Many jokes are identical in structure with the thinking errors of the psychotic, a fact of biological significance. The function of play is best seen in the animal young. The kitten plays by stalking the tail of its litter mate and pouncing on it. Play thus sharpens the coordination of eye and limb, perfecting the skills of a predator and fitting the animal to survive. In man adaptation demands keen judgment. Man must be able to think logically, to associate ideas properly. Nature has made it pleasurable for the child to "play" with ideas, to put them together in various combinations and see what makes sense and what doesn't. This play with ideas, which developes the appreciation of absurdity, gives the child practice in the art of thinking and thus adds to his capacity for adaptation.Abstract Teaser