Albert Einstein used to say that he went to his office at the Institute for Advanced Study “just to have the privilege of walking home with Kurt Gödel.” The two would meet at Einstein’s home each day between 10 and 11 and undertake the half-hour walk to the institute. At 1 or 2 in the afternoon they’d walk back, discussing politics, philosophy, and physics. Biographer Palle Yourgrau estimates that these walks consumed 30 percent of Einstein’s workday.

Einstein’s secretary, Helen Dukas, wrote in 1946, “I know of one occasion when a car hit a tree after its driver suddenly recognized the face of the beautiful old man walking along the street.”

Gödel caused no such problems. “I have so far not found my ‘fame’ burdensome in any way,” he wrote to his mother. “That begins only when one becomes so famous that one is known to every child in the street, as is the case of Einstein.”

(From A World Without Time: The Forgotten Legacy of Godel and Einstein, 2009.)