Still, despite the masquerade, there were a few visible concessions to modern life. For instance, as he stood on the portico of the Juba station, a young woman drove up on a small lorry. "Kemal?" she asked.

Je nodded.

"I'm Diko," she said. "Tagiri's my mom. Toss your bag on and let's go!"

He tossed his bag into the small cargo area and then perched beside her on the driving bench. It was fortunate that this sort of lorry, designed for short hauls, couldn't go faster than about thirty kilometers an hour, or he was sure he would have been pitched out in no time, the way this insane young woman rattled headlong over the ratted road.

"Mother keeps saying we should pave these roads," said Diko, "but then somebody always says that hot pavement will blister the children's feet and so the idea gets dropped."

"They could wear shoes," suggested Kemal. He spoke simply, as clearly as he could, but it still wasn't good, what with his jaws getting smacked together as the lorry bumped through rut after rut.

"Oh, well, they'd look pretty silly, stark naked with sneakers on." She giggled.

Kemal refrained from saying that they looked pretty silly now. He would merely be accused of being a cultural imperialist, even though it wasn't his culture he was advocating. These people were apparently happy living as they did. Those who didn't like it no doubt moved to Khartoum or Entebbe or Addis Ababa, which were modern with a vengeance. And it did make a kind of sense for the Pastwatch people to live in the past even as they watched it.

He wondered vaguely if they used toilet paper or handfuls of grass.

To his relief, the grass hovel where Diko stopped was only the camouflage for an elevator down into a perfectly modern hotel. She insisted on carrying his bag as she led him to his room. The underground hotel had been dug into the side of a bluff overlooking the Nile, so the rooms all had windows and porches. And there was air-conditioning and running water and a computer in the room.

"All right?" asked Diko.

"I was hoping to live in a grass hut and relieve myself in the weeds," said Kemal.

She looked crestfallen. "Father said that we ought to give you the full local experience, but Mother said you wouldn't want it."

"Your mother was right. I was only joking. This room is excellent."

"Your journey was long," said Diko. "The Ancient Ones are eager to talk to you, but unless you prefer otherwise, they'll wait till morning."

"Morning is excellent," said Kemal.

They set a time. Kemal called room service and found that he could get standard international fare instead of pureed slug and spicy cow dung, or whatever was involved in the local cuisine.

The next morning he found himself in the shade of a large tree, sitting in a rocking chair and surrounded by a dozen people who sat or squatted on mats. "I can't possibly be comfortable having the only chair," he said.

"I told you he would want a mat," said Hassan.

"No," said Kemal. "I don't want a mat. I just thought you might be more comfortable ..."

"It's our way, " said Tagiri. "When we work at our machines, we sit in chairs. But this is not work. This is joy. The great Kemal asked to meet with us. We never dreamed that you would be interested in our projects."

Kemal hated it when he was called "the great Kemal." To him, the great Kemal was Kemal Ataturk, who re-created the Turkish nation out of the wreckage of the Ottoman Empire centuries before. But he was weary of giving that speech, too, and besides, he thought there might have been just a hint of irony in the way Tagiri said it. Time to end pretenses.

"I'm not interested in your projects," said Kemal. "However, it seems that you are capturing the attention of a growing number of people outside Pastwatch. From what I hear, you're thinking of taking steps with far-reaching consequences, and yet you seem to be basing your decisions on ... incomplete information."

"So you're here to correct us," said Hassan, reddening.

"I'm here to tell you what I know and what I think, " said Kemal. "I didn't ask you to make this a public gathering. I would just as happily speak to you and Tagiri alone. Or, if you prefer, I'll go away and let you proceed in ignorance. I've offered you what I know, and I see no need to pretend that we are equals in those areas. I'm sure that there are many things you know that I don't -- but I'm not trying to build a machine to change the past, and therefore there is no urgency about alleviating my ignorance."

Tagiri laughed. "It's one of the glories of Pastwatch, that it's not the smooth-talking bureaucrats who head the major projects." She leaned forward. "Do your worst to us, Kemal. We aren't ashamed to learn that we might be wrong."

"Let's start with slavery," said Kemal. "After all, that's what you did. I've read some of the softhearted, sympathetic biographies and the analytical papers that have emerged from your slavery project, and I get the clear impression that if you could, you would find the person who thought of slavery and stop him, so that no human being would ever have been bought or sold on this planet. Am I right?"

"Are you saying that slavery was not an unmitigated evil?" asked Tagiri.

"Yes, that's what I'm saying," said Kemal. "Because you're looking at slavery from the wrong end -- from the present, when we've abolished it. But back at the beginning, when it started, doesn't it occur to you that it was infinitely better than what it replaced?"

Tagiri's veneer of polite interest was clearly wearing thin. "I've read your remarks about the origin of slavery."

"But you're not impressed."

"It's natural, when you make a great discovery, to assume that it has wider implications than it actually has," said Tagiri. "But there is no reason to think that human bondage originated exclusively with Atlantis, as a replacement for human sacrifice."

"But I never said that," said Kemal. "My opponents said that I said that, but I thought you would have read more carefully."

Hassan spoke up, trying to sound mild and forceful, both at once. "I think that this seems to be getting too personal. Did you come all this way, Kemal, to tell us that we're stupid? You could have done that by mail."

"No," said Kemal, "I came for Tagiri to tell me that I have a pathological need to think that Atlantis is the cause of everything." Kemal rose out of his chair, turned around, picked it up, and hurled it away. "Give me a mat! Let me sit down with you and tell you what I know! If you want to reject it afterward, go ahead. But don't waste my time or yours by defending yourselves or attacking me!"

Hassan stood up. For a moment Kemal wondered if he was going to strike him. But then Hassan bent down, picked up his mat from the grass, and held it out to Kemal. "So," said Hassan. "Talk."

Kemal laid out the mat and sat down. Hassan shared his daughter's mat, in the second row.

"Slavery," said Kemal. "There are many ways that people have been held in bondage. Serfs were bound to the land. Nomad tribes adopted occasional captives or strangers, and made them second-class members of the tribe, without the freedom to leave. Chivalry originated as a sort of dignified mafia, sometimes even a protection racket, and once you accepted an overlord you were his to command. In some cultures, deposed kings were kept in captivity, where they had children born in captivity, and grandchildren, and great-grandchildren who were never harmed, but never allowed to leave. Whole populations have been conquered and forced to work under foreign overlords, paying unpayable tribute to their masters. Raiders and pirates have carried off hostages for ransom. Starving people have bound themselves into service. Prisoners have been forced into involuntary labor. These kinds of bondage have shown up in many human cultures. But none of these is slavery."