I'm up to my neck in the real world, every day. Just you try doing your VAT return with a head full of goblins.

Oh, my dear Vimes, history changes all the time. It is constantly being re-examined and re-evaluated, otherwise how would we be able to keep historians occupied? We can't possibly allow people with their sort of minds to walk around with time on their hands.

Give anyone a lever long enough and they can change the world. It's unreliable levers that are the problem.

Only in our dreams are we free. The rest of the time we need wages.

Writing, for me, is a little like wood carving. You find the lump of tree (the big central theme that gets you started), and you start cutting the shape that you think you want it to be. But you find, if you do it right, that the wood has a grain of its own (characters develop and present new insights, concentrated thinking about the story opens new avenues). If you're sensible, you work with the grain and, if you come across a knot hole, you incorporate that into the design. This is not the same as 'making it up as you go along'; it's a very careful process of control.

And then there were cats, thought Dog. He'd surprised the huge ginger cat from next door and had attempted to reduce it to cowering jelly by means of the usual glowing stare and deep-throated growl, which had always worked on the damned in the past. This time they had earned him a whack on the nose that had made his eyes water. Cats, Dog considered, were clearly a lot tougher than lost souls. He was looking forward to a further cat experiment, which he planned would consist of jumping around and yapping excitedly at it. It was a long shot, but it just might work.

However, you do need rules. Driving on the left (or the right or, in parts of Europe, on the left and the right as the mood takes you) is a rule which works, since following it means you're more likely to reach your intended rather than your final destination.