Richard Feynman: No Ordinary Genius

I had the privilege of attending a seminar with Dr Feynman once and a more charming and intelligent man there never was.   He was also never afraid to ask the "stupid" questions that everyone else were too embarrassed to bring up.  One of my favourite moments of the Challenger Disaster inquiries of the 1980s was when Dr Feynman had the guts to speak up and ask what the heck an O ring was.  Turned out, no one else on the panel knew either.