Once, not so long ago but before our time, all people were the same person. That’s not to say that they weren’t immersed in their own lives; they were, of course, as people always have been—millions of fish in their millions of bowls. It’s just that they were equally immersed in everyone else’s.

In those days it was possible to browse the spice aisle at the supermarket while you lay in bed reading a book, harvested lemons from an orchard, went snailing past a traffic accident on the highway, and hammered a piton into a rock face, coloring the air with that marimba-like sound of steel entering granite. Every moment contained the traces of all the others, so that even the most irresistible gust of excitement or laughter was accompanied by someone else’s rage, wistfulness, drowsiness, petulance, and fear. The best experiences were inextricably wrapped up with the worst, the happiest with the most miserable, and no one received so much as an instant of life without also dying somewhere. That was just the way things were. People were accustomed to it, never having known a world in which everyone wasn’t the same person, a big little aging athletic young lazybones who was everywhere anyone was.

Though there was love back then, or something like it, there was no privacy. Dating was effortless, and frequently inadvertent. Now and then people would find themselves spending time together in the flesh rather than apart—that’s all—and how, they might wonder, would it feel if two of their ankles brushed under the table? If two of their hands touched? If two of their bodies made love? Romances were fixed into place with an orderly tock-tock-tock, like tiles a mason was situating on a floor. And if the day came for you to settle down and marry, you would simply turn your gaze inward and sort through your galaxy of other selves until you found one beside whom you could agree to spend a lifetime.

Maybe such love wasn’t love at all. That was what one part of everyone believed. He worked as a dispatcher for a small-town hospital, and on overnight shifts, when no one’s brain or heart or shotgun went off, he would sit at his desk and let his mind wander. What would it be like if people knew as little of each other as that pen standing in his cup knew of that clock hanging on his wall? What if people could be separate, truly separate, a whole planetful of genuine individuals, completely alone inside their bodies? No one but a mystic could imagine such a thing, and even then only in wisps and snatches, but this particular part of everyone could not stop trying to make sense of the idea. He was sure that the world would seem bigger, and he himself bigger inside it, if only it had a little more mystery.

Whenever a portion of himself ruptured an artery or lay jerking for breath on the pavement, he knew it at once, and frequently, if that portion was nearby, the signal on his phone would flash and he would take down the details so that he could dispatch one of the ambulances. The long minutes as he sat rushing toward himself were horrifying. He never grew used to the feeling.

He had learned over the years that to distract himself he should concentrate on being other people, stronger ones, with bodies they could ignore if not indulge. His favorite was a woman on the opposite side of the world who worked repairing floral coolers, servicing their motors, sprayers, thermostats, and condensers. All day long she drove the city streets, from the coast up to the hills and back, maintaining her company’s machines. He was fascinated by the way she could spend a full eight hours wielding pliers, valves, and wrenches and still smell like flowers at the end of it all, a perfume she hardly detected except when she saw herself as he did. They were two small parts of everyone, the pair of them, separated by multiple oceans, and he knew that his was not a life of hers she especially noticed, yet occasionally he wondered if he did not, in fact, love her.

Sometimes he found it hard to be so tiny a fragment of other people. A molecule of her—that’s all he was. No, not even a molecule—an atom. He fantasized about introducing himself to her as a total stranger, a piece of herself she had somehow never met.

“You might like me if you got to know me,” he would say.

“Take a chance,” he would tell her.

Maybe the concept was senseless, but he kept turning it over, examining it again and again in his own poor parcel of people’s minds. Love, he thought, or at least the idea of it, needed risk, impenetrability. It suffered from too much certainty. Somewhere far away he was a little girl making a chain of paper dolls with her safety scissors, snipping them free where their hands came together—and here he was in his office, in the middle of the night, wishing he could make the same series of delicate snips in real life. Everything was connected. It was just that the strings were drawn too tight.

