My greatest debt in the writing of this book is to my teacher Dr. Ulrich Middeldorf, who taught me the methodology of research in art history, and who guided my studies of art theory and criticism. This study, which in an earlier form was accepted as a doctoral dissertation by the University of Chicago, was begun under Dr. Middeldorf's guidance, and during all stages of its preparation I benefited from his invaluable suggestions and criticism. A United States Government Grant enabled me to complete my researches on Rembrandt in the Netherlands, where I studied at the Rijksuniversiteit te Utrecht with Dr. J. G. van Gelder, who was particularly generous with his knowledge and time. He read the manuscript and proofs, and offered numerous suggestions and additions which have been of great benefit to me. Special acknowledgement is made to the Kunsthistorisch lnstituut der Rijksuniversiteit te Utrecht for generously finding a place for this study in the Utrechtse Bij- dragen tot de Kunstgeschiedenis. I am also much indebted to Dr. H. Schulte- Nordholt of the Kunsthistorisch lnstituut for his valuable advice and his help inseeing the book through the press.