Portia is watching art being made.

She is fidgety, nervous—not the fault of the art itself, but she has a great task in front of her, which occupies most of her mind. She never had much patience with sculpture-telling at the best of times. A shame that all this is being done in her honour.

Not just hers, of course. All twelve of her crew are here, being seen and being lauded. Portia is not even nominally in command of the voyage. However, hers is the task of greatest risk. Hers is the name being drummed about the Great Nest district of Seven Trees.

She tries to shrug off her nerves and concentrate solely on the performance. Three nimble male artists are telling the story of the martyr Fabian, the great scientist and enfranchiser. Starting with just a few support lines they have spun themselves a three-dimensional narrative, their threads crossing and knotting and intersecting in a constantly evolving kinetic sculpture of silk that suggests scenes from the famous pioneer’s life, and finally death. Each scene is built on the bones of the last, so that the ephemeral and delicate sculpture they create grows and branches, a constantly evolving visual narrative.

Portia is ashamed to find she is bored. She does not have that poetic turn of mind to properly appreciate this art form— the allusions and memes required to follow the story are not found in her Understandings. She is a pragmatic creature of simple, visceral pleasures. She hunts, she wrestles, she climbs, she mates; traditional pursuits and perhaps a little old-fashioned. She prefers to think of them as timeless.

She could, of course, go to the city library and obtain an Understanding that would immediately allow her to appreciate this art in all its glory, but what would she lose? Some less-regarded ability or knowledge would be shouldered out, for her mind has finite limits on what it can retain. Like many of her kind, she has grown comfortable with what she is, and loathe to change if there is no grand need for it.

She stays still for as long as she can bear, politely eyeing the ever-more-complex structure, while feeling the appreciative stir and tremble of the audience, knowing only that it is something denied to her. At last, she simply cannot stay any longer in that crowd under that grand, tented ceiling, and creeps out as covertly as possible. This is her night, after all. Nobody is going to deny her.

Outside, she finds herself in the centre of the great conurbation that is Seven Trees’ scientific district. Struck by a need for greater height and clear air, she ascends limb over limb, by line and by branch, until she can see the darkness of the sky above, seeking out the pinpoint bright dots that are stars. She knows, by learning and by Understanding, that they are so far away as to make any concept of the real distance meaningless. She recalls nights spent in the wilderness, though

—for there is still wilderness despite the growth of the spider communities and their attendant support structures. Once away from the constant glare of the bioluminescent city lights, the stars can seem clear and close enough to touch.

Here, though, she can barely see them at all, with everything around her lit up in a hundred shades of green and blue and ultraviolet. A strange thing that she, whose work places her at the very fang-point of scientific advance, feels that life is outstripping her, actually leaving her behind.

Within her she has Understandings that were first held by some distant hunting ancestress whose life was constant toil: working to feed herself and her kin, fighting off ancient enemies who are now safely domesticated or extinct or driven to the wildest corners of the map. Portia—this Portia—can look back at the simplified, even romanticized, recollections of

that time that she has inherited, and yearn for a less complex life.

She feels tremors from below, and sees someone climbing up towards her. It is Fabian—her Fabian, just one of countless males named after the great liberator. He is one of two males in her twelve-strong crew, and her personal assistant—chosen for his quick mind and agile body.

It is overwhelming, is it not?

He has a knack for saying the right things, and it doesn’t matter whether he means the performance below or the great lit-up tangle that is the city around them. Tomorrow, history will be made.

Fabian dances for her, then, because he senses that she is unhappy, and a little flattery and attention tonight will help her on the morrow. Away from the crowd, he now performs for her the ancient courtship of their kind, and is received in turn. Monogamy—monandry, rather—is not a concept the spiders have much familiarity with, but some pairs grow used to each other. Fabian dances only for her, and she rebuffs the advances of any other.

As always, at the height of his performance, when he has set down his offering before her, she feels that deep-buried jab to push the matter on to a fatal consummation. But this is all part of the experience, adding zest and immediacy before swiftly being overridden by her more civilized nature. These days such things hardly ever happen.

