The librarian shook his head, and tugged insistently.

“Ook,” he explained, “Ook.”

He dragged her reluctantly down a side alley-way in the maze of ancient shelving a few seconds before a party of senior wizards, drawn by the noise, rounded the corner.

“The books have been fighting again . . . .”

“Oh, no! It'll take ages to capture all the spells again, you know they go and find places to hide . . . .”

“Who's that on the floor?”

There was a pause.

“He's knocked out. A shelf caught him, by the looks of it.”

“Who is he?”

“That new lad. You know; the one they say has got a whole head full of brains?”

“If that shelf had been a bit closer we'd be able to see if they were right.”

“You two, get him along to the infirmary. The rest of you better get these books rounded up. Where's the damn librarian? He ought to know better than to let a Critical Mass build up.”

Esk glanced sideways at the orang-outan, who waggled his eyebrows at her. He pulled a dusty volume of gardening spells out of the shelves beside him, extracted a soft brown banana from the recess behind it, and ate it with the quiet relish of one who knows that whatever the problems are, they belong firmly to human beings.

She looked the other way, at the staff in her hand, and her lips went thin. She knew her grip hadn't slipped. The staff had lunged at Simon, with murder in its heartwood.

The boy lay on a hard bed in a narrow room, a cold towel folded across his forehead. Treatle and Cutangle watched him carefully.

“How long has it been?” said Cutangle.

Trestle shrugged. “Three days.”

“And he hasn't come around once?”

“No.”

Cutangle sat down heavily on the edge of the bed, and pinched the bridge of his nose wearily. Simon had never looked particularly healthy, but now his face had a horrible sunken look.

“A. brilliant mind, that one,” he said. “His explanation of the fundamental principles of magic and matter - quite astounding.”

Trestle nodded.

“The way he just absorbs knowledge,” said Cutangle: “I've been a working wizard all my life, and somehow I never really understood magic until he explained it. So clear. So, well, obvious.”

“Everyone says that,” said Trestle gloomily. “They say it's like having a hoodwink pulled off and seeing the daylight for the first time.”

“That's exactly it,” said Cutangle, “He's sourcerer material, sure enough. You were right to bring him here.”

There was a thoughtful pause.

“Only -”said Trestle.

“Only what?” asked Cutangle.

“Only what was it you understood?” said Trestle. “That's what's bothering me. I mean, can you explain it?”

“How do you mean, explain?” Cutangle looked worried.

“What he keeps talking about,” said Trestle, a hint of desperation in his voice. “Oh, it's the genuine stuff, I know. But what exactly is it?”

Cutangle looked at him, his mouth open. Eventually he said, “Oh, that's easy. Magic fills the universe, you see, and every time the universe changes, no, I mean every time magic is invoked, the universe changes, only in every direction at once, d'you see, and -” he moved his hands uncertainly, trying to recognise a spark of comprehension in Trestle's face. “To put it another way, any piece of matter, like an orange or the world or, or -”

“- a crocodile?” suggested Trestle.

“Yes, a crocodile, or - whatever, is basically shaped like a carrot.”

“I don't remember that bit,” said Trestle.

“I'm sure that's what he said,” said Cutangle. He was starting to sweat.

“No, I remember the bit where he seemed to suggest that if you went far enough in any direction you would see the back of your head,” Trestle insisted.

“You're sure he didn't mean someone else's head?”

Trestle thought for a bit.

“No, I'm pretty sure he said the back of your own head,” he said. “I think he said he could prove it.”

They considered this in silence.

Finally Cutangle spoke, very slowly and carefully.

“I look at it all like this,” he said. “Before I heard him talk, I was like everyone else. You know what I mean? I was confused and uncertain about all the little details of life. But now,” he brightened up, “while I'm still confused and uncertain it's on a much higher plane, d'you see, and at least I know I'm bewildered about the really fundamental and important facts of the universe.”

Trestle nodded. “I hadn't looked at it like that,” he said, “but you're absolutely right. He's really pushed back the boundaries of ignorance. There's so much about the universe we don't know.”

They both savoured the strange warm glow of being much more ignorant than ordinary people, who were ignorant of only ordinary things.

Then Trestle said: “I just hope he's all right. He's over the fever but he just doesn't seem to want to wake up.”

A couple of servants came in with a bowl of water and fresh towels. One of them carried a rather tatty broomstick. As they began to change the sweat-soaked sheets under the boy the two wizards left, still discussing the vast vistas of unknowingness that Simon's genius had revealed to the world.

Granny waited until their footsteps had died away and took off her headscarf.

“Damn thing,” she said. “Esk, go and listen at the door.” She removed the towel from Simon's head and felt his temperature.

“It was very good of you to come,” said Esk. “And you so busy with your work, and everything.”

