He smiled. ‘Well, not quite. Some of the worlds have small seas, and people sail on them, I know. But it’s not the same as solar sailing. A boat can sail into the wind, but we can’t – there’s no other medium for us to push against, the way a boat’s keel works against the water. So we can’t tack, in the nautical sense. But we can use orbital mechanics to our advantage. We’re in a gravity well, you see, and that means we have angular momentum to play with. The sails can add or subtract from our motion around the Old Sun, if we tilt them – and that means we can move between orbits, provided we’re patient. Which we are, most of the time. And if we’re in a hurry, there’s the ion engine. The sails can serve as energy collectors as well – they have both a reflective surface and an absorbent one, and Hirtshal can flex one or other to face the Sun. There’s no part of the Congregation we can’t reach in under two years of sail, and many worlds are only weeks or months apart – some even closer.’

‘How many of those worlds have you seen, Captain?’

‘You can drop the formality, Fura. I invited you here, didn’t I?’ But he still gave some consideration to what I’d asked. ‘It must be fewer than a hundred. Which means that for every world I’ve stood on, there are at least two hundred I’ve yet to see. And that’s just a tiny fraction of all the worlds – just the few to which we’ve given names, and found a way to live on.’ He beckoned me nearer. ‘Here. We spoke of the Book of Worlds before. I think these might be of interest.’

It was a bit awkward, being alone with him. Adrana never cared for books as much as I did, so she’d turned her nose up when I mentioned visiting his library. I wasn’t sweet on him either, no matter what Adrana might have cooked up in her head. He was handsome enough, but he was a lot older than me and there was something stiff and serious about him that made him seem more like an uncle or a teacher. It wasn’t that I had anything against him, although I don’t suppose at that point I’d had much chance to really know him. But he was the captain and I was the newcomer, and it was the right and proper way of it that I should be timid and respectful around him.

The truth was, though, whatever I thought of Rackamore, I was sweet on his books.

‘These can’t be real,’ I said. ‘There can’t be this many of them, all different from each other, all in one place . . .’

I caught the pride in his answer.

‘They’re real. All of them.’