One day, as this part of everyone drove home from work, another car went jackrabbiting through a red light and struck the edge of his front bumper. He was concentrating when it happened—concentrating hard—on the woman who worked with hand tools but smelled like flowers. She gave a short puff of compressed effort as she severed a length of copper tubing. The aroma of oil and daisies lay thick in the air, and the heavy round cutter filled her bone-slender hands, and for just a second, as his brakes cried out, she disappeared from his awareness. He was everyone except her, all the same millions of people as always, including the actuary driving the other car and the bank teller buckled into the passenger seat. But where she had been there was nothing.

His car tugged forward against its frame. Instantly she was one of him again. His limbs buzzed with adrenaline. What on Earth was that?

The crunch of glass and resin had hardly left his ears, and already he was trying to figure out what had happened. She was such an insignificant spoonful of him, the woman, yet suddenly she seemed so important. That night, after dinner, as he settled down to watch TV, he felt her trembling into a stretch. The morning sun had set her curtains aglow. She was preparing to climb out of bed, and along with the sensation of her toes crackling and her shoulders shaking came all the usual everything elses: the cough of a fraternity boy who had downed a scotch and soda, and the shared elation of a crowd cheering at a stadium, and the billows and trills a tourist heard diving for pearls in the Gulf, and the heartbrokenness of a kid unfolding a note with the no box checked, and the power-grin of the kid who had checked it, and the tightness in the knuckles of a barber who had been at his scissors since half past seven, and the otherworldly distress of childbirth—not only the stabbed agony of the mother but the baby’s first blast of amazed sensation—and the roaming sadness of innumerable old men and women—a sadness that was more like wonder—as they lay back into their minds asking themselves where the years had gone. The part of him that was the woman who lived on the other side of the world rubbed the grit from her eyes. There was something comical about the way she folded her blanket over before she slid out from underneath it, her hands so neat and formal as they completed the operation, as if she were creasing the corner of a page in a book. She was like a child playing grown-up, he thought, fussing through some ceremony she had only just invented. He wished he could greet the sight with adoration. How could he, though, when everything she did was so familiar?

Stop it, he told himself. You’re obsessing again.

It was crazy, wishing that people could be disentangled from each other, pointless, like thirsting for some other air to breathe.

All the same, he continued to pose his what-ifs.

As the days passed, he busied himself more and more as the woman who repaired the floral coolers. The moment of the car accident, when who knows what mishap or coincidence had hidden her away from him, had been thrilling, so extraordinary that he only half trusted that it had really occurred, and for hours at a time, as he stood at the grocery store testing the softness of the avocados or worked behind his desk placing calls to the vehicle bay, he was actually tap-tap-tapping at the plaster of her life, waiting to see if the experience would repeat itself.

Early the next Saturday it did. The part of everyone who was so desperate and preoccupied was collecting his car from the auto body shop when another part of everyone met him with his car keys. “We got your bumper ready. Right now we’re tightening up the chassis. Give us a few and we’ll have her all done for you.” For the second night in a row, the part of everyone who barely smelled the flowers on her skin was enjoying a late-late dinner in a neighborhood restaurant, dipping a tuna roll into her soy sauce, first one side and then the other, so that the wasabi leached deep into the rice. Just then, as she popped it into her mouth, the part of everyone who was reclining beneath the car in the garage accidentally kicked a chock loose from one of the tires. There was a long groan of springs, followed by a quick procession of pings and snaps, and the front end came down with a crash. The noise was so explosive that even the mechanic himself presumed he had been crushed. Then he came rolling out from under the rear bumper on his automotive creeper. Beneath the striplights he lay coughing and twisting his eyes shut, untouched except for the shiny gray talc on his face. It was only after his pulse had slowed that the part of everyone who was in the waiting room, his hand resting on a tall display of truck tires, realized that for the second time in as many weeks the woman had gone missing. He was toying with the bristly rubber cilia along the tire treads, and he was everywhere else, too, or at least he thought he was, and suddenly he was one place more: perched beside the bamboo counter finishing off the saké she had ordered.

Unbelievable.

Scarcely an hour went by before he sat hunched at his kitchen table scribbling on a sheet of paper. Fear + Concentration = Estrangement—that seemed to be the equation. The more unexpected the fright that overtook him, and the more intently he was studying another part of himself when it did, the likelier a rupture was to open up between his lives.

