Concerning the Nature of Good, Against the Manichaeans

Those things which our faith holds and which reason in whatever way has traced out, are fortified by the testimonies of the divine Scriptures, so that those who by reason of feebler intellect are not able to comprehend these things, may believe the divine authority, and so may deserve to know. But let not those who understand, but are less instructed in ecclesiastical literature, suppose that we set forth these things from our own intellect rather than what are in those Books.

Accordingly, that God is unchangeable is written in the Psalms: "You shall change them and they shall be changed; but Thou yourself art the same." And in the book of Wisdom, concerning wisdom: "Remaining in herself, she renews all things." Whence also the Apostle Paul: "To the invisible, incorruptible, only God." And the Apostle James: "Every best giving and every perfect gift is from above, descending from the Father of light, with whom there is no changeableness, neither obscuring of influence." Likewise because what He begot of Himself is what He Himself is, it is said in brief by the Son Himself: "I and the Father are one." But because the Son was not made, since through Him were all things made, thus it is written: "In the beginning was the Word, and the Word was with God, and God was the Word; this was in the beginning with God.

All things were made through Him, and without Him was made nothing;" that is, without Him was not anything made.