Egypt and Syria were conquered between A.D. 632-39, and Persia about A.D. 632-51. Their attempts to take Constantinople by siege failed both in A.D. 673 and 716. But they were more successful on the African shores of the Mediterranean, which they swept along till they crossed the Straits of Gibraltar and entered Spain in A.D. 709. Their further progress--through France--was stayed by their defeat in a great battle fought at Tour’s, when the Gauls, under Charles Martel, forced them to retire ultimately across the Pyrenees. Internal dissension had, however, arisen amongst them, and the ruling dynasty of the Ommiades was overthrown in A.D. 750 by the Abassides, who established themselves at Damascus; and with them began that cultivation of the arts and sciences which has thrown such lustre on the Arabian school. One of the princes of the Ommiades who had escaped made his way to Spain and there re-established the power of his family, with Cordova as a centre, about A.D. 755. Thus it was that the Saracenic power was divided into an Eastern and a Western Caliphate. It was under the prosperous rule of the Abassides that such an impulse was given to learning of every kind, and that the Arabian school of philosophy, which has left behind it such glorious records of its greatness, was founded. The Caliph Al-Mansour was the first, so far as we know, who earnestly encouraged the cultivation of learning; but it was to Haroun Al-Raschid, A.D. 786-808 (?), that the Arabians owed the establishment of a college of philosophy. He invited learned men to his kingdom from all nations, and paid them munificently; he employed them in translating the most famous books of the Greeks and others, and spread abroad throughout his dominions numerous copies of those works. His second son, Al-Mamoon, while governor of the province of Kohrassan, we are told, formed a college of learned men from every country, and appointed as the president John Mesue, of Damascus. It is said that his father, complaining that so great an honour had been conferred on a Christian, received the reply--“That Mesue had been chosen, not as a teacher of religion, but as an able preceptor in useful arts and sciences; and my father well knows that the most learned men and the most skilful artists in his dominions are Jews and Christians.”