‘No,’ said Nijel.

He was trembling with rage, or possibly with cold, and was nearly as pale as the glaciers that rumbled past below them.

Conina sighed. ‘Well, just how do you think-’ she began.

‘Take me down somewhere a few minutes ahead of them,’ said Nijel.

‘I really don’t see how that would help.’

‘I wasn’t asking your opinion,’ said Nijel, quietly. ‘Just do it. Put me down a little way ahead of them so I’ve got a while to get sorted out.’

‘Get what sorted out?’

Nijel didn’t answer.

‘I said,’ said Conina, ‘get what-’

‘Shut up!’

‘I don’t see why-’

‘Look,’ said Nijel, with the patience that lies just short of axe-murdering. ‘The ice is going to cover the whole world, right? Everyone’s going to die, okay? Except for us for a little while, I suppose, until these horses want their, their, their oats or the lavatory or whatever, which isn’t much use to us except maybe Creosote will just about have time to write a sonnet or something about how cold it is all of a sudden, and the whole of human history is about to be scraped up and in these circumstances I would like very much to make it completely clear that I am not about to be argued with, is that absolutely understood?’

He paused for breath, trembling like a harpstring.

Conina hesitated. Her mouth opened and shut a few times, as though she was considering arguing, and then she thought better of it.

They found a small clearing in a pine forest a mile or two ahead of the herd, although the sound of it was clearly audible and there was a line of steam above the trees and the ground was dancing like a drumtop.

Nijel strolled to the middle of the clearing and made a few practice swings with his sword. The others watched him thoughtfully.

‘If you don’t mind,’ whispered Creosote to Conina, ‘I’ll be off. It’s at times like this that sobriety loses its attractions and I’m sure the end of the world will look a lot better through the bottom of a glass, if it’s all the same to you. Do you believe in Paradise, o peachcheeked blossom?’

‘Not as such, no.’

‘Oh,’ said Creosote. ‘Well, in that case we probably won’t be seeing each other again.’ He sighed. ‘What a waste. All this was just because of a geas. Um. Of course, if by some unthinkable chance-’

‘Goodbye,’ said Conina.

Creosote nodded miserably, wheeled the horse and disappeared over the treetops.

Snow was shaking down from the branches around the clearing. The thunder of the approaching glaciers filled the air.

Nijel started when she tapped him on the shoulder, and dropped his sword.

‘What are you doing here?’ he snapped, fumbling desperately in the snow.

‘Look, I’m not prying or anything,’ said Conina meekly, ‘but what exactly do you have in mind?’

She could see a rolling heap of bulldozed snow and soil bearing down on them through the forest, the mind-numbing sound of the leading glaciers now overlaid with the rhythmic snapping of tree trunks. And, advancing implacably above the treeline, so high that the eye mistook them at first for sky, the blue-green prows.

‘Nothing,’ said Nijel, ‘nothing at all. We’ve just got to resist them, that’s all there is to it. That’s what we’re here for.’

‘But it won’t make any difference,’ she said.

‘It will to me. If we’re going to die anyway, Iii rather die like this. Heroically.’

‘Is it heroic to die like this?’ said Conina.

‘I think it is,’ he said, ‘and when it comes to dying, there’s only one opinion that matters.’

‘Oh.’

A couple of deer blundered into the clearing, ignored the humans in their blind panic, and rocketed away.

‘You don’t have to stay,’ said Nijel. ‘I’ve got this geas, you see.’

Conina looked at the backs of her hands.

‘I think I should,’ she said, and added, ‘You know, I thought maybe, you know, if we could just get to know one another better-’

‘Mr and Mrs Harebut, was that what you had in mind?’ he said bluntly.

Her eyes widened. ‘Well-’ she began.

‘Which one did you intend to be?’ he said.

The leading glacier smashed into the clearing just behind its bow wave, its top lost in a cloud of its own creation.

At exactly the same time the trees opposite it bent low as a hot wind blew from the Rim. It was loaded with voices - petulant, bickering voices - and tore into the clouds like a hot iron into water.

Conina and Nijel threw themselves down into snow which turned to warm slush under them. Something like a thunderstorm crashed overhead, filled with shouting and what they at first thought were screams although, thinking about them later, they seemed more like angry arguments. It went on for a long time, and then began to fade in the direction of the Hub.

Warm water flooded down the front of Nijel’s vest. He lifted himself cautiously, and then nudged Conina.

Together they scrambled through the slush and mud to the top of the slope, climbed through a logjam of smashed timber and boulders, and stared at the scene.

The glaciers were retreating, under a cloud stuffed with lightning. Behind them the landscape was a network of lakes and pools.

‘Did we do that?’ said Conina.

‘It would be nice to think so, wouldn’t it?’ said Nijel.

‘Yes, but did-’ she began.

‘Probably not. Who knows? Let’s just find a horse,’ he said.

