more imperfectly the divine power becomes known to us from creatures. And according to this sense the reason of St. Thomas is probable. For since communicating one's perfection seems to follow, at least according to a certain fittingness, upon being completely in act, just as God also, who is pure act, is also the first cause of being for all things; it seems probable that God, who gives being in act to creatures, also gives them to act; and if it be posited that he gives being in act without their acting, it seems to be derogated from the divine goodness, as having not communicated itself, and having not manifested itself to us, according to the communication of an operation as it were due to the creature.

5. It could also be maintained that this reason concludes necessarily, by saying that to operate and to act virtually, that is, to have the power of acting, necessarily follows upon this: to be in perfect and complete act according to the condition of one's own nature. And therefore he who gives being completely in act, necessarily also gives the power of acting. And thus, if it be posited that it cannot belong to a creature to act, it follows that the divine power is posited as imperfect, as being unable to give perfect and complete being to a creature. — Nor is what is said valid, that God is a voluntary agent. Because even a voluntary agent, having the power of producing something in complete act, can also give to it that which follows upon being in perfect act. Indeed, if he gives the first, he necessarily gives the second.

The first answer, however, seems better. Because those who say that a creature can have no action would deny that having the power of acting necessarily follows being in act.

IV. Fifth: and it is a confirmation of the preceding. God is the highest good. Therefore it belongs to him to make all things in the best way. Therefore he communicated his goodness to created things in such a way that one thing, what it has received, can pour forth into another thing. Therefore to take away proper actions from created things is to derogate from the divine goodness. — The first consequence is proved. Because just as it belongs to the good to make good things, so it belongs to the highest good to make something in the best way: that is, it is fitting for him to make in the best way according to the exigency of the thing made. — The second is also proved. Because it is better that a good bestowed upon one be common to many, than that it be proper: since the more common a good is, the more divine it is. But the good of one becomes common to many if it is derived from one into others through its own proper action.

Sixth. To withdraw actions from things is to withdraw from them their order to one another. Therefore it is to withdraw from them that best thing which they have. Therefore the first is unfitting. — The antecedent is proved. Because there is no binding of diverse natures into the unity of order except through the fact that some act and some are acted upon. — But the first consequence is proved. Because individual things in themselves are good, but all together are best, on account of the order of the universe: since the whole is always better than the parts, and their end.

Seventh. If effects are not produced from the action of created things, then it is impossible that the power of any created cause be manifested through effects. Therefore the nature of any created thing can never be known through an effect. Therefore all knowledge of natural science, in which demonstrations are chiefly taken through the effect, is withdrawn from us. — The first consequence is proved. Because an effect does not show the power of a cause except by reason of an action which, proceeding from the power, is terminated at the effect. — But the second is proved. Because the nature of a created thing is not known through an effect except insofar as through it the power is known, which follows upon the nature.

Eighth. It appears through induction that like acts on its like. But what is generated in lower things is not form alone, but the composite of matter and form: since generation is from matter and is terminated at form. Therefore the generator is a composite of matter and form. Therefore it is not a separate species of things, as the Platonists maintained; nor an agent intelligence, as Avicenna maintained.

Note that this reason is taken from Aristotle, VII Metaph. ¹¹, against Plato. And it convinces both the Platonists and Avicenna: because they presupposed one false thing, namely, that the form alone is generated, and not the composite, and they could not preserve any univocal generation.

Ninth: and it is a reason particularly against Avicenna. Accidental forms that are in bodily things have proper actions, namely, according to Avicenna. Therefore substantial forms do also. Therefore, since its action is not to dispose matter, because accidental forms suffice for this, the form of the generator is the principle of the introduction of the substantial form into the generated thing. — The first consequence is proved. Because, since acting follows upon being in act, it is unfitting that a more perfect act, which is the substantial form, should be devoid of action, when, namely, it belongs to an accidental form.

V. As to the third ¹², St. Thomas answers the reasons of the aforesaid opinion.

To the first reason indeed, which was that of the Saracens, he answers that, just as form is called a being not as if it has being itself (namely, primarily), but because through it the composite is; so neither is it properly made, but it begins to be through the fact that the composite is reduced from potency into the act which is the form.

Note that St. Thomas from these things wishes to have it that it is not necessary for form to be created, although it is not made from matter: because it is not that which is made, but it is that by which the composite is made; and consequently no production is primarily terminated at it.

