century and after, in spite of the strength of Ambrose, and the massive genius of Augustine, the intellectual centre of gravity of the Church was in the East. Rome accepted the elaboration of the doctrine of the Trinity from the East. It is true that by a flash of inspired political wisdom she stepped in at the critical moment and said the word that settled the orthodoxy of the whole Church for all subsequent ages; for Leo's Tome determined the decision of Chalcedon. But it was the thought which the great pope had received from the East that he was able to enshrine in that immortal document. After this, the West, absorbed in its own practical problems, came to view with weary indifference the hair-splitting controversies of the Eastern Church. She was concerned for orthodoxy, and again and again she struck in with a word of authority to save the situation. But as first the Nestorians by the Euphrates, and then the Monophysites in Egypt and Syria, were cut off, Rome came to have less and less vital connection with what was now essentially the Byzantine Church, identical in area with the Byzantine Empire.
2. A second influence that worked gradually but with inevitable consequences towards this cleavage of the Church was the separation of the Eastern and Western Empires, followed by the slow dissolution of the latter, and then its marvellous resurrection as an independent power, no longer a Roman Empire at all except in name. This process began when the emperors ceased to treat Rome as the centre of government. Diocletian thoroughly Orientalised the administration with its headquarters at Nicomedia. But the most significant fact in this connection was the founding of Constantinople. When Constantine transferred the centre of social influence and intellectual life, as well as the centre of government, from the banks of the Tiber to the shores of the Bosphorus, he began to make a fissure which nothing could stop. Subsequently this severance was widened by the Gothic invasions—the establishment of a Gothic kingdom, only nominally subject to the emperor in the East as its suzerain lord—the failure of the exarch at Ravenna to
