Quotation by Karl Meninger

It might seem desirable to attempt a definition of play—not a dictionary definition but one that takes into account the psychological principles involved. We might define it as pleasurable activity in which the means is more important than the ostensible end. This clearly distinguishes it from work, and is in line with our hypothesis that, like work, play is an end in itself, an opportunity for the discharge of aggressive energy in not only painless but actually pleasurable forms, energy which would otherwise be repressed at a definite psychological expense or else expressed in harmful ways. Play acts out timelessly in pantomime, symbol, and gesture the unfulfillable aggressive and erotic wishes of the players. I say unfulfillable, although the fantasies of some play are actually realized later, as, for example, in the little girl's play with her doll.