But did that mean that the urge to live was the result of some sort of illusion? Was the reality, in fact, that nothing mattered and people were fools to think that anything did? Were the choices either despair, the rejection of reason for some idiot faith, or a sort of defensive solipsism?

Valseir might have had something useful to say on the matter, Fassin thought. But then, he was dead too.

He looked at Oazil and wondered if this self-proclaimed wanderer really had known the dead Cuspian whose house this had been. Or was he just a chancer, a blow-hard, a fantasist and liar?

Thinking like this, circling round his studied despair, Fassin only half-listened to the old Dweller with his theories about gas-giant fauna development and his tales of wandering.

Oazil told how once he had circumnavigated the South Tropical Band without seeing another Dweller in all those hundred and forty thousand kilometres, how he had once fallen in with a gang of Adolescent Sculpture Pirates, semi-renegades who seeded public RootCloud and AmmoniaSluice forests, him becoming their figurehead, mascot, totem, and how, many millennia ago in the little-travelled wastes of the Southern Polar Region, he had wandered into a vast warren of empty CloudTunnel. (The work of a troop of rogue Tunnel-building machines since disappeared? An artwork? The lost prototype for a new kind of city? He didn’t know — nobody had ever heard of this place, this thing.) He was lost inside this vast tree, this giant lung, this colossal root system of a labyrinth for a thousand years, exiting eleven-twelfths starved and nearly mad. He had reported the find and people had looked for it but it had never been found again. Most people thought he’d imagined it all, but he had not. They believed him, did they not?

The tapping noise was there again. He had been vaguely aware of it but had ignored it, not even getting as far as dismissing it as some function of the house’s plumbing or differential expansion or reaction to some brief current in the surrounding gas. It had stopped after a while — he had half-noticed that, too, though still thought no more about it. Now it was there again, and slightly louder.

Fassin was in Library Three, one of the inner libraries, speed-reading through the contents of a sub-library that Valseir appeared to have picked up as part of a job lot untold ages ago. From the earliest date that anybody had bothered to note, this stuff had been lying around uncalled-up and unread for thirty millennia, dating from an era several different species of Slow Seers ago, long before humans had come to Ulubis. Fassin suspected this was traded material, data — second-hand, third-hand, who knew how many-hand — dredged from who knew where, possibly auto-translated (it certainly read like it whenever he dipped into the text itself, to make sure that the contents were what the abstracts claimed), bundled and presented and handed over to the Dwellers of Nasqueron by some long-superseded (possibly even long-extinct) species of Seer in return for — presumably — still older information. He wondered at what point most of the data the Dwellers held would become traded data, and if that point had already been reached. He was not the first Seer to think of this and, thanks to the absolute opaqueness of the Dwellers’ records, he would certainly not be the last.

The volumes he was checking were mostly composed of stories concerning the romantic adventures and philosophical musings of some group of Stellar Field Liners, though they were either much-translated or the work of not just another species but another species-type altogether. They seemed fanciful, anyway.

The tapping wasn’t going to go away.

He looked up from the screen to the round skylight set in the ceiling. Library Three, though now surrounded and surmounted by other spheres, had once been on the upper outskirts of the house and had a generous expanse of diamond leaf at its crown, though nowadays — even had the house been situated in less gloomy regions — it would let in little natural light.

There was something small and pale out there. When Fassin looked up the tapping stopped and the thing waved. It looked like a Dweller infant, a pet-child. Fassin watched it waving for a while, then went back to the screen and the not especially feasible exploits of the S’Liners. The tapping started again. He felt himself attempt to sigh inside his little gascraft. He stopped the screen scroll and lifted out of the dent-seat, rising to the centre of the ceiling.

It was indeed a Dweller child: a rather elongated, deformed-looking one, to human eyes more like a squid than a manta ray. It was dressed in rags and decorated with a few pathetic-looking life charms. Fassin had never seen an infant wearing clothes or decorations. It was oddly, maturely dark for one so young. It pointed in at what looked like some sort of catch or lock on the side of one of the skylight’s hexagonal panes.

Fassin looked at the curious infant for a while. It kept pointing at the catch. There had been no sign of pet-children round the house in all the time they’d been here. This one looked entirely like it might belong to Oazil, but he had not displayed any earlier, and hadn’t mentioned owning one. The child was still indicating the pane’s lock. It started to mime pressing and twisting and pulling motions.

Fassin opened the pane and let the creature in. It flipped inside, made a sign that was probably meant to be the Dweller equivalent of “Shh!” and floated towards him, curling and cupping its body so that it formed a sickle shape, just a metre away from the prow of the arrowhead craft. Then, on its signal skin, now shielded from sight in all directions save that Fassin was watching from, it spelled out,

OAZIL: MEET ME 2KM STRAIGHT DOWN, HOUR 5. RE. VALSEIR.

It waited till he light-signalled back OK, then it sped out the way it had come, one slim tentacle staying behind after the rest of it had exited just long enough to pull the ceiling pane shut after it. It disappeared into the night-time gloom between the dark library globes outside.

Fassin looked at the time. Just before hour Four. He went back to his studies, finding nothing, thinking about nothing, until just before five, when he went back to Library Twenty-One and slipped out through the secret doorway again. He dropped the two thousand metres down through the slowly increasing heat and pressure and met the old Dweller Oazil, complete with his float-trailer. Oazil signalled,

— Fassin Taak?

— Yes.

· What did Valseir once compare the Quick to? In some detail, if you please.

· Why?

The old Dweller sent nothing for some time, then, — You might guess, little one. Or do this just because I ask. To humour an old Dweller.

Fassin waited a while before answering. — Clouds, he sent, eventually. — Clouds above one of our worlds. We come and we go and we are as nothing compared to the landscape beneath, just vapour compared to implacable rock, which lasts seemingly beyond lasting and is always there long after the clouds of the day or the clouds of the season have long gone, and yet other clouds will always be there, the next day and the next and the next, and the next season and the next year and for as long as the mountains themselves last, and the wind and the rain wear away mountains in time.

· Hmm, Oazil sent, sounding distracted. — Mountains.

Curious idea. I have never seen a mountain.

· Nor ever will, I imagine. Do you want me to add any more?

I don’t think I recall much else.

· No, that will not be necessary.

· Then?

· Valseir is alive, the old Dweller said. — He sends his regards.

· Alive?

· There is a GasClipper regatta at the C-2 Storm Ultra-Violet 3667, beginning in seventeen days’ time.

· That’s in the war zone, isn’t it?

· The tournament was arranged long before the hostilities were first mooted and so has been cleared with the Formal War Marshals. A special dispensation. Be there, Fassin Taak. He will find you.