Meanwhile, in the village in which Hilin’s doomed lover Sale had been born, the local transients were trying another tactic to win his favour. Perhaps it was another outcome of Hilin’s clever exploits, or perhaps it had been inherent in the situation all along.

Girls, elfin girls with dark elusive eyes: as the generations ticked by, he seemed to see more of them running in the corridors, making eyes at muscular wall-scrubbing boys, dandling children on their knees. They were like cartoon versions of Lora: tall Loras and short, thin Loras and fat, happy Loras and sad.

It was selective breeding, if presumably unconscious, people turning themselves into replicas of the images in the Virtual. They were appealing directly to his own cold heart: if the Elder loved this woman so much, then choose a wife that looks like her, if only a little, and hope to have daughters with her delicate looks, and so win favour.

Rusel was simultaneously touched, and appalled. But he did not interfere. They could do what they liked, he told himself, as long as they got their jobs done.

Meanwhile in the old amphitheatre, on the other side of the barricade he had erected, the Autarchs and their long-lived families had not died out as Rusel had expected - indeed hoped. They had lived on. And as they inbred ferociously, their lives were stretched out longer and longer.

Again this made sense in terms of their heredity, he thought. In their cordoned-off compartment there was simply no room to expand their population. So the genes’ best bet of propagating themselves into the future, always their only objective, was to stretch out the lives of their carriers. Adults in there now lived for centuries, and for the vanishingly few children born, childhood lasted decades.

Rusel found these creatures, with their blank eyes and wizened-faced children, peculiarly disturbing. On the other hand, he still couldn’t bring himself to kill them off. Perhaps in them he saw a distorted reflection of himself.

There was one constant throughout the Ship. On both sides of the barrier the transients were clearly getting dumber.

As generations passed - and by now, for fear of repeating Hilin’s fate, potential mates were repelled by any signs of higher-than-average intelligence - it was obvious that the transients were breeding themselves into stupidity. If anything the Autarchs’ environment was less stimulating than that of their cousins in the rest of the Ship, and despite their slower generational cycle they were shedding their unnecessary intelligence with even more enthusiasm, perhaps a response to sheer boredom.

The transients kept the Ship working, however, and in their increasingly brutish liaisons followed the genetic-health mandates scrupulously. This puzzled Rusel: surely by now they could have no real understanding of why they were doing these peculiar things.