In 518 Justin I. succeeded Anastasius on the throne of Constantinople, and in the task of defending the empire against the Persians. And this task became every year more difficult, as the Greek population of his Egyptian and Asiatic provinces fell off in numbers. For some years after the division of the empire under the sons of Constantine, Antioch in Syria had been the capital from which Alexandria received the emperor's commands. The two cities became very closely united; and now that the Greeks were deserting Antioch, a part of the Syrian church began to adopt the more superstitious creed of Egypt. Severus, Bishop of Antioch, was successful in persuading a large party in the Syrian church to deny the humanity of Christ, and to style Mary the mother of God. But the chief power in Antioch rested with the opposite party. They answered his arguments by threats of violence, and he had to leave the city for safety. He fled to Alexandria, and with him began the friendship between the two churches which lasted for several centuries. In Alexandria he was received with the honour due to his religious zeal. But though in Antioch his opinions had been too Egyptian for the Syrians, in Alexandria they were too Syrian for the Egyptians. The Egyptians, who said that Jesus had been crucified and died only in appearance, always denied that his body was liable to corruption. Severus, however, argued that it was liable to corruption before the resurrection; and this led him into a new controversy, in which Timotheus, the Alexandrian bishop, took part against his own more superstitious flock, and sided with his friend, the Bishop of Antioch. Severus has left us, in the Syriac language, the baptismal service as performed in Egypt. The priest breathes three times into the basin to make the water holy, he makes three crosses on the child's forehead, he adjures the demons of wickedness to quit him, he again makes three crosses on his forehead with oil, he again blows three times into the water in the form of a cross, he anoints his whole body with oil, and then plunges him in the water. Many other natives of Syria soon followed Severus to Alexandria; so many indeed that as Greek literature decayed in that city, Syriac literature rose. Many Syrians also came to study the religious life in the monasteries of Egypt, and after some time the books in the library of the monastery at Mount Nit-ria were found to be half Arabic and half Syriac.