Men at Arms (Discworld 15)

'The alchemists? Their idea of civic duty is mixing up things to see what happens.'

'I hear the bangs, even here.'

'And then, of course, along comes someone like you—'

'I really am terribly sorry.'

Lord Vetinari turned the model flying machine over and over in his fingers.

'You dream of flying,' he said.

'Oh, yes. Then men would be truly free. From the air, there are no boundaries. There could be no more war, because the sky is endless. How happy we would be, if we could but fly.'

Vetinari turned the machine over and over in his hands.

'Yes,' he said, 'I daresay we would.'

'I had tried clockwork, you know.'

'I'm sorry? I was thinking about something else.'

'I meant clockwork to power my flying machine. But it won't work.'

'Oh.'

'There's a limit to the power of a spring, no matter how tightly one winds it.'

'Oh, yes. Yes. And you hope that if you wind a spring one way, all its energies will unwind the other way. And sometimes you have to wind the spring as tight as it will go,' said Vetinari, 'and pray it doesn't break.'

His expression changed.

'Oh dear,' he said.

'Pardon?' said Leonard.

'He didn't thump the wall. I may have gone too far.'

Detritus sat and steamed. Now he felt hungry – not for food, but for things to think about. As the temperature sank, the efficiency of his brain increased even more. It needed something to do.

He calculated the number of bricks in the wall, first in twos and then in tens and finally in sixteens. The numbers formed up and marched past his brain in terrified obedience. Division and multiplication were discovered. Algebra was invented and provided an interesting diversion for a minute or two. And then he felt the fog of numbers drift away, and looked up and saw the sparkling, distant mountains of calculus.

Trolls evolved in high, rocky and above all in cold places. Their silicon brains were used to operating at low temperatures. But down on the muggy plains the heat build-up slowed them down and made them dull. It wasn't that only stupid trolls came down to the city. Trolls who decided to come down to the city were often quite smart – but they became stupid.

Detritus was considered moronic even by city troll standards. But that was simply because his brain was naturally optimized for a temperature seldom reached in Ankh-Morpork even during the coldest winter . . .

Now his brain was nearing its ideal temperature of operation. Unfortunately, this was pretty close to a troll's optimum point of death.

Part of his brain gave some thought to this. There was a high probability of rescue. That meant he'd have to leave. That meant he'd become stupid again, as sure as

10-3(Me/Mp)a6aG – N = 10N.

Better make the most of it, then.

He went back to the world of numbers so complex that they had no meaning, only a transitional point of view. And got on with freezing to death, as well.

Dibbler reached the Butchers' Guild very shortly after Cuddy. The big red doors had been kicked open and a small butcher was sitting just inside them rubbing his nose.

'Which way did he go?'