Then Kynes saw the salt pan.

His 'thopter, flying between stations far out on the bled, was blown off course by a storm. When the storm passed, there was the pan—a giant oval depression some three hundred kilometers on the long axis—a glaring white surprise in the open desert. Kynes landed, tasted the pan's storm-cleaned surface.

Salt.

Now, he was certain.

There'd been open water on Arrakis—once. He began reexamining the evidence of the dry wells where trickles of water had appeared and vanished, never to return.

Kynes set his newly trained Fremen limnologists to work: their chief clue, leathery scraps of matter sometimes found with the spice-mass after a blow. This had been ascribed to a fictional "sandtrout" in Fremen folk stories. As facts grew into evidence, a creature emerged to explain these leathery scraps—a sandswimmer that blocked off water into fertile pockets within the porous lower strata below the 280° (absolute) line.

This "water-stealer" died by the millions in each spice-blow. A five-degree change in temperature could kill it. The few survivors entered a semidormant cyst-hibernation to emerge in six years as small (about three meters long) sandworms. Of these, only a few avoided their larger brothers and pre-spice water pockets to emerge into maturity as the giant shai-hulud. (Water is poisonous to shai-hulud as the Fremen had long known from drowning the rare "stunted worm" of the Minor Erg to produce the awareness-spectrum narcotic they call Water of Life. The "stunted worm" is a primitive form of shai-hulud that reaches a length of only about nine meters.)

Now they had the circular relationship: little maker to pre-spice mass; little maker to shai-hulud; shai-hulud to scatter the spice upon which fed microscopic creatures called sand plankton; the sand plankton, food for shai-hulud, growing, burrowing, becoming little makers.

Kynes and his people turned their attention from these great relationships and focused now on micro-ecology. First, the climate: the sand surface often reached temperatures of 344° to 350° (absolute). A foot below ground it might be 55° cooler; a foot above ground, 25° cooler. Leaves or black shade could provide another 18° of cooling. Next, the nutrients: sand of Arrakis is mostly a product of worm digestion; dust (the truly omnipresent problem there) is produced by the constant surface creep, the "saltation" movement of sand. Coarse grains are found on the downwind sides of dunes. The windward side is packed smooth and hard. Old dunes are yellow (oxidized), young dunes are the color of the parent rock—usually gray.

Downwind sides of old dunes provided the first plantation areas. The Fremen aimed first for a cycle of poverty grass with peatlike hair cilia to intertwine, mat and fix the dunes by depriving the wind of its big weapon: movable grains.

Adaptive zones were laid out in the deep south far from Harkonnen watchers. The mutated poverty grasses were planted first along the downwind (slipface) of the chosen dunes that stood across the path of the prevailing westerlies. With the downwind face anchored, the windward face grew higher and higher and the grass was moved to keep pace. Giant sifs (long dunes with sinuous crest) of more than 1,500 meters height were produced this way.

When barrier dunes reached sufficient height, the windward faces were planted with tougher sword grasses. Each structure on a base about six times as thick as its height was anchored—"fixed."

Now, they came in with deeper plantings—ephemerals (chenopods, pigweeds, and amaranth to begin), then scotch broom, low lupine, vine eucalyptus (the type adapted for Caladan's northern reaches), dwarf tamarisk, shore pine—then the true desert growths: candelilla, saguaro, and bis-naga, the barrel cactus. Where it would grow, they introduced camel sage, onion grass, gobi feather grass, wild alfalfa, burrow bush, sand verbena, evening primrose, incense bush, smoke tree, creosote bush.

They turned then to the necessary animal life—burrowing creatures to open the soil and aerate it: kit fox, kangaroo mouse, desert hare, sand terrapin... and the predators to keep them in check: desert hawk, dwarf owl, eagle and desert owl; and insects to fill the niches these couldn't reach: scorpion, centipede, trapdoor spider, the biting wasp and the wormfly... and the desert bat to keep watch on these.

Now came the crucial test: date palms, cotton, melons, coffee, medicinals—more than 200 selected food plant types to test and adapt.

"The thing the ecologically illiterate don't realize about an ecosystem," Kynes said, "is that it's a system. A system! A system maintains a certain fluid stability that can be destroyed by a misstep in just one niche. A system has order, a flowing from point to point. If something dams that flow, order collapses. The untrained might miss that collapse until it was too late. That's why the highest function of ecology is the understanding of consequences."

Had they achieved a system?

Kynes and his people watched and waited. The Fremen now knew what he meant by an open-end prediction to five hundred years.

A report came up from the palmaries:

At the desert edge of the plantings, the sand plankton is being poisoned through interaction with the new forms of life. The reason: protein incompatibility. Poisonous water was forming there which the Arrakis life would not touch. A barren zone surrounded the plantings and even shai-hulud would not invade it.

Kynes went down to the palmaries himself—a twenty-thumper trip (in a palanquin like a wounded man or Reverend Mother because he never became a sandrider). He tested the barren zone (it stank to heaven) and came up with a bonus, a gift from Arrakis.

The addition of sulfur and fixed nitrogen converted the barren zone to a rich plant bed for terraform life. The plantings could be advanced at will!

"Does this change the timing?" the Fremen asked.

Kynes went back to his planetary formulae. Windtrap figures were fairly secure by then. He was generous with his allowances, knowing he couldn't draw neat lines around ecological problems. A certain amount of plant cover had to be set aside to hold dunes in place; a certain amount for foodstuffs (both human and animal); a certain amount to lock moisture in root systems and to feed water out into surrounding parched areas. They'd mapped the roving cold spots on the open bled by this time. These had to be figured into the formulae. Even shai-hulud had a place in the charts. He must never be destroyed, else spice wealth would end. But his inner digestive "factory," with its enormous concentrations of aldehydes and acids, was a giant source of oxygen. A medium worm (about 200 meters long) discharged into the atmosphere as much oxygen as ten square kilometers of green growing photosynthesis surface.

He had the Guild to consider. The spice bribe to the Guild for preventing weather satellites and other watchers in the skies of Arrakis already had reached major proportions.

Nor could the Fremen be ignored. Especially the Fremen, with their windtraps and irregular landholdings organized around water supply; the Fremen with their new ecological literacy and their dream of cycling vast areas of Arrakis through a prairie phase into forest cover.

From the charts emerged a figure. Kynes reported it. Three per cent. If they could get three per cent of the green plant element on Arrakis involved in forming carbon compounds, they'd have their self-sustaining cycle.

"But how long?" the Fremen demanded.

"Oh, that: about three hundred and fifty years."

So it was true as this umma had said in the beginning: the thing would not come in the lifetime of any man now living, nor in the lifetime of their grandchildren eight times removed, but it would come.

The work continued: building, planting, digging, training the children.