Commentaria in Summam contra Gentiles, Liber I

After Saint Thomas has determined concerning the intellect and the will, from which life can be known, he consequently determines concerning the divine life ¹. Concerning this, however, he does two things: first, he determines concerning life itself; second, concerning the species of that life, in chapter 3.

Concerning the first, he does three things: first, he determines concerning it with respect to whether it is; second, with respect to what it is ²; third, with respect to its duration ³.

I. First, therefore, this conclusion is laid down: God is a living being. It is proved first. God is intelligent and willing. Therefore He is living: because to understand and to will belongs to nothing but a living being. Second ⁴. God acts not from another but most of all from Himself. Therefore living belongs to Him in the highest degree. — The antecedent is proved: because God is the first efficient cause. — The consequence is proved: because living is attributed to certain things on this ground, that they are seen to move of themselves, not from another. And since sensible operations are accompanied by motion, it is said further of that which moves itself to its proper operations, even though these are not accompanied by motion, that it lives. — This assumption is explained. And from those things which we call living by similitude, as we call living water and quicksilver, because they seem to move of themselves, since the common people do not perceive their movers. And from those things which we call living properly and solely, namely those which alone are moved of themselves properly, being composed of a mover and a moved, as are ensouled things.

II. Concerning this argument, a twofold doubt arises. For Saint Thomas seems to wish to say that all things that move themselves properly are animate, and that all living and animate things move themselves. Against the first it is argued. For heavy and light bodies move themselves, and yet they are not animate; therefore etc. The antecedent is proved: because if they were said to be moved per se by another, this would be only because they are moved by the generator. But this cannot be. For it sometimes happens that the generator does not exist, and yet they themselves are moved. But an effect in act requires a cause in act ⁵. If it is said that this generator is the heaven, and that this is always in act: against. To a particular effect one must assign a particular cause, as is said in II Physics ⁶; but the heaven is not a particular cause, but a universal one; therefore etc. — Second, because the Commentator, IV On the Heavens, comment 25 ⁷, says that motion upward is caused by levity. But it is evident that levity is intrinsic to the light body.

Against the second position it is argued ⁸, because Saint Thomas, in the Questions On the Soul, a. 9, ad 6, places in the same order the motion of the heart, the motion of fire, the motion of growth and diminution, and the motion of nourishment diffused through the whole body. He adds, moreover, that the heart does not move itself, but is moved naturally, as fire is. Therefore things that grow and diminish, such as plants, do not move themselves. And thus it is false that all living things move themselves.

III. For the clarification of the first doubt, it must be considered that the natural motions of simple bodies, as is set forth in Book III of this work, chapter XXIII, follow from natural forms, just as all other natural properties do. Therefore the motion of heavy and light bodies must be treated in the same way as the other properties of things. Now this property of a thing has the following character: it is caused first and principally by the giver of the form, but secondarily and proximately by the form of the thing itself, though differently. For from the giver of the form it is produced through a mediating action, which is terminated first at the form and secondarily at the property. But from the form it is produced by a certain natural resultant without any mediating action, as Saint Thomas seems to intend in Prima Pars, q. lxxvii, a. 6 ⁹ and 7 ¹⁰. Hence the giver of the form is simply the cause of the properties, producing them by his own proper action. The form, however, is in a certain way and in a qualified sense their cause, inasmuch as it does not produce them by its own mediating action, but they result naturally from it as from the principal agent that first produced them: just as Socrates' capacity for laughter is produced first and principally by the one who generates Socrates, and secondarily, by a natural resultant, from the nature of Socrates himself.