VI. To the first reason for the opinion of Plato and Avicenna ¹³, he answers that it is not necessary that that which has form as if participated should receive it immediately from that which is essentially form; but immediately from something having form participated in a similar way, which nevertheless acts in virtue of that separate form, if there is any such.

Note that he spoke with hesitation concerning a separate form if there is any such, because he does not think it true that there are separate ideas which Plato posited; nor that there is one created intelligence whose role it is to give all substantial forms to lower things, after the manner of Avicenna. But nevertheless, because it is not his intention to dispute in this place concerning their positions, he therefore answers having admitted their position even with respect to the being of those separate substances.

2. To the second he answers that, although every action of lower bodies comes about through active and passive qualities, which are accidents; it is not, however, necessary that nothing except an accident be produced from their action. Because they act in virtue of the substantial form; and thus from their action substantial forms are produced, insofar as they act instrumentally in the power of substantial forms.

3. To the third he says, first, that in things generated from putrefaction the form is generated not from a separate substance immediately, but from a bodily agent, namely, from the celestial body.

He says, secondly, that although for producing some imperfect forms the celestial power suffices without a univocal agent, because the celestial body is the first altering cause, in whose power all things moving toward form act in these lower things; nevertheless, for producing more perfect forms, such as are the forms of perfect animals, a univocal agent is required along with the celestial agent; because such animals are not generated except from seed, that is, except with seed concurring with the power of the celestial body.

For the evidence of this answer, it must be considered that, although here mention is made only of the power of the celestial body in the production of those things that are generated through putrefaction, nevertheless in VII Metaph., lect. 8, St. Thomas posits, and it is of the mind of Averroes in XII Metaph., comment 13, that besides the power of the celestial body, there is also in the matter from which animals of this kind are generated, some principle similar to the active power that is in seed, from which the souls of animals of this kind are caused. Because, however, a principle and power of this kind does not proceed from a soul, as does the power that is in seed from which perfect animals are generated, but only from the celestial body, in which virtually all generated forms are contained as in an active principle; therefore the generation of these is attributed to the celestial body alone in this place, and in other places as well ¹⁴, and the power of the sun is said to be related to the generation of these as the formative power that is in seed is in the generation of perfect animals.

VII. Whether, however, the same thing according to species can be generated from putrefaction and from seed? — it seems, according to the doctrine of St. Thomas, that it can. For in VII Metaph., lect. 6 and lect. 8, where he determines this matter on purpose, he holds this to be of the mind of Aristotle in imperfect natures.

Moreover, this seems to be reasonable. For in many things of this kind, as in bees, which the Commentator seems to say are generated in both ways, XII Metaph., comment. 18, we see that there is the same shape, the same accidents, the same operations, the same motions, and the same organs of motion; likewise the same conserving things, and the same corrupting things; from which we are accustomed to come to the knowledge of species. And Scotus uses this reason for the confirmation of the position of St. Thomas, in I Sent., d. 11, q. 7 ¹⁵. It is also the express mind of Aristotle, VII Metaph., text. 23 ¹⁶, as also appears from the Greek text, where he says that some identical things are made both from seed and without seed.

2. But concerning this a difficulty is made, first, by the words of Aristotle, I de Gen. Animal., ch. 1 and 16, where he maintains that those which come forth not from the copulation of animals, but from putrid matter, although they generate, nevertheless do not procreate offspring of their own genus.

3. Second, a difficulty is brought by certain sayings of St. Thomas that seem to sound to the contrary. For in the First Part, q. LXXI, a. 1, ad 1, he says that those things which are naturally generated from seed cannot naturally be generated without seed. — In the First Book of the Sentences also, d. x, a. 5, he says that the same thing in species is not through putrefaction and semination. — In De Potentia also, q. III, a. 11, ad 1, he says that animals generated from seed and from putrefaction agree in genus, and differ in species. — In De Veritate also, q. XII, a. 2, ad 4 ¹⁷, he seems to admit that mice generated from seed cannot be of the same species as those that are generated from putrefaction.

4. Third, a difficulty is brought by the reasons of Averroes, VIII Phys., comment 46, and in the Paraphrase on De Gen. Animal., book I, ch. 1. The first is: If matters are diverse, forms are also diverse. But it is agreed that putrid matter is one thing, and menstrual blood another. Therefore etc. — The major premise is proved. Both because otherwise there would not be a proper form of this matter, and then anything could be generated from anything; and because matters would be idle.

