It pays to heed a warning. Argentinean race driver Juan Manuel Fangio discovered that after the opening lap of the 1950 Monaco Grand Prix. As he approached a dangerous bend for the second time, Fangio noticed that something was wrong. The faces of the spectators, which he usually saw as a whitish blur as he drove by, were all turned away from him. "If they are not looking at me," Fangio thought, "they must be looking at something more interesting around the corner." So he braked hard and carefully rounded ...