mostly harmless

Be careful. People like to be told what they already know. Remember that. They get uncomfortable when you tell them knew things. New things… well, new things arent what they expect. They like to know that, say, a dog will bite a man…. They dont want to know that man bites a dog, because the world is not supposed to happen like that.In short, what people think they want is news, but what they really crave is olds… not news but olds, telling people that what they think they already know is true.

-Terry Pratchett as Lord Vetinari, The Truth: a Novel of Discworld