The calm serenity of the man-made lagoon thrilled Sojoban from balls to bones. The lovely beaches of Nuevo Zihuatenejo stretched as far as he could see. Children raced up and down the coastline. His eyesight was fading, but in his mind it was clear — when a child (perhaps 35 kg) dives into an incoming tide, it flows around him, making waves that ripple outward and wander about until they fade into a thin line of seafoam on the fine beach sand. In a few moments the new coastline vanishes under the hot sun, but, in the space of those seconds, the form of the coast was pre-ordained from the moment the boy waded into the ocean.

In the lagoon, there were no waves. Inside the pontoons, a series of paddles fluttered back and forth in a curious way, dampening the waves and using their energy to turn a dynamo. The whole set-up made clean, cheap, renewable energy so efficiently it made the thrice-damned Geothermals department gnash their teeth with envy. Sojoban grinned with pride and strolled back to his flat in the hills to take his siesta.

He was still young, he thought. Twenty years ago, a man his age would be begging on the streets for enough hydrocarbon to light his funeral pyre. At that time Sojoban was a mechanic for the Mexican infantry, refitting old American Army surplus tanks to run on Mexican biodiesel. At night, he sat naked on his bunk, shaking an induction torch and reading what math books he could get with his cigar ration. The calm, stately dance of the symbols kept him sane with their undisputed certainty, even as the war tried to sweep him up in its chaos.

Sojoban's most sacred book was a molding Russian text on fluid dynamics. It had come to him by a greasy old friend who sadly had no way of protecting it during a two week-long mission. The sweltering heat only hastened its deterioration. The binding had long since rotted away, so he carefully kept the individual signatures in a plastic bag. Reading these pages carried the air of meditating over a palimpest.

Everything he read of fluid dynamics led him back to a brick wall — the Navier-Stokes equations. It was the Holy Grail of fluid motion, the law that governed the movement of liquids. Little was known about it save a few approximations that worked in trivial circumstances, and that they were, in general, unsolvable. Sojoban attacked the problem, drawing upon his little biblothéque. His hunger for a resolution to the great gap in his Holy Writ eclipsed the hunger brought on by starvation rations during the war's final years. The biodiesel engines Sojoban helped install ate deeply into Mexico's grainery — one already scarce from drought and the scarcity of pesticides.

Finally, just as it seemed that the fog of war would swallow him and drive him into madness, the war ended. Winter was thankfully brief and mild (even by Mexican standards) and by spring Sojoban had been decommissioned. He moved north into the land he helped conquer and invested his pension into Our Lady of the City of Angels, born from the ruins of Caltech. As a token he was granted an honourary professorship, and then shocked the department by assuming its responsibilities. Gradually he proved himself and worked his way into teaching the very top-level courses. Teaching, he joked, was much the same work as he had done during the war, refitting those damn Bradleys; rip out the bullshit and magic tricks that had worked before and replace it with a foundation that would last a lifetime.

Still, he yearned for a solution to his problemcito. For eight years he hammered away at it until the wall buckled under his command. Cautiously, yet some error prove all his work meaningless, he spent a further three years verifying his logic and refining his methods. His magnum opus, "A Solution to the Navier-Stokes Existence and Smoothness Problem, with Applications to Fluid Engineering," became an instant hit among both the academic community for its rigor and the engineering community for its pragmatism.

The development of the wavepool hydroelectric generator was a natural application of Sojoban's methods. Previous generators were far too limited to specialized locales, needing waterfalls or swift-moving rivers. A Sojoban generator (as they became known to the public) had none of these restrictions and greatly improved efficiency. They weren't perfect, but they were damn close.

As Sojoban lay rocking in his hammock, he gazed into the impromptu lamppost that he had erected in his garden. Soon, he thought, all of my city will be lit, just like it was long ago. The future will be as bright as the lights of my City of Angels.

For Swap.