And then (Vimes) realized he was wondering if the attack on Goriff's shop had been organized by the same people, and whether those same people had set fire to the embassy.

And then he realized why he was thinking like this.

It was because he wanted there to be conspirators. It was so much better to imagine men in some smoky room somewhere, made mad and cynical by privilege and power, plotting over the brandy. You had to cling to this sort of image, because if you didn't then you might have to face the fact that bad things happened because ordinary people, the kind who brushed the dog and told their children bedtime stories, were capable of then going out and doing horrible things to other ordinary people. It was so much easier to blame it on Them. It was bleakly depressing to think that They were Us. If it was Them, then nothing was anyone's fault. If it was Us, what did that make Me? After all, I'm one of Us. I must be. I've certainly never thought of myself as one of Them. No one ever thinks of themselves as one of Them. We're always one of Us. It's Them that do the bad things.