This image captures the intellectual essence of Einstein who, standing erect at a chalkboard, casually writes down some indecipherable equation only a few could possibly understand.
This particular shot was taken while Einstein was giving a lecture at California's Carnegie Institute on Jan 14, 1931.
Einstein spent three winters in Pasadena, Calif., in the early 1930s, spending two of them as a visiting professor at Caltech. He spent his time working, lecturing and making public appearances there and throughout the greater Los Angeles area.