The second is: If it were so, then the same species would be from nature and from chance. But this is false. Both because what comes about from nature is opposed to that which comes about from chance; and because no species is from chance.

The third is: If what is generated from seed can be generated as the same thing by an equivocal agent through putrefaction, either this will come about of necessity and always; or in the majority of cases; or rarely. If the first, therefore it will never be generated from seed. If the second, therefore it will naturally be generated equivocally, and thus rarely will it be generated from seed: which is agreed to be false. If the third, therefore it will be generated by chance: but this was said above to be repugnant to species. Therefore etc.

The fourth is: Of one thing there is only one mode of proceeding from another. Therefore etc.

To the reason brought forward above ¹⁸ for the position of St. Thomas, however, it could be said, from the things that are contained as brought forward in the Paraphrase, that the likeness between things generated through putrefaction and through semination does not necessarily argue specific identity: because sense cannot judge in all things that in which a species is one or many. For even between what is natural and what is artificial there can be so great a likeness that they will be judged to be one according to species: as is clear concerning silver generated by nature, and concerning silver produced through the art of alchemy.

VIII. For the resolution of these doubts, it should be known that things generated from putrefaction fall into a twofold difference. For some claim this determinate mode of generation for themselves by nature, so that they are generated only by an equivocal agent and from putrid matter. But others are generated from putrid matter by an equivocal agent in such a way that they can also be generated by an univocal agent through semination. Now, each genus has it from the imperfection of its nature that it can be generated from putrid matter by an equivocal agent, but the first genus is more imperfect than the second: for in the first genus certain worms and the like are placed; but in the second, mice, frogs, and similar things. Concerning those that are generated from putrefaction in the first way, it is evident that they cannot be the same in species with anything begotten through semination: for it is repugnant that such a nature be generated only through putrefaction and also through semination. Hence things of this sort either do not generate at all; or, if they do generate, they generate something diverse from their own species that is neither male nor female, such as certain little worms, as Aristotle says in the passage cited,¹⁹ chapter XVI. But concerning those that are generated in the second way, it is manifest that they can be the same according to species with something produced through semination. And therefore it is not unfitting that they generate something similar to themselves according to species.

IX. To the authority of Aristotle,²⁰ therefore, it is said that it is not to be understood universally of all things begotten through putrefaction, but only of those that belong to the first genus, which, I say, have it by nature to be generated only from putrid matter and by an equivocal agent. For of these, some do not generate, according to Aristotle's mind in the aforesaid chapter, such as gnats and little worms; while others do indeed generate, but another genus, such as fleas, flies, and the like.

If it be urged that the aforesaid authority is to be understood universally of all, because the reason he brings forward extends to all, namely this: If animals were to arise from the coitus of those that did not arise from animals, these, if they were of the same genus, would require that the first origin of the parents also be such. But if they were dissimilar, yet able to copulate with one another, again from these another certain nature would be procreated, and another from that, and so on to infinity²¹: — it is said that this reason does not conclude universally of all, but only of the first genus. For if from those things that have it to be generated only from putrid matter and by an equivocal agent, something similar according to species were produced through semination, it follows that the parents too would be of such a nature as could be procreated through semination. But this is impossible, by hypothesis. Also, if male and female were produced diverse from their parents according to species, and they likewise procreated others diverse, and so to infinity: which nature abhors. — But speaking of the second genus, it is not unfitting, if they produce something of their own genus, that the parents also have a similar origin: that is, that they have a nature which in a similar way could, as far as it is of itself, have been procreated in them through semination.

X. To the difficulty that arises from the words of St. Thomas,²² the answer is made.

To the statement from the First Part, it is said that St. Thomas does not intend to deny that some things begotten from seed can also be generated the same according to species from putrid matter; but that those things which are generated from seed by the inclination and active power of their own nature cannot, by the power of such a nature of theirs, be generated through putrefaction; for the active power of one nature is determined to one mode of producing. But it is not repugnant to this that they can be generated from putrid matter through the power of a celestial body, acting in place of the power of such a nature.

