" Do you know where 'policeman' comes from, sir? ... 'Polis' used to mean 'city', said Carrot. That's what policeman means: 'a man for the city'. Not many people knew that. The word 'polite' comes from 'polis', too. It used to mean the proper behaviour from someone living in a city. "

― Terry Pratchett , Men at Arms (Discworld, #15; City Watch #2)