On the other hand, it was certainly a fascinating building. Its builders had been obsessed with the number eight. The floor was a continuous mosaic of eight-sided tiles, the corridor walls and ceilings were angled to give the corridors eight sides if the walls and ceilings were counted and, in those places where part of the masonry had fallen in Twoflower noticed that even the stones themselves had eight sides.

“I don’t like it,” said the picture imp, from his box around Twoflower’s neck.

“Why not?” inquired Twoflower.

“It’s weird.”

“But you’re a demon. Demons can’t call things weird. I mean, what’s weird to a demon?”

“Oh, you know,” said the demon cautiously, glancing around nervously and shifting from claw to claw. “Things. Stuff.”

Twoflower looked at him sternly. “What things?”

The demon coughed nervously (demons do not breathe, however, every intelligent being, whether it breathes or not, coughs nervously at some time in its life. And this was one of them as far as the demon was concerned). “Oh, things,” it said wretchedly. “Evil things. Things we don’t talk about is the point I’m broadly trying to get across, master.”

Twoflower shook his head wearily. “I wish Rincewind was here,” he said. “He’d know what to do.”

“Him?” sneered the demon. “Can’t see a wizard coming here. They can’t have anything to do with the number eight.” The demon slapped a hand across his mouth guiltily.

Twoflower looked up at the ceiling.

“What was that?” he asked. “Didn’t you hear something?”

“Me? Hear? No! Not a thing,” the demon insisted.

It jerked back into its box and slammed the door. Twoflower tapped on it. The door opened a crack.

“It sounded like a stone moving,” he explained.

The door banged shut. Twoflower shrugged.

“The place is probably falling to bits,” he said to himself.

He stood up.

“I say!” he shouted. “Is anyone there?”

AIR, Air, air, replied the dark tunnels.

“Hullo?” he tried. lo, Lo, lo.

“I know there’s someone here, I just heard you playing dice! “

ICE, Ice, ice.

“Look, I had just—”

Twoflower stopped. The reason for this was the bright point of light that had popped into existence a few feet from his eyes. It grew rapidly, and after a few seconds was the tiny bright shape of a man. At this stage it began to make a noise, or, rather Twoflower started to hear the noise it had been making all along. It sounded like a sliver of a scream, caught in one long instant of time.

The iridescent man was doll-sized now, a tortured shape tumbling in slow motion while hanging in mid-air. Twoflower wondered why he had thought of the phrase “a sliver of a scream”…and began to wish he hadn’t.

It was beginning to look like Rincewind. The wizard’s mouth was open, and his face was brilliantly lit by the light of—what? Strange suns, Twoflower found himself thinking. Suns men don’t usually see. He shivered.

Now the turning wizard was half man-size. At that point the growth was faster, there was a sudden crowded moment, a rush of air, and an explosion of sound. Rincewind tumbled out of the air, screaming. He hit the floor hard, choked, then rolled over with his head cradled in his arms and his body curled up tightly.

When the dust had settled Twoflower reached out gingerly and tapped the wizard on the shoulder.

The human ball rolled up tighter.

“It’s me,” explained Twoflower helpfully. The wizard unrolled a fraction.

“What?” he said.

“Me.”

In one movement Rincewind unrolled and bounced up in front of the little man, his hands gripping his shoulders desperately. His eyes were wild and wide.

“Don’t say it!” he hissed. “Don’t say it and we might get out! “

“Get out? How did you get in? Don’t you know—”

“Don’t say it!”

Twoflower backed away from this madman

“Don’t say it!”

“Don’t say what?”

“The number.”

“Number?” said Twoflower. “Hey, Rincewind—”

“Yes, number! Between seven and nine. Four plus four”

“What, ei—”

Rincewind’s hands clapped over the man’s mouth. “Say it and we’re doomed. Just don’t think about, right. Trust me!”

“I don’t understand,” wailed Twoflower.

Rincewind relaxed slightly; which was to say that he still made a violin string look like a bowl of jelly.

“Come on,” he said. “Let’s try and get out. And I’ll try and tell you.”

After the first Age of Magic the disposal of grimoires began to become a severe problem on the Discworld. A spell is still a spell even when imprisoned temporarily in parchment and ink. It has potency. This is not a problem while the book’s owner still lives, but on his death the Spell book becomes a source of uncontrolled power that cannot easily be defused.

In short, spell books leak magic. Various solutions have been tried. Countries near the Rim simply loaded down the books of dead mages with leaden pentagrams and threw them over the Edge. Near the Hub less satisfactory alternatives were available. Inserting the offending books in canisters of negatively polarized octiron and sinking them in the fathomless depths of the sea was one (burial in deep caves on land was earlier ruled out after some districts complained of walking trees and five-headed cats) but before long the magic seeped out and eventually fishermen complained of shoals of invisible fish or psychic clams.

