Commentaria in Summam contra Gentiles, Liber I

Having excluded from God the composition of supposit and nature, Saint Thomas consequently excludes from Him likewise the composition of esse and essence¹, and shows that in God the esse of actual existence and essence are one and the same.

For the clarification of this conclusion, it should be known that esse and the actuality of existing are nothing other than that which is signified by this verb est when we say, This is. And indeed in creatures, according to the teaching of Saint Thomas², it is really distinguished from quiddity; on account of which it is true to say of Adam that he is a man, but it is not true to say that he is. In God, however, the actuality of existing and deity are the same; and the same in reality is signified when it is said, God is God, and when it is said, God is.

I. That this is so, Saint Thomas proves with many arguments. And first, it is supposed that God is of himself necessary being. Then thus. Esse that is necessary, if joined to a quiddity distinct from itself, either is repugnant to that quiddity, just as existing per se is repugnant to whiteness; or is consonant and akin to it, just as being in a subject is to whiteness. The first cannot be given: because it does not befit that quiddity, just as neither does existing per se befit whiteness. — If the second is granted, then esse depends on the essence; or both on the same cause; or the essence on esse. Not the first two: because it is contrary to the notion of necessary being that it depend on another. Not even the third: because then that quiddity would befall the thing accidentally, since what follows upon the esse of a thing is accidental to it; and thus it would not be its quiddity. Therefore in God the quiddity is his own esse.

If it is said that the first is in some way true, and that it does not conflict with what is necessary being: because that esse depends on the essence not absolutely, as though it would not be at all unless that essence were, but with respect to its being joined to it; for that esse is necessary of itself, but its being joined to the quiddity is not necessary of itself — against: Either that esse can be understood without that quiddity, or it cannot. If the first, then that essence is related accidentally to that esse. But what is necessary being is that esse. Therefore it follows that that essence is also related accidentally to what is necessary being. Therefore it will not be its quiddity, but something posterior to it. — If the second, then that esse depends absolutely on that from which its conjunction with the essence depends. And thus the same as before.

2. Note concerning that proposition, That it is repugnant to the quiddity of whiteness to exist per se, that this repugnance is not logical, that is, resulting from the terms themselves: but it is a repugnance in relation to a natural agent. For it is repugnant to the quiddity of whiteness that it should have existence per se from a created agent, and thus subsist naturally. It does not, however, repugn to itself that it be created by God as existing per se: as Saint Thomas holds in many places, especially Quodlibet VII, q. 4, a. 3³.

3. Concerning that disjunctive proposition, Either that esse can be understood without that essence, or it cannot be understood without it, it should be noted that to be understood without the essence is not taken there with respect to the first operation of the intellect, but with respect to the second. And the sense is: Either it can be understood (namely, truly) that such an esse is not conjoined to that essence, or it cannot be understood not to be conjoined to it. Whichever of these is granted, the force of the argument is not removed, as has been deduced.

Concerning this objection, however, there is a doubt: for it seems that what ought to be proved is being assumed. For it is assumed that that which is necessary being is that being itself. But one who says that the essence of God, or its necessary being, is distinguished from its esse would deny that proposition, just as he denies that the essence of God is esse itself.

It is answered that, if something is posited that is of itself necessary being, it must be that it is its own esse, from the very meaning of the term. For that which is of itself necessary being is that which is from itself by necessity and from nothing else. But if its esse were distinguished from it, it would have to have it from another, since nothing is the cause of being for itself; and thus it would not be of itself necessary being. Hence, however much someone may say that the quiddity of God is distinguished from his esse, if he admits that God is of himself necessary being, unless he is ignorant of the meaning of the terms, he must concede that he is his own esse. And therefore what ought to be proved is not assumed, but is shown to be true from the very meaning of the term itself.

II. Second. God is of himself necessary being. Therefore he is his own esse. The consequence is evident: because that which is not its own esse is not of itself necessary being, since each thing exists through its own esse. If God is his own esse, then his quiddity also is esse itself: because, as has been shown ⁴, God is his own quiddity. Therefore etc.

It must be noted that a thing is said to be both through its esse and through its form, but in different ways. For through its form a thing is said to be as through the principle and formal cause of its actuality of being, where esse is distinguished from the thing. But through esse itself it is said to be as through the ultimate actuality of being, which awaits no other act. And thus is understood the proposition of Saint Thomas, Each thing is through its own esse.

III. Third. It is supposed that, if esse is distinguished from the quiddity in God, it cannot be a part of it, since God is simple. Then the argument runs: God is the first cause having no cause. Therefore in him essence and esse are the same. — The consequence is proved. Because everything that is not of the essence of a thing belongs to it through some cause. Therefore, if esse were distinguished from essence, it would belong to it through some cause. But not through the essence itself, or through something that is of the essence: because, since the essence exists through that esse, something would be for itself the cause of being; which is impossible with respect to substantial being, since what is prior according to understanding is to be a cause than an effect. Therefore it would belong to it through some other cause. Therefore God would be caused. And thus he would not be the first cause.

