Caravaggio was on a defiant mission to change the art world. Before him, there were pastel-colored idealized visions, polite paintings for a polite society. After him, there were slews of imitators, trying to grasp his brilliant slashes of light and dark, his people who looked more like your neighbor than a model of perfection. Bold with his brush, the young rebel was equally brash in his life, picking fights and getting arrested for things as silly as throwing a plate of artichokes in a waiter's face. Until he faced the ultimate punishment, condemned for a murder he didn't commit-at least not intentionally.