If little else, the brain is an educational toy. While it may be a frustrating plaything – one whose finer points recede just when you think you are mastering them – it is nonetheless perpetually fascinating, frequently surprising, occasionally rewarding, and it comes already assembled; you don’t have to put it together Christmas morning.
The problem with possessing such an engaging toy is that other people want to play with it too. Sometimes 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.