“Humans, as a rule, don't like mad people unless they are good at painting, and only then once they are dead. But the definition of mad, on Earth, seems to be very unclear and inconsistent. What is perfectly sane in one era turns out to be insane in another. The earliest humans walked around naked with no problem. Certain humans, in humid rainforests mainly, still do so. So, we must conclude that madness is sometimes a question of time, and sometimes of postcode. Basically, the key rule is, if you want to appear sane on Earth you have to be in the right place, wearing the right clothes, saying the right things, and only stepping on the right kind of grass.”