Its lot was to be forever the mediator between two great oceans which others would sail in serenity, while it knew only the ceaseless tumult of the air and the biting cold of vacuum.

             Cley watched silently, clinging to one of the sticky patches on the compartment's walls. There was a solemn majesty to the Pinwheel, a remorseless resignation to the dip of its leading arm into the battering winds. She saw the snug pocket where they had been moored show a flare of ivory light—plasma conjured up by the shock of re-entry. Yet the great arm plunged on, momentum's captive, for its next touchdown.

             She saw why it had momentarily hung steady over the forest; at bottom, the rotation nearly canceled the orbital velocity. Craft on such a scale bespoke enormous control, and she asked in a whisper, "Is it intelligent?"

             "Of course," Seeker said. "And quite old."

             "To do that ..."

             "Forever moving, forever going nowhere."

             "What thoughts, what dreams it must have."

             "It is a different form of intelligence from you—neither greater nor lesser."

             "Who made it?"

             "It made itself, in part."

             "How can anything that big . . . ?"

             Seeker spun itself playfully in air, clicking its teeth in a disjointed rhythm. It seemed uninterested in answering her.

             "Alvin and the others made it, right?"

             Seeker yelped in high amusement. "Time is more reliable than intelligence."

             "Somebody planned that thing."

             "Some body? Yes, the body plans—not the mind."

             "Huh? No, I mean—"

             "In far antiquity there were beasts designed to forage for icesteroids among the cold spaces beyond the planets. — ooof! — They knew enough of genecraft to modify themselves. — ah! — Perhaps they met other life-forms which came from other stars—I do not know. — uh! — I doubt that this matters; time's hand shaped some such creatures into this. — ooj! —" Seeker seldom spoke so long, and it had managed this time to punctuate each sentence with a bounce from the walls.

             "Creatures that gobbled ice?"

             Seeker settled onto a sticky patch, held on with two legs, and fanned its remaining legs and arms into the air. "They were sent to seek such, then spiral it into the inner worlds."

             "Water for Earth?"

             "By that time the robots had decreed a dry planet. The outer icesteroid halo was employed elsewhere."

             "Why not use spaceships?"

             "Of metal? They do not reproduce."

             "These things'd give birth, out there in the cold?"

             "Slowly, yes."

             "How'd they make Pinwheel? It's not an ice-eater, I can tell that much."

             "Time is deep. Circumstance has worked on it. More so than upon your kind."

             "Is it smarter?"

             "You humans return to that subject always. Different, not greater."

             Embarrassed without quite knowing why, Cley said, "I figured it must be smarter than me, to do all that."

             "It flies like a bird, without bother. And thinks long, as befits a thing from the great slow spaces."

             ''How does it fly? The wind alone—" The question spoken, she saw the answer. As the other arm of Pinwheel rose to the top of its circular arc, she could make out thin plumes of white jetting behind it. She had seen Supra craft do that, leaving a line of cloud in their wake.

             "Consider it a tree that flies," Seeker said.

             "Huh? Trees have roots."

             "Trees walk, why not fly? We are guests inside a flying tree."

             "Ummm. What's it eat?"

             "Some from air, some—" Seeker gestured ahead, along their trajectory. They shot above and away from the spinning, curved colossus. And Cley saw a thin haze now hanging against the black of space, dimmer than stars but more plentiful. There was a halo around the Earth, fireflies drawn to the planet's immense ripe glow. Beyond the nightline the gossamer halo hung like a wreath above Earth's shadow.

             One mote grew as they sped on. It swelled into a complex structure of struts and half-swollen balloons. It had sinews like knotty walnut. Fleshy vines webbed its intersections. Cley tried to imagine Pinwheel digesting this oddity and decided she would have to see it to believe.

             But this minor issue faded as she peered ahead. Other trees like theirs lay fore and aft, some spinning slightly, others tumbling. But all were headed toward a thing that reminded her of a pineapple, prickly with spikes and fur. Around this slowly revolving thing a haze of pale motes clustered.

             "All that . . . alive?"

             "In a way. Are robots alive?"

             "No, of course—are those robots?"

             "Not of metal, no. But even robots can make copies of themselves."

             Cley said with exasperation, "You know what I mean when something's alive."

             "I am deficient in that."

             "Well, if you don't know, I can't tell you," she said irritably.

             "Good."

             "What?"

             "Talk is a trick for taking the mystery out of the world."

             Cley did not know what to say and decided to let sleeping mysteries lie. Their tree convoy was approaching the fog-glow swathing the pineapple.

             Gravity imposes flat floors, straight walls, rectangular rigidities. Weightlessness allows the ample symmetries of the cylinder and sphere. In the swarm of objects, large and small, Cley saw an expressive freedom of effortless new geometries. Necessity dictates form, and the myriad spokes and limbs that jutted from the many shells and rough skins conformed to the demands of momentum.

             She watched an orange sphere extend a thin stalk into a nearby array of cylinders. It began to spin about the stalk. This gave it stability so that the stalk punched surely through the thin walls of its prey. Cley wondered how the sphere spun itself up, and suspected that internal fluids had to counterrotate. But was this an attack? The odd array of rubbery columns did not behave like a victim. Instead, it gathered around the sphere. Slow stems embraced and pulses worked along their crusted brown lengths. Cley wondered if she was watching an exchange, the cylinders throbbing energetically to negotiate a biochemical transaction.

             Their flotilla of trees cut through the insectlike haze of life, passing near myriad forms that sometimes veered to avoid them. Some, though, tried to catch them. These had angular shapes, needle-nosed and surprisingly quick. But the trees still plunged on, outstripping pursuit, directly into the barnacled pineapple.

             But she saw now that only parts of the huge thing seemed solid. There were large caps at the ends which looked firm enough, but the main body revealed more and more detail as they approached. Sunlight glinted from multifaceted specks until Cley realized that these were a multitude of spindly growths projected out from a central axis. She could see the axis buried deep in the profusion of stalks and webbing, like a bulbous brown root.