A sensor blinked on the flitter’s tiny control panel. The ship was picking up low-frequency radiation.

Was the thing trying to talk to him?

…And now, with a sudden, shocking loss of grace, it was falling.

No. It is not my time. I have a full day, yet. And I still have not mated, or budded, or found my Hill —

But he never would. His limbs buckled; his body sank towards the ground. Like independent creatures the tips of his limbs pried at the ice, seeking purchase. It was the heat, of course; his blood had been unable to sustain its superfluid properties, and his body had run through its cycle ahead of its time. Now, like his father before him, he would die on this cold, level ground.

He tried once more to rise, but he couldn’t feel his limbs.

“It’s a tree stump!” Poole snapped excitedly into the radio link. “Don’t you see, the toolmakers are the tree stumps! Bill, look at the pictures, damn it. They are different phases of a single life cycle: an active intelligent phase, followed by a loss of mobility.”

“Maybe,” Dzik said. “But we didn’t find anything like a nervous system in that tree stump we opened up.”

“So their brains, their nervous systems, are absorbed. When they’re no longer needed.” A memory came to Poole. “The juvenile sea-squirt. Of course.”

“The what?”

“It’s an exact analogy. The sea-squirt seeks the rock to which it’s going to cling, for the rest of its life. Then, its function fulfilled, its brain dissolves back into its body…”

Dzik sounded doubtful. “But these were toolmakers.”

“Yeah.” Poole peered up at the empty sky. “But what use is intelligence, on a world like this? No raw materials. Nowhere to get to. An unchanging sky, inaccessible… Bill, they must have abandoned their toolmaking phase ages ago. Now they use their intelligence solely to find the best place to lie in the Sun. The shadows of hills; the places with the highest temperature differentials. Perhaps they compete. Then their awareness dissolves—”

But the stationary, kneeling titan before him, drawn by the flitter, had come to rest on a plain, he realized now. No shade; useless. It would die, never reaching the tree stump stage.

“Mike.” Dzik’s voice crackled. “You’re right, we think. We’re looking over some of our photos again. There’s a whole herd of the damn things, on the far side of the worldlet from our beachhead.”

Poole rested his hands on the controls. This would take care — a delicacy of touch he wasn’t sure he had. He applied a single, brief impulse to the jets. The flitter sailed smoothly into the sky.

Dzik was still talking. “The superfluid helium must be crucial to the animal phase. Superfluid gives you a huge mechanical advantage; in microgravity helium pumps could exploit tiny temperature differences to move bulky masses of ice.” He laughed. “Hey, I guess we don’t need to worry about funds for the future. The whole System is going to beat a path to our door to see this — as long as we can work out a way to protect the ecology…”

“Right.” Using verniers Poole took the flitter through slow curves around the fallen toolmaker; with brief spurts of his main motor he raised wakes in the ice, sculpting them carefully. “And if we can’t, we’ll implode the damn wormhole. We’ll get funds for the Cauchy some other way.”

The argument went on for some time.

It took Poole five or six sweeps before he was satisfied with the hill he’d built.

Then, still careful, he lifted away from Alaska for the last time.

The Sun dipped, as the world turned. A shadow fell across Sculptor. Blood pulsed through him. With renewed energy his roots snuggled into the ground.

Consolidation.

Sculptor, unable any longer to move, stared at the place where the Sun-person had stood. The ice was melted, blasted, flowed together, the Hills flattened.

But the Sun-person had built the Hill that shaded Sculptor now. Somehow the Sun-person had understood and helped Sculptor. Now the Sun-person had gone, back to the world that had borne him.

Sculptor’s thoughts softened, slowed. His awareness seemed to expand, to encompass the slow, creaking turn of the world, the ponderous vegetable pulse of his hardening body.

His name melted away.

His father’s face broke up, the fragments falling away into darkness.

At the end only one jagged edge of consciousness remained, a splinter of emotion which impaled the blazing image of the Sun-person.

It wasn’t hatred, or resentment. It was envy.

Eve said, “As Poole and his followers opened up the Solar System — as they undid the relative isolation of previous centuries — they shone a clear light into darkened corners of their own history. Watch…”

This time he would reach the Sky. This time, before the Culling cut him away…

The tree of axiomatic systems beneath him was broad, deep, strong. He looked around him, at sibling-twins who had branched at choice-points, most of them thin, insipid structures. They spread into the distance, infiltrating the Pool with their webs of logic. He almost pitied their attenuated forms as he reached upwards, his own rich growth path assured…

Almost pitied. But when the Sky was so close there was no time for pity, no time for awareness of anything but growth, extension.

Little consciousness persisted between Cullings. But he could remember a little of his last birthing; and surely he had never risen so high, never felt the logical richness of the tree beneath him surge upwards through him like this, empowering him.

Now there was something ahead of him: a new postulate, hanging above him like some immense fruit. He approached it warily, savoring its compact, elegant form.

The fibers of his being pulsed as the few, strong axioms at the core of his structure sought to envelop this new statement. But they could not. They could not. The new statement was undecidable, not deducible from the set within him.

His excitement grew. The new hypothesis was simple of expression, yet rich in unfolding consequence. He would absorb its structure and bud, once more, into two siblings; and he knew that whichever true-false branch his awareness followed he would continue to enjoy richness, growth, logical diversity. He would drive on, building theorem on mighty theorem until at last — this time, he knew it would happen — this time, he would touch the Sky itself.

And then, he would—

But there was a soundless pulse of light, far below him.

He looked down, dread flooding him. It was as if a floor of light had spread across the Pool beneath him, shining with deadly blandness, neatly cauterizing his axiomatic roots.

A Culling.

In agony he looked up. He tried to nestle against the information-rich flank of the postulate fruit, but it hung — achingly — just out of reach.

And already his roots were crumbling, withdrawing.

In his rage he lunged past the hypothesis-fruit and up at the Sky, stabbed at its bland completeness, poured all his energies against it!

…And, for a precious instant, he reached beyond the Sky, and into something warm, yielding, weak. A small patch of the Sky was dulled, as if bruised.

He recoiled, exhausted, astonished at his own anger.

The Sky curved over him like an immense, shining bowl as he shriveled back to the Culled base floor, he and millions of bud-siblings, their faces turned up to that forever unreachable light…

No, he told himself as the emptiness of the Cull sank into his awareness. Not forever. Each time I, the inner I, persists through the Cull. Just a little, but each time a little more. I will emerge stronger, more ready, still hungrier than before.