In 1921, Einstein was away from Berlin for more than six months. He traveled
within Continental Europe and, for the first time, to the United States and England,
lecturing on his work to both specialized and general audiences, and promoting in-
ternational reconciliation and collaboration among scientists of former enemy
countries.
Einstein had become a well-known scientist and an increasingly visible public
figure. His work on relativity was being widely discussed among physicists, astron-
omers, and mathematicians. During this year, his scientific activities centered on
theoretical work on the unification of gravity and electromagnetism, and on exper-
imental investigations concerning certain implications of quantum theory. Mean-
while, the number of scientific books and articles that followed up on his earlier
researches rose dramatically, an effervescence to which Einstein himself contribut-
ed through his lectures and appearances that popularized relativity among scientists
and general audiences. He was also called upon to take concrete action or, at least,
to clarify his views on myriad other topics. He worked toward the establishment of
the Hebrew University, and acted decisively on behalf of international reconcilia-
tion and cooperation. But his voluminous correspondence documents many other
significant events, and provides rich material for a deeper understanding of the
multiplying spheres of Einstein’s interests, activities, and interactions.
The present volume draws on more than 2,000 documents written by, to, and
about Einstein during 1921. It opens with eleven letters pertaining to dates earlier
than 1921 that are followed by 349 letters selected for full-text presentation.
Of the 291 available letters authored by Einstein in 1921, we present 169 as full
texts, together with 180 from among the more than 500 extant letters that he re-
ceived. The Calendar contains references to several hundred items. Among them,
a substantial exchange with various publishers testifies to the growing demand for
Einstein’s publications in their original German version, and also for translations
of his writings into English, French, Spanish, Italian, Russian, Polish, Hungarian,
Ukrainian, Japanese, Romanian, Yiddish, and Hebrew. The letters reveal many un-
known or hitherto little-explored facets of both his work and of his relationships to
not only colleagues, friends, and family, but also the many people, institutions, and
causes that he encountered for the first time during 1921.
INTRODUCTION TO VOLUME 12