No serious historical work is worth the writing or the reading unless it conveys a moral, but to be useful the moral must develop itself in the mind of the reader without being obtruded upon him. Especially is this the case in a history treating of a subject which has called forth the fiercest passions of man, arousing alternately his highest and his basest impulses. I have not paused to moralize, but I have missed my aim if the events narrated are not so presented as to teach their appropriate lesson. It only remains for me to express my thanks to the numerous friends and correspondents who have rendered me assistance in the arduous labor of collecting the very varied material, much of it inedited, on which the present work is based. Especially do I desire to record my gratitude to the memory of that cultured gentleman and earnest scholar, the late Hon. George P. Marsh, who for so many years worthily represented the United States at the Italian court. I never had the fortune to look upon his face, but the courteous readiness with which he aided my researches in Italy merit my warmest acknowledgments. To Professor Charles Molinier, of the University of Toulouse, moreover, my special thanks are due as to one who has always been ready to share with a fellow-student his own unrivalled knowledge of the Inquisition of Languedoc. In the Florentine archives I owe much to Francis Philip Nast, Esq., to Professor Felice Tocco, and to Doctor Giuseppe Papaleoni; in those of Naples, to the Superintendent Cav. Minieri Riccio and to the Cav. Leopoldo Ovary; in those of Venice to the Cav. Teodoro Toderini and Sig. Bartolomeo Cecchetti: in those of Brussels to M. Charles Rahlenbeck. In Paris I have to congratulate myself on the careful assiduity with which M.L. Sandret has exhausted for my benefit the rich collections of MSS., especially those of the Bibliothèque Nationale. To a student, separated by a thousand leagues of ocean from the repositories of the Old World, assistance of this nature is a necessity, and I esteem myself fortunate in having enlisted the co-operation of those who have removed for me some of the disabilities of time and space. Should the remaining portion of my task be hereafter accomplished, I hope to have the opportunity of acknowledging my obligations to many other gentlemen of both hemispheres who have furnished me with unpublished material illustrating the later development of the Holy Office. PHILADELPHIA, _August_, 1887. CONTENTS. BOOK I.--ORIGIN AND ORGANIZATION OF THE INQUISITION. CHAPTER I.--THE CHURCH. Page Domination of the Church in the Twelfth Century 1 Causes of Antagonism with the Laity 5 Election of Bishops 6 Simony and Favoritism 7