Ponder turned his head, dreading the sight he was about to see.

Mrs Whitlow had a tray of cutlery in one hand and was prodding ineffectually at the air with the stick that she held in the other.

'Ai only moved it to get things through,' she said. 'Now Ai can't seem to quate find where the silly thing is supposed to go.'

Where there had been a dark rectangle opening into the geographer's dingy study, there was now only waving palms and sunlit sand. Strictly speaking, it could be said to be an improvement. It depended on your point of view.

Rincewind surfaced, gasping for breath. He'd fallen into a waterhole.

It was in... well, it looked as though once there had been a cave, and the roof had collapsed. There was a big circle of blue right above him.

Rocks had fallen down here, and sand had blown in, and seeds had taken root. Cool, damp and green... the place was a little oasis, tucked away from the sun and the wind.

He pulled himself out of the water and looked around while he drained off. Vines had grown among the rocks. A few small trees had managed to take root in the crack. There was even a little bit of a beach. By the look of the stains on the rocks, the water had once been a lot higher.

And there... Rincewind sighed. Wasn't that just typical? You got some quiet little beauty spot miles from anywhere, and there was always some graffiti artist ready to spoil it. It was like that time when he was hiding out in the Morpork Mountains, and right in the back of one of the deepest caves some vandal had drawn loads of stupid bulls and antelopes. Rincewind had been so disgusted he'd wiped them off. And they'd left lots of old bones and junk lying around. Some people had no idea how to behave.

Here, they'd covered the rock walls with drawings in white, red and black. Animals again, Rincewind noticed. They didn't even look particularly realistic.

He stopped, water dripping off him, in front of one. Someone had probably wanted to draw a kangaroo. There were the ears and the tail and the clown feet. But they looked alien, and there were so many lines and cross-hatchings that the figure seemed... odd. It looked as though the artist hadn't just wanted to draw a kangaroo from the outside but had wanted to show the inside as well, and then had wanted to show the kangaroo last year and today and next week and also what it was thinking, all at the same time, and had set out to do the whole thing with some ochre and a stick of charcoal.

It seemed to move in his head.

He blinked, but it still hurt. His eyes seemed to want to wander off in different directions.

Rincewind hurried further along the cave, ignoring the rest of the paintings. The piled rubble of the collapsed ceiling reached nearly to the surface, but there was space on the other side, going on into darkness. It looked as though he was in a piece of tunnel that had collapsed.

'You walked right past it,' said the kangaroo.

He turned. It was standing on the little beach.

'I didn't see you get down here,' said Rincewind. 'How did you get down here?'

'Come on, I've got to show you something. You can call me Scrappy, if you like.'

'Why?'

'We're mates, ain't we? I'm here to help you.'

'Oh, dear.'

'Can't make it alone across this land, mate. How d'you think you've survived so far? Water's bloody hard to find out here these days.'

'Oh, I don't know, I just keep falling into—'

Rincewind stopped.

'Yeah,' said the kangaroo. 'Strike you as odd, does it?'

'I thought I was just naturally lucky,' said Rincewind. He thought about what he'd just said. 'I must have been crazy.'

There weren't even flies down here. There was the occasional faint ripple on the water, and that wasn't comforting, since there wasn't apparently anything to stir the surface. Up above, the sun was torching the ground and the flies swarmed like, well, flies.

'Why isn't there anyone else here?' he said.

'Come and see,' said the kangaroo.

Rincewind raised his hands and backed away. 'Are we talking teeth and stings and fangs?'

'Just look at that painting there, mate.'

'What, the one of the kangaroo?'

'Which one's that, mate?'

Rincewind looked along the wall. The kangaroo picture wasn't where he remembered it.

'I could've sworn—'

'That's the one I want you to look at, over there.'

Rincewind looked at the stone. What it showed, outlined in red ochre, were dozens of hands.

He sighed. 'Oh, right,' he said, wearily. 'I see the problem. Exactly the same thing happens to me.'

'What're you talking about, mister?'

'It's just the same with me when I try to take snaps with an iconograph,' said Rincewind. 'You set up a nice picture, the demon paints away, and when you look at it, whoops, you had your thumb in the way. I must have got a dozen pictures of my thumb. No, I can see your lad there, doing his painting, in a bit of a hurry, got his brush all ready then, splosh, he'd forgotten to take his hand off the—'

'No. It's the painting underneath I'm talking about, mister.'

Rincewind looked closer. There were fainter lines there, which you'd think were just flaws in the rock if you weren't looking. Rincewind squinted. Other lines seemed to fit... Yes, someone had painted figures... They were...

He blew away some sand.

Yes, they were...

... curiously familiar...

'Yes,' said Scrappy, his voice apparently coming from a distance. 'Look a bit like you, don't they...?'

'But they're—' he began. He straightened up. 'How long have these paintings been here?'

'Well, lessee,' said the kangaroo. 'Out of the sun and the weather, nothing to disturb 'em... Twenty thousand years?'

'That's not right!'

'Nah, true, prob'ly thirty thousand, in a nice sheltered spot like this.'

'But these are... That's my...'

'O' course, when I say thirty thousand years,' said the kangaroo, 'I mean it depends how you look at it. Even them hand paintings on the top've been there five thousand years, see. And those faint ones... Oh, yes, got to be pretty old, tens of thousands of years, except—'

'Except what?'

They weren't here last week, mate.'

'You're saying they've been here for ages... but not for very long?'

'See? I knew you was clever.'

'And now you're going to tell me what the hell you're talking about?'

'Right.'

'Excuse me, I'll just find something to eat.'

Rincewind lifted up a rock. There were a couple of jam sandwiches underneath.

The wizards were civilized men of considerable education and culture. When faced with being inadvertently marooned on a desert island they understood immediately that the first thing to do was place the blame.

'It really was very clear!' shouted Ridcully, waving his hand frantically in the air at the place where the window had been. 'And I put a sign on it!'

'Yes, but you've got a "Do Not Disturb" sign nailed to your study door,' said the Senior Wrangler, 'and you still expect Mrs Whitlow to bring you your tea in the mornings!'

'Gentlemen, please!' said Ponder Stibbons. 'We've got to sort some things out right now!'

'Yes indeed!' roared the Dean. 'And it was his fault! The sign wasn't large enough!'

'I mean we have to—'

'There are ladies present!' snapped the Senior Wrangler.

'Lady.' Mrs Whitlow uttered the word carefully and with deliberation, like a gambler putting down a winning hand. She stood primly watching them. Her expression said: I'm not worried, because with all these wizards around nothing bad can happen.

The wizards adjusted their attitudes.

'Ai do apologize if Ai've done something wrong,' she said.

'Oh, not, not wrong,' said Ridcully quickly. 'Not exactly wrong. As such.'