A joke is always a thought; it is grave and formal writing that can be literally thoughtless. This applies to jokes when they are not only quite verbal but quite vulgar. A good pun, or even a bad pun, is more intellectual than mere polysyllables. The man who invented the phrase “when is a door not a door; when it’s ajar,” made a serious and successful effort and mental selection and combination. But a German professor might begin on the same problem, “When is a door not a door; when its doorishness is a becoming rather than a being, and when the relativity of doorishness is co-ordinated with the evolution of doors from windows and skylights, from which approximation of new function, etc… etc…”–and the German professor might go on like that forever and never come to the end because he would never come to the point. A pun or a riddle can never be in that sense a fraud. Real wisdom may be better than real wit, but there is much more sham wisdom than there is sham wit.
– G. K. Chesterton, The Uses of Diversity