Soon Robert . . . was erasing a drawing by de Kooning and declaring this act to be its own work of art. Yves Klein was inviting Parisians to an opening of an exhibition at which there was nothing to see. He called the show Le Vide (The Void), and a mob of 1,000 people jammed the empty Iris Clert Gallery, spilling onto the surrounding streets (the police and firemen had to be called in), drinking special blue cocktails, a mixture of gin, Cointreau, and methylene blue mixed for Klein by La Coupole, the famous brasserie, which caused the urine of drinkers to turn blue for about a week, roughly the planned run of the show.