The formal establishment of Christianity by Constantine the Great, in the early part of the fourth century, might have led to Jewish apprehension lest the Synagogue should be eclipsed by the splendour of its triumphant rival, the Christian Church; but the Rabbinical authority had raised an insurmountable barrier around the Synagogue. And, unhappily, the Church had lost its most effective means of conversion--its miraculous powers, its simple doctrine, and the blameless lives of its believers. Constantine enacted severe laws against the Jews, which seem in great part to have been occasioned by their own fiery zeal. But, still earlier than these enactments, Spain had given the signal for hostility towards the Jews. A decree was passed at the Council of Elvira prohibiting Jewish and Christian farmers and peasants from mingling together at harvest home and other festivals. In Egypt, during the reign of Constantius, who succeeded his father Constantine, the hot-headed Jews of Alexandria provoked the enactment by that emperor of yet severer laws, by mingling themselves in the factions of Arians and Athanasians, which distracted that restless city. They joined with the pagans on the side of the Arian bishop, and committed frightful excesses. An insurrection in Judea, which terminated in the destruction of Dio Cæsarea, gave further pretext for exaction and oppression. But the apostasy of the emperor for a time revived the hopes of the race, especially when he issued his memorable edict decreeing the rebuilding of the Temple on Mount Moriah, and the restoration of the Jewish worship in its original splendour. The whole Jewish world was now in commotion. Julian entrusted the execution of the project to his favourite, Alypius, while he advanced with his ill-fated army to the East. The Jews crowded from the most distant quarters to assist in the work. But terrible disappointment ensued. Fire destroyed the work, and various catastrophes frustrated the enterprise, and the death of Julian rendered it hopeless. The irruption of the Northern Barbarians during the latter half of the fourth to about the end of the fifth century so completely disorganised the whole frame of society that the condition of its humblest members could not but be powerfully influenced thereby. The Jews were widely dispersed in all those countries on which the storm fell--in Belgium, the Rhine districts, Germany, where it was civilised, Gaul, Italy, and Spain. Not only did the Jews in their scattered colonies engage actively in mercantile pursuits, but one great branch of commerce fell chiefly into their hands--the internal slave-trade of Europe.