These were dangerous thoughts, he knew. They were the....

“ These were dangerous thoughts, he knew. They were the kind that crept up on a Watchman when the chase was over and it was just you and him, facing one another in that breathless little pinch between the crime and the punishment.And maybe a Watchman had seen civilization with the skin ripped off one time too many and stopped acting like a Watchman and started acting like a normal human being and realized that the click of the crossbow or the sweep of the sword would make all the world so clean.And you couldn’t think like that, even about vampires. Even though they’d take the lives of other people because little lives don’t matter and what the hell can we take away from them?And, too, you couldn’t think like that because they gave you a sword and a badge and that turned you into something else and that had to mean there were some thoughts you couldn’t think.Only crimes could take place in darkness. Punishment had to be done in the light. That was the job of a good Watchman, Carrot always said. To light a candle in the dark. ”

Terry Pratchett

From : Feet of Clay