4. The removal of the capital of the Empire from Rome to Constantinople in 330, left the Western Church, practically free from imperial power, to develop its own form of organisation. The Bishop of Rome, in the seat of the Cæsars, was now the greatest man in the West, and was soon forced to become the political as well as the spiritual head. To the Western world Rome was still the political capital--hence the whole habit of mind, all ambition, pride, and sense of glory, and every social prejudice favoured the evolution of the great city into the ecclesiastical capital. Civil as well as religious disputes were referred to the successor of Peter for settlement. Again and again, when barbarians attacked Rome, he was compelled to actually assume military leadership. Eastern Emperors frequently recognised the high claims of the Popes in order to gain their assistance. It is not difficult to understand how, under these responsibilities, the primacy of the Bishop of Rome, established in the pre-Constantine period, was emphasised and magnified after 313. The importance of this fact must not be overlooked. The organisation of the Church was thus put on the same divine basis as the revelation of Christianity. This idea once accepted led inevitably to the mediæval Papacy. The priesthood came, in consequence, to assume all the powers of the great Founder. The Mosaic forms, as well as the Roman Empire, suggested convenient models and authoritative examples for the new structure. It is not difficult to detect in the oligarchical Church polity of the fourth and fifth centuries a yearning for unity. It was but natural, therefore, that Rome should boldly take the remedy into her own hands and pose as the authorised representative of the visible unity demanded by the Christian world. The position Rome had already attained and the worthy part played in the organisation and spread of the gospel gave her a superior advantage, and enabled, nay compelled, her bishop to become the one high-priest, the "universal bishop."