The three hundred years begin with the formal acknowledgement of St. Leo’s primacy, as consisting in the descent from St. Peter, bearer of the keys and feeder of the flock, made to him by the Council of Chalcedon in the letter soliciting the confirmation of their decrees by him; a letter to which the eastern emperor Marcian, husband of the noble grand-daughter and heiress of Theodosius, adds his own request for confirmation, and with his wife, St. Pulcheria, in his character as the head of the temporal power, acknowledges St. Leo, the Pope, as “the very person entrusted by the Saviour with the guardianship of the vine”. The three hundred years end with the Pope emerging a temporal sovereign from the Iconoclast persecution. The eastern empire also has fulfilled its work in these three centuries, and the soldier of fortune, who, at the end of many revolutions has become the successor of Marcian, has ridden his warhorse into the Church of God, and attempted to substitute himself as its governor for the successor of St. Peter, to dictate its creed, and interfere with its worship. In recompense he is expelled from the Italy which he and his predecessors had stripped and sacrificed during two hundred years. Then the crown of temporal sovereignty is added to the papal mitre of spiritual power, which Leo the Isaurian had sought to displace. And, moreover, the “advocate of the Church,” who, “as Christian prince and Roman emperor,” had used _against_ the Church the very God-given power which it was his first duty to use _for_ her, was on the eve of seeing the same powerful race which had enfranchised Rome and dowered the Roman See exalted to the imperial throne in the face of both the Byzantine and the Saracen. The emperor of the East had lowered his dignity to the poor ends of ambition, and the task of degrading God’s Church. In Leo the Isaurian, and in his son Kopronymus we see, in fact, that the man who sits on the throne of the first Christian emperor is become the chief enemy of the Church. The deeds of Heraclius and Constans II. had given adequate cause for the Divine Providence to allow the rise of Mohammed and the severance of its eastern and southern provinces for ever from the empire of Constantine and Theodosius. Thereupon Leo and his son Kopronymus interpreted the lesson thus given as entitling them to meet the assumption of the prophet-emperor enthroned in the Damascus which had ceased to be theirs with equal arrogance in the counter assumption to be emperor-priest. The enemy from Mecca had seized Both Powers in his claim to be prophet; the enemy at Byzantium seized both as emperor. Civil power was the appendage to Mohammed, but became the root of spiritual authority to Leo the Isaurian. Let us now retrace the period of civic disaster which the Popes encountered from the last years of St. Leo the Great. The following may be considered the main causes:—