Council of Aquileia, 381

“We recognize in the letter of your holiness [Pope Siricius] the vigilance of the good shepherd. You faithfully watch over the gate entrusted to you, and with pious care you guard Christ’s sheepfold [John 10:7], you that are worthy to have the Lord’s sheep hear and follow you.” (The Synod of St. Ambrose, Synodal Letter to Pope Siricius [A.D. 389]).