It was Vorbis's voice. Brutha hurried out into the courtyard and into Vorbis's cell.

“Ah, Brutha.”

“Yes, lord?”

Vorbis was sitting cross-legged on the floor, staring at the wall.

“You are a young man visiting a new place,” said Vorbis. “No doubt there is much you wish to see.”

“There is?” said Brutha. Vorbis was using the exquisitor voice again-a level monotone, a voice like a strip of dull steel.

“You may go where you wish. See new things, Brutha. Learn everything you can. You are my eyes and ears. And my memory. Learn about this place.”

“Er. Really, lord?”

“Have I impressed you with my use of careless language, Brutha?”

“No, lord.”

“Go away. Fill yourself. And be back by sunset.”

“Er. Even the Library?” said Brutha.

“Ah? Yes, the Library. The Library that they have here. Of course. Crammed with useless and dangerous and evil knowledge. I can see it in my mind, Brutha. Can you imagine that?”

“No, Lord Vorbis.”

“Your innocence is your shield, Brutha. No. By all means go to the Library. I have no fear of any effect on you. ”

“Lord Vorbis?”

“Yes?”

“The Tyrant said that they hardly did anything to Brother Murduck . . .”

Silence unrolled its restless length.

Vorbis said, “He lied.”

“Yes.” Brutha waited. Vorbis continued to stare at the wall. Brutha wondered what he saw there. When nothing else appeared to be forthcoming, he said, “Thank you.”

He stepped back a bit before he went out, so that he could squint under the deacon's bed.

He's probably in trouble, Brutha thought as he hurried through the palace. Everyone wants to eat tortoises.

He tried to look everywhere while avoiding the friezes of unclad nymphs.

Brutha was technically aware that women were a different shape from men; he hadn't left the village until he was twelve, by which time some of his contemporaries were already married. And Omnianism encouraged early marriage as a preventive against Sin, although any activity involving any part of the human anatomy between neck and knees was more or less Sinful in any case.

Brutha wished he was a better scholar so he could ask his God why this was.

Then he found himself wishing his God was a more intelligent God so it could answer.

He hasn't screamed for me, he thought. I'm sure I would have heard. So maybe no one's cooking him.

A slave polishing one of the statues directed him to the Library. Brutha pounded down an aisle of pillars.

When he reached the courtyard in front of the Library it was crowded with philosophers, all craning to look at something. Brutha could hear the usual petulant squabbling that showed that philosophical discourse was under way.

In this case:

“I've got ten obols here says it can't do it again!”

“Talking money? That's something you don't hear every day, Xeno.”

“Yeah. And it's about to say goodbye.”

“Look, don't be stupid. It's a tortoise. It's just doing a mating dance . . .”

There was a breathless pause. Then a sort of collective sigh.

“There!”

“That's never a right angle!”

“Come on! I'd like to see you do better in the circumstances!”

“What's it doing now?”

“The hypotenuse, I think.”

“Call that a hypotenuse? It's wiggly.”

“It's not wiggly. It's drawing it straight and you're looking at it in a wiggly way!”

“I'll bet thirty obols it can't do a square!”

“Here's forty obols says it can.”

There was another pause, and then a cheer.

“Yeah!”

“That's more of a parallelogram, if you ask me,” said a petulant voice.

“Listen, I knows a square when I sees one! And that's a square.”

“All right. Double or nothing then. Bet it can't do a dodecagon.”

“Hah! You bet it couldn't do a septagon just now.”

“Double or nothing. Dodecagon. Worried, eh! Feeling a bit avis domestica? Cluck-cluck?”

“It's a shame to take your money . . .”

There was another pause.

“Ten sides? Ten sides? Hah!”

“Told you it wasn't any good! Whoever heard of a tortoise doing geometry?”

“Another daft idea, Didactylos?”

“I said so all along. It's just a tortoise.”

“There's good eating on one of those things . . .”

The mass of philosophers broke up, pushing past Brutha without paying him much attention. He caught a glimpse of a circle of damp sand, covered with geometrical figures. Om was sitting in the middle of them. Behind him was a very grubby pair of philosophers, counting out a pile of coins.

“How did we do, Urn?” said Didactylos.

“We're fifty-two obols up, master.”

“See? Every day things improve. Pity it didn't know the difference between ten and twelve, though. Cut one of its legs off and we'll have a stew.”

“Cut off a leg?”

“Well, a tortoise like that, you don't eat it all at once.”

Didactylos turned his face towards a plump young man with splayed feet and a red face, who was staring at the tortoise.

“Yes?” he said.

“The tortoise does know the difference between ten and twelve,” said the fat boy.

“Damn thing just lost me eighty obols,” said Didactylos.

