Concerning the Nature of Good, Against the Manichæans 24
24 It is Proved by the Testimonies of Scripture that God is Unchangeable. The Son of God Begotten, Not Made PL 42, 558
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: "Thou shalt change them and they shall be changed; but Thou thyself 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 begat 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.
Testimoniis Scripturae probatur Deum esse incommutabilem. Filium Dei esse genitum, non factum. Haec quae nostra fides habet, et utcumque ratio vestigavit, divinarum Scripturarum testimoniis munienda sunt: ut qui ea minore intellectu assequi non possunt, divinae auctoritati credant, et ob hoc intelligere mereantur. Qui autem intelligunt, sed ecclesiasticis Litteris minus instructi sunt, magis ea nos ex nostro intellectu proferre, quam in illis Libris esse, non arbitrentur. Itaque Deum esse incommutabilem, sic scriptum est in Psalmis: Mutabis ea, et mutabuntur; tu autem idem ipse es . Et in libro Sapientiae de ipsa Sapientia: In se ipsa manens innovat omnia . Unde et apostolus Paulus: Invisibili, incorruptibili soli Deo . Et apostolus Jacobus: Omne datum optimum, et omne donum perfectum desursum est, descendens a Patre luminum, apud quem non est commutatio, nec momenti obumbratio . Item quia id quod de se genuit, hoc est quod ipse est, ita ab ipso Filio breviter dicitur: Ego et Pater unum sumus . Quia autem non est factus Filius, quippe cum per illum facta sint omnia; sic scriptum est: In principio erat Verbum, et Verbum erat apud Deum, et Deus erat Verbum; hoc erat in principio apud Deum. Omnia per ipsum facta sunt, et sine ipso factum est nihil : id est, non est factum sine ipso aliquid.