Justinian mounted the throne with the ideals of an emperor both Roman and Christian. Considering himself a successor of the Roman Caesars, he deemed it his sacred duty to restore a single Empire extending to the same boundaries it had had in the first and second centuries. As a Christian ruler he could not allow the German Arians to oppress the orthodox population. The rulers of Constantinople, as lawful successors of the Caesars, had historical rights to western Europe, occupied at this time by barbarians. The Germanic kings were but vassals of the Byzantine Emperor, who had delegated them to rule in the West. The Frankish king, Clovis, had received his rank of consul from Anastasius; it was Anastasius also who had given official recognition to the Ostrogothic king, Theodoric. When he decided to wage war against the Goths, Justinian wrote, The Goths, having seized by violence our Italy, have refused to give it back. He remained, he felt, the natural suzerain of all the rulers within the boundaries of the Roman Empire. As a Christian emperor, Justinian had the mission of propagating the true faith among the infidels, whether they were heretics or pagans. This theory, expressed by Eusebius in the fourth century was still alive in the sixth century. It was the basis of Justinian's conviction of his duty to re-establish a united Roman Empire which, in the words of one Novel, formerly reached the shores of two oceans, and which the Romans had lost because of their carelessness. From this old theory arose also Justinian's belief in his duty to introduce in the restored empire a sole Christian faith among the schismatics as well as among the pagans. Such was Justinian's ideology, which made this all-embracing statesman and crusader dream of conquering the entire known world.