To the statement from the First Book of the Sentences, it is similarly said that the sense of those words is that it is not the same in species by the active power of its own nature in both of those modes. — It can also be said that the sense is that the same in species is not produced per se from semination and putrefaction, comparing them to particular causes. For, as St. Thomas says in VII Metaph.,²³ the generation of an animal from putrefaction, if it be referred to particular causes acting here below, is found to be per accidens and by chance: because it is beside the intention of the heat that causes the putrefaction that this animal should be generated from the putrefaction.

To the statement in the Qu. de Potentia, it is said that it is understood of those things that have to be generated only from putrefaction on account of the utmost imperfection of their nature; but not universally of everything begotten through putrefaction. Moreover, III Sent., d. xxxiii,²⁴ a. 2, quª. 4, ad 1, expresses this sense, if it be closely examined.

To the statement from the Qu. de Ver., it can first be said that he is speaking according to the mind of the Commentator. Hence in arguing he also cites him. — It can secondly be said that he is not speaking universally of the whole genus of mice begotten from putrefaction, but of a certain determinate species of them that can be generated only from putrefaction. For such a species is distinguished from that species of mice which can be generated both from semination and from putrefaction.

XI. Next, to the arguments taken from Averroes,²⁵ the answer is made.

To the first, indeed, it is said that the proximate matter of a thing is twofold: one inhering and remaining in the thing begotten, just as flesh and bone are the matter of the human body; the other transient and not remaining in the thing begotten, just as menstrual blood is the matter of the human body. If the major premise be understood of the first matter, it is universally true. But it is said that such matter in things begotten from seed and from putrefaction that are of the same species is of the same nature in both: for such an animal is not generated from putrid matter by the power of a celestial body unless by that very power it is brought back to that disposition of matter which such a form requires. — But if it be understood of the second matter, it has truth only in perfect natures. For there are some natures that can be produced not only from matter brought back to a certain perfection, as from transient matter, but also from matter imperfectly disposed and putrid.

To his first proof, it is said that, although for any specific matter there is one proper specific form from which it is constituted, yet it is not necessary that for any such matter there be one proper form, namely one that can be educed from that matter alone. For we see in man that the nature of blood is generated from foods of diverse species. — Yet it does not follow that anything can be generated from anything. For the form determines for itself the matter of some determinate genus, so that it could not be educed from matter outside that genus, although it may be educed from several species of that genus: for although blood is generated from many species of things, yet not from each and every thing.

To the second proof also, it is clear that the consequence is false.

2. To the second argument it is said, according to the doctrine of Aristotle in VII Metaph., text 22, and of St. Thomas in the same place,²⁶ that it is not unfitting for some species to be made by nature according to some individual of it, and to be made by chance according to another, if reference be made to particular causes. Hence the falsity of the consequent is denied, if such generation be referred to the particular causes themselves. — But if the generation from putrefaction be referred to the celestial power, the consequence is denied. For, as St. Thomas says in the same place, it is of the intention of the celestial power that all forms that are in the potency of matter be educed into act.

To the first disproof of the consequent, it is said that, although to be made by nature and to be made by chance are modes opposed of themselves, yet it is not unfitting that, in relation to diverse causes, they belong to one and the same species. For the discovery of a treasure that is intended by one person happens per accidens to another.

To the second, it is said that, although no whole species is by chance, yet it is not unfitting that some individual of a species, in relation to some one of the lower causes, should happen by chance.

3. To the third argument it is said first that, if we speak absolutely, such an animal is generated more rarely from putrefaction than from semination.

It is said secondly that, if generation from putrefaction be referred to the celestial cause, it happens for the most part: for for the greater part, from matter so putrefied, the celestial power generates an animal of this sort. For as was said above according to the mind of St. Thomas, it is of the intention of the celestial power that all forms that are in potency in matter be educed into act. Therefore, just as other natural causes produce for the greater part the effects to which they are naturally inclined, if they act upon disposed matter, so also must it be said of the heaven.

Now when it is urged against the first statement that then the species would be by chance: — the consequence is denied. For that something should happen rarely in an absolute sense does not make it to be said to happen by chance: otherwise the conjunction of all the planets in the sign of Pisces, which happens exceedingly rarely, would be said to be by chance. But something is said to happen by chance when, beside the intention of the agent, it is rarely conjoined to its effect, as is clear from II Physics.²⁷

When it is also argued against the second statement that then such an animal will be generated naturally equivocally: it is said that this is not unfitting. For it has been said both that animals of this sort, on account of the imperfection of their nature, have it that they can be produced by an equivocal agent,²⁸ and that the celestial power is inclined toward their generation.²⁹

4. To the fourth argument, it can first be answered that that assumption has truth only in perfect natures, but not in imperfect natures.

