[4]     jfr Matt 16:18; Leo den Store, Sermo, 4, 3: CCL 88, 19-20 (PL 54, 151); Sermo 51, 1: CCL 88A, 296-297 (PL 54, 309); Sermo 62, 2: CCL 88A, 377-378 (PL 54, 350-351); Sermo 83, 3: CCL 88A, 521-522 (PL 54, 432).