Aristotle, Rhetoric
J. H. Freese, Ed.

[6] Most smart sayings are derived from metaphor,
and also from misleading the hearer beforehand.¹ For it becomes more evident to him that he has learnt something, when the conclusion turns out contrary to his expectation, and the mind seems to say, “How true it is! but I missed it.” And smart apophthegms arise from not meaning what one says, as in the apophthegm of Stesichorus, that “the grasshoppers will sing to themselves from the ground.”² And clever riddles are agreeable for the same reason; for something is learnt, and the expression is also metaphorical. And what Theodorus calls “novel expressions” arise when what follows is paradoxical, and, as he puts it, not in accordance with our previous expectation; just as humorists make use of slight changes in words. The same effect is produced by jokes that turn on a change of letter; for they are deceptive. These novelties occur in poetry as well as in prose; for instance, the following verse does not finish as the hearer expected: “ And he strode on, under his feet—chilblains,

” whereas the hearer thought he was going to say “sandals.” This kind of joke must be clear from the moment of utterance. Jokes that turn on the word are produced, not by giving it the proper meaning, but by perverting it; for instance, when Theodorus said to Nicon, the player on the cithara, “you are troubled” （ θράττει）; for while pretending to say “something troubles you,” he deceives us; for he means something else.³
Therefore the joke is only agreeable to one who understands the point; for if one does not know that Nicon is a Thracian, he will not see any joke in it.