It can secondly be answered that it has truth concerning the mode by which the nature itself is communicated by the supposit of the nature. For, since the supposit of a nature, in so far as it is such, does not generate except by the active power of such a nature, while the power of the nature is limited to one mode of communication, it follows that the supposit of the nature itself generates in only one mode. But it is not repugnant to this that such a nature can also be communicated by a universal power in another mode.

If, however, it be urged against this that productions of diverse ratios terminate at terms distinct in species, since movements receive their species from their terms: — it is said that this is true of productions that are of diverse ratios essentially, but not of those that are of diverse ratios accidentally, of which kind are generation through putrefaction and generation through semination of the same specific nature. For these are not of diverse ratios except because one is from an univocal agent, and the other from an equivocal agent, not indeed as it is distinguished from an univocal agent, but as it contains the power of that univocal agent within itself.

5. It should be noted, however, that although the Commentator, from the arguments adduced, seems to oppose the opinion of St. Thomas, yet from what he says elsewhere, it seems that he agrees with that opinion. For concerning fire, which it is certain is sometimes generated by an univocal agent, he posits in III De Caelo, comment 56, and XII Metaph., comment 18, that it is also generated through local motion, and from a stone, and consequently by an equivocal agent. On account of which it seems to some that his statement in VIII Phys. is to be understood of perfect natures only, of which alone he gives examples there.

6. But to the reply that was given to the argument for the opinion of St. Thomas,³⁰ it is said that it is not satisfactory. For granted that sometimes, on account of similarity in figure and color, we cannot clearly discern the specific diversity of certain things; yet similarity in figure, and operation, and motion and organs of motion, and agreement in the same conservants and corruptives, does not seem to exist between those things that are diverse in species. And therefore agreement in these is a sufficient indication of specific identity. For a posteriori we do not come into knowledge of specific unity or diversity in any other way than from the consideration of these.

XII. To the first argument of Avicebron,³¹ St. Thomas says first that quantity does not impede the action of form except per accidens, in so far as all continuous quantity is in matter: but a form that is in matter, since it is of less actuality, is also of less power in acting.

He says secondly that, supposing the mode of action that a form existing in matter can have, quantity does not diminish, but rather increases action and natural motion: although heavy bodies are of slower unnatural motion when they are of greater quantity.

Concerning that proposition, All continuous quantity is in matter, observe that St. Thomas determines himself to continuous quantity: both because the objection intended that, and because according to some, discrete quantity is found even in immaterial things. For although with him discrete quantity is found only in material things, just as continuous quantity is,³² yet so that his response might be more absolute and further removed from cavil, he determined himself to continuous quantity, concerning which no one in the way of Aristotle doubts that it follows matter.

2. To the second he says first that, although corporeal substance is lowest in the order of things, yet it is not necessary that every body lack action: because even among bodies one is higher, and more formal, and more active than another; as is clear concerning fire with respect to the lower bodies.

He says secondly that not even the lowest body is excluded from acting. Because every body acts according to its form, to which another body is compared according to its matter as a subject, in so far as its matter is in potency to the form of the agent. But if conversely the matter of the acting body is also in potency to the form of the patient body, they will be acting and patient mutually: as happens in the elements. But if not, one will be agent only, and the other patient only with respect to it: as the heaven is related to the elements.

3. To the third he answers by denying that a body is at the maximum distance from God. For prime matter, which is pure potency, is that which is most distant from God, who is pure act. Therefore it belongs to it to be acted upon only, but not to act. But bodies approach the divine likeness in so far as they have form. Therefore they act according as they have form, but are acted upon according as they have matter.

XIII. To the argument of the Moors³³ he answers that it is ridiculous. Because a hot body is not said to heat as though the numerically same heat that is in the heating body passed into the heated body: but because by its power another heat numerically is made in act in the heated body, which previously was in it in potency. And this is common to every natural agent.

Observe from St. Thomas, Pot., q. III, a. 7, that that proposition, The same accident does not migrate from subject to subject, is understood of the same accident numerically: but not to prevent a similar one according to species, by the power of the accident existing in some subject, from being able to be induced into another subject.