2. It must be considered, secondly, that those properties which cannot be prevented from occurring once the thing is posited—because they are perfections of the first order that at once possess the character of a complete form, such as risibility—are placed in complete act by the action by which the thing itself is produced: since one action of the agent terminates in both, namely in one primarily and in the other secondarily. But those properties which can be prevented, once the thing is posited, from being in formal and complete act—inasmuch as they are acts of the second order, and a way toward acquiring something extrinsic, such as motion to a place—can be placed in complete formal act even after the action of the producer of the nature has ceased: for when the impediment is removed, they result naturally. They are nevertheless said to be from the generator and producer of the nature even as regards their completion, because from him is the foundation and cause from which they result naturally and according to their completion, namely the substantial form; not because he produces them through a new action. Ignorance of this makes many go astray. For they think that St. Thomas wishes heavy and light bodies to be moved thus by the generator, even when he himself has been corrupted, as though he moved them through some new action and a new impulse: which he never dreamed. But his meaning is that they are moved by the generator as by him who gave the form from which motion naturally results, and consequently as by him who fundamentally produced the motion; nor is it necessary to posit anything else by which they are moved through impulse or action, but it suffices that there be the remover of what prevents them, and the form of the thing, in which the power of the agent is preserved, toward which the motion naturally results once the impediment is removed. Just as, if it could be prevented that risibility follow upon the generation of a man, yet once the impediment was removed it would result naturally, it would be said that the generating man is the first and per se cause of that risibility, but not the man generated.

3. To the argument ¹¹, therefore, the antecedent is denied, when we speak of what moves itself properly and simply. — In reply to the proof, it is said that things are moved per se by the generator as by the one giving the form to which motion naturally results: just as the other perfections that naturally follow upon the form are from the generator. But they are moved accidentally by the one who removes an impediment. When this is objected to, in answer to the first objection it is said that an effect in act requires a cause in act, either in itself or in something in which its power is preserved. For an effect which was not previously in act in any way requires a cause in act in itself; but for an effect which preexisted in its root and natural foundation—as motion, though impeded, preexists in the form of a heavy thing—it suffices that the principal cause be in power in the form to which such an effect naturally results. And thus it is granted that it is not in itself able to move by a power remaining in a form produced by it, and to cause a motion which preexisted radically and fundamentally in the form, and which, once the impediment is removed, results naturally and without mediate action upon that very form. If it is said: Therefore we may say that the heavy form itself is what moves the heavy thing, since no mover in act appears besides that form itself, in which is the power of the agent; and thus the heavy thing will move itself,—it is said that if we speak of the mover simply and first, the consequence is denied; but it does follow well that it is that by which the mover moves. And when it is said that no mover existing in act appears, the reply is that it is not necessary to assign to that motion any mover simply which is in act in itself; because such a motion is not produced wholly anew, since it preexists in the root and foundation, to which, once the impediment is removed, it follows of necessity through natural resultance, not however through mediate action. — If, however, we speak of the mover in a qualified sense and secondarily, because something comes about through it mediately from the agent, then it is granted that the heavy form itself moves the heavy thing. And consequently, that the heavy thing moves itself in a qualified sense, insofar as there is in it in some way an active principle of its own motion. Yet it does not follow that it moves itself simply: for that is said to move itself simply which is divided into two parts, one of which moves through mediate action and the other is moved; which cannot be the case in simple bodies.

To the second objection it is said that the mind of the Commentator is that light motion is caused by lightness in a qualified sense, namely as by a formal principle from which, through natural resultantia, it proceeds; but not as from a principal agent and through a mediating action producing the motion.

IV. To the second ¹² it must be said that Saint Thomas placed all those motions in the same order, because they all agree in this common character, namely that they are natural motions. For, since animal motion is distinguished into animal and natural—into that motion which is through apprehension and appetite, inasmuch as it is from the sensitive soul qua sensitive soul; and into that motion which is through a natural form, namely the motion which is from the soul of an animal inasmuch as it contains the perfections of other lower forms—the enumerated motions are not among those motions called animal, but among those called natural. Yet under this common character they are distinguished. For the motion of the heart is from an extrinsic principle, namely from the generator giving it its form, just as the motion of fire: therefore the heart is not said to move itself, any more than fire. But the motion of nutrition and augmentation is from an intrinsic mover, namely from that part in which the nutritive and augmentative power resides subjectively: and therefore what is nourished and augmented is said to move itself. Hence it is said in Prima, q. XVIII, a. 3, that plants move themselves according to the form implanted in them by nature. And thus it is clear that plants are moved naturally as the heart is, because by a natural form: and they are moved by themselves, inasmuch as they are distinguished into a moving part and a moved part, wherein their distinction from the heart lies.

V. Thirdly ¹³. Divine esse is to live. Therefore etc. — The antecedent is proved: because divine esse comprehends every perfection of being. Now to live is a certain perfect esse — understand, one importing no imperfection according to its formal account.

It is confirmed by Deuteronomy 32, and the Psalms, etc.