A temporary solution was the construction, in various centres of magical lore, of large rooms made of denatured octiron, which is impervious to most forms of magic. Here the more critical grimoires could be stored until their potency had attenuated.

That was how there came to be at Unseen University the Octavo, greatest of all grimoires, formerly owned by the Creator of the Universe. It was this book that Rincewind had once opened for a bet. He had only a second to stare at a page before setting off various alarm spells, but that was time enough for one spell to leap from it and settle in his memory like a toad in a stone.

“Then what?” said Twoflower.

“Oh, they dragged me out. Thrashed me, of course.”

“And no-one knows what the spell does?”

Rincewind shook his head.

“It’d vanished from the page,” he said. “No-one will know until I say it. Or until I die, of course. Then it will sort of say itself. For all I know it stops the universe, or ends Time, or anything.”

Twoflower patted him on the shoulder.

“No sense in brooding,” he said cheerfully. “Let’s have another look for a way out.”

Rincewind shook his head. All the terror had been spent now. He had broken through the terror barrier, perhaps, and was in the dead calm state of mind that lies on the other side. Anyway, he had ceased to gibber.

“We’re doomed,” he stated. “We’ve been walking around all night. I tell you, this place is a spiderweb. It doesn’t matter which way we go, we’re heading twoards the centre.”

“It was very kind of you to come looking for me, said Twoflower. “How did you manage it it was very impressive.”

“Well,” began the wizard awkwardly. “I just ‘I can’t leave old Twoflower there’ and—”

“So what we’ve got to do now is find this Bel-Shamharoth person and explain things to him and perhaps he’ll let us out,” said Twoflower.

Rincewind ran a finger around his ear.

“It must be the funny echoes in here,” he said. “I thought I heard you use words like find and explain.

“That’s right.”

Rincewind glared at him in the hellish purple glow. “Find Bel-Shamharoth?” he said.

“Yes. We don’t have to get involved.”

“Find the Soul Render and not get involved? Just give him a nod, I suppose, and ask the way to the exit? Explain things to the Sender of Eignnnngh,” Rincewind bit off the end of the word just in time and finished, “You’re insane. Hey! Come back!”

He darted down the passage after Twoflower, and after a few moments came to a halt with a groan.

The violet light was intense here, giving everything new and unpleasant colours. This wasn’t a passage, it was a wide room with walls to a number that Rincewind didn’t dare to contemplate, and 7 passages radiating from it.

Rincewind saw, a little way off, a low altar with the Same number of sides as four times two. It didn’t occupy the centre of the room, however. The centre was occupied by a huge stone slab with twice as many sides as a square. It looked massive. In the strange light it appeared to be slightly tilted with one edge standing proud of the slabs around it.

Twoflower was standing on it.

“Hey. Rincewind! Look what’s here!

The Luggage came ambling down one of the other passages that radiated from the room.

“That’s great,” said Rincewind. “Fine. It can lead us out of here. Now.”

Twoflower was already rummaging in the chest

“Yes,” he said. “After I’ve taken a few pictures Just let me fit the attachment—”

“I said now—”

Rincewind stopped. Hrun the Barbarian was standing in the passage mouth directly opposite him, a great black sword held in one ham-sized fist.

“You?” said Hrun uncertainly.

“Ahaha. Yes,” said Rincewind. “Hrun, isn’t it? Long time no see. What brings you here?”

Hrun pointed to the luggage.

“That,” he said. This much conversation seemed to exhaust Hrun. Then he added, in a tone that combined statement, claim, threat and ultimatum: “Mine.”

“It belongs to Twoflower here,” said Rincewind.

“Here’s a tip. Don’t touch it.”

It dawned on him that this was precisely the wrong thing to say, but Hrun had already pushed Twoflower away and was reaching for the Luggage… which sprouted legs, backed away, and raised its lid threateningly. In the uncertain light Rincewind thought he could see rows of enormous teeth, white as bleached beechwood.

“Hrun,” he said quickly, “there’s something I ought to tell you.”

Hrun turned a puzzled face to him.

“What?” he said.

“It’s about numbers. Look, you know if you add seven and one, or three and five, or take two from ten. You get a number. While you’re here don’t say it and we might all stand a chance of getting out of here alive. Or merely just dead.”

“Who is he?” asked Twoflower. He was holding a cage in his hands, dredged from the bottom-most depths of the Luggage. It appeared to be full of sulking pink lizards.