Heinz Skunk quoted Moving Pictures by Terry Pratchett (Discworld, part 10)
It contained forbidden knowledge. Well, not actually forbidden. No-one had ever gone so far as forbidding it. Apart from anything else, in order to forbid it you'd have to know what it was, which was forbidden.
— Moving Pictures by Terry Pratchett (Discworld, part 10) (Page 174)
