Perhaps there are few events in history more impressive than the conversion of the wild and ignorant Arab tribes of the seventh century from stone-worship to monotheism. The series of conquests which followed had also, as an indirect and unforeseen result, effects of vast importance in the revival and spread of Greek culture from the Tigris to the Guadalquivir. It is not easy, neither does the inquiry fall within our present purpose, to discover the special impulses which led Mohammed, the leader of the movement, to preach a new faith whose one creed, stripped of all subtleties, was the unity of God. Large numbers of Jews and Christians had settled in Arabia long before his time, and he had become acquainted with the narrowness of the one, and with the causes of the wranglings of the other, riven, as these last-named were, into sects quarrelling over the nature of the Person of Christ. These, and the fetichism of his fellow-countrymen, may, perhaps, have impelled him to start a crusade the mandate for which he, in fanatic impulse, believed came from heaven. The result is well known. The hitherto untamed nomads became the eager instruments of the prophet. Under his leadership, and that of the able Khalifs who succeeded him, the flag of Islam was carried from East to West, till within one hundred years of the flight of Mohammed from Mecca (622 A. D.) it waved from the Indian Ocean to the Atlantic. With the conquest of Syria there was achieved one of the greatest and most momentous of triumphs in the capture of Jerusalem, and the seizure of sites sanctified to Christians by association with the crucifixion, burial, and resurrection of Jesus. Only a few years before (614 A. D.), the holy city had been taken by Chosroes; the sacred buildings raised over the venerated tomb had been burned, and the cross--a spurious relic--carried off by the Persian king. These places have been, as it were, the cockpit of Christendom from the time of the siege of Jerusalem under Titus to that of the Crimean war, when blood was spilt like water in a conflict stirred by squabbles between Latin and Greek Christians over possession of the key of the Church of the Nativity at Bethlehem. In the Church of the Holy Sepulchre these sectaries are still kept from flying at one another's throats by the muskets of Mohammedan soldiers.