‘The Apogee,’ said War, ‘or something. I’m pretty sure.’

They had staggered out of the inn and were sitting on a bench in the afternoon sunshine. Even War had been persuaded to take off some of his armour.

‘Dunno,’ said Famine, ‘Don’t think so.’

Pestilence shut his crusted eyes and leaned back against the warm stones.

‘I think,’ he said, ‘it was something about the end of the world.’

War sat and thoughtfully scratched his chin. He hiccuped.

‘What, the whole world?’ he said.

‘I reckon.’

War gave this some further consideration. ‘I reckon we’re well out of it, then,’ he said.

People were returning to Ankh-Morpork, which was no longer a city of empty marble but was once again its old self, sprawling as randomly and colourfully as a pool of vomit outside the all-night takeaway of History.

And the University had been rebuilt, or had rebuilt itself, or in some strange way had never been unbuilt; every strand of ivy, every rotting casement, was back in place. The sourcerer had offered to replace everything as good as new, all wood sparkling, all stone unstained, but the Librarian had been very firm on the subject. He wanted everything replaced as good as old.

The wizards came creeping back with the dawn, in ones or twos, scuttling for their old rooms, trying to avoid one another’s gaze, trying to remember a recent past that was already becoming unreal and dream-like.

Conina and Nijel arrived around breakfast time and, out of kindness, found a livery stable for War’s horse.[25] It was Conina who insisted that they look for Rincewind at the University, and who, therefore, first saw the books.

They were flying out of the Tower of Art, spiralling around the University buildings and swooping through the door of the reincarnated Library. One or two of the more impudent grimoires were chasing sparrows, or hovering hawk-like over the quad.

The Librarian was leaning against the doorway, watching his charges with a benevolent eye. He waggled his eyebrows at Conina, the nearest he ever got to a conventional greeting.

‘Is Rincewind here?’ she said.

‘Oook.’

‘Sorry?’

The ape didn’t answer but took them both by the hand and, walking between them like a sack between two poles, led them across the cobbles to the tower.

There were a few candles alight inside, and they saw Coin seated on a stool. The Librarian bowed them into his presence like an ancient retainer in the oldest family of all, and withdrew.

Coin nodded at them. ‘He knows when people don’t understand him,’ he said. ‘Remarkable, isn’t he?’

‘Who are you?’ said Conina.

‘Coin,’ said Coin.

Are you a student here?’

‘I’m learning quite a lot, I think.’

Nijel was wandering around the walls, giving them the occasional prod. There had to be some good reason why they didn’t fall down, but if there was it didn’t lie in the realms of civil engineering.

‘Are you looking for Rincewind?’ said Coin.

Conina frowned. ‘How did you guess that?’

‘He told me some people would come looking for him.’

Conina relaxed. ‘Sorry,’ she said, ‘we’ve had a bit of a trying time. I thought perhaps it was magic, or something. He’s all right, isn’t he? I mean, what’s been happening? Did he fight the sourcerer?’

‘Oh, yes. And he won. It was very … interesting. I saw it all. But then he had to go,’ said Coin, as though reciting.

‘What, just like that?’ said Nijel.

‘Yes.’

‘I don’t believe it,’ said Conina. She was beginning to crouch, her knuckles whitening.

‘It is true,’ said Coin. ‘Everything I say is true. It has to be.’

‘I want to-’ Conina began, and Coin stood up, extended a hand and said, ‘Stop.’

She froze. Nijel stiffened in mid-frown.

‘You will leave,’ said Coin, in a pleasant, level voice, ‘and you will ask no more questions. You will be totally satisfied. You have all your answers. You will live happily ever after. You will forget hearing these words. You will go now.’

They turned slowly and woodenly, like puppets, and trooped to the door. The Librarian opened it for them, ushered them through and shut it behind them.

Then he stared at Coin, who sagged back on to the stool.

‘All right, all right,’ said the boy, ‘but it was only a little magic. I had to. You said yourself people had to forget.’

‘Oook?’

‘I can’t help it! It’s too easy to change things!’ He clutched his head. ‘I’ve only got to think of something! I can’t stay, everything I touch goes wrong, it’s like trying to sleep on a heap of eggs! This world is too thin! Please tell me what to do!’

The Librarian spun around on his bottom a few times, a sure sign of deep thought.

Exactly what he said is not recorded, but Coin smiled, nodded, shook the Librarian’s hand, and opened his own hands and drew them up and around him and stepped into another world. It had a lake in, and some distant mountains, and a few pheasants watching him suspiciously from under the trees. It was the magic all sourcerers learned, eventually.

Sourcerers never become part of the world. They merely wear it for a while.

He looked back, halfway across the turf, and waved at the Librarian. The ape gave him an encouraging nod.

And then the bubble shrank inside itself, and the last sourcerer vanished from this world and into a world of his own.