Beyond the oasis, he could see in this failing light the land Fremen called "The Emptiness" - the land where nothing grows, the land never fertile. Water and the great ecological plan were changing that. There were places now on Arrakis where one could see the plush green velvet of forested hills. Forests on Arrakis! Some in the new generation found it difficult to imagine dunes beneath those undulant green hills. To such young eyes there was no shock value in seeing the flat foliage of rain trees. But Leto found himself thinking now in the Old Fremen manner, wary of change, fearful in the presence of the new.

He said: "The children tell me they seldom find sandtrout here near the surface anymore."

"What's that supposed to indicate?" Ghanima asked. There was petulance in her tone.

"Things are beginning to change very swiftly," he said.

Again the bird chimed in the cliff, and night fell upon the desert as the hawk had fallen upon the partridge. Night often subjected him to an assault of memories - all of those inner lives clamoring for their moment. Ghanima didn't object to this phenomenon in quite the way he did. She knew his disquiet, though, and he felt her hand touch his shoulder in sympathy.

He struck an angry chord from the baliset.

How could he tell her what was happening to him?

Within his head were wars, uncounted lives parceling out their ancient memories: violent accidents, love's languor, the colors of many places and many faces... the buried sorrows and leaping joys of multitudes. He heard elegies to springs on planets which no longer existed, green dances and firelight, wails and halloos, a harvest of conversations without number.

Their assault was hardest to bear at nightfall in the open.

"Shouldn't we be going in?" she asked.

He shook his head, and she felt the movement, realizing at last that his troubles went deeper than she had suspected.

Why do I so often greet the night out here? he asked himself. He did not feel Ghanima withdraw her hand.

"You know why you torment yourself this way," she said.

He heard the gentle chiding in her voice. Yes, he knew. The answer lay there in his awareness, obvious: Because that great known-unknown within moves me like a wave. He felt the cresting of his past as though he rode a surfboard. He had his father's time-spread memories of prescience superimposed upon everything else, yet he wanted all of those pasts. He wanted them. And they were so very dangerous. He knew that completely now with this new thing which he would have to tell Ghanima.

The desert was beginning to glow under the rising light of First Moon. He stared out at the false immobility of sand furls reaching into infinity. To his left, in the near distance, lay The Attendant, a rock outcropping which sandblast winds had reduced to a low, sinuous shape like a dark worm striking through the dunes. Someday the rock beneath him would be cut down to such a shape and Sietch Tabr would be no more, except in the memories of someone like himself. He did not doubt that there would be someone like himself.

"Why're you staring at The Attendant?" Ghanima asked.

He shrugged. In defiance of their guardians' orders, he and Ghanima often went to The Attendant. They had discovered a secret hiding place there, and Leto knew now why that place lured them.

Beneath him, its distance foreshortened by darkness, an open stretch of qanat gleamed in moonlight; its surface rippled with movements of predator fish which Fremen always planted in their stored water to keep out the sandtrout.

"I stand between fish and worm," he murmured.

"What?"

He repeated it louder.

She put a hand to her mouth, beginning to suspect the thing which moved him. Her father had acted thus; she had but to peer inward and compare.

Leto shuddered. Memories which fastened him to places his flesh had never known presented him with answers to questions he had not asked. He saw relationships and unfolding events against a gigantic inner screen. The sandworm of Dune would not cross water; water poisoned it. Yet water had been known here in prehistoric times. White gypsum pans attested to bygone lakes and seas. Wells, deep-drilled, found water which sandtrout sealed off. As clearly as if he'd witnessed the events, he saw what had happened on this planet and it filled him with foreboding for the cataclysmic changes which human intervention was bringing.

His voice barely above a whisper, he said: "I know what happened, Ghanima."

She bent close to him. "Yes?"

"The sandtrout..."

He fell silent and she wondered why he kept referring to the haploid phase of the planet's giant sandworm, but she dared not prod him.

"The sandtrout," he repeated, "was introduced here from some other place. This was a wet planet then. They proliferated beyond the capability of existing ecosystems to deal with them. Sandtrout encysted the available free water, made this a desert planet... and they did it to survive. In a planet sufficiently dry, they could move to their sandworm phase."

"The sandtrout?" She shook her head, not doubting him, but unwilling to search those depths where he gathered such information. And she thought: Sandtrout? Many times in this flesh and other had she played the childhood game, poling for sandtrout, teasing them into a thin glove membrane before taking them to the deathstill for their water. It was difficult to think of this mindless little creature as a shaper of enormous events.

Leto nodded to himself. Fremen had always known to plant predator fish in their water cisterns. The haploid sandtrout actively resisted great accumulations of water near the planet's surface; predators swam in that qanat below him. Their sandworm vector could handle small amounts of water - the amounts held in cellular bondage by human flesh, for example. But confronted by large bodies of water, their chemical factories went wild, exploded in the death-transformation which produced the dangerous melange concentrate, the ultimate awareness drug employed in a diluted fraction for the sietch orgy. That pure concentrate had taken Paul Muad'Dib through the walls of Time, deep into the well of dissolution which no other male had ever dared.

Ghanima sensed her brother trembling where he sat in front of her. "What have you done?" she demanded.

But he would not leave his own train of revelation. "Fewer sandtrout - the ecological transformation of the planet..."

"They resist it, of course," she said, and now she began to understand the fear in his voice, drawn into this thing against her will.

"When the sandtrout go, so do all the worms," he said. "The tribes must be warned."

"No more spice," she said.

Words merely touched high points of the system danger which they both saw hanging over human intrusion into Dune's ancient relationships.

"It's the thing Alia knows," he said. "It's why she gloats."

"How can you be sure of that?"

"I'm sure."

Now she knew for certain what disturbed him, and she felt the knowledge chill her.

"The tribes won't believe us if she denies it," he said.

His statement went to the primary problem of their existence: What Fremen expected wisdom from a nine-year-old? Alia, growing farther and farther from her own inner sharing each day, played upon this.

"We must convince Stilgar," Ghanima said.

As one, their heads turned and they stared out over the moonlit desert. It was a different place now, changed by just a few moments of awareness. Human interplay with that environment had never been more apparent to them. They felt themselves as integral parts of a dynamic system held in delicately balanced order. The new outlook involved a real change of consciousness which flooded them with observations. As Liet-Kynes had said, the universe was a place of constant conversation between animal populations. The haploid sandtrout had spoken to them as human animals.