Chapter 29 — Continuation of the foregoing

If, however, we consider the production of a particular creature, it will be possible to find in it a debt of justice by comparing a subsequent creature to a preceding one. And I say preceding, not only in time but also in nature.

Accordingly, in those divine effects which were to be produced first, we find no debt, but in the subsequent production we find a debt, yet in a different order. For if those things that are first naturally are also first in being, those which follow become due on account of those which precede. For given the causes, it is due that they should have actions by which to produce their effects. On the other hand, if those which are first naturally are subsequent in being, then those which are first become due on account of those which come afterwards: thus it is due that medicine precede in order that health may follow. And in either case there is this in common—that what is due or necessary is claimed by that which is naturally first from that which is naturally subsequent.

Now the necessity that arises from that which is subsequent in being, and yet is first by nature, is not absolute but conditional necessity (namely, if this must be done, then that must precede). Accordingly, with regard to this necessity, a debt is found in the production of creatures in three ways. First, so that the conditional debt is on the part of the whole universe of things in relation to each part of it that is necessary for the perfection of the universe. For if God willed such a universe to be made, it was due that he should make the sun, moon, and such things, without which the universe cannot be. Second, so that the conditional debt be in one creature in relation to another. For instance, if God willed the existence of plants and animals, it was due that he should make the heavenly bodies, by which those things are preserved, and if he willed the existence of man, he had to make plants and animals and the like, which man needs for perfect existence, although God made both these and other things of his mere will. Third, so that the conditional debt be in each creature in relation to its parts, properties, and accidents, on which the creature depends either for its being, or for some one of its perfections. Thus, given that God willed to make man, it was due, on this supposition, that he should unite in him soul and body, and furnish him with senses and other like aids, both within and without. In all of which, if we consider the matter rightly, God is said to be a debtor not to the creature, but to the fulfilment of his purpose.

There is also in the universe another kind of necessity by which a thing is said to be necessary absolutely. This necessity depends on causes which precede in being: for instance, on essential principles, and on efficient or moving causes. But this kind of necessity cannot find place in the first creation of things as regards efficient causes. For there God alone was the efficient cause, since to create belongs to him alone, as we have proved above. (Ch. 21.) But in creating, he works not by a necessity of his nature, but by his will, as we have shown above. (Ch. 23.) And those things which are done by the will cannot be necessitated except only by the supposition of the end, on account of which supposition it is due to the end that those things should be by which the end is obtained.

On the other hand, with regard to formal and material causes, nothing hinders us from finding absolute necessity even in the first creation of things. For from the very fact that certain bodies were composed of the elements, it was necessary for them to be hot or cold, and from the very fact that a surface was drawn in the shape of a triangle, it was necessary that it should have three angles equal to two right angles. Now this necessity results from the relation of an effect to its material or formal cause. Therefore, on this account God cannot be said to be a debtor, but rather the debt of necessity falls on the creature. But in the propagation of things, where the creature is already an efficient cause, an absolute necessity can arise from the created efficient cause: thus the lower bodies are necessarily influenced by the movement of the sun.

Accordingly, from the aforesaid kinds of debt, natural justice is found in things both as regards the creation of things, and as regards their propagation. Therefore, God is said to have produced and to govern all things justly and reasonably.

Therefore, by what we have said we remove a twofold error, namely, of those who, setting limits to the divine power, said that God cannot make except what he makes, because he is bound so to make, (Ch. 28.) and of those who assert that all things result from his simple will, without any other reason either to be sought in things, or to be assigned. (Ch. 24.)