The present work took its rise, and is largely drawn, from the very learned Father Passaglia's "Commentary on the Prerogatives of St. Peter, Prince of the Apostles, as proved by the authority of Holy Writ," which was published in Latin, in 1850. The eighth and ninth chapters are, indeed, translations, respectively, of the twenty seventh of his first book, and the first of his second book And as to the rest, my obligations are more than I can specify. I owe, on the other hand, many excuses to Father Passaglia, for while I have only partially observed his order in treating the subject, I have considered his whole work as a treasure-house of learning, whence I might draw at my pleasure "things old and new," adapting them, as I thought good, to the needs of the Protestant mind, as familiar to me in England. Thus I have not scrupled to translate, to omit, or to insert matter of my own, according to my judgment. It seemed to me of paramount importance to present to the English reader the whole chain of scriptural evidence for the Primacy and prerogatives of St. Peter. This chain of evidence is so strong, that, when I first saw it completely drawn out, it struck my own mind, brought up in the prejudices of Protestantism, with the force of a new revelation. I put to myself the question; is it possible that they who specially profess to draw their faith from the written Word of God, would refuse to acknowledge a doctrine set forth in Holy Scripture with at least as strong evidence as the Godhead of Our Lord itself, if they could sec it not broken up into morsels, like hits of glass reflecting a distorted and imperfect image, according to the fashion of citing separate texts without regard to the proportion of the faith, but presented in a complete picture on the mirror of God's Word? This picture is thus complete and perfect in Father Passaglia's work. Yet the form of that work, no less than its bulk, the scrupulous minuteness with which every opposite interpretation of so many adversaries in modern times is answered, as well as the fulness with which every part of the suhject is treated, made me feel that a simple translation would not be tolerated by the impatience of a population, which has little time and less mind for studies of this character. I have pursued, therefore, the humble task of popularising, so far as I could, Father Passaglia's work, omitting, as I trust, no essential part of the argument, and grouping it under different combinations, each of which might he in turn presented to the eye, and so more readily embraced.