On a night like this, one of the coldest in January, the atrium inside the main entrance of the hospital becomes an eternal bus depot or a postapocalyptic air terminal. The lights are sickly dim and the seats are bolted to the floor so that everyone faces the same direction, looking at nothing, waiting for sleep or some other transport that will never come. Each person has a suitcase or heap of duffels and no one is going anywhere. Every grunt or shuffle of bags echoes and swims around the high walls, diffused so that it seems to come from all places at once. A security guard staffs the desk, but no one at this hour seems to be waiting for any hospital function. The guard looks bored and tired, too, hunching over the desk and swiveling in his one non-bolted chair.

Eating is not permitted in this place, he says from time to time. He says little else; there are worse things than food, everyone knows, but it is his strategy to focus his announcements on the most common problems rather than the worst. Perhaps it is that cases of real danger require action, not words, and when it is a matter of urine or vomit a warning is of little help anyway.

When the volunteers from the Comunità di Sant’Egidio – young men and women bundled thick, with cheeks red from the cold – arrive with their great bags of sandwiches and boxes of pasta, the people in the bolted-down seats are caught in the thought-dance of deciding whether to risk leaving their things for a moment. The bread-bringers wait outside the atrium in the nearest arcade, and the people come in turns to accept their food, opening it immediately. They find places just outside the atrium to eat, preferably places from which their belongings are still visible, or if they prefer the warmth they station themselves behind the grand central staircase where the guard cannot see. He says nothing, though of course he knows. One man in heavy-laden cargo pants, eating fettuccine out of the plastic container, walks back into the atrium without hiding behind the staircase, and the guard’s shoulders unhunch and he calls out his typical phrase, and the man is a bit startled but nods and holds his hand up in mea culpa understanding, and leaves the atrium, and comes back in through the next opening and leans against the back of the staircase with the others.

During the day, the Policlinico Umberto I is a citadel of conventional mercies: a newly grafted lung, a second try at doxorubicin, fluids, gauze, the careful cleaning around a feeding tube. The adjustments of footrests of wheelchairs, hurried baptisms of blue-gray infants, nurses helping old women sit up in their beds to try to drink some water.

By area it ranks among the largest hospitals in Europe, thanks to the wide, meandering spread of forty-six peach-pink and buttercream buildings, laced with green spaces, tiny parks, plazas, and paths that allow patients and caregivers to walk around the maze of grounds before a procedure or after receiving some kind of difficult news. Arcade walkways, covered but open, run along the outsides of the buildings and also between them, so that even when it rains a patient can take a step outdoors and breathe, and move between clinics undrenched, and the surgeons can step out and smoke. The low benches built into these arcades allow those with unsteady legs or hearts to rest along their walks, because the clinics are many and spread out and the walk through the maze can be long.

Though the wall around the policlinico is patchwork – sometimes iron fence, sometimes stucco wall, sometimes brick-and-grate – it is complete. But the front gate remains open, even by night, for the purposes of the emergency department, and the security guard in the booth only checks vehicle traffic. He does not much mind who comes in or out on foot.

And so after the egress of secretaries, schedulers, technicians, nurses, and doctors from the business-hours clinics, a nightly immigration begins of men and women from the Termini train station, from the front steps of churches and grocery stores, from trudging around the city, all seeking a place to sleep. The reasons are simple. The interior hallways of the policlinico are warmer than the streets, and even the exterior corridors and the little lawns in between are safer and quieter, and no one tells them to leave, unless there’s trouble.

It is a cold night, and the Sant’Egidio youth have clean blankets to give out in exchange for ones that are darkened with dust, rainwater, or sweat. Many people have emerged from the endless maze of hallways and clinics into the main atrium knowing that Monday nights at this time there are people who bring these things. Not all of the inhabitants of the policlinico emerge in this way, so there are rounds to make, to deliver food and to check on people.

The volunteers put their knit-capped heads together and plan their routes through the maze. The leader of this group, Valentino, has more the air of a soldier than a volunteer: strong and tense, and not inclined to smile, he is more guardlike than the guards themselves. Some members of Sant’Egidio, like the high school students who started it, wanted to follow Christ and so began to serve; others, seeing something useful happening, joined in the service and, sometimes, to their great surprise, found Christ there. Valentino is in this second camp, still a bit alarmed at the idea of finding something alive underneath what was supposed to be a clean-cut set of helpful logistical tasks. He carries more supplies than the others but says fewer words. With a grunt and a gesture he splits the others into groups of three or four, and they divide the supplies and disappear every which way into the labyrinth.

