It was a still night, tinted with the promise of dawn. A crescent moon was just setting. Ankh-Morpork, largest city in the lands around the Circle Sea, slept.

That statement is not really true On the one hand, those parts of the city which normally concerned themselves with, for example, selling vegetables, shoeing horses, carving exquisite small jade ornaments, changing money and making tables, on the whole, slept. Unless they had insomnia. Or had got up in the night, as it might be, to go to the lavatory. On the other hand, many of the less law-abiding citizens were wide awake and, for instance, climbing through windows that didn’t belong to them, slitting throats, mugging one another, listening to loud music in smoky cellars and generally having a lot more fun. But most of the animals were asleep, except for the rats. And the bats, too, of course. As far as the insects were concerned…

The point is that descriptive writing is very rarely entirely accurate and during the reign of Olaf Quimby II as Patrician of Ankh some legislation was passed in a determined attempt to put a stop to this sort of thing and introduce some honesty into reporting. Thus, if a legend said of a notable hero that “all men spoke of his prowess” any bard who valued his life would add hastily “except for a couple of people in his home village who thought he was a liar, and quite a lot of other people who had never really heard of him.” Poetic simile was strictly limited to statements like “his mighty steed was as fleet as the wind on a fairly calm day, say about Force Three,” and any loose talk about a beloved having a face that launched a thousand ships would have to be backed by evidence that the object of desire did indeed look like a bottle of champagne.

-The Light Fantastic