A Zen master posed his monks with a problem: “Two monks went walking in the rain. One didn’t get wet. Why?” The monks suggested that one had an umbrella, that the rain was scattered in places, that one walked under the cover of awnings, but the master said that the students were too focused on the words. When the monks finally gave up, the master told them that both got wet. “Two monks went walking in the rain. One didn’t get wet. Two got wet.”
The joke works just as well in ancient Chinese as it does in modern English because language has grey areas and ambiguities. When the master said, “One didn’t get wet”, he could mean that it is the case that one didn’t get wet, such that one remained dry, or he could mean that it isn’t the case that one got wet, rather two got wet. All of the solutions proposed by the monks assumed that one didn’t get wet, the first case, making them blind to the second. It isn’t that the first case is the literal meaning of the words and the second metaphorical or derivative, but rather that we do not expect to hear about one monk and not the other if both got wet or both stayed dry. The joke would also work if the master said both stayed dry, as one didn’t get wet, and the other didn’t get wet either.