This seems to refer to St. Prosper of Aquitaine, Sentent., VII (PL 51:428), as in S.T., I-II, 65, 2, obj. 1; cf. St. Augustine, Enarr. in psalmos, super 103:3 (PL 37:1343-44).
St. Augustine, De Trinitate, VI, 4 (PL 42:927).
Aristotle, Ethica Nicomachea, VI, 13 (1144b 30).
In q. 14, a. 4.