Chapter 28 — Of the divine perfection

Now, although things that exist and live are more perfect than those which only exist, yet God, who is not distinct from his own existence, is universally perfect being. (ST I.4.2.) And by universally perfect I mean that he lacks not the excellence of any genus.

For every excellence of anything whatsoever is ascribed to it in respect of its being: for no excellence would accrue to man from his wisdom unless he were wise by it, and likewise with other things. Therefore, a thing’s mode of excellence is according to its mode of being: for according as its being is drawn to some special mode of excellence more or less great, it is said to be more or less excellent. Hence, if there be a thing to which the whole possibility of being belongs, it cannot lack any excellence that belongs to anything. Now, to a thing which is its own being, being belongs according to the whole possibility of being. Thus, if there were a separate whiteness, nothing of the whole possibility of whiteness could be wanting to it: for something of the possibility of whiteness is lacking to a particular white thing through a defect in the recipient of whiteness, which receives it according to its mode and, maybe, not according to the whole possibility of whiteness. Therefore, God, who is his own being, as shown above, (Ch. 22.) has being according to the whole possibility of being itself: consequently, he cannot lack any excellence that belongs to anything.

And just as every excellence and perfection is in a thing according to its being, so every defect is in a thing according as that thing, in some sense, is not. Now, just as God has being wholly, so is non-being wholly absent from him, since according as a thing has being it fails in non-being. Therefore, all defect is removed from God, and consequently he is universally perfect.

But those things which only exist are imperfect not on account of an imperfection in absolute being itself (for they do not have being according to its whole possibility), but because they participate in being in a particular and most imperfect way.

Again. Every imperfect thing must be preceded by some perfect thing: for example, seed is from some animal or plant. Therefore, the first being must be supremely perfect. Now it has been shown (Ch. 13.) that God is the first being. Therefore, he is supremely perfect.

Moreover. A thing is perfect insofar as it is in act, and imperfect insofar as it is in potency and void of act. Therefore, that which is no way in potency but is pure act must be most perfect. Now such is God. (Ch. 16.) Therefore, he is most perfect.

Further. Nothing acts except according as it is in act: therefore, action follows upon the mode of act in the agent. And consequently it is impossible for the effect that results from an action to have a more excellent act than that of the agent, although it is possible for the act of the effect to be more imperfect than that of the active cause, since action may be weakened on the part of that in which it terminates. Now in the genus of efficient cause we come at length to the one cause which is called God, as explained above, (Ch. 13.) from whom all things proceed, as we shall show in the sequel. (Bk. 2, ch. 15.) Therefore, it follows that whatever is actual in any other thing is found in God much more eminently than in that thing, and not conversely. Therefore, God is most perfect.

Again. In every genus there is some thing most perfect in that genus, by which every thing in that genus is measured, since everything is shown to be more or less perfect according as it approaches more or less to the measure of that genus. Thus white is said to be the measure in all colors, and the virtuous among all men. (Aristotle, Nicomachean Ethics 3.4, 1113a20–32.) Now the measure of all beings can be none other than God, who is his own being. Therefore, no perfection that belongs to any thing is lacking to him, otherwise he would not be the universal measure of all.

Hence it is that when Moses sought to see the face of God, the Lord answered him: I will make all goodness pass before you (Exod 33:19), giving thus to understand that the fullness of all good is in him. And Dionysius (On the Divine Names 5) says: God exists not in any single mode, but embraces and prepossesses all being within himself, absolutely and without limit.

It must, however, be observed that perfection cannot fittingly be ascribed to God if we consider the meaning of the word in respect of its derivation, since what is not made cannot, it seems, be described as perfect. Yet since whatever is made has been brought from potency to act, and from non-being to being, when it was made; it is rightly described as perfect (that is, completely made) when its potency is completely reduced to act, so that it retains nothing of non-being, and has complete being. Accordingly, by a kind of extension of the term, “perfect” is applied not only to that which has arrived at complete act through being made, but also to that which is in complete act without being made at all. It is thus that we say that God is perfect, according to Matthew 5:48: be you perfect, as also your heavenly Father is perfect.