Vimes reflects on this well before he confronts Ahmed, but it takes Ahmed for the penny to drop:

> It was because he wanted there to be conspirators...

> ..It was 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.

It's a far greater commentary on racism and xenophobia than Witches Abroad could ever be.

No writer comes out of the womb aged 55, poised with the worldwise knowhow to write bestseller after bestseller. They grow. They change.

New Discworld readers are told not to start with Colour of Magic and Light Fantastic for a good reason: parody ages fast, and spoils faster. They've never been Pratchett at his best.

But satire? Once you understand the world's stories, and sympathise with the people those stories are about, a great satire never tarnishes. Johnathan Swift's "Modest Proposal" is as morbidly funny and cathartic today as it was nearly three centuries ago.

Few, if any of us, no matter how pious, get it right the first time. So we grow; so we change.

Pratchett missed a lot in Witches Abroad that is to the story's detriment. Left to the author's trust in the reader to pick up what they're putting down, the nuance missing in that story will always be problematic.