ACKNOWLEDGMENTS Like many other scholars, we are deeply indebted to Miss Helen Dukas for the years of effort she dedicated to creating and maintaining the Einstein Archive. The Editor also had the pleasure of working closely with her for several years at the Institute for Advanced Study, Princeton. We are grateful as well to Dr. Otto Nathan for his twenty-five years of service as a trustee of the Einstein Estate. This volume is dedicated to their memory. We are also indebted to the many scholars whose labors contributed so much to our understanding of Einstein, his work, and his times. We cannot attempt to list them all with a catalogue of what we have learned from each. Because we regularly cite primary sources for information about Einstein, our debt to these scholars is unfortunately often not reflected in the list of Literature Cited. We thank them all. Our search for additional contemporary documents and other primary sources for information used in this volume drew upon a number of bio- graphies and other secondary sources of information about Einstein. Chief among these are: Clark 1971, Dukas and Hoffmann 1979, Fluckiger 1974, Frank 1979, Hoffmann 1972, Holton 1973, Pais 1982, Pyenson 1982, Sanesi 1982, Seelig 1960, and Trbuhovic-Gjuric 1983. We are very grateful for the aid given to us by The Hebrew University of Jerusalem. Prof. Reuven Yaron, our liaison with the University, facilitated access to the Einstein Archive and has assisted our work in many other ways. The American Friends of The Hebrew University kindly gave us access to the Einstein Archive before it was moved to Jerusalem, for which we thank Charles Bloom and Ehud Benamy. We also thank Prof. Milton Handler, the University's lawyer. The Archive is now housed in the Department of Manuscripts and Archives of the Jewish National and University Library. We thank Dr. Mordechai Nadav, former head of the department, Margot Cohn, Hannah Katzenstein, and Kitty Steinschneider for their patient and cheerful help. For granting us access to the riches of the Einstein Family Correspondence Trust, we would like to express our appreciation to Prof. Elizabeth R. Einstein, Dr. Thomas Einstein, and Michael Ferguson. We thank Dr. Hans R. Denzler of the ETH for permission to publish docu- ments deposited at that institution and for assistance in interpreting them.