IN acknowledging with gratitude the assistance I have received, it is fitting that I should mention first those to whom my obligations are greatest--the trustees and director the Huntington Library who have most generously allowed me to devote to this book whatever time I could spare from my official duties and other research projects. Without the liberty to carry on my researches while at the Library and to use its collections, I could not have completed this volume; with it, I could work as conveniently in San Marino as anywhere in the world. Moreover, I have had the advantage of being able to consult colleagues, both permanent and temporary, about different sections of my book. Mr. C. H. Collins Baker effected many improvements in my chapter on the arts; Dr. Max Farrand, the director of the Huntington Library, not only facilitated my studies in various ways, but also found time to improve the order and style of several of my chapters; Professor Edwin F. Gay read through 'Social and Economic History' and made some valuable additions; Dr. Hubert C. Heffner and Dr. Hoyt H. Hudson gave me much assistance with 'Literature', the former with the drama and the latter with poetry; Dr. Francis R. Johnson made a thorough revision of 'Science'; Dr. Fulmer Mood kindly read 'Foreign Trade and the Colonies'; Dr. Conyers Read went through many chapters and gave me much sound advice; Dr. Louis B. Wright allowed me to draw freely on his knowledge of literature, and Dr. Marjorie H. Nicolson has given advice on that subject and on science and education. In addition Dr. G. N. Clark exercised a very beneficial editorial supervision; the late Sir Charles Firth most generously lent me some unpublished lectures on the social history of the Protectorate, from which I have taken many references, facts, and comments; Dr. Edwin P. Hubble helped me by reading and discussing 'Science'; Dr. C. K. Judy commented on 'Literature'; and Professor Jacob Viner not only allowed me to make a very great use of his writings on mercantilism but also corrected 'Foreign Trade'. Finally I owe much to two members of the Huntington Library staff, Mr. M. H. Crissey and Mrs. Marion Tinling, for the care they have taken in the preparation of my manuscript.