
“The demagogue is one who preaches doctrines he knows to be untrue to men he knows to be idiots.”
Part 2, chapter 4 http://books.google.com/books?id=Xw-DAAAAMAAJ&q=%22The+demagogue+is+one+who+preaches+doctrines+he+knows+to+be+untrue+to+men+he+knows+to+be+idiots%22&pg=PA103#v=onepage
1920s, Notes on Democracy (1926)
Context: The demagogue is one who preaches doctrines he knows to be untrue to men he knows to be idiots. The demaslave is one who listens to what these idiots have to say and pretends to believe it himself.