Medieval Catholicism had various strategies in preserving and relaxing the tension between the ideal of religion and the practical needs of men and society. It made fewest demands upon the individual. He was permitted to indulge almost all the natural appetites and ambitions which characterize the life of the average man. For him the religion of the church was a magic which guaranteed divine intervention in critical moments and which offered a rather easy short-cut to the prizes of the spirit which ought to be won only by virtuous achievement. Yet this same church had an uncompromising attitude toward the various social institutions which Protestantism has never equaled. It insisted on the sacramental nature of the family union with such intransigeance that it may fairly be accused of failing to make necessary accommodations of its spiritual ideal to the imperfections of human nature. It dealt with economic relations with less severity but enforced ethical ideals upon them which must seem unusually exacting to an age which has become accustomed to the connivance of Protestantism with laissez-faire economics. The master of the medieval church, Thomas Aquinas, had elaborated a theory of the just price for all commercial transactions, which the church made every effort to apply and which it enforced through the canonical law. The church did not organize the guilds but it blessed them; and their efforts to regulate wages, fix fair profits, insure high quality of merchandise and organize mutual aid among their members were prompted by a religiously inspired moral idealism. While it dealt less successfully with the ethical implications of the relations between landowners and peasants, it impressed the owners with a sense of their obligation toward those who were economically dependent upon them which to this day gives the landed aristocracy of European nations a certain moral superiority over the industrial overlords who have been trained in more modern schools of thought. The ambition of the medieval church to dominate the life of the nations is well known but frequently misinterpreted. The contest between the papacy and the empire was indeed in some of its aspects no more than a conflict between two great political organizations lusting for the power which easily becomes the sole end of the life of social and political organisms. Yet there was a measure of ethical idealism in the political aspirations of the popes to which Protestant thought has given scant justice. In the two greatest exponents of the papacy as an international political force, Gregory VII and Innocence III, particularly in Gregory, the ethical ideal of a unified Christian society which knows how to hold the capricious self-will of nations in check and how to set bounds to their natural lust for power is of no small moment in the development of papal policy. The very autocracy of the papacy, which the modern world finds so little to its liking, was