Strange as it may seem, the two races settled down side by side in peace and friendship. Both acknowledged {38} the holiness of the Israelites of old, whose bones lay buried in the neighbourhood of the Holy City. Within its walls the Mohammedans treated with respect, if not with reverence, the worship of Him whom they regarded as a prophet not far inferior to their own. Thus four centuries rolled quietly away, until the old distinction between conquerors and conquered had almost ceased to exist, and pilgrims from all parts of Christendom were welcomed by Christian and Moslem alike. Meantime the forces of Islam threatened to overrun the greater part of the known world. The Saracens "rode masters of the sea," throughout the Greek archipelago; their sway was recognised towards the East up to the sources of the Euphrates and Tigris, to the North they had spread over Asia Minor deep to the very walls of Constantinople, the seat of the Eastern Empire. Egypt was conquered by Amrou, one of the most famous generals of the Caliph Omar. With Egypt fell Alexandria, a city renowned for its learning, and especially for its magnificent library, through the civilised world. "I have taken," Amrou told the Caliph, "the great city of the West. It contains four thousand palaces, four thousand baths, four hundred theatres or places of amusement, twelve thousand shops for the sale of vegetable food, and forty thousand tributary Jews. The town has been subdued by force of arms, without treaty or capitulation, and the Moslems are impatient to seize the fruits of their victory." Fortunately for the inhabitants, who were the last to be referred to, Omar would not allow slaughter or pillage. But if the tale be true, the fate of the famous library of Alexandria shows very clearly the narrow limits of Saracen culture in those days. {39} A learned scholar of the city, who had won the liking and respect of Amrou, entreated that the library might be given over to him, as the Moslems would have no use for it. The question was referred to Omar, who replied, "If these writings of the Greeks agree with the Book of God, they are useless, and need not be preserved; if they disagree, they are harmful, and should be destroyed." And forthwith the priceless volumes were committed to the flames. Six years later (647 A.D.) the warrior Othman accomplished the conquest of Northern Africa; and a little more than sixty years later, a small expedition of Saracens crossed the Straits of Gibraltar and set foot in Spain. Their leader, Tarif, gave his name to the place (Tarifa) where he landed, and likewise to the "tariff" or "duty" levied upon the vessels which passed through the straits.