Chapter 22 — That in God essence and existence are the same

From what has been shown above, we may go on to prove that in God essence or quiddity is not distinct from his existence.

For it has been shown above (Ch. 13.) that there is a thing which exists of itself necessarily, and this is God. Now necessary existence, if it belong to a quiddity which is not that existence itself, is either inconsistent with or repugnant to that quiddity—as existence in itself is to the quiddity of whiteness—or else is consistent or associated with it—for instance, that whiteness exist in some other thing. In the first way, the existence that is necessary in itself will not be consistent with that quiddity—for instance, whiteness does not exist in itself. In the second way, either this existence must be dependent on the essence, or both of them on some other cause, or the essence on the existence. The first two are in contradiction with the very notion of necessary existence in itself: for if it depends on something else, it no longer exists necessarily. From the third, it follows that this quiddity is added accidentally to the thing which exists necessarily in itself, because whatever follows on the essence of a thing is accidental to it. Therefore, God does not have an essence distinct from his existence.

Against this, however, it might be urged that this existence does not depend absolutely on this essence, and in such a way that it would not be at all without the essence, but that it depends as regards the conjunction by which they are united together. And thus this existence is necessary in itself, while the conjunction is not necessary in itself.

But this answer does not avoid the above impossibility. For if this existence can be understood without this essence, it will follow that this essence is related accidentally to this existence. Now this existence is that which exists necessarily in itself. Therefore, this essence is related accidentally to that which exists necessarily in itself. Therefore, it is not its quiddity. But God is that which exists necessarily in himself. Therefore, this existence is not God’s essence, but something subsequent to it. But if this existence cannot be understood without that essence, then it absolutely depends on whatever its conjunction to that essence depends on: and thus the same conclusion follows.

Further. Each thing exists by its own existence. Therefore, that which is not its own existence does not exist necessarily in itself. But God exists necessarily in himself. Therefore, God is his own existence.

Moreover. If God’s existence is not his essence—and it cannot be a part of him, since the divine essence is simple, as shown above— *(Ch. 18.)*it follows that this existence is something besides his essence. Now whatever is becoming to a thing (besides its essence) is becoming to it through some cause: for those things which are not one essentially must be united through some cause, if they are united together. Therefore, existence is becoming to that quiddity through some cause. Either, then, this cause is something essential to that thing, or the essence itself, or else it is some other thing. If the former, and the essence exists according to that existence, it follows that a thing is a cause of its own existence.

But this is impossible, for, according to the understanding, the cause exists before the effect. And consequently, if a thing is the cause of its own existence, it would be understood to exist before having existence, which is impossible unless it be understood that a thing is the cause of its own accidental existence, which is a relative existence. Now this is not impossible: for we find an accidental being caused by the principles of its subject before the substantial being of the subject is understood to exist. However, we are now speaking not of accidental but of substantial existence. If, on the other hand, existence is becoming to the essence by reason of some other cause, then whatever acquires existence from another cause is caused, and is not the first cause. But God is the first cause having no cause, as shown above. (Ch. 13.) Therefore, this quiddity that acquires existence elsewhere is not the quiddity of God. Therefore, it is necessary that God’s existence is his own quiddity.

Moreover. Existence denotes a kind of act, since a thing is said to exist not through being in potency, but through being in act. Now, everything to which an act is becoming, and which is distinct from that act, is related thereto as potency to act: for act and potency are reciprocal terms. Accordingly, if the divine essence is distinct from its existence, it follows that his essence and existence are mutually related as potency and act. Now it has been proved that in God there is nothing of potency, and that he is pure act. (Ch. 16.) Therefore, God’s essence is not distinct from his existence.

Again. All that cannot exist unless several things concur is composite. Now no thing in which essence and existence are distinct from one another can exist unless several things concur—namely, its essence and existence. Therefore, everything in which essence and existence are distinct is composite. But God is not composite, as proved above. (Ch. 18.) Therefore, God’s existence is his essence.

Further. Everything exists through having existence. Therefore, nothing whose essence is not its existence exists by its essence, but by participation of something, namely, existence. Now that which exists by participation of something cannot be the first being, because that in which a thing participates in order to exist is prior to it. But God is the first being, to whom nothing is prior. (Ch. 13.) Therefore, God’s essence is his existence.

This sublime truth Moses was taught by the Lord, for when he asked the Lord: if . . . the people of Israel . . . ask me, ‘what is his name?,’ what shall I say to them? The Lord answered: I am who I am. Say this to the people of Israel: ‘he who is has sent me to you’ (Exod 3:13–14); thus declaring his own name to be “he who is.” Now every name is appointed to signify the nature or essence of a thing. Therefore, it follows that God’s very existence itself is his essence or nature.

Moreover. The Catholic doctors have professed this truth. For Hilary says in his book On the Trinity: (Hilary, On the Trinity, bk. 7, ch. 11.) Existence is not an accident in God, but the subsisting truth, the abiding cause, and the natural property of his essence. And Boethius also says, in his book On the Trinity 2, that the divine substance is existence itself, and all other existence proceeds therefrom.