The introduction explains how the book complements existing historiography. Where existing scholarship sees the early sixteenth century as a caesura, the book directs attention instead to topics such as uncertainty about dogma, the relation between indulgences and penance, judges delegate, control of entry into marriage and problems connected with baptism. It suggests that the relevance of the Papal States to papal religious governance should be relativised: they constitute a sub-plot, not a key to the early modern papal system. The main archives used are the Archivio Apostolico Vaticano, the Archivio del Dicastero per la Dottrina della Fede and the Archivio Storico di Propaganda Fide. These are used to construct an analytical history of the papacy rather than a more conventional pope-by-pope narrative of events.