He had a theory. Now he needed to test it. He harnessed his attention to the piece of him that was the woman and waited patiently for something to shock him. For days he enclosed himself in her experience. His thoughts hardly wavered. She might be cleaning a set of condenser coils or coaxing her work van up a hill, brushing her teeth or trying to ply a knot from her collarbone. It didn’t matter—he was there, always there, as alert to her life as he was to his own. Once, walking downstairs in the dark, he misjudged a step and for a quick little whiplash of seconds she melted away. He barely had time to notice she was gone before she resurfaced. A few mornings later, it happened again. He was buttering his toast when a bird smacked into his kitchen window. Flash—she vanished—and flash—she reappeared. He was afraid of heights, so he took an elevator to the top floor of a hotel, peering over the safety rail into the abyss of the lobby. This time he was halfway home before she finally loomed back up in him. It was his most successful experiment yet. Soon he realized he could generate a good productive vertigo using any life he chose. Someone somewhere was always tarring a roof or crossing a pedestrian bridge, and with each gust of wind, as the man imagined himself plummeting to the earth, a wave of panic would pour through him and swallow the woman whole. Some of the episodes lasted only a second or two, but some considerably longer. He cultivated the sensation, teaching himself to nurse each dim flicker of terror until his feet felt like bricks and the rest of him like a hanging sculpture, a strange stack of bones drifting and swaying on their metal wires. After a while he was able to reproduce the effect at will. It wasn’t so difficult once he developed the knack for it. The periods he spent without the woman grew to fill his hours and his days. Again and again he blew her out like a candle flame. Eventually she began to seem like someone he had never been.

That all people were the same person had never troubled anyone else—he knew it beyond a doubt—but isolating yourself from one person, he discovered, made it easier to isolate yourself from another. Bit by bit he took each scrap and morsel of himself and swept them away. And presently, to his great surprise, he was alone.

That was the beginning. In the years that followed, the fashion for being a single distinct individual spread until it was no longer a fashion at all but a custom, and ultimately something more like a law. People traded their ability to be one another for this passion or that: anger, pity, kindness, pride, reverence, desire, regret. Gradually, body by body, they shed themselves of their multimillion lives, until hardly anyone was more than a person or two.

But before the rest of them, there was the man who was no one else. Beneath his skin he carried an endless wispy feeling of alarm, a nervous tension that thinned and thickened by the moment but never completely dissipated, so that in time he found it easy to suppose he had gotten used to it. But when he thought about the woman who repaired the floral coolers, whose life not so long ago had been one of his own, it was with a foreignness and an affection that went fanning out inside him insuppressibly. Maybe it was love, and maybe it wasn’t—who could say? All he knew was that some part of him seemed to yield around it like soil around the roots of a tree.

What, if anything, the feeling might signify, he had no idea, but he had already scheduled his vacation from the hospital, and when his two weeks arrived, he traveled to her city on the other side of the world. He found her, as he had hoped he would, at her favorite restaurant, sitting alone at a corner of the sushi bar. He took the first stool along the adjoining bend.

“Excuse me,” he said. He had a skill with languages and had not forgotten hers.

“Yes,” she asked, and then, “Do I know you?” and suddenly the puzzled look she had given him dropped deeper into itself. “I don’t know you.”

He tried to strike the smile from his face and could not tell if she noticed. How extraordinary. “That’s true. I can show you how it’s done, if you’d like.”

She was slow to reply, but at last she gave a decisive nod.

For her, it turned out, sadness was the key, not fear, but she was a much more skillful learner than he had been, and the day soon came when she was no one but herself and he was no one but himself, two separate people sealed tight in their own privacies. One night, to celebrate, he cooked her dinner, and she uncorked a bottle of wine, and afterward, as they stood eye to eye trading gazes, it was nothing like looking into a mirror. As their fingers met, each of them wondered what the other was thinking, how the other was feeling. They were living in an entirely new world, one not so different from yours and mine, a world where you could fall in love, promise your heart, and say I do, without ever knowing for certain if you really were, or if you sincerely could, or if you truly did.