“Yes. But tomorrow . . .” the boy began, his eyes glazing as if he was carefully repeating something he'd just heard “. . . tomorrow . . . you should be able to get odds of at least three to one.”

Didactylos's mouth dropped open.

“Give me the tortoise, Urn,” he said.

The apprentice philosopher reached down and picked up Om, very carefully.

“You know, I thought right at the start there was something funny about this creature,” said Didactylos. “I said to Urn, there's tomorrow's dinner, and then he says no, it's dragging its tail in the sand and doing geometry. That doesn't come natural to a tortoise, geometry.”

Om's eye turned to Brutha.

“I had to,” he said. “It was the only way to get his attention. Now I've got him by the curiosity. When you've got 'em by the curiosity, their hearts and minds will follow.”

“He's a God,” said Brutha.

“Really? What's his name?” said the philosopher.

“Don't tell him! Don't tell him! The local gods'll hear!”

“I don't know,” said Brutha.

Didactylos turned Om over.

“The Turtle Moves,” said Urn thoughtfully.

“What?” said Brutha.

“Master did a book,” said Urn.

“Not really a book,” said Didactylos modestly. “More a scroll. Just a little thing I knocked off.”

“Saying that the world is flat and goes through space on the back of a giant turtle?” said Brutha.

“Have you read it?” Didactylos's gaze was unmoving. “Are you a slave?”

“No,” said Brutha. "I am a-

“Don't mention my name! Call yourself a scribe or something!”

“-scribe,” said Brutha weakly.

“Yeah,” said Urn. “I can see that. The telltale callus on the thumb where you hold the pen. The inkstains all over your sleeves.”

Brutha glanced at his left thumb. "I haven't-

“Yeah,” said Urn, grinning. “Use your left hand, do you?”

“Er, I use both,” said Brutha. “But not very well, everyone says.”

“Ah,” said Didactylos. “Ambi-sinister?”

“What?”

“He means incompetent with both hands,” said Om.

“Oh. Yes. That's me.” Brutha coughed politely. “Look . . . I'm looking for a philosopher. Um. One that knows about gods.”

He waited.

Then he said, “You aren't going to say they're a relic of an outmoded belief system?”

Didactylos, still running his fingers over Om's shell, shook his head.

“Nope. I like my thunderstorms a long way off.”

“Oh. Could you stop turning him over and over? He's just told me he doesn't like it.”

“You can tell how old they are by cutting them in half and counting the rings,” said Didactylos.

“Um. He hasn't got much of a sense of humor, either.”

“You're Omnian, by the sound of it.” Yes."

“Here to talk about the treaty?”

“I do the listening.”

“And what do you want to know about gods?”

Brutha appeared to be listening.

Eventually he said: “How they start. How they grow. And what happens to them afterwards.”

Didactylos put the tortoise into Brutha's hands.

“Costs money, that kind of thinking,” he said.

“Let me know when we've used more than fifty-two obols' worth,” said Brutha. Didactylos grinned.

“Looks like you can think for yourself,” he said. “Got a good memory?”

“No. Not exactly a good one.”

“Right? Right. Come on into the Library. It's got an earthed copper roof, you know. Gods really hate that sort of thing.”

Didactylos reached down beside him and picked up a rusty iron lantern.

Brutha looked up at the big white building.

“That's the Library?” he said.

“Yes,” said Didactylos. “That's why it's got LIBRVM carved over the door in such big letters. But a scribe like you'd know that, of course.”

The Library of Ephebe was-before it burned down-the second biggest on the Disc.

Not as big as the library in Unseen University, of course, but that library had one or two advantages on account of its magical nature. No other library anywhere, for example, has a whole gallery of unwritten books-books that would have been written if the author hadn't been eaten by an alligator around chapter 1, and so on. Atlases of imaginary places. Dictionaries of illusory words. Spotters' guides to invisible things. Wild thesauri in the Lost Reading Room. A library so big that it distorts reality and has opened gateways to all other libraries, everywhere and everywhen . . .

And so unlike the Library at Ephebe, with its four or five hundred volumes. Many of them were scrolls, to save their readers the fatigue of having to call a slave every time they wanted a page turned. Each one lay in its own pigeonhole, though. Books shouldn't be kept too close together, otherwise they interact in strange and unforeseeable ways.

Sunbeams lanced through the shadows, as palpable as pillars in the dusty air.

Although it was the least of the wonders in the Library, Brutha couldn't help noticing a strange construction in the aisles. Wooden laths had been fixed between the rows of stone shelves about two meters from the floor, so that they supported a wider plank of no apparent use whatsoever. Its underside had been decorated with rough wooden shapes.

“The Library,” announced Didactylos.

He reached up. His fingers gently brushed the plank over his head.

It dawned on Brutha.

“You're blind aren't you?” he said.

“That's right.”

“But you carry a lantern?”