Seeker said they should skirt along these working perimeters of the forest. The biting vapors made Cley cough, but she understood that the shifting brown fogs also cloaked their movements against discovery from above. The night sky had cleared of Supra ships.

             They slipped into the shadows of the enveloping woods, but Cley felt uneasy. Soon they looked down on the spreading network of narrow valleys they had traversed. She could see the grasp of life had grown even since she had observed it from Alvin's flyer.

             Broad green patches lay ready to serve as natural solar-energy stations. Already some followed the snaking lines of newborn streams, growths cunningly spreading through the agency of animals. Such plants used animals often, following ancient precept. Long ago the flowers had recruited legions of six-legged insects and two-legged primates to serve them. Tasty nectar and fruit seduced many into propagating seeds. The flowers' radiant beauty charmed first humans and later other animals into careful service, weeding out all but the lovely from gardens; a weed, after all, was simply a plant without guile.

             But it was the grasses that had held humanity most firmly in thrall for so long, and now they returned as well. Already great plains of wheat, corn and rice stretched between the forks of river-valleys, tended by animals long bred for the task. Humanity had delegated the tasks of irrigation and soil care. As the Supras had revived species, they re-created the clever, narrowly focused intelligences harbored in large rodents. These had proved much more efficient groomers of the grasses than the old, cumbersome technology of tractors and fertilizers.

             Cley felt more at home now as they trekked through dense woods. She kindled her hormones and food reserves to fend ofi^ sleep and kept up the steady pace needed to stay with Seeker, who showed no signs of fatigue. 1 he forest resembled no terrain that had ever existed before. Assembled from the legacy of a perpetually fecund biosphere, it boasted forms separated by a billion years. The Supras had reactivated the vast index of genotypes in the Library with some skill. Few predators found easy prey, and seldom did a plant not find some welcoming ground after the lichen had made their mulch.

             Still, all had to struggle and adjust. The sun's luminosity had risen by more than ten percent since the dawn of humanity. The rub of tides on shorelines had further slowed the planet's whirl, lengthening the day by a fourth. Life had faced steadily longer, hotter days as the crust itself drifted and broke. In the Era of Oceans the wreckage of continental collisions had driven up fresh mountains and opened deep sutures in the seabeds—all as patient backdrop to the frantic buzz of life's adjustments to these immense constraints. Species rose and died because of minute tunings of their genetic texts.

             And all the hurried succession and passionate ferment was a drama played out before the gaze of humanity—which had its own agenda.

             Over the past billion years the very cycles of life on Earth had followed rhythms laid down by governing intelligences. For so long had Nature been a collaboration between Humanity and Evolution that the effects were inseparable. Yet Cley was startled when they came upon a valley of silent, trudging figures.

             "Caution," Seeker whispered.

             They were crossing a foggy lowland ripe with the thick fragrance of soil-making lichen. Out of the mist came shambling shadows. Cley and Seeker struck a defensive pose, back to back, for the stubby forms were suddenly all around them. Cley switched to infrared to isolate movements against the pale, cloudy background and found the figures too cool to be visible. Ghostly, moving warily, they seemed to spring everywhere from the ground.

             "Robots?" she whispered, wishing for a weapon.

             "No." Seeker peered closely at the slow, ponderous shapes. "Plants."

             "What?" Cley heard now the squish squish as limbs labored to move.

             "See—they unhinge from their elders."

             In the murky light Cley and Seeker watched the slow, deliberate pods separate from the trunks of great trees. "Plants led, once," Seeker said. "From sea to land, so animals could follow. Flowers made a home for insects—invented them, in my view."

             "But why . . . ?"

             "Every step was an improvement in reproduction," Seeker said. "Here is another."

             "I never heard—"

             "This came long after my time, as I came after yours."

             Plants had long suffered at the appetites of rodents and birds, who ate a thousand of the seeds for each one they accidentally scattered. Yet plants held great power over their animal parasites; the replacement of ferns by better adapted broad-leaved trees had quickly ended the reign of the dinosaurs. Plants' age-old strategy lay in improving their reproduction, and throughout the Age of Mammals this meant hijacking animals to spread their seeds. When ponderous evolution finally found an avenue of escape from this wastefulness, plants elected to copy the primates' care in tending to their young.

             Cley approached one of the stubby, prickly things. It was thick at the base and moved by jerking forward broad, rough appendages like roots. They looked like wobbly pineapples out for a slow stroll. Each great tree exfoliated several walkers, which then moved onto wetter ground enjoying better sunlight. Cley thought of eating one, for the resemblence to pineapples was striking, but their sharp thorns smelled to Seeker of poison. Farther up the valley they found a giant bush busily dispatching its progeny as rolling balls, which sought moist bottomland and warmth.

             They kept to the deep canyons. Cloaking mist gave some shelter from the Supra patrols, which now crisscrossed the sky. "They do not know this luxuriance well," Seeker remarked, clicking its sharp teeth with satisfaction. "Nor do their robots."

             Cley saw the truth in this, though she had always assumed that the mechanical wonders were of an innately higher order. Humanity had long managed the planet, tended the self-regulating soup of soil and air, of ocean and rich continents. Finally, exhausted and directionless, they had handed this task over to the robots, only to find after more millions of stately years that the robots were intrinsically cautious, perhaps even to a fault.

             Evolution shaped intelligences born in silicon and metal as surely and steadily as it did those minds which arose from carbon and enzymes. The robots had changed, yet kept to their ingrained Mandate of Man: to sustain the species against the wearing of the world. It had been the robots, then, who decided that they could not indefinitely manage a planet moist with organic possibility. A miserly element in them decreed that the organic realm should be reduced to a minimum. They had persuaded the leaders of the crumbling human cities to retreat, to let the robots suck Earth's already dwindling water into vast basaltic caverns.

             So the Supras' servants had for hundreds of millions of years managed a simple, desiccated Earth.

             "Machines feared the small, persistent things," Seeker explained that night. "Life's subtle turns." They had camped around a bris-thng bush that gave off warmth against the chilly fogs.

             "Couldn't they adjust those?" Cley asked. She had seen the routine miracles of the robots. It was difficult to believe those impassive, methodical presences could not master even this rich world with their steady precision.