The era which witnessed the climax of Papal supremacy was coincident with the most thoroughly concerted and menacing attempt at its overthrow ever directed by any secular potentate. The birth of Frederick II. preceded the election of Innocent III. to the Holy See only three years. In the deadly struggle that arose between these two mighty antagonists,--a struggle which was far more political than religious, and whose tempting prize was the dominion of the earth,--the influence of the Saracen was a powerful, and, in many instances, a predominant factor. Moslem laws, institutions, and customs had for centuries, amidst communities hostile in origin and belief, survived alike the existence of their own dynasties and the domination of their conquerors. Tribal dissensions and hereditary enmity had prompted and facilitated the destruction of the splendid Mohammedan empire in Sicily. In its turn, the Norman kingdom, after a prolonged and stormy existence, in which the Moorish tributaries played no inconsiderable part, lost its identity; and, by the marriage of Constance, the mother of Frederick II., with Henry VI., was merged into the German Empire. During the great political and moral revolutions which disposed of crowns and repeatedly changed the destinies of the island, the Arab element of the population maintained an undisputed superiority in arts, in commerce, in literature,--in short, in all professions and employments save that of war alone. The semi-barbarian conqueror, whose only passports to distinction were the dexterity with which he wielded lance and sword and the undaunted courage with which he faced tenfold odds, early recognized the advantages of that intellectual power which enabled his Moorish vassals to cope with, and overreach, in both trade and diplomacy, the astute politicians of Christian Italy. This exotic population, notwithstanding the successive calamities which had afflicted it, exhibited through long periods of time no extraordinary diminution of numbers, a fact no doubt largely attributable to the prevalence of polygamous customs. In the centre of the island many Moorish settlements, defended by impregnable fortresses, subsisting by pastoral occupations, and whose comparative poverty offered little inducement to invasion, remained in tranquillity and in the enjoyment of a rustic independence. In the great seaports, on the other hand, the Moslem tributaries retained under foreign domination all of the refinement and much of the splendor which had distinguished the luxurious court of the emirs. In these vast emporiums, where were constantly assembled the merchants of every Christian and of every Mohammedan state, a numerous, motley, and industrious people pursued, without oppression or hinderance, all the avocations of thriving mercantile communities. The peculiar adaptability of the genius of the Norman to novel social and political conditions, a quality which