The study of ecclesiastical history presents unique problems: the events it deals with are not ordinary events and fundamental questions of faith may be involved in their interpretation. The Church historian is often required to be a student of dogma as much as of history. It is the complex relationships between history, Church history and theology that Dr Sykes examines, using as illustrations some of the vital issues arising from the revival of interest in Church history in the sixteenth and seventeenth centuries. The disputes during the Reformation about the claims of the papacy centred on the historical question of Peter's supremacy over the other apostles. Another problem involving historical evidence was the relative authority of scripture and tradition. Finally, Dr Sykes reviews the changing pattern of relations between Church and states and particularly the way in which events in nineteenth-century Europe foreshadowed the problems of the Church under the modern totalitarian regime. This historical study displays how the secular and the theological are intertwined in many of the issues which confront the historian of the Church.