Augustine, De civitate Dei Book XV c.25 is concerned with God's anger and seems irrelevant to any point that Harrison is making here, though the book in which it occurs devotes a good deal of space to Noah's ark; Book XII cc. 14-22 of Augustine's `Contra Faustum Manichaeum', in Augustini Opera VIII, PL 42 (1845), cols. 262-7, are also concerned with the ark and its significance.