If, however subtly, we start to think of “deserved mercy” and “undeserved mercy,” we are no longer speaking of mercy.

Some hallways are unexpectedly open, others closed off, the locked doors ambiguously guarding occupied or empty rooms. Any overnight inpatients are out of sight behind the locked doors. From the hallways there is no sign of patients sleeping in beds, but many others have made beds for themselves, stretching out on the preschool-bright floor tiles or on the rows of seats where, in the day, daughters wait for news of fathers in surgery. Outside, in the intermittent arcades between the clinics, the ones with dogs or uncertainties about walls stretch out on the built-in benches, leaning on piles of blankets and bags, sleeping or smoking or talking to their dogs, feeding them bits of the sandwiches.

Deep in the complex, a young man and woman have found a recessed doorway in a dead-end corner of an empty hallway. The doorway provides a bit of shade from the harsh light. They have lined the patch of floor with blankets and are nestled together, dozing. When the blanket-bringers come quietly toward them, they want to sleep, not speak.

This place, when the sun goes down, becomes the ancient version of its names. Clinico was once clinicus, sometimes meaning the bedridden one, sometimes the one tending the bed, derived from words for bed and stretching out. In English, too, clinic follows this path back to lying down. Ospedale was once hospitālis, “hospice, shelter, guesthouse,” from hospes (host, guest, stranger). English’s own hospital, from those same roots, first arrived in the 1300s as “a house or hostel for the reception and entertainment of pilgrims, travellers, and strangers” (Oxford English Dictionary). In the 1400s it grew to mean “a charitable institution for the housing and maintenance of the needy,” and only after this did it take on its medical connotation.

Always, these places have first meant a bed, a place to lie down at night. Long before fluorescent wards with tile floors, before anesthetic and billing and patient privacy and disinfectant, long before the concept of a germ, these places have meant refuge from the elements, and the uneasy navigations of host and guest and stranger.

When most of the boxes and bags and blankets have been exhausted, and the cold has deepened a few degrees, and nearly the whole of the maze has been searched, so the knowledgeable ones say, there is one more place Valentino must go, and anyone else can come if they want, but it has to be Valentino. He leads a few others through the arcades and then the interior hallways, up one story in an elevator in which the low overhead lights are stuffed with trash and covered in marker ink, past several inaccessible wards, through massive double doors that appear locked but open slowly when two of them push, around a corner to a dead end where the fluorescents are flickering spastically. A white-haired woman is sitting there with all her belongings. She looks over, startled for a moment, and then remembers herself. Valentino, who in most circumstances keeps his jaw locked and his eyes scanning, breaks into a wide smile and lets his eyes go soft and easy.

This dead end is not a dead end in the daytime, when the gray door at the end opens into a clinic. In the day, patients wait for their appointments in the hallway on a row of six bright blue plastic seats, bolted to the floor and to each other. In the day and in the night there is Maria Lucia. Her size and her conditions make it difficult to walk, and difficult to get up if she were to lie down, so as the clinic opens and closes and opens again she stays upright in the plastic seats. She has tucked her belongings underneath on the floor, mostly hidden in plastic bags, and empty food containers are stacked on one side.

She has her coat on, like everyone who sleeps in these unheated hallways, but it is not quite large enough to button. And so it cannot act as an apron to catch what falls from her shaking hands when she eats something difficult like soup or pasta. Trails of dried yellow drips run from her chest to her lap, and as she talks with Valentino she scratches away the bits she can reach, in apology and courtesy.

His voice is gentle with her. They talk about the weather, how she has been since last week, what she has seen and thought about. She has been fine, she says, the same as usual, and she is glad to see him. To look at him she stretches her neck up like the oldest, gentlest tortoise, and otherwise stays still except for the brushing away of crumbs, the wiping away of stains. It is not clear what effort it might take her to change her clothing, or how often she would have the privacy to do so, or if there would be anything for her to change into anyway. She sits there to sleep, and on Mondays to wait for Valentino.

