threatening the faith by fostering undue independence of thought, and tempting to scepticism regarding the office of the church as universal teacher. The subsequent persecution of Galileo and Bruno was anticipated in the hatred and fear which were awakened by such names as Ben-Musa (ninth century), Avicenna (tenth century), Alhazan and Algazzali (eleventh century). The diverse spirits of the age are illustrated by the Giralda, the tower of Seville, which was built by the Moors for an observatory, but on the Catholic conquest was used only for a belfry. _The Turks._—The Saracenic conquests caused only a part of the Mohammedan menace in the eleventh century. A new power appeared, which has since dominated the middle Orient. For generations the Turks, or Tartars, had been steadily pressing southward and westward, from Turkestan and the borders of China towards the fertile plains and rich cities of the eastern Roman empire. Of nomadic habits, their entire property was in their camps and the driven herds that sustained them. They were skilled horsemen, cradled in the saddle, tireless on the march, loving the swift foray better than luxurious residence, inured to danger, and careless of blood. In the course of their migrations they came in contact with the followers of Mohammed. The Koran, with its celestial indorsement of sensuality, easily captivated in such a people that demand of common human nature for some religious faith and pursuit. They became the most enthusiastic devotees of the new faith, although in their deeper passion for selfish conquest they often slaughtered their fellow-religionists of other races. Early in the eleventh century one division of this people—the Seljukian Turks, so named from their great chieftain, Seljuk—overran Armenia and conquered Persia. Togrul-Beg, the grandson of Seljuk, had been elected to the chieftaincy according to the ancient custom, the chance drawing, by the hand of a child, of an arrow inscribed with his name. He was further honored by being chosen a temporal vicar of the caliph of Bagdad, then the chief of Arabic Mohammedanism. In 1055 Togrul-Beg was proclaimed “Commander of the Faithful and Protector of Mussulmans.” He was clothed in the seven robes of honor, was presented with seven slaves born in the seven climates of Araby the Blest, was crowned with two crowns and girded with two cimeters, emblematic of dominion over both the West and the East.