We shall first call attention to a certain general relaxation of the rules of reasoning.  The reasonings at which we laugh are those we know to be false, but which we might accept as true were we to hear them in a dream.  They counterfeit true reasoning just sufficiently to deceive a mind dropping off to sleep.  There is still an element of logic in them, if you will, but it is a logic lacking in tension and, for that very reason, affording us relief from intellectual effort.  Many “witticisms” are reasonings of this kind, considerably abridged reasonings, of which we are given only the beginning and the end.  Such play upon ideas evolves in the direction of a play upon words in proportion as the relations set up between the ideas become more superficial:  gradually we come to take no account of the meaning of the words we hear, but only of their sound.  It might be instructive to compare with dreams certain comic scenes in which one of the characters systematically repeats in a nonsensical fashion what another character whispers in his ear.  If you fall asleep with people talking round you, you sometimes find that what they say gradually becomes devoid of meaning, that the sounds get distorted, as it were, and recombine in a haphazard fashion to form in your mind the strangest of meanings, and that you are reproducing between yourself and the different speakers the scene between Petit-Jean and The Prompter. [Footnote:  Les Plaideurs (Racine).]

There are also comic obsessions that seem to bear a great resemblance to dream obsessions.  Who has not had the experience of seeing the same image appear in several successive dreams, assuming a plausible meaning in each of them, whereas these dreams had no other point in common.  Effects of repetition sometimes present this special form on the stage or in fiction:  some of them, in fact, sound as though they belonged to a dream.  It may be the same with the burden of many a song:  it persistently recurs, always unchanged, at the end of every verse, each time with a different meaning.

Not infrequently do we notice in dreams a particular Crescendo, a weird effect that grows more pronounced as we proceed.  The first concession extorted from reason introduces a second; and this one, another of a more serious nature; and so on till the crowning absurdity is reached.  Now, this progress towards the absurd produces on the dreamer a very peculiar sensation.  Such is probably the experience of the tippler when he feels himself pleasantly drifting into a state of blankness in which neither reason nor propriety has any meaning for him.  Now, consider whether some of Moliere’s plays would not produce the same sensation:  for instance, Monsieur de Pourceaugnac, which, after beginning almost reasonably, develops into a sequence of all sorts of absurdities.  Consider also the Bourgeois gentilhomme, where the different characters seem to allow themselves to be caught up in a very whirlwind of madness as the play proceeds.  “If it is possible to find a man more completely mad, I will go and publish it in Rome.”  This sentence, which warns us that the play is over, rouses us from the increasingly extravagant dream into which, along with M. Jourdain, we have been sinking.