What gives a government -- even a repressive regime -- the power to rule? The answer, he realized, was people's belief in its power. Even dictatorships require the cooperation and obedience of the people they rule to stay in charge.

Gene Sharp: A dictator's worst nightmare - CNN.com

He's an unlikely radical -- an 84-year-old American academic. But his ideas about using non-violence to overthrow repressive regimes are literally revolutionary.