"The new exhibition at London’s Tate Modern features three heavy hitters, the Frenchmen Marcel Duchamp and Francis Picabia, and the American Man Ray. They are associated with the Dada and Surrealism movements, but they were friends before these existed, and after they ended. Of the three, Duchamp is the towering genius. Out of his own interests, phobias and distractions, he created a new aesthetic that has survived to become the reigning spirit of today’s art world. Its key idea is that anything can be a work of art."