Concerning the Nature of Good, Against the Manichaeans

The highest good, than which there is no higher, is God, and consequently He is unchangeable good, hence truly eternal and truly immortal. All other good things are only from Him, not of Him. For what is of Him, is Himself. And consequently if He alone is unchangeable, all things that He has made, because He has made them out of nothing, are changeable. For He is so omnipotent, that even out of nothing, that is out of what is absolutely non-existent, He is able to make good things both great and small, both celestial and terrestrial, both spiritual and corporeal.

But because He is also just, He has not put those things that He has made out of nothing on an equality with that which He begot out of Himself. Because, therefore, no good things whether great or small, through whatever gradations of things, can exist except from God; but since every nature, so far as it is nature, is good, it follows that no nature can exist save from the most high and true God: because all things even not in the highest degree good, but related to the highest good, and again, because all good things, even those of most recent origin, which are far from the highest good, can have their existence only from the highest good.

Therefore every spirit, though subject to change, and every corporeal entity, is from God, and all this, having been made, is nature. For every nature is either spirit or body. Unchangeable spirit is God, changeable spirit, having been made, is nature, but is better than body; but body is not spirit, unless when the wind, because it is invisible to us and yet its power is felt as something not inconsiderable, is in a certain sense called spirit.