“The way I solved the theoretical problem was to go into the shop and build something concrete.”
finding out that he was not a theoretical but an experimental physicist, as quoted in his biographical memoir. [Jesse L. Greenstein, Robert B. Leighton, 1919—1996, Biographical Memoirs v.75, National Academy of Sciences, 1998, 0-309-06295-0, 164, http://www.nap.edu/openbook.php?record_id=9649&page=164]