‘The truth is that we are as baffled by the phenomenon as Dante would have been if he’d suddenly been given a glimpse of Hubble’s expanding universe. Even the language we use to describe it is probably no more correct than the pack-of-cards analogy that most people feel at home with: the Long Earth as a large pack of three-dimensional sheets, stacked up in a higher-dimensional space, each card an Earth entire unto itself.

‘And, most significantly, to most people, the Long Earth is open. Almost anybody can travel up and down the pack, drilling, as it were, through the cards themselves. People are expanding into all that room. Of course they are! This is a primal instinct. We plains apes still fear the leopard in the dark; if we spread out he cannot take all of us.

‘It is all profoundly annoying. None of it fits! And why has this tremendous pack of cards been dealt to mankind just now, when we have never been more in need of room? But then science is nothing but a series of questions that lead to more questions, which is just as well, or it wouldn’t be much of a career path, would it? Well — whatever the answers to such questions, believe you me, everything is changing for mankind… Is that enough, Jocasta? Some idiot clicked a pen while I was doing the bit about Dante.’

Of course, Joshua understood, transEarth existed to profit from all these changes. Which, presumably, was why Joshua had been brought here, more or less against his will, from a world a long way away.

At last the door opened. A young woman came in, nursing a laptop as thin as a sheet of gold leaf. Joshua kept such a machine in the Home, a fatter, antiquated model, mostly to look up wild-food recipes. ‘Mr Valienté? It’s so kind of you to come. My name is Selena Jones. Welcome to the transEarth Institute.’