The game, with its charm and simplicity, had survived through the twenty centuries which had worn away since the death of that forgotten clown. Lieserl stared at him, trying to understand the appeal of his baggy trousers, walking cane and little moustache.

She grew interested in the numbers embedded in the various versions of the game. The twelve-to-four ratio of Moksha-Patamu clearly made it a harder game to win than Kismet’s thirteen-to-eight — but how much harder?

She began to draw new boards in the air. But these boards were abstractions clean, colorless, little more than sketches. She ran through high-speed simulated games, studying their outcomes. She experimented with ratios of snakes to ladders, with their placement. Phillida sat with her and introduced her to combinatorial mathematics, the theory of games — to different forms of wonder.

On her fifteenth day she tired of her own company and started to attend classes again. She found the perceptions of others a refreshing counterpoint to her own, high-speed learning.

The world seemed to open up around her like a flower; it was a world full of sunlight, of endless avenues of information, of stimulating people.

She read up on nanobots. She learned the secret of Anti-Senescence, the process which had rendered humans effectively immortal.

Body cells were programmed to commit suicide.

Left alone, a cell manufactured enzymes which cut its own DNA into neat pieces, and quietly closed itself down. The suicide of cells was a guard against uncontrolled growth — tumors — and a tool to sculpt the developing body: in the womb, for example, the withering of unwanted cells carved fingers and toes from blunt tissue buds.

Death was the default state of a cell. Chemical signals had to be sent out by the body, to instruct cells to remain alive. It was a dead-man’s-switch control mechanism: if cells grew out of control — or if they separated from their parent organ and wandered through the body — the reassuring environment of chemical signals would be lost, and they would be forced to die.