"It's people's minds that cause the problem. Man cannot enslave man. Man enslaves himself," he says. "I'm never going to make a joke about mac donalds again, because i was really guilty of doing it." 'How large is your office? Our trading floor occupies one room. It's not huge. 12 people in it on the desk,' Warren Buffett adds. "'You can't win if you're always looking over your shoulder' You've got to be able to look at yourself and say: What am I thinking here?' And then act like an adult.'"