Commentaria in Summam contra Gentiles, Liber I

After the determination concerning divine cognition in itself, Saint Thomas further determines it on the side of the medium of knowing ¹. And he posits this conclusion: The divine intellect understands by no other intelligible species than its own essence.

I. It is proved first. Because if it understood through a species other than its own essence, something else would be the principle and cause of the divine essence. — The consequence is proved. Because the species is the formal principle of intellection, just as the form of any agent is the principle of its proper operation. Since therefore the intellectual operation of God is his essence, something else will be the principle of the essence.

Note here that the form, which is the ratio of acting inherent in the immediate principle of operation, is formally the specifying principle of the operation, and its elicitive principle as well as its effective productive one—yet as a principle by which, not as a principle which. Therefore, if there were in the divine intellect a species distinct from the essence, it would be some effective and specifying principle of that intellection, and consequently of the essence itself.

Second. The divine intellect would be in potency with respect to something. For the species is related to the intellect as act to potency, since by means of it the intellect is actualized and becomes actually understanding.

It should be noted that through the species the intellect becomes actually understanding, not indeed with ultimate actuality, because, as we said ², through understanding it becomes actual in a completive way within the genus of intelligibles; but only in first act, in that manner in which something becomes actual through a form when operation is set aside.

Third. In God there can be no accident. Therefore neither a species distinct from the intellect. — The consequence is evident, because a species distinct from the essence of the intellect has accidental esse.

Note that the divine essence, which is united to the intellect of the blessed in the manner of a species, must be excluded from the universality of this proposition: for it does not have accidental esse. — Or it should be said that Saint Thomas is speaking here of a species that is united to the intellect formally with respect to its esse: and in that way the divine essence is not united to the intellect of the blessed.

Fourth. That species will be a likeness either of the divine essence or of another thing, because an intelligible species is the likeness of something understood. Not of the divine essence: for then it would not be intelligible through itself, but would be made intelligible through that species. — Nor of another thing: because it would be impressed upon it either by itself or by another. Not by itself: then because the same thing would be agent and patient; and also because there would be some agent that induced in the patient not a likeness of itself but of another, and thus not every agent would produce what is like itself. Nor by another: because then there would be some agent prior to it. — Therefore, etc.

II. But several doubts arise in this argument. The first is that it does not seem to follow that, if there is in the divine intellect a likeness of the divine essence itself, the latter is not intelligible through itself. For one angel, as will be shown below ³, understands another through its species, and yet each is intelligible in itself, since it is immaterial.

The second is that it does not seem unfitting on the part of the intellect that the same thing should be agent and patient. For the intellect produces in itself the act of understanding and the concept.

The third is that it does not seem unfitting for something to produce a likeness of another thing: just as the intellect in act produces a concept, which is a likeness of the thing understood; and the imagination produces within itself the likeness of a golden mountain.

III. To the first it is answered that St. Thomas does not make that inference as though no actually intelligible thing could be understood absolutely through a species, but because it does not need a species in order to be understood by itself. For, since it is present to itself, there is no need for a species representing it to the intellect in intelligible being, if it is actually intelligible. And if the essence of some thing needs a species in order to be understood by itself, this is a sign that of itself it is not intelligible, nor is it placed among intelligibles as an act or as existing in act, but as a potency: just like our intellect.

To the second it is said that even in the intellect the agent and the patient cannot be altogether the same. For the intellect, together with the species by which it understands, produces both the act of understanding and the concept; but it alone receives that species. Hence agent and patient are not altogether the same. If, however, the divine intellect were to cause in itself the intelligible species by which it understands, then agent and patient would be altogether the same.

To the third it is said that it is not unfitting for something to produce the likeness of another when that other is also like the agent: for what is the likeness of a thing is also the likeness of that to which the thing is assimilated. But it would be unfitting for an agent to produce a form which is only the likeness of another and not of the agent itself. This would happen if the divine intellect, considered in itself alone, caused in itself the likeness of some intelligible object.

But as to the objection pressed from the intellect and the imagination: — it is said that the concept produced by the intellect is not only a likeness of the thing understood, but also a likeness of the intellect informed by the intelligible species, inasmuch as the intellect in act has a likeness, indeed a kind of identity, with the thing understood. — Similarly, the likeness of the golden mountain formed by the imagination is also a likeness of the imagination having within itself the species of gold and the species of mountain.

IV. Fifth. It would follow that it would be through something other than its essence. — The consequence is proved. Because God's understanding is his essence.

Note that this argument differs from the first. For the first argued about the essence, that it would have a beginning and a productive cause; but in this one it is argued that esse itself would be produced by another, just as its understanding is, and thus God would be in the order of things through another, as through the cause of his esse. And although esse and essence are identical in him, yet because they are formally distinguished on the part of our intellect, diverse arguments can be drawn from them.