Einstein in Montevideo, 1925. Courtesy of the Leo Baeck Institute.

ALICE CALAPRICE: What attracted you to Einstein's travel diaries? Was it Einstein himself, the subject of traveling, or something from your own background?

JOSEF EISINGER: As a physicist I have long been fascinated by the work and the life of Einstein, a fascination I evidently share with many others. But it was a tenuous, indirect link to Einstein that led me to his travel diaries and, in time, to this book.

Some 67 years ago I was living in Toronto as a member of the household of the Mendel family, finding myself in that fortunate position through the vagaries of wartime and thanks to the generosity of that extraordinary family. The Mendels had been friends of Einstein when they all resided in Berlin, and Einstein had then been particularly close to the widow, Toni Mendel. They often went sailing together and they read Freud's latest writings jointly. When I knew Toni Mendel in the late 1940s, she was a sprightly, intelligent, though elderly lady who still corresponded with Einstein, then living in Princeton. A few years ago a researcher working on the history of the Mendel family came to see me in order to dredge my distant memory, and in the course of our conversation, he mentioned the diaries Einstein kept during his far-flung travels and that they were available for scrutiny in the duplicate Einstein archive at Princeton University. The archivists there kindly provided me with copies of the various diaries, and I found reading them very evocative, for instance, when Einstein, aboard a ship in the Atlantic, records his gratitude to Toni Mendel for having supplied him with some licorice for his journey. But more importantly, I quickly realized that these diaries represented a unique and unvarnished record of Einstein's views and activities from 1922, the year Einstein and his wife Elsa made their epic journey to the Far East, until 1933, when Hitler attained power in Germany and the couple left Europe and settled in Princeton.

CALAPRICE: In what language does Einstein write? Did you have any problems reading his writing or understanding what he wrote?

EISINGER: Einstein wrote in German, the only language he ever felt comfortable using. He used ordinary ruled notebooks for his journals, and his handwriting was neat and exceedingly legible. When he felt rushed he wrote "telegraph style," but his meaning is never obscure. As a native German-speaker with wide translation experience, I enjoyed the challenge of rendering Einstein's elegant German into English while preserving the author's mood and spirit in my narrative. The book is not a translation of the diaries but a narrative based on them, with excerpts from the diaries incorporated.

Einstein and Hayasi Myake en route to Japan from Marseille. Courtesy of the Leo Baeck Institute.

CALAPRICE: What years did these travels occur? Why did he undertake the travels to the various places at those times?

EISINGER: Einstein's travel diaries span the years from 1922 to 1933, while he was a resident of Berlin--although he had been a Berliner since 1914--from the Great War to the end of the Weimar Republic. Throughout these turbulent years Einstein played an active role in public affairs and politics, marking him as a prime target of the Nazis and others, particularly after he became an international celebrity. His lecture tours offered an opportunity to escape the political turmoil for a while, but he had other motivations: he was paid huge honoraria in hard currencies, funds Einstein needed to support his first wife and their two sons living in Switzerland. Furthermore, having become a world celebrity in 1919 and remaining one throughout his travel years, the long sea voyages offered a way to escape the reporters and photographers who beleaguered him on land. And finally, he really was interested in seeing and exploring these new and exotic places and cultures-Japan, China, Singapore, Palestine, South America, and yes, Pasadena.

Not all his voyages were due to lecture tours: his several stays at Caltech and in Oxford were opportunities to interact and collaborate with many physicists and astronomers.

CALAPRICE: What sources did you use in writing the book?

EISINGER: My main sources were Einstein's travel diaries themselves, and they guide my narrative. Where the diaries were not informative enough or lacked the needed context, I provided bridging sections that are based on numerous other sources, including well-researched Einstein biographies, contemporary newspaper accounts, and unpublished memoirs in various archives.

CALAPRICE: Did you need to do much additional research to put the diary into historical context? Did you enjoy doing that?

EISINGER: Because so many of the events and personalities that Einstein encountered on his travels are no longer widely known, I have provided the reader with the most basic and essential historical background, both within the narrative and in the lengthy end notes. I found the requisite historical research particularly absorbing and it helped me to put myself in Einstein's shoes, as it were, and to see the world as he saw it. It is my hope that readers of my book will have a similar experience.

Einstein and captain of the Portland, 1931. Bundesarchiv.

CALAPRICE: What in the diaries surprised you the most?

EISINGER: I suppose it is the breadth of Einstein's interests. The diaries tell us what books he chose to read on the long sea voyages, and the selection was surprisingly eclectic, ranging from Geoffrey Chaucer and Henri Bergson to Hans Christian Andersen and Egon Friedell. The tireless devotion with which he pursued his principal interests becomes evident from the diaries.

First and foremost, there is his pursuit of physics. He does not let a day pass without working on his latest theory; but his urge to understand the world in terms of physical laws extends to everything around him: to tropical weather patterns, the shape of the Milky Way, the sun's magnetism, and fata morganas. I was also surprised by evidence of Einstein's enduring interest in scientific instruments and patents, and by how deeply he was involved in the design of a practical gyrocompass.

Music runs a close second to science in Einstein's interests. He brought his violin along on his voyages, and he is never more content than with the instrument under his chin, preferably playing second violin in a Mozart quartet. And along with physics and music, Einstein's powerful moral convictions are apparent in his diaries. Lengthy lectures and endless receptions may have left him exhausted, but he never failed to meet with yet another peace delegation or supplicant, and every worthy humanitarian cause could count on his fervent support.

On a more mundane level, the diaries remind us how slow and uncomfortable sea travel without air conditioning was and how greatly the world has changed in the past eighty years.