Free Science of Discworld III by Terry Pratchett

to all your offices … .’
    There was more staring.
    ‘It had a green cover … .’ Ponder prompted.
    The staring was quite intense now. Ponder gave in.
    ‘Perhaps I should remind you of the important points?’ he said.
    The faces lit up.
    ‘Just jog our memories,’ said the Dean, cheerfully.
    ‘I discussed alternate timelines in phase space,’ 1 said Ponder. That was a mistake, he could see. His fellow wizards weren’t stupid, but you had to be careful to shape ideas to fit the holes in their heads.
    ‘Two different legs in the Trousers of Time,’ said Ponder. ‘In the year 1859, by the counting system commonly in use in that part of Roundworld, a book changed the way a lot of people thought about the world. It just happened to be the wrong book—’
    ‘Prove it,’ said the Chair of Indefinite Studies.
    ‘Pardon, sir?’
    ‘Well, correct me if I’m wrong, but supposing Theology of Species was the right book?’ said the Chair.
    ‘It muted scientific – that is, technomantic – progress for almost a hundred years, sir,’ said Ponder, wearily. ‘It slowed down humanity’s understanding of its place in the universe.’
    ‘You mean that it was built by wizards and left on a shelf in a corridor?’ said the Chair.
    ‘That’s only true on the outside, sir,’ said Ponder. ‘My point is, something happened to Mr Darwin at some time in his life that caused him to write the wrong book. And it was wrong. Yes, it would have been the right book here on Discworld, sir. We know there is a God of Evolution.’
    ‘That’s right. Skinny old chap, lives on an island,’ said Ridcully. ‘Decent sort, in his way. Remember? He was redesigning the elephant when we were there. With wheels, very clever. Very keen on beetles, too, as I recall.’
    ‘So why’d Darwin write this theology book instead?’ the Chair of Indefinite Studies persisted.
    ‘I don’t know, sir, but as I wrote on page 4, I’m sure you recall, it was the wrong book at exactly the right time. Nevertheless, it made sense. There was something in it for everyone. All the technomancers had to do was leave a place in their science for the local god, and all the priests had to give up were a few beliefs that none of the sensible ones believed anyway—’
    ‘Such as what?’ said the Dean.
    ‘Well, that the world was created in a week and isn’t very old,’ said Ponder.
    ‘But that’s true!’
    ‘Once again, only on the outside, Dean,’ said Ponder smoothly. ‘As far as we can tell, Theology of Species polarised intellectual opinion in a curious way. In fact, haha, it equatorialised it, you might say.’
    ‘I don’t think we would,’ said Ridcully. ‘What does the word mean?’
    ‘Ah … er, on a globe, the equator is an imaginary line around the middle,’ said Ponder. ‘What happened was that the bulk of the technomancers and the priests got behind the ideas expressed in Darwin’s book, because they gave everyone pretty much what they wanted. Quite of few of the technomancers had a strong belief in the god, and most of the brighter priests could see big flaws in the dogma. Together, they were a very large and influential force. The hard-line religionists and the unbending technomancers were marginalised. Out in the cold. Polarised, in fact.’ This rather neat pun, although he said it himself, failed to get even a groan of acknowledgement, so he went on: ‘They didn’t agree with the united group and they certainly didn’t agree with one another. And, thus, happy compromise ruled. For well over sixty years.’
    ‘That’s nice,’ said the Lecturer in Recent Runes.
    ‘Er … yes, sir, and then again, no,’ said Ponder. ‘Technomancy doesn’t work well in those circumstances. It can’t make real progress by consensus. Hah, being led by a bunch of self-satisfied old men who are more interesting in big dinners than asking questions is a recipe for stagnation, anyone can see that.’
    The wizards nodded sagely.
    ‘Very