When Godfrey de Bouillon took the cross, the Byzantine Empire was already sinking. The Eastern trade which, for so many centuries, had nourished its population, was beginning to flow directly from Asia into Italy, and, as the economic aristocracy of the capital lost its nutriment, it lost its energy. Apparently it fell in 1081, in the revolution which raised Alexius Comuenus to the throne. Because Alexius sacked Constantinople with a following of mongrel Greeks, Slavs, and Bulgarians, he has been called the first Greek emperor, but in reality the pure Greek blood had long since perished. The Byzantine population at the end of the eleventh century was the lees of a multitude of races,--a mixture of Slavs, Armenians, Jews, Thracians, and Greeks; a residuum of the most tenacious organisms, after all that was higher had disappeared. The army was a mixed horde of Huns, Arabs, Italians, Britons, Franks; of all in short who could fight and were for sale, while the Church was servile, the fancy dead, and art and literature were redolent of decaying wealth. Nevertheless, ever since the fall of Rome, Constantinople had been the reservoir whence the West had drawn all its materialistic knowledge, and therefore, it was during the centuries when the valley of the Danube was closed, that the arts fell to their lowest ebb beyond the Alps and Rhine. After pilgrimages began again in the reign of Stephen, the Bosphorus lay once more in the path of travel, and as the returning palmers spread over the West, a revival followed in their track; a revival in which the spirit of Byzantium may yet be clearly read in the architecture of Italy and France. Saint Mark is a feeble imitation of Saint Sophia, while Viollet-le-Duc has described how long he hesitated before he could decide whether the carving of Vézelay, Autun, and Moissac was Greek or French; and has dwelt upon the laborious care with which he pored over all the material, before he became convinced that the stones were cut by artists trained at Cluny, who copied Byzantine models.[103] But the great gulf between the economic and the imaginative development, separated the moribund Greek society from the semi-childhood of the Franks; a chasm in its nature impassable because caused by a difference of mind, and which is, perhaps, seen most strikingly in religious architecture; for religious architecture, though always embodying the highest poetical aspirations of every civilization, yet had in the East and West diametrically opposite points of departure.