“Mmmph.” Granny pursed her lips. She pulled up Simon's eyelids and sought his pulse. She laid an ear on his xylophone chest and listened to his heart. She sat for some time quite motionless, probing around inside his head.

She frowned.

“Is he all right?” said Esk anxiously.

Granny looked at the stone walls.

“Drat this place,” she said. “It's no place for sick people.”

“Yes, but is he all right?”

“What?” Granny was startled out of her thoughts. “Oh. Yes. Probably. Wherever he is.”

Esk stared at her, and then at Simon's body.

“Nobody's home,” said Granny, simply.

“What do you mean?”

“Listen to the child,” said Granny. “You'd think I taught her nothing. I mean his mind's Wandering. He's gone Out of his Head.”

She looked at Simon's body with something verging on admiration.

“Quite surprisin', really,” she added. “I never yet met a wizard who could Borrow.”

She turned to Esk, whose mouth was a horrified O.

“I remember when I was a girl, old Nanny Annaple went Wanderin'. Got too wrapped up with being a vixen, as I recall. Took us days to find her. And then there was you, too. I never would have found you if it wasn't for that staff thing, and what have you done with it, girl?”

“It hit him,” Esk muttered. “It tried to kill him. I threw it in the river.”

“Not a nice thing to do to it after it saved you,” said Granny.

“It saved me by hitting him?”

“Didn't you realise? He was callin' to - them Things.”

“That's not true!”

Granny stared into Esk's defiant eyes and the thought came to her mind: I've lost her. Three years of work down the privy. She couldn't be a wizard but she might have been a witch.

“Why isn't it true, Miss Clever?” she said.

“He wouldn't do something like that!” Esk was near to tears. “I heard him speak, he's - well, he's not evil, he's a brilliant person, he nearly understands how everything works, he's -”

“I expect he's a very nice boy,” said Granny sourly. “I never said he was a black wizard, did I?”

“They're horrible Things!” Esk sobbed. “He wouldn't call out to them, he wants everything that they're not, and you're a wicked old -”

The slap rang like a bell. Esk staggered back, white with shock. Granny stood with her hand upraised, trembling.

She'd struck Esk once before - the blow a baby gets to introduce it to the world and give it a rough idea of what to expect from life. But that had been the last time. In three years under the same roof there had been cause enough, when milk had been left to boil over or the goats had been carelessly left without water, but a sharp word or a sharper silence had done more than force ever could and left no bruises.

She grabbed Esk firmly by the shoulders and stared into her eyes.

“Listen to me,” she said urgently. “Didn't I always say to you that if you use magic you should go through the world like a knife goes through water? Didn't I say that?”

Esk, mesmerised like a cornered rabbit, nodded.

“And you thought that was just old Granny's way, didn't you? But the fact is that if you use magic you draw attention to yourself. From Them. They watch the world all the time. Ordinary minds are just vague to them, they hardly bother with them, but a mind with magic in it shines out, you see, it's a beacon to them. It's not darkness that calls Them, it's light, light that creates the shadows!”

“But - but - why are They interested? What do They wwant?”

“Life and shape,” said Granny.

She sagged, and let go of Esk.

“They're pathetic, really,” she said. “They've got no life or shape themselves but what they can steal. They could no more survive in this world than a fish could live in a fire, but that doesn't stop them trying. And they're just bright enough to hate us because we're alive.”

Esk shivered. She remember the gritty feel of the cold sand.

“What are They? I always thought they were just a sort - a sort of demon?”

“Nah. No one really knows. They're just the Things from the Dungeon Dimensions outside the universe, that's all. Shadow creatures.”

She turned back to the prone form of Simon.

“You wouldn't have any idea where he is, would you?” she said, looking shrewdly at Esk. “Not gone off flying with the seagulls, has he?”

Esk shook her head.

“No,” said Granny, “I didn't think so. They've got him, haven't they.”

It wasn't a question. Esk nodded, her face a mask of misery.

“It's not your fault,” said Granny, “His mind gave them an opening, and when he was knocked out they took it back with them. Only. . . .”

She drummed her fingers on the edge of the bed, and appeared to reach a decision.

“Who's the most important wizard around here?” she demanded.

“Um, Lord Cutangle,” said Esk. “He's the Archchancellor. He was one of the ones who was in here.”

“The fat one, or the one like a streak of vinegar?”

Esk dragged her mind from the image of Simon on the cold desert and found herself saying: “He's an Eighth Level wizard and a 33° mage, actually.”

“You mean he's bent?” said Granny. “All this hanging around wizards has made you take them seriously, my girl. They all call themselves the Lord High this and the Imperial That, it's all part of the game. Even magicians do it, you'd think they'd be more sensible at least, but no, they call around saying they're the Amazing-Bonko-and-Doris. Anyway, where is this High Rumtiddlypo?”