When critics attacked Andy Warhol's Marilyn paintings as shallow, the Pop artist was happy to present himself as shallower still: He claimed that he silkscreened to avoid the hard work of painting, although he was actually a meticulous workaholic; in interviews he presented himself as a silly naïf when in private he was the canniest of sophisticates. Blake Gopnik's definitive biography digs deep into the contradictions and radical genius that led Andy Warhol to revolutionise our cultural world.