The papacy of the Middle Ages was first made illustrious by Leo I., surnamed the Great. Called to be Bishop of Rome by the people and the clergy in 440, when twenty years of age, he rendered the greatest possible services to civilisation during the twenty-two years of his reign. His preachings, his writings, his decrees, aimed chiefly at the education of his clergy and his flock, at the maintenance of the Nicene Creed (Fig. 206), the moral improvement of the clergy, and the upholding of discipline. He fought the heretics with equal energy and authority; he continued the struggle of orthodoxy against the errors which attacked the dogma of the Incarnation, which is the basis of Christianity, and upheld with vigilant perseverance the primitive doctrine of the Church, so clearly defined and proclaimed during the reign of one of his predecessors at the Council of Ephesus in 431. He was, above all things, a skilful diplomatist and a great politician. He firmly maintained the apostolic pre-eminence of Rome over Constantinople--a pre-eminence which was, moreover, recognised by the Council of Chalcedon. [Illustration: Fig. 205.--St. Peter.--Fac-simile of a Wood Engraving of the Old Masters, by Hans Baldung, otherwise Grum (1470–1550), in the National Library, Paris.] [Illustration: Fig. 206.--A Council held in the ninth or tenth century to commemorate the second Council of Nice.--From a Miniature of a _menologium_ in the Vatican Library (Manuscript of the Tenth Century).] The empire, like the Church, needed such a man as St. Leo in its days of adversity. The invasion of the barbarians was triumphant in the West, and nearly all of the conquerors were either Arians, who denied the divinity of Christ, or idolaters. Leo triumphed over all these calamities. Rome had already been ravished by Alaric in 410, but even he respected the churches in which the population had fled for refuge. Attila, at the head of seven hundred thousand men, marched on Rome for the purpose of devastating it with fire and sword; resistance seemed out of the question, and the Emperor was preparing to escape. Amidst the universal panic, Pope Leo, accompanied by a consul, went out to meet the dreaded chieftain, and induced him to turn back. Some years later, Genseric poured his vandals into Italy, and again Leo boldly presented himself before his fierce assailant, and made him renounce his intention of burning the city and slaying the inhabitants. Thus did circumstances lead the way for the temporal power of the popes in Rome, of which they eventually became the sole guardians and defenders.