"The art of mentally ill people inspired Klee as well as Kandinsky and Max Ernst, after Hans Prinzhorns book "Bildnerei der Geisteskranken" (Artistry of the Mentally Ill) was published in 1922.In 1937, some papers from Prinzhorn's anthology were presented at the National Socialist propaganda exhibition "Entartete Kunst" in Munich, with the purpose of defaming the works of Kirchner, Klee, Nolde and other artists by likening them to the works of the insane.