The truth of this miracle, of which, unless it took place, St. Ambrose could not have spoken in a public address, is also supported by St. Augustine, who was at this time in Milan, and if not himself on the spot, as he may well have been, would at least know whether such an event had taken place. See St. Augustine, De Civ. Dei. XXII. 8, and specially, Sermo in natali Martyrum Gervasii et Protasii.