THE CONTENT of this book was first presented to the public in a series of lectures delivered at the Lowell Institute in Boston in March 1944. The author wishes to express his thanks to the Trustees of the Lowell Institute, and also to Professor J. Douglas Bush. He feels particularly indebted to Dr. Arthur Burkhard for having revised the language of the text of the lectures.
For publication, the text has been enlarged and provided with notes. The author is indebted to the library of the Fogg Museum of Art, to Widener Library and Houghton Library of Harvard University, to the Boston Public Library, and to the Print Room of the Museum of Fine Arts, Boston, for the use of books and photographs needed for the illustrations.
Most valuable to the author was the advice and criticism given him by Professor Zechariah Chafee, Jr., when he had the privilege of discussing the text with him before its revision for publication. May he accept this book as a token of the author's gratitude.
Fogg Museum of Art July 1945