A translation of The Collected Papers of Albert Einstein is being published by Prin-
ceton University Press, under the supervision of Diana Kormos Buchwald, General
Editor. Volume 12, containing translations of selected texts, was prepared by Ann
Hentschel, translator. Klaus Hentschel was the consultant, and Alice Calaprice was
the copyeditor. At the Einstein Papers Project, Rosy Meiron and Carol Chaplin
assisted in the translation. Osik Moses prepared the index, typeset and finalized the
volume, and, together with Rudy Hirschmann, produced camera-ready copy. The
translation volumes, produced in paperback, are intended to be read in conjunction
with the documentary edition, as they contain none of the editorial commentary of
this edition.
NOTE ON THE TRANSLATION