As reported in the December 1960 issue of The Month at Caltech, [William McLellan] walked into [Feynman]’s lab with this tiny marvel that took him 2.5 months of lunch hour breaks to build.

Feynman's lecture was, in truth, a very minor incident in his brilliant career, but if we were to look for the source of its later power, the starting point must be the figure of Feynman himself.