Concerning the Nature of Good, Against the Manichaeans

Yet even these privations of things are so ordered in the universe of nature, that to those wisely considering they not unfittingly have their vicissitudes. For by not illuminating certain places and times, God has also made the darkness as fittingly as the day. For if we by restraining the voice fittingly interpose silence in speaking, how much more does He, as the perfect framer of all things, fittingly make privations of things? Whence also in the hymn of the three children, light and darkness alike praise God, that is, bring forth praise in the hearts of those who well consider.