They know that people need witches; they need the unofficial people who understand the difference between right and wrong, and when right is wrong and when wrong is right. The world needs the people who work around the edges. They need the people who can deal with the little bumps and inconveniences. And little problems. After all, we are almost all human. Almost all of the time.

WHERE'S MY COW? ARE YOU MY COW?

As we all know, the Discworld is a flat planet - like a geological pizza, but without the anchovies.

There are plenty of people who believe that Elvis is alive, or that aliens occasionally land here to do highly personal things to people, or that the whole idea of evolution is a conspiracy of godless scientists. Almost all of these people can vote and some of them have got guns.

I think when people mean that Discworld books have become darker they really mean the series is growing up. In 'The Colour of Magic' most of the city is set alight. It's a joke, in much the same way that the Earth is destroyed almost at the start of Douglas Adams's 'The Hitchhikers Guide to the Galaxy.'

He's out of his depth on a wet pavement.

Its useful to go out of this world and see it from the perspective of another one.