Pablo Picasso was the most inventive artist the West has ever known, and his drawings let us watch him inventing. Picasso worked out his ideas on paper much as Einstein scribbled his first thoughts for equations. (E=mb2, anyone?) The latest exhibition lets us in on any number of “eureka” moments. First Picasso completely reconsiders how a body can be built, then he takes on how space can be rendered, then he goes at what a drawing can be. And then he rethinks his rethinkings, as fast as pen or scissors will go. Picasso is as challenging as any artist. He challenges us to love his inventions–and we do.