Below them, the performance also reaches its climax. Later, the artists will take it all down, consume their swathes of webbing and dismantle their masterpiece. Art, like so much else, is transient.

Elsewhere in the city, in the hub of learning and research that is also the Great Nest temple for the dwindling number of parishioners who still need to embrace the unknown in their lives, Bianca is at work making her last minute preparations. She is not one of Portia’s select crew, but she has had a hand in

the mission as a whole. Her interest in tomorrow’s departure is almost maternal, for she has been the motivating force behind so much that is about to happen. Her true intentions are not quite what others suspect—nothing nefarious—but she has an unusual mind equipped for thinking broader thoughts and seeing further.

Bianca is a born polymath, in this context meaning she is able to absorb far more Understandings than the average spider. Unlike Portia, she changes her mind regularly. The core of what she considers herself to be is simply her capacity and desire to learn, not any individual facility she might briefly take within her. Currently she is an expert radio operator, chemist, astronomer, artificer, theologian and mathematician, her mind crammed to bursting with a complex interlacing of knowledge.

Now, long past the time when her kin are all resting, she checks and rechecks her calculations, and designs troubleshooting architecture for the ant colony she has instructed to model and double check her figures.

Her newfound theology combines with the basic thoughtfulness of her nature to give her a sense of awe and reverence about the venture in hand. Hubris is not quite a concept she grasps, but she comes very close here, alone in her control centre, as she walks through the complex stages of the plan within her mind.

She has a rare perspective that enables her to look back on so many generations of struggle and growth and be able to give a shape and a texture to history, to appreciate the incremental contributions of all those Portias and Biancas and, yes, Fabians down through the generations. Each has contributed Understandings to the sum total of arachnid knowledge. Each has been a node in the expanding web of progress. Each has planned out the path one step beyond their ancestors. In a very real way, Bianca is their child, the product of their learning, daring, discovery and sacrifice. Her mind throngs with the living learning of dead ancestors.

She understands, in a real and immediate way, how she stands on the backs of giants, and that her own back, too, will be strong enough to bear the weight of many generations to come.

Next morning Portia and her crew assemble at a point beyond where the last buildings of the city taper into nothing, in the midst of a great swathe of farmland, among stands of stubby, warty trees stretching to the horizon, separated by firebreaks and the well-trodden pathways of the farming ants. The weather is fine: cloudy but with only a little breeze, as predicted. This moment has already been put off twice previously owing to inclement conditions.

Portia remains tense and still. The others deal with their nervousness each in their own way. Some crouch, some run about, some tussle or talk nonsense, feet stamping out a fretting staccato. Viola, the leader, goes from each to each, with a touch, a stroke, a twitch of palps, reassuring them.

Fabian is the first to see the Sky Nest.

Even at this distance, it is absurdly huge as it floats majestically over Seven Trees, coasting smoothly over the Great Nest district like an optical illusion. The vast, silvery bulk of its gasbag is currently three hundred metres long, dwarfing the long, slender cabin suspended beneath. Later, they will extend the envelope to twice its current size until the lift-to-weight ratio reaches the extreme proportions that their project will require.

The spiders have been using silk for gliding since before the earliest Understanding, and their increasing intelligence has led to multiple refinements of this art. Their chemical synthesis meanwhile gives them access to as much hydrogen as they need. With a technology of silk and lightweight wood, even their experiments with powered heavier-than-air flight result in something feather-light and buoyant. Constructing dirigibles is something they have taken to readily.

Lines are dropped by the skeleton flight crew, unravelling a hundred metres to reach the ground. Glad to be in motion at

last, Portia and the others scramble up, a climb barely worth mentioning. There is a brief, ceremonial handover from the flight leader to Viola, and then the flight crew abseil down their own lines and leave the Sky Nest to its new occupants.

The airship is a triumph of engineering, rugged enough to withstand the turbulent weather of the lower air, and yet—with the gasbag fully extended and filled—capable of ascending to previously inaccessible heights. The aerodynamic profile of the entire vessel is fluid, and determined, moment to moment, by the tensioned cords of its internal structure. Now it is lifting into a stiffening breeze, its structure shifting in automatic response as the new crew settles in.

