I'll be honest, Baum could have been dreaming about Sigmund Freud and Hitler was the scarecrow, FDR was the Tin man as he was in leg braces, Churchill the cowardly lion, but doesn't account for a Wizard that had a screen in front of him and seemed to be pulling levers, but probably a mouse and it doesn't account for the young girl he saw in his dreams with the Ruby slippers that a young Spears immediately identified with to search for the Wizard.