The Pseudo Isidorian Decretals

As we saw, the papacy, now in the person of Leo III (795-816) again declared by its act of crowning Charles (The Great) emperor, that it lay within its power to give and withhold kingdoms and to appoint and depose its kings, and that, such being its power, it took away from the Eastern emperor, who sat in Constantinople, the crown and bestowed it on Charles. Actually, as was explained, the pope now was subject and vassal of the mighty Charles, but in his own mind, he stood out as Charles'...