Commentaria in Summam contra Gentiles, Liber I

As to the second ¹, this conclusion is put forward: God is His own beatitude.

I. It is proved first. God is his own act of understanding. But his beatitude is his intelligible operation. Therefore, etc.

Second. God principally wills his own essence, as was shown above. Therefore his essence is his beatitude. — The consequence is proved. Because beatitude, since it is the ultimate end, is that which anyone is born to have, or which one who has it principally wills ².

Third. He wills all things on account of his goodness and essence. Therefore, etc. — The inference is proved. Because beatitude is that toward which all the movements of desire of one who desires one thing on account of another are terminated, lest the movement of desire be infinite.

It must be noted that, just as natural motion does not proceed to infinity, but each motion has a determinate terminus—as heavy things have the center of the world, and light things the concavity of the sphere of the moon—so too sensitive and intellective appetite does not tend to infinity privatively, although it can tend to infinity perfectionally, as in God. And therefore, although it may be carried from one desired object to another, there is nevertheless some end fixed for it beyond which it can desire nothing further. And this is the ultimate end, which is beatitude and the highest good, toward which all motions of desire are finally terminated. Just as, if someone gathers herbs for making a medicine, and takes the medicine for the sake of health, and desires health so that he may be free for study, and seeks study also on account of beatitude: he indeed desires all the preceding things on account of something else, but beatitude itself he seeks not on account of another thing, but for its own sake, as the ultimate end toward which he is naturally inclined.

For this reason, Saint Thomas says that all movements of desire terminate in beatitude: lest such a movement of desire be infinite, while one thing is desired on account of another. For unless something were posited which is not desired on account of another but all other things on account of it, the movement of desire would tend to infinity, and thus would be infinite—which the nature of appetite does not admit.

IV. Fourth. If God's beatitude were not God, there would be two highest goods: for beatitude is the highest good, since it is the ultimate end; and also God. But this is impossible: because if one thing lacks something that the other has, it is no longer the highest good. Therefore God is his own beatitude.

But that argument seems not to conclude. For by it it would be proved that the formal beatitude of a creature is God. For the beatitude of a creature is also the highest good, insofar as it is the ultimate end. And thus the opinion of those saying that God is the formal beatitude of creatures, and not merely the objective beatitude, would be true.

It is answered, according to the doctrine of Saint Thomas, Prima, q. 26, a. 3, ad 1, that the beatitude of the created intellect, with respect to its object, is the highest good simply; but with respect to the act itself, it is the highest good in the genus of goods participable by a creature. Now it is not unfitting that there be two highest goods, one simply, and the other in some order; but it is indeed unfitting that there be two highest goods simply. And thus it is not necessary that the formal beatitude of the creature be God himself. But the beatitude of God is the highest good simply, because nothing belongs to him participatively. Therefore, since there cannot be two highest goods simply, it must be that the beatitude of God is God himself. And thus the argument of Saint Thomas concludes concerning the beatitude of God, not concerning the beatitude of the creature. Indeed, insofar as it could conclude concerning the beatitude of the creature, Saint Thomas dissolves it in the place cited above.