It's hard to do your best thinking when your feet hurt. That's true even for geniuses. On a crisp fall morning back in 1952, Peter Hulit was tending to business at his shoe store on Nassau Street--the venerable main drag of Princeton, N.J.--when he got an emergency call. Helen Dukas, Albert Einstein's secretary-housekeeper, was on the line. Could Hulit come to the physicist's home? "Dr. Einstein's shoes are hurting him," Dukas said. Recalls Hulit: "I'd never made a house call before or since. But this was Einstein."
Hulit, who is now 82, a D-day survivor and long retired, was used to...