We are pleased to be publishing this translation of selected documents of Volume 13 of The Collected Papers of Albert Einstein, the companion volume to the annotated, original-language documentary edition. As we have stated in all earlier volumes, these translations are not intended for use without the documentary edition, which provides the extensive editorial commentary necessary for a full historical and scientific understanding of the source documents. The translations strive first for accuracy, then literariness, though we hope that both have been achieved. The documents were selected for translation by the editors of The Collected Papers of Albert Einstein. We thank Ann M. Hentschel, Osik Moses, and Klaus Hentschel for their continuing good work and dedication to making Einstein’s writings and correspondence available to the English-speaking world Diana Kormos Buchwald for her attention to the translation project Rosy Meiron and Jennifer E. James for stylistic suggestions and A.J. Kox for typesetting the manuscript and producing the camera-ready copy, assisted by Rudy Hirschmann, Terri O’Prey, and Linny Schenck. Many thanks to Alice Calaprice for her thorough copyediting of the manuscript. Finally, we are most grateful to the National Endowment for the Humanities, Grant RQ-50267-7, and to the National Science Foundation, Grant No. SES-1058125, for their support of our project. Princeton University Press June 2012 PUBLISHER’S FOREWORD