Five o’clock a.m. on a morning last fall, in the Walgreens of an affluent suburb on Chicago’s North Shore, where I have gone to buy batteries for my flashlight on my way to the beach to watch the sun rise, and where the only other customer, a man in his early twenties with a thicket of curly blonde hair, approaches me. “Excuse me,” he says, his deep set brown eyes singing a song that should be accompanied by a twelve-string guitar. “Do you know of anywhere that I could maybe get a cup of coffee at this hour?” I direct him to the Dunkin’ Donuts over on the highway, and what I notice as soon as he leaves is that his loneliness remains behind, staining the too-bright air in the pharmacy’s aisles between the Advil and the Band-Aids and the Nyquil and the Crest like the afterburn left on a retina when a camera’s flashbulb has gone off.

Later, when I’m ankle deep in sand with my back against the lifeguard chair and Lake Michigan a tapestry of moonlight and mystery spread out before me, I find myself thinking about that moment and about that man, and about how, if I had looked out the store window just after he left, I would have seen his taillights etching their red scribbles across the darkness and then dwindling into the distance; and about how, if I had driven past the Dunkin’ Donuts soon after that, I would most likely have seen him sitting there, beyond the neon pink and orange OPEN 24 HOURS sign—on a stool at the counter, maybe, or in one of the beige vinyl booths—a solitary figure fossiled within the amber of the fluorescence and framed by the blackness of the night, while, outside the windows, the eighteen-wheelers would have whistled past, swallowing the highway up into the speedblur beneath their tires.

I know a woman who worked the overnight shift at that Dunkin’ Donuts for a time, who walked there every evening after night had set, and walked back home before morning had broken, to the room at the top of a splintered, sagging stairway, up above a bowling alley, where she lived with her five children, in a tiny town nearby that has become home to immigrant and migrant laborers. I asked her once if she was afraid of the darkness she had to walk through for what took her nearly half an hour, and of the highway she had to cross, and the shrug she offered me as an answer needed no translation. What choice did she have? it said. I think that, if she had had the words, she also would have said that she has so many fears, in so many shapes and sizes, that she keeps them all close to her and wears them in layers, like sweaters, knowing that any she peels off and leaves lying around will be snatched up by her children, who will wrap them around themselves and button them up to their chins.

“Do you know if my mom is working tonight?” her eight-year-old daughter asked me one Saturday morning when I was driving her to the library to get some information for a school project she was working on, and I told her that I was pretty sure she wasn’t, that I thought I’d heard her mention that she had this weekend off. “Good,” she said, turning to the window to watch the train tracks that bordered the road we were traveling on slip past, and I heard her release a sigh that made its way forward to hover beside me.

I glanced in the rearview mirror and she turned to face me, our eyes meeting midair. “When she’s out at the night?” she said, shrugging a shrug that echoed the one I’d seen her mother give. “My heart keeps jumping around inside me and counting the minutes until she’ll be back.” When she sighed again, though, it was with satisfaction. “Did I tell you? She’s teaching me how to make flan? Maybe she’ll teach me tonight again even. I love it when Mami stays home.” It was the third room they had lived in in as many months, one from which they would be forced by fire a few weeks later, but that’s what she called it: home.

That’s what that man in Walgreens could use, too, I find myself thinking on the beach that morning. Not a place to have a stranger pour him a cup of coffee, but a place to have someone he loves teach him how to make flan. Strangers with coffee pots are easier to find, of course, I know, envisioning all of them out there across the land. All those pink and orange OPEN 24 HOURS signs aglow all through the night—on the street corners of New York City, where the windows of the high rises are punching rows of yellow squares out of the darkness up above, and in coastal towns in Florida, where the parking lots in front of them are fogged with ocean mist, and in hamlets far out in the middle of the prairies of Wyoming and Montana, beneath stars that are clustering into bouquets that purple the dark.

I see them in smokestacked cities up north, and in the farming villages of the quilted midwest, and in southern towns that twitch with restless heat, and I see them out in Las Vegas, surrounded by zippers of sequined marquees that are working overtime to prove that loneliness lives elsewhere. All those pink and orange OPEN 24 HOURS signs and all those people sitting at all the booths and counters beyond them, waiting for the morning light to paint a new day onto the face of a world they wish felt more like home. And then I find myself envisioning all the people behind those counters, too, pouring coffee into Styrofoam cups and tucking doughnuts into white paper bags, all the time thinking of their sleeping children, who, in fact, aren’t sleeping at all, but are tossing and turning on top of their covers, waiting for the sound of the key in the door that will let them know they can breathe evenly again.

