Third, St. Thomas indicated his own position with the formula “On the contrary …” (Sed contra). The brief argument that follows the statement of his position here is usually an argument from authority, i.e., from Scripture, the Fathers of the Church, or recognized wise men. The medievals well knew their own maxim that “the argument from authority is the weakest of all arguments.” But they also believed in doing their homework and in learning from their ancestors—two habits we would do well to cultivate