This survey of key popes documents the evolution of the papacy from its beginning to its monarchical trappings in our own day. Other recent histories of the papacy treat the office or the bishop of Rome as a political or social phenomenon. Upon this Rock examines the links between the teachings of Jesus in the New Testament, the interpretations of his teachings by the Apostles, and the changes and developments in the nature and understanding of the papal office under successive bishops of Rome.