How fatally restrictive the cult of the completed Sacred Book can be is obvious in the history of Byzantium. It was in terms of the claims of the Christian creed that the Eastern Emperors proscribed pagan philosophy and science, reducing the life of the whole Eastern world as far as possible to one rigid and unreasoned code. That the mental life of Italy and France was relatively progressive even in the Middle Ages was substantially due--(1) to Saracen stimulus, and (2) to the friction and ferment set up by the diversity of life in the Italian republics, and the Italian and French and German universities. Byzantium was in comparison a China or an Egypt. The saving elements of political diversity, culture competition, and culture contact have in later Europe completed the frustration of the tendency of church, creed, and Bible to destroy alike science and philosophy. In Islam, on the other hand, the arresting force finally triumphed over the progressive because of the social and political conditions. (1) The political field, though stormy, finally lacked diversity in terms of the universality of the monarchic principle, which was imposed by the military basis and bound up with the creed: uniformity of ideal was thus furthered. (2) There was practically no fresh culture contact possible after the assimilation of the remains of Greek science and the stimulus of Jewish philosophy; for medieval Christendom had no culture to give; and the more thoroughly the Papacy and the Christian monarchy in Spain were organised, the more hostile they grew to the Moors. (3) The economic stimulus among the latter tended to be restricted more and more to the religious class, till that class was able to suppress all independent mental activity.