‘Yes. Remarkable, isn’t it? As if life is a great circle. That’s why we smile all the time.’ He tapped the green tetrahedron on his breast. ‘A lot of them seem comforted to see this too. We’re not sure why. It must be a very ancient symbol, of something.’

Symat asked the Curator about the medical-station numbers.

‘They are for our purposes. We number them in order of age, as best we can. When one dies you have to renumber those younger - though young scarcely seems appropriate for creatures such as these! - but there are so few it isn’t a great burden.’

As they walked the age numbers fell away, below twenty, fifteen, and at last to single figures. Symat felt his heart unaccountably thump. And then the Curator brought them to a bed, where a short, slim form lay, obscured by her translucent tent. The bed was adorned by a single digit: 1.

‘The oldest,’ Mela breathed.

‘She has been called many names,’ the Curator said. ‘Leropa, Luru Parz, other variants; perhaps one of these is her original given name. If she knows she won’t tell us. She claims to know the date of her birth, but it’s so long ago we can’t reconcile her dates with current chronologies more precisely than within five thousand years . . . Take a good look, Symat. She is certainly the oldest human being any of us will ever see. She is probably a million years old. Think of that!’

Suddenly the woman’s eyes flickered open. Mela gasped.

Symat stepped forward, his pulse hammering in his ears. And as he came by the bed a hand like a claw shot out to grab his wrist. He forced himself not to flinch, for fear he might snap bones like dry twigs.

Her black eyes were on him. She opened a ruined mouth and whispered, ‘There are questions you need to ask.’

To a fourteen-year-old she was a figure from a nightmare. But her leathery palm was warm on his skin. She was old, she was very strange, but she was human, he could feel that. ‘I don’t know how it must be,’ he said.

‘What?’

‘To be like you.’

She closed her eyes briefly; he could actually hear the dry skin rustle on her eyeballs. ‘If you knew how many times I have been asked that . . . I have thought the same thoughts so often they don’t need me to think them any more. Perhaps I am a robot, then. Certainly I am no longer human, if I ever was, since the moment I took that pill given me by Gemo Cana, that murderous witch . . .’

‘Who?’

‘But that is why I am valuable, you see. I and my kind. For, long after love and hate are gone, even after meaning is lost, we keep on and on and on. And, given enough time, we achieve greatness.’

‘You moved the Earth.’