‘That book is nine hundred years old,’ Rackamore said, in a low and reverent tone, as if some ghost or spirit hiding in the book might be roused if he spoke too harshly. ‘There are only five thousand entries. The number of worlds occupied by people was about a quarter as many as there are today. Supposedly there are even earlier editions, each rarer than the last, although I’ve never chanced upon one of them. These books trace our expansion from a single starting point – the gradual spread from world to world, slow and difficult at first. Then we got better at it, and more confident, and the number of occupied worlds swelled far beyond ten thousand.’ He took the old edition back from me, slotted it back onto the shelf, and ran his finger halfway along the row of spines. ‘Here. A 1384 edition. Four hundred and fifteen years ago.’ He drew out the volume, blew dust off it, stroked his finger against the binding, then offered it to me. ‘Many more pages, and fewer lines per entry. There were seventeen thousand occupied worlds at that point and the rate of expansion was slowing down. There might be fifty million potential worlds in the Congregation, but we can only live on about twenty thousand of them. The rest are cracked wide open – no lungstuff, no water, and too knotty to seal them off and bring in those things even if we had the will. Or they’re already totally bottled in, with no way in or out that we know. Or in some other way inimical to settlement – haunted by bad things left over from earlier Occupations. Wrapped in bauble fields that we can’t break through and that don’t show any sign of opening any time soon. That’s the wonder and frustration of it, Arafura – fifty million prizes, and we’ll never know most of them before our time is done.’

I found Mazarile:

Prosperous sphereworld in the thirty-fifth processional, with a diameter of eight and one third leagues. A swallower sits at its core. Seven principal settlements, of which Hadramaw and Incer are the two largest. Opposing spacedocks, amenable to improvement. Population at last census, two and four fifths million . . .

‘Our time,’ I said, with a little shiver. ‘You think it will end?’

‘Most assuredly. You’ve seen the Hall of History on Mazarile – there are similar institutions on most worlds. Each of those coloured bars represents an empire, a dominion, a parliament of worlds, much like our own. Earlier Occupations, earlier phases of expansion, settlement and stagnation. They passed. So, eventually, will we.’

‘But not today.’