On St. Leo’s Christology

Pope St. Leo the Great ca. 400-461

[I]f they think there is any doubt about our teaching, let them at least not reject the writings of such holy priests as Athanasius, Theophilus and Cyril of Alexandria, with whom our statement of the Faith so completely harmonizes that any one who professes consent to them disagrees in nothing with us. (Letter 117.3)