Luca found this terrifying, the notion that the great structure of the Expansion was so fragile. Equally terrifying was the realisation of how much knowledge he still had to acquire. ‘And you think the religious outbreak at the Core is one such destabilising grain?’

‘I’m hoping it won’t be,’ Dolo said. ‘But the only way to know is to go there and see.’

‘And stop the grain falling.’

‘And make the right decision,’ Dolo murmured, correcting him.

They left the factory world and passed ever inwards towards the Core, through more veils of stars.

At last they faced a vast wall of light. These were star-birthing clouds. Against the complex, turbulent background Luca could pick out globular clusters, tight knots of stars. Ships sailed silently everywhere, as deep as the eye could see. But from behind the curtain of stars and ships a cherry-red light burned, as if the centre of the Galaxy itself was ablaze.

Teel said, ‘We are already within the Core itself, strictly speaking. Surrounding the Galaxy’s centre is a great reservoir of gas some fifteen hundred light years across - enough to bake a hundred billion stars, crammed into a region smaller than that spanned by the few thousand stars visible to human eyes from Earth. That wall you see is part of the Molecular Ring, a huge belt of gas and dust clouds and star-forming regions and small clusters. The Ring surrounds the centre itself, and the Xeelee concentrations there.’

Dolo said evenly, ‘The Ring is expanding. It is thought that it was thrown off by an explosion in the Core a million years ago. We have no idea what caused it.’

‘How remarkable,’ Luca said. ‘In this dense place, this is the debris of an explosion: a great rolling wave of star birth. And what is that pink light that glows through the clouds?’

For the first time in the days since he had met her Teel looked directly at him. Her blue eyes seemed as wide as Earth’s oceans, and he felt his breath catch. ‘That,’ she said simply, ‘is the Front. By that light people are dying.’

Luca felt a complex frisson of fear and anticipation. All his life he had lived in a human space thousands of light years deep. He could look up into the sky and pick out any star he chose, and know that either humans were there, or they had been there and moved on, leaving the system lifeless and mined out. But now it was different. This slab of sky with its teeming clouds and young stars was not human. Up to now, he had been too concerned with his relationships with Teel and Dolo, and beyond that his duty, to have thought ahead. He realised he had no idea what he might find here at the Core, none at all.

He said reflexively, ‘ “A brief life burns brightly.” ’

‘Here we have a different slogan,’ murmured Teel. ‘ “Death is life.” ’