Concerning that proposition, It is prior according to the intellect for a thing to be a cause than an effect, it must be noted that the cause does not always precede its effect in duration, but it does precede it well enough in the order of nature. For cause and effect can exist simultaneously in duration if the effect is not produced through motion, as will be shown below⁵; yet nevertheless the effect presupposes the cause according to its very nature, when we speak of an efficient cause. And consequently, if something is conceived by the intellect to be from another, it is first conceived to be the cause than the effect, as though the being of the effect presupposes the being of the cause. Therefore when it is said here, *It is prior according to the intellect for a thing to be a cause than an effect, this must not be understood as though that priority were only from the conceiving intellect and had no foundation in reality; but because the complement of that priority comes from the intellect, while the foundation lies on the side of the thing, provided there is truly a cause and a caused thing there.

IV. Fourth. In God there is no potency, but He is pure act. Therefore His quiddity is not distinguished from esse. — The consequence is proved. Because wherever they are distinguished, esse is compared to essence as act to potency. For everything to which an act distinct from itself is joined stands to that act as potency to act. But esse is act.

It should be noted that a simple essence, lacking all matter, is the proper recipient of esse. And although in itself and absolutely it is a certain act, nevertheless, in comparison with esse distinct from itself, it is related as potency to act, because esse is the actuality of every form and nature, as is said in the Prima, q. III, a. 4; for no nature is completely and ultimately a being in act unless it is under the esse of actual existence. But that which receives an act has the character of potency when compared to that act.

V. Fifth. God is not composed. Therefore his essence is his esse. — The consequence is proved. Because if essence were distinct from esse, God could not exist except by several things concurring, namely esse and essence. But what cannot exist except by several things concurring is composed.

It must be known here that something is said to be composite in two ways, as is taught in the doctrine of St. Thomas, Quol. II, a. 3 ⁶: in one way, because its essence results from the union of several things; in another way, because it itself is joined to another as potency to act; in which sense it is said to be composed not from other things, but from itself and another. Therefore what cannot be except with several things concurring is composite—not indeed of necessity in the first way, unless those things integrated its essence—but either in the first or in the second way.

VI. Sixth. If in God the quiddity is distinguished from esse, God is not through his essence, but through participation of esse itself. Therefore he is not the first being. This is false. Therefore, etc. — The second consequence is proved: because that by which something participates in order to be is prior to it. — But Saint Thomas does not prove the first consequence; he leaves it as known from the terms. For each thing exists through esse itself. Where, therefore, essence is not esse, it follows that that thing does not exist through its own essence. And since being such through essence and being such through participation are opposed, therefore from the fact that something does not exist through essence it follows that it exists through participation.

But it must be noted, from what is held by the holy Doctor in I Metaph., l. 10 ⁷, and Quolib. II, q. II ⁸, and super Boet. de Hebd. ⁹, that esse such by essence can be taken in two ways. In one way, because that which is predicated of it is of its essence: as man is animal by essence because animal is of the essence of man. And conversely something is said to be such by participation because that which is attributed to it is not of its essence: as red-hot iron is said to be fire by participation. And then to participate in something is nothing other than to have it as added to one's essence and nature. — In the second way, esse such by essence is taken for that which is esse totally the essence of the thing of which it is predicated, and does not have anything else by which it is determined. Conversely, to be such by participation is not to be totally the essence of the thing which is predicated, but to have something else joined to it. In this way we say that man is rational animal by essence, but animal by participation: because, although he has the whole essence of animal, he nevertheless has it limited by rational, as Saint Thomas says in the book de Hebdomadibus.

These two modes, however, are so related that they imply one another in reverse. For being by essence in the second mode implies being by essence in the first mode. For what belongs to something according to its whole essence and totally must be its essence or of its essence: because, if it were received in it as added to its essence, it would be limited by its essence to some particular mode of esse; for every act received in another receives some limitation in the receiver. — But being by participation in the second mode does not imply the first mode of participation: rather, what is such by participation can be so by essence in the first mode; just as man is an animal by participation in the second mode, yet he is an animal by essence in the first mode. But the first mode of participation implies the second. For what has something as added to its essence does not have it totally as its essence, but has it according to some determinate mode of it: just as what is white by participation is not whiteness totally, but has whiteness according to some mode of whiteness.

In this argument, therefore, it is inferred that God exists by participation in both ways from the fact that his essence is posited as distinct from esse. For, this having been granted, it follows that he does not exist through essence in the first way, that is, through something that is of his essence or is his very essence. And consequently it follows that he is by participation, that is, through something added to the essence. — From this it is further established that he is by participation in the second way: that is, he is not esse itself altogether, and has esse not according to every mode of being, but in a determinate mode. And thus he is not the first being.

VII. Finally, he confirms the conclusion by the authority of Sacred Scripture, namely Exodus 3, where it is said that God's proper name is "He Who Is"; and by the authority of Hilary in his book on the Trinity; and of Boethius in his book on the Trinity.