Saul pushed himself away from the wall, and headed further into the tunnel until he came to a door. ‘Tell me how the growths are saving us,’ he asked, still stalling for time.

‘You think they’re killing people,’ said Mitchell, ‘but they’re not. They’re preserving them.’

A UP-enabled menu sprang up in front of the door, just as Saul stepped closer. The interface was primitive, a set of simple textual menus displayed in lines of bright-green text hovering in the blackness before him.

‘Preserving them?’

A light blinked on above the same door, and it swung slowly open. Saul took a step back, suddenly afraid of Mitchell lunging out at him – but there was no one there. He stepped inside and found himself standing by the top of a ladder set into an unpressurized shaft that fell away into darkness. He lowered himself over the edge and began to descend, his suit’s shallow lights illuminating the shaft walls around him. It felt too much like descending into some bottomless pit.

‘Our lives are meaningless without free will,’ Mitchell continued. ‘The wormholes’ very existence reduces us to automatons following predestined paths. The growths are incredible, Saul; they copy everything, all the way down to the superposition of every particle in the bodies of every living organism on Earth. Every living human being is going to wake up as if nothing happened – but way, way up the time-stream. They’ll find themselves in a place that looks just like Earth, but they’ll be truly free for the first time in their lives. It would be wrong not to let the growths preserve everyone, Saul. I mean everyone.’

‘You want the same thing to happen to the colonies?’

‘Of course,’ Mitchell replied, sounding surprised as if the answer were self-evident. ‘The pools showed me everything: a grand strategy, to recover sentient life from all through the period of the universe fixed by the wormhole networks, and rebirth it in the deep, deep future, at a point when the wormholes no longer exist. They showed me glimpses of it, Saul. It’s beautiful – and we can all be a part of it. But if you shut the Array down, you’re dooming the colonies to a living death. That’s why I had to stop you any way I could, because I knew you would never understand. Not if you hadn’t seen what I’ve seen.’

Saul paused, letting his helmet rest gently against a rung. He felt like he couldn’t move an inch further, but he had no idea just how far down the shaft went. He forced himself to start moving again, tightly clenching his jaw, and stopped only when a black wave of dizziness threatened to suck him into unconsciousness. He then thrust his elbows through the bars of the ladder to support him, and waited until it passed.