And I even find myself envisioning those truckers in the driver’s seats of all those eighteen-wheelers whizzing past, and wondering what images (of what lit windows in what waiting houses or apartments or trailers or rooms, on what streets in what neighborhoods in what towns in what states) they might have hung from their rearview mirrors or pasted up beside the moon beyond their windshields, like a night light plugged into the loneliness, to guide them through until dawn.

Standing there in the sand, with the first screes of the gulls and the first bass notes of the ducks just starting to intertwine with the shhshhing of the waves against the shore, I’m almost certain that I can hear the clacketing of those tires on all those highways, and even more certain that I can hear the litany of longing within it, the way the jazz composer Dave Brubeck once heard the embryo of a riff within the galloping of the hooves of the horse he was riding. Ba da dump, ba da dump, ba da dump, he heard, as he explained in an interview years later, and there it was, a syncopated symphony in 3/4 time, writing its blue notes across the lead sheet of his mind.

There would be more than enough time, I imagine, for a trucker motoring at 75 miles per hour in the general direction of whatever loading dock he’d been instructed to head to next to start giving thought to what it means to have a permanent place in this world. So that, somewhere along the way, out there in the vastness of a nameless, starless distance, as he’s being devoured by the dark and then rebirthed by each light post he passes, only to be devoured again as soon as he moves beyond the outer reaches of the range of its glow, and as he’s twirling his radio dial and diving into, say, KAGH’s pool of listeners in and around Cressett, Arkansas, and then shooting out its other side, toweling off its music and diving right on into KHMB’s pool of listeners in neighboring Hamburg, and as he’s slicing past lit billboards that shout out to him like preachers from the pulpits of their stilts in the grass along the highway, to REFRESH ON THE COCA-COLA SIDE OF LIFE and to MAKE AN APPOINTMENT FOR A HUNGERECTOMY WITH SNICKERS and to TAKE STOCK IN AMERICA WITH U.S. SAVINGS BONDS, and as he’s ghosting past or around or sometimes even straight on through sleeping towns that will never guess he’s been there when they wake in the morning, it’s possible that he might start working out the algorithms of the algebra of absence and the geometry of goneness in such a way that will leave him feeling homesick for a place he’s never been. A place, he might start to speculate, that could exist just past that not yet illuminated point where the land will meet the sky once day arrives, or even, who knows? just around the next bend in the highway.

Or maybe here, you might be thinking, in this suburb on Chicago’s North Shore where I’m now standing just beyond the glistening ruffle of the waves upon the sand, shawled in the sapphire dreamlight of almost-morning, but don’t be so sure. Because here, when I drove through the silent, charcoaled streets on my way to this beach, past houses with porch lights on and curtains drawn, I saw televisions and computer screens flickering in upstairs windows, and couldn’t help but think about all the separate stories being played out, side by side, within those houses’ walls, and about how you don’t have to be sitting at a counter beyond a pink and orange neon sign to know that longing is OPEN 24 HOURS, and so is fear.

So that, even right here, swaddled in the middle of a suburb in the middle of the country, several layers above the uppermost tier of the upper middle class, when you find yourself awake in the middle of the night, it wouldn’t take much for you, too, to start reciting the basic tenets of the algebra of absence to yourself: If x = what if the deal doesn’t go through? or what if the promotion isn’t offered? or what if the bid isn’t accepted, or the meeting comes to naught? and y = what if one of us gets sick, or one of the children gets into trouble, or the marriage doesn’t last, or all this luck just runs out? then wouldn’t x + y = you, tossing and turning on top of the covers, or bleary eyed at your computer, searching for iwantguarantees.com, or propped on the couch with the remote in your hand, flipping from a man in a green apron touting the virtues of the Veg-O-Matic, to a documentary on the mating habits of the Tanzanian wildebeest, to a rerun of Roseanne and back, waiting to breathe evenly again?

We’re all proficient in the algebra of absence and the geometry of goneness, I think. All aware of how hard we have to fight to find a place in the world, and then of how much harder to keep it from slipping away once we do. Remember that song sung by the eyes of the man who approached me in Walgreens? Forget about setting it to the accompaniment of a twelve-string guitar. It’s probably better to imagine it as a choral piece, with parts for all of us, instead. Soprano, alto, tenor, bass, it really doesn’t matter which we choose, as long as we’re all lending our voices to the mix; as long as we’re all harmonizing our hunger into a communal composition that, sung tutti, all together, as a drumming of desires, can’t help but thrum with solace when it echoes back to us.