Concerning the Nature of Good, Against the Manichæans 19
19 To Have True Existence is an Exclusive Prerogative of God PL 42, 557
Magnificently and divinely, therefore, our God said to his servant: "I am that I am," and "Thou shalt say to the children of Israel, He who is sent me to you." For He truly is because He is unchangeable. For every change makes what was not, to be: therefore He truly is, who is unchangeable; but all other things that were made by Him have received being from Him each in its own measure. To Him who is highest, therefore nothing can be contrary, save what is not; and consequently as from Him everything that is good has its being, so from Him is everything that by nature exists; since everything that exists by nature is good. Thus every nature is good, and everything good is from God; therefore every nature is from God.
Esse vere, proprium Dei. Magnifice igitur et divine Deus noster famulo suo dixit, Ego sum qui sum; et, Dices filiis Israel, Qui est misit me ad vos . Vere enim ipse est, quia incommutabilis est. Omnis enim mutatio facit non esse quod erat: vere ergo ille est, qui incommutabilis est; caetera quae ab illo facta sunt, ab illo pro suo modo esse acceperunt. Ei ergo qui summe est, non potest esse contrarium nisi quod non est: ac per hoc sicut ab illo est omne quod bonum est, sic ab illo est omne quod naturaliter est; quoniam omne quod naturaliter est, bonum est. Omnis itaque natura bona est, et omne bonum a Deo est: omnis ergo natura a Deo est.