In the days of its strength the Eastern Empire was the staunch bulwark of Christendom against the dangerous assaults of Persian, Saracen, and Turk; alike in prosperity and in calamity, it proved to be the teacher and civilizer of the western world. The events which, at the close of the eleventh century, brought thousands upon thousands of adventurous, keen-witted people from western Europe into this home of wealth and refinement, were the occasion of the most remarkable intellectual awakening that the world had ever witnessed up to that time. The Crusades, in their beginning, were a symptom of the growing energy of western Europe under the ecclesiastical reformation effected by the mighty Hildebrand. They were the military response of Europe to the most threatening, and, as time has proved, the most deadly of all the blows that have ever been aimed at her from Asia. Down to this time the Mahometanism with which Christendom had so long been in conflict was a Mahometanism of civilized peoples. The Arabs and Moors were industrious merchants, agriculturists, and craftsmen; in their society one might meet with learned scholars, refined poets, and profound philosophers. But at the end of the tenth century, Islam happened to make converts of the Turks, a nomad race in the upper status of barbarism, with flocks and herds and patriarchal families. Inspired with the sudden zeal for conquest which has always characterized new converts to Islam, the Turks began to pour down from the plains of central Asia like a deluge upon the Eastern Empire. In 1016 they overwhelmed Armenia, and presently advanced into Asia Minor. Their mode of conquest was peculiarly baleful, for at first they deliberately annihilated the works of civilization in order to prepare the country for their nomadic life; they pulled down cities to put up tents. Though they long ago ceased to be nomads, they have to this day never learned to comprehend civilized life, and they have been simply a blight upon every part of the earth's surface which they have touched. At the beginning of the eleventh century, Asia Minor was one of the most prosperous and highly civilized parts of the world;[320] and the tale of its devastation by the terrible Alp Arslan and the robber chiefs that came after him is one of the most mournful chapters in history. At the end of that century, when the Turks were holding Nicaea and actually had their outposts on the Marmora, it was high time for Christendom to rise _en masse_ in self-defence. The idea was worthy of the greatest of popes. Imperfectly and spasmodically as it was carried out, it undoubtedly did more than anything that had ever gone before toward strengthening the wholesome sentiment of a common Christendom among the peoples of western Europe. The Crusades increased the power of the Church, which was equivalent to putting a curb upon the propensities of the robber baron and making labour and traffic more secure.