Commentaria in Summam contra Gentiles, Liber I

After St. Thomas had determined the question of divine knowledge on the side of the knower, he now determines it on the side of the object ¹. In regard to this he does two things: first, he treats of the first and per se object of divine knowledge; second, of its secondary object, in chapter XLIX.

Concerning the first, he does two things: first, he shows that God knows himself perfectly; second, that he knows only himself first and per se, in the chapter that follows.

I. First, therefore, he lays down this conclusion: God perfectly understands himself.

It is proved, however, first. The intelligible species by which the divine intellect understands is entirely the same to God himself, because it is the divine essence. And it is altogether one with the intellect. Therefore he understands himself most perfectly. — The consequence is proved. Because, since the intellect through an intelligible species is directed toward the thing understood, the perfection of intellection consists in this: that the intelligible species be perfectly conformed to the thing understood (namely by a conformity of representation) and perfectly joined to the intellect. But an intelligible species cannot be more conformed to the thing understood than if it were entirely one with it; nor more united to the intellect than if it were one with it in reality. Therefore etc.

II. Second. God is altogether immaterial, and is most one in Himself. Therefore He understands Himself most of all. — The consequence is proved. For a thing is intelligible in itself precisely insofar as it is immaterial, since a material thing is made intelligible through abstraction from matter and from material conditions. But it is understood insofar as it is one in act with the one understanding.

How the intelligible is one in act with the one understanding has been said above ². Yet it must be noted that St. Thomas said that it must become one in act with the intellect. For before the intellect is informed by the intelligible species, it is one with the intelligible only in potency, insofar as the intellect is in potency to its reception. But this is not what is meant here; rather, it is required that it be united to the intellect in act. Likewise, an intellect informed by a species, if it does not actually understand, is indeed one in act with the intelligible, but not in perfect act. Therefore, at that time the thing is understood only in an imperfect way, namely habitually. But when it is in actual consideration, the intelligible is one with the intellect in a perfect manner. Therefore, at that time it is understood perfectly.

III. Third. The divine intellect is always actually understanding, and the divine essence is in itself perfectly intelligible. Likewise, the divine intellect and the divine essence are one. Therefore God perfectly understands himself. — The consequence is proved: because something is understood in act when the intellect in act and the understood in act are one.

Note that this argument is formally distinct from the preceding one. For there the intellect was considered absolutely, and its intelligible union with it. Here, however, the intellect is considered as always actually understanding, and the union in act of the intelligible with an intellect always actually understanding.

IV. Fourth. God understands His own essence. Therefore He understands Himself: because He Himself is His essence. — The antecedent is proved. Because the divine essence is in God in an intelligible manner, since the natural esse and the intelligible esse of God are one and the same, as His esse is His understanding. But whatever is in anything in an intelligible manner is understood by it.

It must be noted that to be in something in an intelligible manner is to be in it as actually intelligible by that thing. And because being actually intelligible follows upon immaterial being, as was shown above ³, therefore whatever is in something immaterially is in it in an intelligible manner. In God, however, all things are as actually intelligible and immaterially: for, since each thing is received according to the mode of the receiver, and the divine natural esse is really identical with understanding, nothing can be in God except in an intelligible manner, since a material thing having esse cannot be in that which is wholly immaterial, and which exists really in the nature of things through His very understanding.

V. Fifth. The operation of the divine intellect is the most noble, since it is the divine esse itself. Therefore God understands himself. — The consequence is proved. For an operation is the more perfect the more perfect the intelligible is, because the acts of the intellect, like those of the other powers of the soul, are distinguished and specified by their objects. But the divine essence is the most perfect intelligible, since it is the most perfect act and the first truth. Therefore the most perfect act of understanding must terminate at the divine essence.

It should be noted that, since being and the true are the object of the intellect—the one as that which terminates the act of the intellect, the other as that which accompanies every act of understanding—Saint Thomas attributes to the divine essence, in both respects, the character of the most perfect object: because, I say, it is both the most perfect act and the first and consequently supreme truth.

It must also be noted that, when Saint Thomas says that the acts of the intellect are distinguished by their objects, he also gives us to understand that they are specified and receive their perfection from the objects: for it is the act which distinguishes formally and separates. Therefore, to say that they are distinguished by their objects is to say that the objects are the forms of those acts: and consequently, from them they have both their species and their perfection. But this will perhaps be treated more fully below.

VI. Sixth. To understand God is the greatest perfection. Therefore it belongs most of all to God: because the perfections of all things belong most of all to God. — The antecedent is proved. Because the intellectual nature excels all other natures; and the noblest intelligible object is God. From which it follows, since by understanding the intellectual nature excels the other natures, and the most perfect understanding is that which terminates in the most perfect intelligible object, which is God, that the nature which understands God excels all others absolutely. And thus to understand God is the greatest perfection.

It is confirmed also by the authority of the Apostle, I Cor. II, who says that the Spirit of God searches even the deep things of God.