Goodnight, they say, next week, and Valentino and the others retrace their steps through the hallways. Everywhere the air smells of smoke and survival. The tile is tracked with dirt, and they step over and around drifting plastic bags, cigarette butts, spilled liquid.

The nightly habitation of the policlinico raises the usual controversies: concerns about security and sanitation, the occasions of urine and feces, and the constant exhaustion of the cleaning staff who are too few and paid too little for the bewildering task of scrubbing an inhabited labyrinth back into a proper hospital every morning. The common refrain: this is not the place, this is not ideal.

Ideally, they say, people have work and sound minds and no great debilitating pain and are able to live in homes of their own. Or, if they cannot house themselves, ideally they fill out the proper forms and enter the appropriate government program, ideally for a short time before finding a job and regaining stability. If they cannot enter government housing, ideally they find a place in a shelter. If they cannot stay in a shelter, ideally they are at least clean, neat, no trouble, and out of sight. Ideally they do not stretch themselves out in a place meant only for sanitized, daylight mercies.

Which kind of mercy do we prefer? In its definition, mercy shows us two sets of recipients: those in a position of powerlessness or subjection and those with no right or claim to receive kindness. That is, the powerless and the undeserving. It is easy to see mercy for the powerless as beautiful, as long as they have not done anything wrong, nor anything grating to the senses. We celebrate the mercies that look, to us, like justice. But if, however subtly, we start to think of “deserved mercy” and “undeserved mercy,” we are no longer speaking of mercy.

Many convents and charities in Rome provide guest rooms for the parents of children being treated in one of the children’s hospitals. This is beautiful, and good. A few convents and charities open shelters for men who are still reeking of liquor and shouting curses. This is ugly, and beautiful, and good. And somehow, despite so many things, a person who has found herself at Termini alone and homeless can find a safe enough place to sleep in the hallways of the public hospital, and no one will keep her out.

No, it is not ideal. Surely the best place for people to sleep is not the hospital floor, and surely their presence is not the best imaginable thing for the hospital. But mercy has never arisen from an ideal situation – it grows as a garden at the end of this long maze of non-ideals.

Ideally, replies another logic, the earth shakes and swells and changes so that no one ever needs to sleep rough; nothing happens to anyone that leaves them without a stable and homelike place to live. If that is not possible, ideally a rapid and thorough societal response makes such things rare and brief. If not, ideally one person will at least take another in, personally, as a friend, at personal expense and in personal care, because no one could bear to leave someone outside. Or some collective – city workers, a church – will see to it that a person’s needs, physical and internal, are addressed to the greatest possible extent. If not that, if each of us must be on our own, ideally there are at least functional institutions where one is permitted to go, which feel safe enough to enter. If not, perhaps there are at least institutions that let one sleep in the corners.

At this juncture sits the policlinico. No, this is not the greatest mercy which could be shown. But without this limited, non-ideal mercy, there would remain one pristine, non-liable, empty hospital, and perhaps a hundred more people out in the dark, attempting to stretch their mats out in terrain far less hospitable to human life.

So we look again at mercy. The Italian misericordia is stitched together from miser (misery) and cor (heart) – it means both “mercy” and a thin, sharp knife that could slip between a knight’s armor plates and kill him, for pity or vengeance. Our English mercy grows from merci (reward, gift, grace, kindness) from merces (reward, wages, pay) from merx (wares, commodities, goods) – the same merx from which have grown the words market, merchant, commerce, and merchandise.

In some ways mercies are wares like any other: physical, practical things. When you need purple cloth at the market, you are more likely to inquire of those who sell red cloth or curtains or bedsheets than of those who sell only garlic cloves and no cloth at all.

Where will Maria Lucia go for water, for a place to sit? It is as simple as anything. She will go where there is water, where there is a seat. When people seek shelter, they will go wherever there is shelter, whether or not it was built for them. People seeking mercy will go wherever mercy can be found, even if the place was not originally meant for them or for the kind of mercy they seek.

We must know, when we call ourselves merciful, when we designate ourselves as people or institutions of mercy, when we display our neat, quick, beautiful merciful acts in the day: people will see them and come to us for mercies we have not yet shown. Mercies that, like the night, are longer, quieter, stranger.