How was medieval Europe held together? People of dissimilar occupations and economic interests, living in widely separate parts of western Europe, came to recognise and act upon a common set of cultural beliefs. This framework of shared social customs and values, that is distinctively medieval and European, arose from the interaction between secular and ecclesiastical power, but these developments can no longer be convincingly viewed as arising solely from events such as the Wars of Investiture and the Fourth Lateran Council. The medieval mental framework was not solely concerned with the great struggles between Rome and lay rulers, but neither can we assume that local communities were islands of cohesion in a wider world of chaos and conflict. The case studies demonstrate how texts were used as weapons by ecclesiastical authorities in defining their relationships with lay powers; how land and kinship was used to define social relations between laity and clergy; and how conflicts were resolved.