Estelle Havva points us to Baltasar Gracián y Morales:
"Know how to sell your wares, Intrinsic quality isn’t enough. Not everyone bites at substance or looks for inner value. People like to follow the crowd; they go someplace because they see other people do so. It takes much skill to explain something’s value. You can use praise, for praise arouses desire. At other times you can give things a good name (but be sure to flee from affectation). Another trick is to offer something only to those in the know, for everyone believes himself an expert, and the person who isn’t will want to be one. Never praise things for being easy or common: you’ll make them seem vulgar and facile. Everybody goes for something unique. Uniqueness appeals both to the taste and to the intellect."