Their target height is so far above their world that it barely qualifies as height at all. And even then there will be a greater journey for the most adventurous of them: for Portia.

Viola checks that her crew members are in place, and then joins Portia at the forward edge of the cylindrical crew compartment, gazing out through the faintest shimmer at the receding ground below. Already the gasbag is expanding further, bloating out with more hydrogen, its leading edge reshaping itself for streamlining, as the Sky Nest lifts away faster and faster. Here, in the bows, is the radio and also the main terminal for the airship’s brain.

Viola places her palps into paired pits in the lectern before her, and the Sky Nest tells her how it feels, how all its component pieces are holding up. It is almost like speaking on the radio, almost like talking to a living thing. She spoke to the Messenger once, did Viola, and communicating with the Sky Nest feels much like that.

Tiny antennae brush and twitch the sensitive hairs of her palps, feeding her information by touch and by scent. Two of her crew stand ready to give chemical commands to the terminal here, which will swiftly spread across the ship.

The ongoing calculations required to take an object of gossamer and hydrogen to the upper reaches of the atmosphere would challenge even the polymath Bianca, who therefore

designed the ship to think for itself: a patient, dedicated intelligence subordinate to the commands of its spider crew. The airship is crawling with ants. This particular species is small—two centimetres at most for the workers—but bred to be receptive to complex conditioning. In fact the colony writes much of its own conditioning, its standing chemical architecture allowing it to receive direct information about the ship’s situation and constantly respond to it without the intervention of the crew.

Although the ants can go everywhere, their physical pace would be too slow to coordinate the vast ship’s constant metamorphoses. Spider bioengineering sidesteps this problem with cultured tissue. Just as, for generations, artificial muscle has been used as a motive source for their monorail capsules and other brute-force devices, so Bianca has pioneered artificial neural networks that link to chemical factories. Hence the ants in the crew capsule do not need to walk to the other widely spaced elements of their colony. Instead they send impulses through the ship’s nerves, and these are translated to chemical instructions at the other termini. The neural network

—unliving and living all at once—is a part of the colony, as if it was some bizarrely overspecialized caste. The ants are even capable of altering its complex structure, severing links and encouraging the growth of others.

Bianca is probably the only spider to wonder if the thing she has created—or bred perhaps—may one day cross some nebulous line that separates the calculating but unaware from what she herself would understand as true intellect. The prospect, which will probably alarm her peers when they consider it, has been working on her mind for some time now. In fact, her current private project has a great deal to do with some of her more speculative thoughts in that direction.

Aboard the Sky Nest, the crew are preparing for the conditions of the upper atmosphere. The capsule is double-hulled, a layer of air between the sheets of silk providing the insulation they will need in the thinner reaches of the atmosphere. The outer skin of capsule and balloon is woven

with silvery, glittering thread, an organic material that disperses and reflects the sunlight.

The Sky Nest carries them on up towards the light dusting of clouds. Two of the crew don suits of light silk to pass through the airlock and check on the operation of the god-engines, so called because they are a development of an idea apparently received direct from the Messenger. Before it was dictated as part of the old divine mandate, nobody had considered the idea of rotary motion. Now, bioelectric fields spin light metal propellers that steadily separate the Sky Nest from the ground.

Some of the crew gather at the shimmering windows, crowding for a view of the city as it shrinks from a vast swathe of layered civilization to an untidy scrawl like a child’s knotted picture. The mood is high and excitable. Portia is the only one there who does not share it. She remains serious, inward-looking, trying to prepare herself for her own task. She seeks solace away from the others, and carefully knots and picks her way through a mantra that has travelled alongside her people for centuries, the ancient, reassuring mathematics of the first Message. It is not that she is some atavistic true believer, but that tradition comforts and calms her, as it did her distant ancestors.

In the fore-cabin space, Viola gestures to her radio operator, and they signal that all’s well. Down in Great Nest district, Bianca will receive their message and then send a communication of her own, not to the Sky Nest but further still.

Bianca is hailing God with a simple announcement: We are coming.