'Discworld' is taking something that you know is ridiculous and treating it as if it is serious, to see if something interesting happens when you do so.

Granddad was superstitious about books. He thought that if you had enough of them around, education leaked out, like radioactivity.

Aliens don't get stuck in air ducts. It's practically a well-known fact.

Well, it would have to be “The Man Who Was Thursday.” It’s a damn good read that I believe should be read by everyone in politics.

Education had been easy. Learning things had been harder.

Sergeant Colon of the Ankh-Morpork City Guard was on duty. He was guarding the Brass Bridge, the main link between Ankh and Morpork. From theft. When it came to crime prevention, Sergeant Colon found it safest to think big.

This is space. It's sometimes called the final frontier. (Except that of course you can't have a final frontier, because there'd be nothing for it to be a frontier to, but as frontiers go, it's pretty penultimate . . .)