Ambrose of Milan : Now let us inquire by what order they entered into the ark, how long they remained there, and in what order they went out; how in the first instance Noah entered, and after him his sons; then his wife, and the wives of his sons; and when they went out, in what order they went forth. For it is written: 'Noah went forth, and his wife, and his sons, and the wives of his sons' (Genesis 8:18). And the letter indeed signifies, in the entrance, the abstinence from generation, and in the going out, the use of generation. For at that time the father entered first with his sons, and the sons with their parent, and afterwards his wife, and the wives of his sons; that is, the sexes were not mixed in entering, but were mixed in leaving. Therefore, as if in the very order of entering, he emits a certain voice, declaring that that time is not for intercourse or pleasures, which would bring destruction upon all... But later, the proper practice and care for marriage followed after the flood subsided. — On Noah and the Ark, 21.76