Symat said testily, ‘Let’s get on with it.’ He wasn’t about to hesitate in front of Mela. He stepped forward boldly. The door slid aside.

He entered a low, wide room, white-walled, flooded with pale light. There were beds here - no, they were more like medical stations; each had boxes of equipment hovering in the air beside it. Bots cleaned the walls and ferried supplies. He saw no human attendants, but there were many Virtuals who nodded at the Curator. Rotund individuals like him, they all seemed to have broad faces and wide smiles.

Symat inspected a station more closely. A bot hovered suspiciously, but he wasn’t impeded. The station was a pallet covered by a translucent bubble. It was marked with a number: 247, in bold digits. Inside the bubble, lying on the pallet, was a man. His limbs like sticks, his belly imploded, and with tiny bots crawling over his body, he looked more dead than alive. But as Symat cast a shadow over his face, that skull-like head turned. Symat shuddered and stepped back.

They walked on, between the rows of stations. The floor was soft and Symat’s footsteps made no sound.

The Curator said, ‘They are unimaginably old, some of them - and several of them, with no real memory of their own deepest past, don’t even know how old they are themselves. The best way to date them is actually through the anti-ageing technology embedded in their bodies. But even that is unreliable.’

As they passed, the naked Ascendents stirred and whispered, dry skin rustling.

‘We’re disturbing them,’ Mela said softly.

‘Don’t worry about it. They are creatures of routine - as are we all, but in them it is taken to an extreme. And anything that disturbs that routine disturbs them. That’s why only bots and Virtuals are used as attendants. You don’t want to frighten them with a new face every century or so!’

Symat wondered how old the Curator himself was.

One old woman, to Symat’s astonishment, was out of bed. She was naked, her skin so flaccid she looked as if she had melted, and tubes snaked out of all her orifices. But she managed to walk to a cabinet a few paces from her bed, where, with a trembling hand, she picked out fragments of food that she pushed into a toothless mouth.

‘She likes to feed herself,’ the Curator said. ‘Or at least to believe she does. It’s good for her to have some independence. But look here.’

The floor was cut through by a deep rut, hard metal and ceramic worn away by this old woman’s soft feet. And where she had lain in her bed she had left the shape of her body compressed into the mattress.