The receptivity of the masses is very limited, their intelligence is small, but their power of forgetting is enormous. In consequence of these facts, all effective propaganda must be limited to a very few points and must harp on these in slogans until the last member of the public understands what you want him to understand by your slogan.
To them belong, not only the truly great statesmen, but all other great reformers as well. Beside Frederick the Great stands Martin Luther as well as Richard Wagner.