This is a comprehensive survey of the history of the Church in Western Europe from c. 900 to c. 1125, which is considered both as a set of institutions and as a spiritual body. The first half concentrates on the structures of religious belief and practice in the period 900-1050; the second half concentrates on the revolutionary changes associated with the rise of the papacy to a new level of rulership. It shows how far one can talk of a "reform movement," and how the idea and ideal of papal monarchy became both the prisoner and the leader of those who sought for a renewal of Christian life. Tellenbach's survey is the work of a scholar who has been working in the field for over sixty years. It is characterized by the freshness and maturity of its judgments, which cut through many fashionable theories. No other work on this topic offers comparable range, depth and authority.