"The art of propaganda lies in understanding the emotional ideas of the great masses and finding, through a psychologically correct form, the way to the attention and thence to the heart of the broad masses. The receptivity of the great 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 slogans until the last member of the public understands what you want him to understand...
"The broad mass of a nation does not consist of diplomats, or even professors of political law, or even individuals capable of forming a rational opinion; it consists of plain mortals, wavering and inclined to doubt and uncertainty. As soon as our own propaganda admits so much as a glimmer of right on the other side, the foundation for doubt in our own right has been laid. The masses are then in no position to distinguish where foreign injustice ends and our own begins."
Mein Kampf, Adolph Hitler