[xi] Since it would be impossible to express my gratitude to all those who have in some way contributed to this volume, I limit myself here to acknowledging only the most direct indebtedness.

Professor Giles Constable of Harvard University prepared me for the task and saw me through it, and it was to his unfailingly exquisite historical judgement that I turned for help in matters of doubt. To Professor Jocelyn Hillgarth, now of the Pontifical Institute, I owe my acquaintance with the particulars of medieval Spanish history, and to him also enormous thanks for practical assistance of every sort at each stage of preparation of this study. These two men have been responsible for much of this book through their inspiration and help.

Professor Thomas Glick of Boston University read the manuscript and made many valuable suggestions, and Professor David Herlihy of Harvard read and criticized portions of it.

Harvard University provided the funds for the year in Spain during which I completed the bulk of my archival research, and I am extremely grateful for its generosity to me. The directors of the Archive of the Crown of Aragon in Barcelona were extremely kind and helpful to me, as were the archivists and staff. To all of them I am indebted not simply for the relative ease with which I was able to conduct my investigations, but for the pleasantness of my residence in Barcelona.

[xii]Finally, I wish to extend the most heartfelt thanks to Ralph Hexter and David Frusti for practical assistance in the preparation of the manuscript. Their cheerful generosity contributed as much as their actual labor to lightening tasks which would otherwise have been burdensome.

New Haven, August 1, 1977