It's not for nothing that advanced mathematics tends to be invented in hot countries. It's because of the morphic resonance of all the camels, who have that disdainful expression and famous curled lip as a natural result of an ability to do quadratic equations.

It's not generally realised that camels have a natural aptitude for advanced mathematics, particularly where they involve ballistics. This evolved as a survival trait, in the same way as a human's hand and eye co-ordination, a chameleon's camouflage and a dolphin's renowned ability to save drowning swimmers if there's any chance that biting them in half might be observed and commented upon adversely by other humans.

The fact is that camels are far more intelligent than dolphins.[21]

They are so much brighter that they soon realised that the most prudent thing any intelligent animal can do, if it would prefer its descendants not to spend a lot of time on a slab with electrodes clamped to their brains or sticking mines on the bottom of ships or being patronised rigid by zoologists, is to make bloody certain humans don't find out about it. So they long ago plumped for a lifestyle that, in return for a certain amount of porterage and being prodded with sticks, allowed them adequate food and grooming and the chance to spit in a human's eye and get away with it.

And this particular camel, the result of millions of years of selective evolution to produce a creature that could count the grains of sand it was walking over, and close its nostrils at will, and survive under the broiling sun for many days without water, was called You Bastard.

And he was, in fact, the greatest mathematician in the world.

You Bastard was thinking: there seems to be some growing dimensional instability here, swinging from zero to nearly forty-five degrees by the look of it. How interesting. I wonder what's causing it? Let V equal 3. Let Tau equal Chi/4. cudcudcud Let Kappa/y be an Evil-Smelling-Bugger[22] differential tensor domain with four imaginary spin co-efficients...

Ptraci hit him across the head with her sandal. 'Come on, get a move on!' she yelled. You Bastard thought: Therefore H to the enabling power equals V/s. cudcudcud Thus in hypersyllogic notation . . .

Teppic looked behind him. The strange distortions in the landscape seemed to be settling down, and Dios was . . .

Dios was striding out of the palace, and had actually managed to find several guards whose fear of disobedience overcame the terror of the mysteriously distorted world.

You Bastard stood stoically chewing. . . cudcudcud which gives us an interesting shortening oscillation. What would be the period of this? Let period = x. cudcudcud Let t = time. Let initial period . . .

Ptraci bounced up and down on his neck and kicked hard with her heels, an action which would have caused any anthropoid male to howl and bang his head against the wall.

'It won't move! Can't you hit it?'

Teppic brought his hand down as hard as he could on You Bastard's hide, raising a cloud of dust and deadening every nerve in his fingers. It was like hitting a large sack full of coathangers.

'Come on,' he muttered.

Dios raised a hand.

'Halt, in the name of the king!' he shouted.

An arrow thudded into You Bastard's hump.

. . . equals 6.3 recurring. Reduce. That gives us ouch . . . 314 seconds . . .

You Bastard turned his long neck around. His great hairy eyebrows made accusing curves as his yellow eyes narrowed and took a fix on the high priest, and he put aside the interesting problem for a moment and dredged up the familiar ancient maths that his race had perfected long ago:

Let range equal forty-one feet. Let windspeed equal 2. Vector one-eight. cud Let glutinosity equal 7 .

Teppic drew a throwing knife.

Dios took a deep breath. He's going to order them to fire on us, Teppic thought. In my own name, in my own kingdom, I'm going to be shot.

Angle two-five, cud Fire.

It was a magnificent volley. The gob of cud had commendable lift and spin and hit with a sound like, a sound like half a pound of semi-digested grass hitting someone in the face. There was nothing else it could sound like.

The silence that followed was by way of being a standing ovation.

The landscape began to distort again. This was clearly not a place to linger. You Bastard looked down at his front legs.

Let legs equal four .

He lumbered into a run. Camels apparently have more knees than any other creature and You Bastard ran like a steam engine, with lots of extraneous movement at right angles to the direction of motion accompanied by a thunderous barrage of digestive noises.

'Bloody stupid animal,' muttered Ptraci, as they jolted away from the palace, 'but it looks like it finally got the idea.'

. . . gauge-invariant repetition rate of 3.5/z. What's she talking about, Bloody Stupid lives over in Tsort . . .

Though they swung through the air as though jointed with bad elastic You Bastard's legs covered a lot of ground, and already they were bouncing through the sleeping packed-earth streets of the city.

'It's starting again, isn't it?' said Ptraci. 'I'm going to shut my eyes.'

Teppic nodded. The firebrick-hot houses around them were doing their slow motion mirror dance again, and the road was rising and falling in a way that solid land had no right to adopt.

'It's like the sea,' he said.

'I can't see anything,' said Ptraci firmly.

'I mean the sea. The ocean. You know. Waves.'

'I've heard about it. Is anyone chasing us?'

Teppic turned in the saddle. 'Not that I can make out,' he said. 'It looks as-'

From here he could see past the long, low bulk of the palace and across the river to the Great Pyramid itself. It was almost hidden in dark clouds, but what he could see of it was definitely wrong. He knew it had four sides, and he could see all eight of them.

It seemed to be moving in and out of focus, which he felt instinctively was a dangerous thing for several million tons of rock to do. He felt a pressing urge to be a long way away from it. Even a dumb creature like the camel seemed to have the same idea.

