The title does not appear to me to represent accurately the subject of the book, which is not so much a history of the popes, as a history of the great struggle between catholicism and protestantism, between authority and innovation, in which the popes were indeed actors, but generally rather as the servants than the rulers of events. The chief interest of the work lies in the solution it affords of the greatest problem of modern history. It is impossible to contemplate the rapid and apparently resistless progress of the Reformation in its infancy, without wondering what was the power which arrested and forced back the torrent, and reconquered to the ancient faith countries in which protestantism seemed firmly established. The ebb and flow of this mighty wave are traced with singular vividness as well as accuracy in the following pages. - Translator's preface.