Here, somewhere under the surface of the gentling waves, were formed the basic building blocks of life—sulfur, phosphorus, potassium, and calcium, as well as nitrogen and carbon dioxide and ammonia, in endless combinations. The conditions under which these substances mix to form the basic building blocks of organic material are rare in the extreme. How many times they must all have come together only to fall apart. Somehow, as this endless process of trial and error continued, the simplest form of life—a substance that could propagate itself and metabolize energy—came into being. It is difficult to say whether this was truly life as we know it. Such primeval entities were so simple that it would be hard to define what about them was life and what about them was not. Gradually, however, a hierarchy emerged among them. Some became absorbers while others were absorbed—the opening act in a harsh struggle for survival. From the chaos that ensued, only the most successful entities would emerge. It was almost inevitable that this simple, primal material that sprang up from the rich soup of the ancient shallows would, one day, develop a higher intellect, as if to challenge the very natural world that gave it life.
Meanwhile, a change both gradual and violent was taking place in the sea as well. The narrow sea that had split the land mass in two gradually disappeared, until a single great peak dominated the surface of the planet. Its heights were sheathed in thick ice, hard as steel, from which glaciers flowed, bearing down time and time again upon the land far below.
Four great oceans ruled the climate of the planet and split the land into four great continents that rose above the waters, creating their own unique interior environments.
By now two billion years had already passed on the young planet; the next two billion were fast approaching.
Uncountable new organisms formed in the seas, drifting, swimming, crawling; some dividing and multiplying, some laying eggs.
Trilobites appeared and spread, dominating the shallows across the planet. With their thick carapaces and sensory organs far more advanced than those of their contemporaries, they dominated the early ecosystems; for a long time they held their watery domain against all intruders. Though the mollusks and the echinoderms had developed equivalent internal complexity, their defensive body structures made them particularly unsuited for vying with the trilobites for supremacy. Their rule unchallenged, the trilobites diversified into species ranging in size from two centimeters to a full two and a half meters, and their kind flourished.
And yet, though harried by the trilobite swarms, in the depths of the sea another variety of life was gathering the strength it would require to carry the next age.
Though these creatures too first began with the thick shells that were the fashion of the day, they gradually abandoned their unwieldy carapaces, their armor diminishing to small scales of chitinous plate. External gills folded inside, and flat bodies morphed into more aerodynamic conical shapes. Small, round eyes developed convex lenses, and a multitude of jointed swimming appendages became a smaller number of highly efficient fins.
This kind of change does not come about in a hundred years or a thousand. It was only by fierce tenacity that these new creatures persevered over tens of millions of years until the processes of mutation and selection had remade them into something wholly new. In the face of the incessant onslaught of the trilobites, they paid countless sacrifices, pushed nearly to the brink of extinction on several occasions. Yet every time the fish came back stronger, better suited to their environment. Against such highly efficient, highly energetic life-forms, the offensive weaponry and defensive structures of the past age would ultimately give way. At last the entire vastness of the ocean was a stage for life. The lords of the coastal shallows, the trilobites, could no longer stave off the invasion. There was a limit to how deep the trilobites could survive, and once the fish pushed them and their heavy carapaces down to the seafloor, there was no returning to the shallows.
When members of one species must sink to the seafloor when they stop swimming, and members of another may rest their fins in fatigue and yet remain afloat, it is clear which will win a battle for the same region of water.
To make matters worse, the fish loved to eat trilobite eggs and young above all other food. Surely the trilobites, too, ate what fish eggs and young came drifting in toward the shores. But with the fish controlling the vast reaches of the ocean, the trilobites felt ever more pressure upon their confined habitat.
Amidst the roaring spray along the rocky coast and in warm inlets surrounded by lush jungle, one by one, the trilobites slowly disappeared.
There could hardly be any more dramatic a transition in the history of life on this planet than the one that came when the mantle of dominance passed from trilobite to fish.
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In time, the fish would expand their great realm even farther. Near the end of the age that followed, several groups among them left the receding seas, congregating where the sun shone brightest and the air was clear, braving the dangers of the land and penetrating the continental interiors. These intrepid adventurers were to mark two great achievements in the annals of life.
The first true terrestrial animals appeared. And it was inevitable that eventually, a new sort of animal would arise that could stand on its hind legs alone. Meanwhile the sea rang on, in constant motion, recording the songs of effort and of the rise and fall of the multifarious creatures living within its borders, their unfulfilled dreams and their courage.
Constellations changed their shape in silence: the Leviathan to the Dragon, the Dragon to the Amphora, the Hunter to the Necklace. Many of the twinkling stars burst, spewing immense energy during their brief death fires, and then disappeared from the sky, leaving nebulous clouds of fading light behind.
The long years passed, as they always had and as they always would.
Until the end of time, if such a thing exists.
Surging and receding . . .
Surging and receding . . .
Rolling in, rolling back out again.
Into night, then into day, then back into night.