Monty Burns did it, of course! I can't believe no one else has reported it, but "The Simpsons" solved the 20-year-old Isabella Stewart Gardner Museum robbery. In Sunday's episode, called "American History X-cellent," Homer, Carl and Lenny were loudly partying down in billionaire misanthrope Burns' mansion - long story - and Burns called the cops. But when Springfield's finest arrived, one of them looked at a painting on the mansion wall and recognized it as Vermeer's "The Concert" (right), stolen from the Gardner in March 1990 along with a dozen other works, several of them masterpieces, none of which have ever been found.With very unusual perception for the dimwitted cop, Chief Wiggum asked Burns how he came to possess "this miracle of measure and harmony." Burns contemptuously replied, "Is it a crime to want nice things and then to steal them from a public museum where any gum-chewing monkey in a Tufts University jacket can gawk at them?" Burns was arrested and imprisoned, leading to a "Green Mile" takeoff and - in another nod to the Gardner heist - Homer, Carl and Lenny posed as cops to break him out. Watch the episode here. The key clip: