in the eleventh and twelfth centuries, ‘Latin’ Europe went through a period of growing social differentiation, in which the function of each class became more clearly defined. The king was seen as the holder of an office, the discharge of which must answer to a basically Christian ordering of affairs. The warrior class emerged as a group whose position in society was determined by their ability and duty to bear arms, which gave them a claim to nobility. Differentials in the religious life emerged with the monastic reforms originating in Cluny and the development of new religious orders: Cistercians, Premonstratensians and canons. Religion also became more strongly centred on the Roman church and the pope. The interaction of these processes of transformation, within aristocratic and chivalric society on the one hand and the church on the other, gave rise to a new phenomenon in medieval history: the crusades. What was new was not so much the adoption of war to a religious context as the fact that the pope was summoning the whole of western Christendom to war: to a certain extent, western Christendom constituted itself as such by going jointly to war. No longer was individual withdrawal from the world into the cloister the sole representation of the ideal Christian life. Rather did war, a worldly activity, and the Christian life come together in a previously unknown relationship, no longer opposed one to the other. Fighting, which had previously been a way for the individual to rise above the mass of the population, shook free of this orientation and became part of a greater whole.