So far, so good ... but it gets more complicated. When you read a Discworld story, you play a curious mental game. You react as if the story is true, as if Discworld actually exists, as if Rincewind and the Luggage are real, and Roundworld is but a fragment of a long-forgotten dream. (Please stop interrupting, Rincewind, we know it's different from your point of view. Yes, of course we're the ones that don't exist, we're bundles of rules whose consequences take place only inside a small globe on a dusty shelf in Unseen University. Yes, we do appreciate that, and will you please shut up?) Sorry about that.

People have become very good at playing this game, and we will exploit that by setting Earth and Discworld on the same narrative level, so that each illuminates the other. In the first book, The Science of Discworld, the Discworld defined what is real. That's why reality makes such good sense. Roundworld is a magical construct, designed to keep the magic out, and that's why it makes no sense at all (to wizards, at least). In this sequel Earth acquires inhabitants, the inhabitants acquire minds, and minds do strange things. They bring narrativium to a story-less universe.

A computer can do a billion sums in the blink of a keystroke and get them all right, but it couldn't pretend to be a cowardly wizard if one walked up to it and thumped it on the memory cache. In contrast, we can think ourselves inside the mind of a cowardly wizard with ease, or recognize someone else when they're acting the part of one, but we're completely lost when it comes to doing several million simple sums a second. Even though, to someone not of this universe, that might appear to be a simpler task.

That's because we run on narrativium, and computers don't.

It was three hours later, in the cool of Unseen University. Not much had changed in the High Energy Magic building, except that a screen had been set up to show the output of Ponder's iconograph projector.

T don't see why you need it,' said Rincewind. 'There's only the two of us.'

'Ook,' agreed the Librarian. He was annoyed at having been woken from a doze in his library. It had been a very gentle awakening, sine no one wakes up a 300 lb orangutan roughly (twice, at least) but he was still annoyed.

"The Archchancellor says that we've got to be more organized about these things,' said Ponder.

'He says it's no use just shouting out "Hey, I've got a great idea!" These things have got to be presented properly. Are you ready?'

The very small imp that ran the projector raised a tiny thumb.

'Very well,' said Ponder. 'First slide. This is the Roundworld as it currently—'

'It's the wrong way up,' said Rincewind.

Ponder looked at the image.

'It's a ball,' he snarled. 'It's floating in space. How can it be the wrong way up?'

'That crinkly continent should be at the top.'

'Very well!' snapped Ponder. 'Imp, turn it around. Right? Satisfied?'

'It's the right way up but now it's the wrong way arou—' Rincewind began.

There was a thwack as Ponder's pointer stick smacked into the screen. 'This is the Roundworld!'

he snapped. 'As it exists at present! A world covered in ice! But time on Roundworld is subordinate to time in the real world! All times in Roundworld are accessible to us, in the same way that all pages in a book, though consecutive, are accessible to us! I have ascertained that the Faculty are on Roundworld but not in what appears to be the present time! They are several hundred million years in the past! Which is, from our point of view, perfectly capable of also being the present! I don't know how they got there! It should not be physically possible! Hex has located them! We have to assume that they can't get back the way they came! However -next slide please!'

Click!

'It's the same one,' said Rincewind. 'But now it's sideways—'

'A globe has no sideways!' said Ponder. There was a tinkle of breaking glass from the direction of the projector, and some very small cursing.

'I just thought you wanted to do it properly,' murmured Rincewind. Anyway, this is going to be about L-space, isn't it? I know it is. You know it is.'

'Yes, but I don't say that yet! I've got another dozen slides to come!' gasped Ponder. 'And a flow chart!'

'But it is, isn't it,' said Rincewind wearily. I mean, they say they've found other wizards. That means libraries. That means you can get there through L-space.'

I was going to say that's how we can get there,' said Ponder.

Yes, I know,' said Rincewind. 'That's why I thought I'd take the opportunity of saying "you" at this early juncture.'

'How can there be wizards on Roundworld?' said Ponder. 'When we know magic doesn't work there?'

'Search me,' said Rincewind. 'Ridcully did say they're useless.'

'And why can't the faculty come back by themselves? They were able to send the bottle! That must have used magic, surely?'

'Why not just go and ask them?' said Rincewind.

'You mean by homing in on the distinctive biothaumic signature of a group of wizards?'

'Well, I was thinking of waiting until something dreadful happened and you going to have a look in the wreckage,' said Rincewind. 'Bui the other stuff would probably work.'

"The omniscope locates them in approximately the 40,002,730,907th century,' said Ponder, staring at the globe. 'I can't get an image. But if we can find a way to the nearest library—'

'Ook!' said the Librarian. And then he ooked some more. He ooked at length, with an occasional eek. Once he thumped his fist on the table. He didn't need to thump the table a second time.

There wasn't, at that point, much in the way of table left to thump.

'He says only very senior librarians can use L-space,' said Rincewind, as the Librarian folded his arms. 'He was quite emphatic. He says it's not to be treated like some kind of magic funfair ride.'

'But it's an order from the Archchancellor!' said Ponder. 'There isn't any other way to get there!'

The Librarian looked a little uncertain at that. Rincewind knew why. It was hard to be an orangutan in Unseen University, and the only way the Librarian had been able to deal with it was by acknowledging Mustrum Ridcully as the alpha male, even though the Archchancellor seldom climbed up to a high place on the rooftops and called mournfully over the city at dawn. This meant that, unlike the other wizards, he found it very hard to shrug off an archchancelloric command. It was a direct, fang-revealing, chest-beating challenge. Rincewind had an idea.

'If we put the globe in the Library,' he said to the ape, 'then that would mean that even though you are travelling in L-space you would not be taking Mr. Stibbons anywhere outside the Library. I mean, the globe would be inside the library, so even though you'd wind up in the globe, you really wouldn't have travelled very far at all. A few feet, maybe. The globe's only infinite on the inside, after all.'

'Well, Rincewind, I am impressed,' said Ponder, while the Librarian looked perplexed. 'I'd always thought of you as rather stupid, but that was a remarkable piece of verbal reasoning. If we put the globe down right on the Librarian's desk, say, then the whole journey would take place inside the library, right?'

'Exactly,' said Rincewind, who was prepared to overlook 'rather stupid' in view of this unexpected praise.

And it's perfectly safe in the library, after all ...'

'Big thick walls. Very safe place,' Rincewind agreed.

'So, put like that, no harm will come to us,' said Ponder.

'There you go with the "us" again,' said Rincewind, backing away.

'We'll find them and bring them back!' said Ponder. 'How hard can it be?'