He moved closer to her. His eyecups were wide and empty, his breathing shallow. He seemed huge. His hands were held away from his body. She closed her fingers tighter around the chair handles, watching, half-expecting him to lunge at her.

"Dura, get out of the chair. For a thousand years our Star has crossed space. We have a duty to fulfill, a destiny."

She shook her head. "You've lost yourself in this, Hork. In the glamour of it all... It's not our battle."

He frowned at her, his bearded face a ferocious mask. "If it wasn't for the battle we wouldn't even exist. Generations of humans have lived, died and suffered for this moment. This is the purpose of our race, its apotheosis! I see this now... How can a person like you take the fate of a world in your hands?"

"But I can't — accept — this. I've got to try something. We must try to save ourselves."

Doubt — a kind of longing — spread across Hork's broad face. "Then consider this. Suppose we're right. Suppose our world really is a missile aimed at the Xeelee. Then — if it really is possible to aim the Star with this device — why is the device here?"

She was frightened of him — not just physically, but of this new, unexpected side of his character, this self-immolating fanaticism.

"Think," he demanded. "If you were the designer, the Ur-human who planned this fantastic mission, what would you intend the occupant of that seat to do, now, at the climax of the project?"

She hesitated, thinking. "It's meant to be used to refine the trajectory. To direct the Star even more precisely at its goal."

He threw his arms wide. "Exactly. Perhaps there are devices lying dormant here, messages instructing us — or whoever was planned to be here — how to do just that. And what if we don't, Dura? What if we don't complete our mission? Perhaps the Ur-humans themselves will intervene, to punish our arrogance."

Her palms were slick with sweat; his words were like the articulation of the conflict inside her. Who was she to decide the fate of a world, of generations?

She thought back over her life, the extraordinary, unfolding sequence of events that had led her to this point. Once, not a very large fraction of her life ago, she had been adrift in the Mantle, at the mercy of the smallest stray Glitch along with the rest of the Human Beings. Stage by stage, as events had taken her so far from her home, her understanding of the Mantle, the Star, and the role of mankind had opened out, like the layers of perception opened up gradually by the seeing-walls of this Ur-human construct.

And now she was here, with more power over events than any human since the days of the Core Wars. She was dizzy, vertiginous, a feeling she remembered from her first trips to the fringes of the Crust-forest, as a little girl with her father.