You Bastard was thinking: . . Delta squared. Thus, dimensional pressure k will result in a ninety-degree transformation in Chi(16/x/pu)t for a K-bundle of any three invariables. Or four minutes, plus or minus ten seconds

The camel looked down at the great pads of his feet.

Let speed equal gallop.

'How did you make it do that?' said Teppic.

'I didn't! It's doing it by itself! Hang on!'

This wasn't easy. Teppic had saddled the camel but neglected the harness. Ptraci had handfuls of camel hair to hang on to. All he had was handfuls of Ptraci. No matter where he tried to put his hands, they encountered warm, yielding flesh. Nothing in his long education had prepared him for this, whereas everything in Ptraci's obviously had. Her long hair whipped his face and smelled beguilingly of rare perfume.[23]

'Are you all right?' he shouted above the wind.

'I'm hanging on with my knees!'

'That must be very hard!'

'You get special training!'

Camels gallop by throwing their feet as far away from them as possible and then running to keep up. Knee joints clicking like chilly castanets, You Bastard thrashed up the sloping road out of the valley and windmilled along the narrow gorge that led, under towering limestone cliffs, to the high desert beyond.

And behind them, tormented beyond measure by the inexorable tide of geometry, unable to discharge its burden of Time, the Great Pyramid screamed, lifted itself off its base and, its bulk swishing through the air as unstoppably as something completely unstoppable, ground around precisely ninety degrees and did something perverted to the fabric of time and space.

You Bastard sped along the gorge, his neck stretched out to its full extent, his mighty nostrils flaring like jet intakes.

'It's terrified!' Ptraci yelled. 'Animals always know about this sort of thing!'

'What sort of thing!'

'Forest fires and things!'

'We haven't got any trees!'

'Well, floods and - and things! They've got some strange natural instinct!'

. . . Phi* 1700[u/v]. Lateral e/v. Equals a tranche of seven to twelve . . .

The sound hit them. It was as silent as a dandelion clock striking midnight, but it had pressure. It rolled over them, suffocating as velvet, nauseating as a battered saveloy.

And was gone.

You Bastard slowed to a walk, a complicated procedure that involved precise instructions to each leg in turn.

There was a feeling of release, a sense of stress withdrawn. You Bastard stopped. In the pre-dawn glow he'd spotted a clump of thorned syphacia bushes growing in the rocks by the track.

. . angle left. x equals 37. y equals 19. z equals 43. Bite . . .

Peace descended. There was no sound except for the eructations of the camel's digestive tract and the distant warbling of a desert owl.

Ptraci slid off her perch and landed awkwardly.

'My bottom,' she announced, to the desert in general, 'is one huge blister.'

Teppic jumped down and half-ran, half-staggered up the scree by the roadside, then jogged across the cracked limestone plateau until he could get a good look at the valley.

It wasn't there any more.

It was still dark when Dil the master embalmer woke up, his body twanging with the sensation that something was wrong. He slipped out of bed, dressed hurriedly, and pulled aside the curtain that did duty as a door.

The night was soft and velvety. Behind the chirrup of the insects there was another sound, a frying noise, a faint sizzling on the edge of hearing.

Perhaps that was what had woken him up.

The air was warm and damp. Curls of mist rose from the river, and-

The pyramids weren't flaring.

He'd grown up in this house: it had been in the family of the master embalmers for thousands of years, and he'd seen the pyramids flare so often that he didn't notice them, any more than he noticed his own breathing. But now they were dark and silent, and the silence cried out and the darkness glared.

But that wasn't the worst part. As his horrified eyes stared up at the empty sky over the necropolis they saw the stars, and what the stars were stuck to.

Dil was terrified. And then, when he had time to think about it, he was ashamed of himself. After all, he thought, it's what I've always been told is there. It stands to reason. I'm just seeing it properly for the first time.

There. Does that make me feel any better?

No.

He turned and ran down the street, sandals flapping, until he reached the house that held Gern and his numerous family. He dragged the protesting apprentice from the communal sleeping mat and pulled him into the street, turned his face to the sky and hissed. 'Tell me what you can see!'

Gern squinted.

'I can see the stars, master,' he said.

'What are they on, boy?'

Gern relaxed slightly. 'That's easy, master. Everyone knows the stars are on the body of the goddess Nept who arches herself from . . . oh, bloody hell.'

'You can see her, too?'

'Oh, mummy,' whispered Gern, and slid to his knees.

Dil nodded. He was a religious man. It was a great comfort knowing that the gods were there. It was knowing they were here that was the terrible part.

Because the body of a woman arched over the heavens, faintly blue, faintly shadowy in the light of the watery stars.

She was enormous, her statistics interstellar. The shadow between her galactic breasts was a dark nebula, the curve of her stomach a vast wash of glowing gas, her navel the seething, dark incandescence in which new stars were being born. She wasn't supporting the sky. She was the sky.

Her huge sad face, upside down on the turnwise horizon, stared directly at Dil. And Dil was realising that there are few things that so shake belief as seeing, clearly and precisely, the object of that belief. Seeing, contrary to popular wisdom, isn't believing. It's where belief stops, because it isn't needed any more.