Augustine of Hippo : In the third book there is also a discussion of how the high priest begot sons, since he had the obligation to enter the Holy of Holies twice a day where the altar of incense was, to offer incense morning and evening. Into [this], as the law states, he could not enter while unclean, and the law says that a man is even made unclean as a result of conjugal coition, and indeed it orders him to be washed with water, but it states also that he, although washed, "is unclean until evening." Hence I said, "It follows logically that he either be continent or that, on some days, the offering of incense be interrupted." I did not realize that this is not a logical consequence. For what is written, "he will be unclean until evening," can be understood to mean that he was no longer unclean during the evening itself but up to the evening, so that, cleansed, he could offer incense during the evening even though, after morning offering of incense, he had had conjugal relations with his wife for the procreation of children. — RECONSIDERATIONS 81.2