But though the Latin-speaking Roman Empire died in the fifth century, something else had been born within it that was to avail itself enormously of its prestige and tradition, and that was the Latin-speaking half of the Catholic Church. This lived while the empire died because it appealed to the minds and wills of men, because it had books and a great system of teachers and missionaries to hold it together, things stronger than any law or legions. Throughout the fourth and fifth centuries A.D. while the empire was decaying, Christianity was spreading to a universal dominion in Europe. It conquered its conquerors, the barbarians. When Attila seemed disposed to march on Rome, the patriarch of Rome intercepted him and did what no armies could do, turning him back by sheer moral force. The Patriarch or Pope of Rome claimed to be the head of the entire Christian church. Now that there were no more emperors, he began to annex imperial titles and claims. He took the title of _pontifex maximus_, head sacrificial priest of the Roman dominion, the most ancient of all the titles that the emperors had enjoyed. XLI THE BYZANTINE AND SASSANID EMPIRES The Greek-speaking eastern half of the Roman Empire showed much more political tenacity than the western half. It weathered the disasters of the fifth century A.D., which saw a complete and final breaking up of the original Latin Roman power. Attila bullied the Emperor Theodosius II and sacked and raided almost to the walls of Constantinople, but that city remained intact. The Nubians came down the Nile and looted Upper Egypt, but Lower Egypt and Alexandria were left still fairly prosperous. Most of Asia Minor was held against the Sassanid Persians. The sixth century, which was an age of complete darkness for the West, saw indeed a considerable revival of the Greek power. Justinian I (527-565) was a ruler of very great ambition and energy, and he was married to the Empress Theodora, a woman of quite equal capacity who had begun life as an actress. Justinian reconquered North Africa from the Vandals and most of Italy from the Goths. He even regained the south of Spain. He did not limit his energies to naval and military enterprises. He founded a university, built the great church of Sta. Sophia in Constantinople and codified the Roman law. But in order to destroy a rival to his university foundation he closed the schools of philosophy in Athens, which had been going on in unbroken continuity from the days of Plato, that is to say for nearly a thousand years.