Laughter (n.) is, for Jews, a way of expiating jewish self-hatred.
Laughter (n.) is the surplus energy discharged when primary-process thinking forces its way into consciousness and the effort to inhibit it is suddenly no longer needed.
Laughter (n.) at a refined obscene joke springs from the same source as a peasant's laugh at coarse smut; we only need the joke's help to allow it — so we do not really know what we are laughing at.
Laughter (n.) is the most studied and least explained of acts, and perhaps reflection kills it — so that it would be a contradiction for reflection to find its causes.
Laughter (n.) is the discharge of psychical energy that a joke has suddenly made superfluous: the hearer laughs off the effort of inhibition he no longer needs.
Laughter (n.) is infectious, and we tell our jokes to laugh on the rebound, using the other person to set off the laugh we cannot have ourselves.
Laughter (n.) often confirms an interpretation: when shown a faithful picture of their hidden unconscious, patients laugh even when the content hardly justifies it.
Laughter (n.) comes only when the saved expenditure cannot be used elsewhere and is free for discharge; if it is put to another use, the comic does not appear.