"If little else, the brain is an educational toy. The problem with possessing such an engaging toy is that other people want to play with it, too. Sometime they'd rather play with yours than theirs. Or they object if you play with yours in a different manner from the way they play with theirs. The result is, a few games out of a toy department of possibilities are universally and endlessly repeated. If you don't play some people's game, they say that you have "lost your marbles," not recognizing that, while Chinese checkers is indeed a fine pastime, a person may also play dominoes, chess, strip poker, tiddlywinks, drop-the-soap or Russian roulette with his brain."