While these events were transpiring in the Visigothic kingdom, Mohammedan conquest had spread from Central Arabia to the western extremity of the African continent. Before its irresistible force, the activity of the Berber savage and the discipline of the Roman veteran had alike been humbled in the dust. The dangerous proximity of the Moslem outposts at the south had more than once aroused the apprehensions of the proud and luxurious sovereigns of Spain. But their efforts had been directed rather to the indulgence of their passions and the extirpation of heresy than to the fortification of the frontiers of the kingdom against the ambition of an unknown and underrated foe. The Jews, however, fully realized the gravity of the situation, and were only too willing to promote the designs of an enemy whose success, they were convinced, would enure to their own advantage and security. Numerous considerations of profound significance impelled them to this course. They themselves and the Arabs were derived from a common origin. Both sprang from the same branch of the great human family. Many of their customs were identical; their traditions denote a similar source; their languages vary but little in construction and pronunciation, and have been so slightly modified by the vicissitudes of centuries that the Hebrew rabbi and the Bedouin sheik of to-day can readily communicate with each other by means of their respective idioms. Both nations had for centuries been accustomed to a pastoral life on the vast plains of Asia, where the illimitable monotony of the landscape, the unbroken stillness of immense solitudes, the magnificent spectacle of the unclouded heavens glowing with the most gorgeous constellations of the firmament, have always impressed upon the nations subject to these potent and omnipresent influences the conviction of the unity of God. The caravans that issued from the Desert exchanged the precious commodities of that region for the wares manufactured and imported by the Hebrews of Alexandria, Damascus, and Antioch. Although in the early ages of Islam the Jews were often harshly treated, the Arabs were quick to perceive the advantages to be obtained from their commercial experience and literary knowledge. As Hebrew enterprise was instrumental in opening to the world the lucrative and important trade of the Arabian Peninsula, so Hebrew genius disclosed to the descendants of Ishmael the capacity of their own tongue, which until then had found no permanent mode of expression. The first book which appeared in the Arabic language was written by Javaich, a Syrian Jew. It was the translation of a medical work by a famous practitioner of Alexandria, and the practical character of the subject not only indicates the serious nature of early Hebrew research, but also becomes a matter of curious significance when the subsequent interest and proficiency of Arab scholars in everything concerning the scientific acquirements of