He'd heard stories about the regressives, but had dismissed them as rumour until now. They were the survivors of the war, people who hadn't submitted eagerly to the iron rule of Minla's new Planetary Government. Details that didn't fit into the plan, and which therefore had to be brushed aside or suppressed or given a subhuman name. He pulled the cloak tighter, anxious not to spend a minute longer on the surface than necessary. But even as Minla turned and began walking back to the waiting aircraft - moonlight picked out the elegant sweep of its single great wing - something tugged at him, holding him to the spot.
'Minla,' he called, a crack in his voice.
She stopped and turned around. 'What is it, Merlin?'
'I've got something for you.' He reached under the cloak and fished out the gift she had given him as a girl, holding it before him. He'd had it with him for days, waiting for the moment he hoped would never come.
Impatiently, Minla retraced her steps. 'I said we should be leaving. What do you want to give me?'
He handed her the sliver of whetstone. 'A little girl gave me this. I don't think I know that little girl any more.'
Minla looked at the stone with a curl of disgust on her face. 'That was forty years ago.'
'Not to me. To me it was less than a year. I've seen a lot of changes since you gave me that gift.'
'We all have to grow up sometime, Merlin.' For a moment he thought she was going to hand him back the gift, or at least slip it into one of her own pockets. Instead, Minla let it drop to the ground. Merlin reached to pick it up, but it was too late. The stone fell into a dark crack between two shattered paving slabs, Merlin hearing the chink as it bounced off something and fell even deeper.
'It's gone.'
'It was just a silly stone,' Minla said. 'That's all. Now let's be on our way.'
Merlin looked back at the lapping waters as he followed Minla to the moonlit flying wing. Something about the whetstone, something about the tides of that sea, something about the moon itself kept nagging at the back of his mind. There was a connection, trivial or otherwise, that he was missing.
He was sure it would come to him sooner or later.
Minla walked with a stick, clicking its hard metal shaft against the echoing flooring of the station's observation deck. Illness or injury had disfigured her since their last meeting; she wore her greying hair in a lopsided parting, hanging down almost to the collar on her right side. Merlin could not say for certain what had happened to Minla, since she was careful to turn her face away from him whenever they spoke. But in the days since his revival he had already heard talk of assassination attempts, some of which had apparently come close to succeeding. Minla seemed more stooped and frail than he remembered, as if she had worked every hour of those twenty years.
She interrupted a light-beam with her hand, opening the viewing shields. 'Behold the Space Dormitories,' she said, declaiming as if she had an audience of thousands rather than a single man standing only a few metres away. 'Rejoice, Merlin. You played a part in this.'
Through the window, wheeling with the gentle rotation of the orbital station, the nearest Dormitory loomed larger than Lecythus in the sky. The wrinkled grey sphere would soon reach operational pressure, its skin becoming taut. The final sun-mirrors were being assembled in place, manipulated by mighty articulated robots. Cargo rockets were coming and going by the minute, while the first wave of evacuees had already taken up residence in the polar holding pens.
Twenty Dormitories were ready now; the remaining eighty would come online within two years. Every day, hundreds of atomic rockets lifted from the surface of Lecythus, carrying evacuees - packed into their holds at the maximum possible human storage density, like a kind of three-dimensional jigsaw of flesh and blood - or cargo, in the form of air, water and prefabricated parts for the other habitats. Each rocket launch deposited more radioactivity into the atmosphere of the doomed world. It was now fatal to breathe that air for more than a few hours, but the slow poisoning of Lecythus was of no concern to the Planetary Government. The remaining surface-bound colonists, those who would occupy the other Dormitories when they were ready, awaited transfer in pressurised bunkers, in conditions that were at least as spartan as anything they would have to endure in space. Merlin had offered the services of Tyrant to assist with the evacuation effort, but as efficient and fast as his ship was, it would have made only a token difference to the speed of the exercise.
That was not to say that there were not difficulties, or that the programme was exactly on schedule. Merlin was gladdened by the progress he saw in some areas, disheartened in others. Before he slept, the locals had grilled him for help with their prototype atomic rockets, seemingly in the expectation that Merlin would provide magic remedies for the failures that had dogged them so far. But Merlin could only help in a limited fashion. He knew the basic principles of building an atomic rocket, but little of the detailed knowledge needed to circumvent a particular problem. Minla's experts were frustrated, and then dismayed. He tried explaining to them that though an atomic rocket might be primitive compared to the engines in Tyrant, that didn't mean it was simple, or that its construction didn't involve many subtle principles. 'I know how a sailing ship works,' he said, trying to explain himself. 'But that doesn't mean I could build one myself, or show a master boat-builder how to improve his craft.'
They wanted to know why he couldn't just give them the technology in Tyrant itself.
'My ship is capable of self-repair,' he'd said, 'but it isn't capable of making copies of itself. That's a deep principle, embodied in the logical architecture at a very profound level.'
'Then run off a blueprint of your engines. Let us copy what we need from the plans,' they said.
'That won't work. The components in Tyrant are manufactured to exacting tolerances, using materials your chemistry can't even explain, let alone reproduce.'
'Then show us how to improve our manufacturing capability, until we can make what we need.'
'We don't have time for that. Tyrant was manufactured by a culture that had had over ten thousand years of experience in spacefaring, not to mention knowledge of industrial processes and inventions dating back at least as far again. You can't cross that kind of gap in fifty years, no matter how much you might want to.'
'Then what are we supposed to do?'
'Keep trying,' Merlin said. 'Keep making mistakes, and learning from them. That's all any culture ever does.'
That was exactly what they had done, across twenty painful years. The rockets worked now, after a fashion, but they'd arrived late and there was already a huge backlog of people and parts to be shifted into space. The Dormitories should have been finished and occupied by now, with work already under way on the fleet of Exodus Arks. But the Arks had met obstacles as well. The lunar colonisation and materials-extraction programme had run into unanticipated difficulties, requiring that the Arks be assembled from components made on Lecythus. The atomic rocket production lines were already running at maximum capacity without the burden of carrying even more tonnage into space.
'This is good,' Merlin told Minla. 'But you still need to step things up.'
'We're aware of that,' she answered testily. 'Unfortunately, some of your information proved less than accurate.'
Merlin blinked at her. 'It did?'
'Our scientists made a prototype for the fusion drive, according to your plans. Given the limited testing they've been able to do, they say it works very well. It wouldn't be a technical problem to build all the engines we need for the Exodus Arks. So I'm told, at least.'
'Then what's the issue?'