Labiche shouts out to his neighbour on the floor above, who is in the habit of dirtying his balcony, "What do you mean by emptying your pipe on to my terrace?" The neighbour retorts, "What do you mean by putting your terrace under my pipe?" There is no necessity to dwell upon this kind of wit, instances of which could easily be multiplied.
The reciprocal interference of two sets of ideas in the same sentence is an inexhaustible source of amusing varieties. There are many ways of bringing about this interference, I mean of bracketing in the same expression two independent meanings that apparently tally. The least reputable of these ways is the pun. In the pun, the same sentence appears to offer two independent meanings, but it is only an appearance; in reality there are two different sentences made up of different words, but claiming to be one and the same because both have the same sound. We pass from the pun, by imperceptible stages, to the true play upon words. Here there is really one and the same sentence through which two different sets of ideas are expressed, and we are confronted with only one series of words; but advantage is
