Not for many years has a full-length study of the development of the Papacy been published in English. The ground to be covered is immense. The Church in the New Testament, the vexed questions (sometimes concerned with textual problems) of the early patristic period, the moral grandeur of the great Popes who became trustees of civilization as well as religion when the Western Empire collapsed, the feudal period, the Reformation and the rise of Nationalities, finally the period which ended in the loss of the Temporal Power and the declaration of Papal Infallibility -- each of these subjects deserves a volume of its own; yet all are treated here with some fullness. The authorities are given very fully in the footnotes. The author aims at complete objectivity and some of his conclusions may come as a surprise.