The Degenerate Art Exhibition included works by some of the great international names—Paul Klee, Oskar Kokoschka and Wassily Kandinsky—along with famous German artists of the time such Max Beckmann, Emil Nolde, and Georg Grosz. The exhibition handbook explained that the aim of the show was to "reveal the philosophical, political, racial and moral goals and intentions behind this movement, and the driving forces of corruption which follow them". Works were included "if they were abstract or expressionistic, but also in certain cases if the work was by a Jewish artist", says Jonathan Petropoulos, professor of European History at Claremont McKenna College and author of several books on art and politics in the Third Reich. Hitler had been an artist before he was a politician—but the realistic paintings of buildings and landscapes that he preferred had been dismissed by the art establishment in favor of abstract and modern styles. So the Degenerate Art Exhibition was his moment to get his revenge. He had made a speech about it that summer, saying "works of art which cannot be understood in themselves but need some pretentious instruction book to justify their existence will never again find their way to the German people". The Nazis claimed that degenerate art was the product of Jews and Bolsheviks, although only six of the 112 artists featured in the exhibition were actually Jewish. The art was divided into different rooms by category—art that was blasphemous, art by Jewish or communist artists, art that criticized German soldiers, art that offended the honor of German women. One room featured entirely abstract paintings, and was labelled "the insanity room". The idea of the exhibition was not just to mock modern art, but to encourage the viewers to see it as a symptom of an evil plot against the German people. The curators went to some lengths to get the message across, hiring actors to mingle with the crowds and criticize the exhibits. The Degenerate Art Exhibition in Munich attracted more than a million visitors—three times more than the officially sanctioned Great German Art Exhibition.