Schönbrunn Psychiatric Hospital, 1934. Photo by SS photographer Franz Bauer (Bundesarchiv, Bild 152-04-28 / Friedrich Franz Bauer / CC-BY-SA 3.0)
Adolf Hitler read racial hygiene theory during his imprisonment in Landsberg Prison. He thought that Germany could become strong again only if the state applied the principles of racial hygiene and eugenics to German society.
Hitler believed the nation had become weak, corrupted by the infusion of degenerate elements into its bloodstream. These had to be removed quickly.
He also believed that the strong and the racially pure should be encouraged to have more children, and that the weak and the racially impure should be neutralized by one means or another.