From William Shirer's The Rise and Fall of the Third Reich (New York: Simon and Schuster, 1990 edition), pp. 243-4:
The Germany which had given the world a Duerer and a Cranach had not been pre-eminent in the fine arts in modern times, though German expressionism in painting and the Munich Bauhaus architecture were interesting and original movements and German artists had participated in all the twentieth-century evolutions and eruptions represented by impressionism, cubism and Dadaism.
To Hitler, who considered himself a genuine artist despite his early failures as one in Vienna, all modern art was degenerate and senseless. In Mein Kampf he had delivered a long tirade on the subject, and one of his first acts after coming to power was to “cleanse” Germany of its “decadent” art and to attempt to substitute a new “Germanic” art. Some 6,500 modern paintings—not only the works of Germans such as Kokoschka and Grosz but those of Cézanne, Van Gogh, Gauguin, Matisse, Picasso and many others—were removed from German museums.
What was to replace them was shown in the summer of 1937 when Hitler formally opened the “House of German Art” in Munich in a drab, pseudoclassic building which he had helped design and which he described as “unparalleled and inimitable” in its architecture. In this first exhibition of Nazi art were crammed some nine hundred works, selected from fifteen thousand submitted, of the worst junk this writer has ever seen in any country. Hitler himself made the final selection and, according to some of the party comrades who were with him at the time, had become so incensed at some of the paintings accepted by the Nazi jury presided over by Adolf Ziegler, a mediocre painter who was president of the Reich Chamber of Art, that he had not only ordered them thrown out but had kicked holes with his jack boot through several of them. “I was always determined,” he said in a long speech inaugurating the exhibition, “if fate ever gave us power, not to discuss these matters [of artistic judgment] but to make decisions.” And he had made them.
In his speech -- it was delivered on July 18, 1937 -- he laid down the Nazi line for “German art”:
Works of art that cannot be understood but need a swollen set of instructions to prove their right to exist and find their way to neurotics who are receptive to such stupid or insolent nonsense will no longer openly reach the German nation. Let no one have illusions! National Socialism has set out to purge the German Reich and our people of all those influences threatening its existence and character… With the opening of this exhibition has come the end of artistic lunacy and with it the artistic pollution of our people…
And yet some Germans at least, especially in the art center of Germany which Munich was, preferred to be artistically polluted. In another part of the city in a ramshackle gallery that had to be reached through a narrow stairway was an exhibition of “degenerate art” which Dr. Goebbels had organized to show the people what Hitler was rescuing them from. It contained a splendid selection of modern paintings—Kokoschka, Chagall and expressionist and impressionist works. The day I visited it, after panting through the sprawling House of German Art, it was crammed, with a long line forming down the creaking stairs and out into the street. In fact, the crowds besieging it became so great that Dr. Goebbels, incensed and embarrassed, soon closed it.