I am indebted for help to the following persons, first among my friends and colleagues in Oberlin: Andrew Bongiorno, Ernest Brehaut, Francis W. Buckler, Edward Capps, Jr., Ellsworth Carlson, Charles D. Cremeans, Julian S. Fowler, Emma Frank, Lucius Garvin, James H. Hall, Oscar and Recha Jászi, Frances Keller, William E. Kennick, Thomas S. Kepler, John C. Lapp, John D. and Ewart Lewis, Donald M. Love, Herbert G. May, Charles T. Murphy, Robert D. Murray, Jr., Charles P. Parkhurst, Jr., Helen Senour, Chester L. Shaver, Wolfgang Stechow, Forrest G. Tucker, Jennie Tucker, Mary Venn, Clarence Ward, Seldon S. Wolin, and Hermina Zortz; next to the staff of the Bibliothèque Nationale, Paris, and those of the Widener and Oberlin libraries; and finally to these scholars of other institutions: Milton V. Anastos, Dumbarton Oaks Library; Gray C. Boyce, Northwestern University; Marshall Clagett, University of Wisconsin; Ernest E. Dawn, University of Illinois; Sydney N. Fisher, Ohio State University; Erwin R. Goodenough, Yale University; Henry E. Guerlac, and Charles W. Jones, Cornell University; Theodore E. Mommesen, Princeton University; John C. Murray, Woodstock College; Sidney Painter, Johns Hopkins University; Robert R. Palmer, Princeton University; Anton C. Pegis, University of Toronto; Gaines Post, University of Wisconsin; Dorothy M. Quynn, Frederick, Md.; Raymond de Roover, Wells College; Douglas V. Steere, Haverford College; Anselm Strittmatter, St. Anselm's Priory, Washington, D. C.; and Harold R. Willoughby, University of Chicago.
The aid I received ranged all the way from helping me to get books to reading the entire manuscript and proof. Most of the persons listed read and commented on at least one chapter. I am deeply grateful to all these fellow-workers. They have saved me endless time and have rescued me from divers mistakes. The errors that remain are my own.