 The celebrity of Clert, Klein, and the Galerie Iris Clert continued to rise and blossom with the success of the "Monochrome Propositions", culminating a year later, with another showing of Klein's, "le Vide" ("The Void").The immaterial exhibition opened on April 28, 1958, Klein's 30th birthday.The idea behind "The Void", much like "Micro-Salon d'Avril", was diabolically simple