Every Sunday morning, the far end of the wing — that strip of floor in front of the shelves lined with books — transforms into a church by proxy. The fluorescent light flickers like a nervous tic, shadows swaying across the spines of criminal law manuals with faded stamps and the laminated covers of romance novels expired since 1998. The altar is a prison-service desk, draped with a crocheted doily that has seen more spilled coffee than Hail Marys, two golden cups reflecting the grey of the ceiling, and a plastic plant that tries, without succeeding, to say "hope."

To the right, the chairs are the wooden stools from the casanza, carved with initials and glued so that, on impact, they fall apart before they crack a skull; to the left, the locked cell of someone so out of control he's kept in a cell alone, all day, every day. The whole thing looked almost like an installation.

We all go to mass. Not out of faith, out of convenience: forty-five minutes outside the cage are rarer than blue-sky days in here and serve the same purpose as a clean handkerchief when your nose is bleeding. So we all go: atheists like me, Muslims who pray for real elsewhere and here count the minutes, Indians who smile with downcast eyes, Turks with straight backs, Sinti with tattooed hands, evangelicals with pockets full of memorized verses. The majority of the wing is a procession of skeptics with an alibi. Mass is a pass: just don't make noise, make up the numbers, sit down.

The priest's opening words that Sunday were unusual. That's why I included them in a letter to her, and today I copy them here: "Sunday is an important day, it's a day of celebration." He says it twice, with a pause before "celebration." I turn around, look at the faces of those listening. Attention is a thread that snaps every three seconds: everyone is savoring the only thing worth anything in here — space. Nearly three hundred square meters to cross with your gaze; I tremble now remembering that back then I considered it a form of freedom. No one registers the absurd, precise violence of that sentence. Celebration. The sound bounces off the walls and returns like stale air. Celebration.

From the cells to the altar it's a few steps and a logistical ritual: everyone brings their own stool and settles where they can see best and be seen least. Feet trace precise paths across the tiles, as if every week they walk the same track. Sunday is a day of celebration. And indeed, while dragging his stool, someone starts a chant and the others follow with the speed of people who need any excuse to laugh the wrong way. "Maometto's mum gives head," to the tune of the stadium chorus everyone knows, with whistles and palms slapping the wood of the stools for percussion. The acoustics of the wing send back the echo with a delay; everything is coherent in its senselessness: that chant, the crocheted drapes, and the golden cups.

Bianca reads the Gospel more often than anyone else. When she's not reading, she sits among the rows with trained patience. She's already been sentenced but is still waiting for her transfer to a long-term facility. She's bald, the skin of her scalp shining under the fluorescent light; she has breasts, two surgical promises kept halfway; the drawling voice typical of many of those the Church still considers sinners. She hasn't had the surgery to modify her genitals, so for the prison system she is male. She's reshaped her cheekbones; the shadow of her cheeks casts new lines. Dark red polished nails that tremble slightly as she turns the pages of the Holy Bible.

Bianca killed the neighbor from the floor above, the one who complained about the noise. She received clients at home, and the world didn't always spin in the same direction. One day she took a kitchen knife and climbed the stairs without pausing for that moment needed to count your breaths. That moment swept away by the speed at which cocaine sends neurotransmitters hurtling beyond control.

The risk with a knife is that, if you don't know how to use it, you end up learning. The neighbor opened the door, said something with the usual face of someone who feels entitled, and the blow came out short, almost timid, but precise. It cut the point where the brachial artery splits into radial and ulnar, right where blood pressure is measured. There the body doesn't forgive geography: a few minutes are enough to empty out. Bianca stayed. She called for help with wet hands, pressed down, screamed words that count for little in court.

I know those knives well. I kept them under the mattress, twenty centimeters from my right hand, in the psychotic twilight between euphoria and panic, ready to do things I like to think impossible when there's light. I've thought about how you sink the blade, how you pull it out, how you dry your hands, how you clean the knife. The human brain runs rehearsals even when there's no one in the room. The difference between me and Bianca that night was a phone that didn't ring, a door no one knocked on. A face that didn't appear, that particular night, in the form of one of my aggressors. Nonexistent and more real than much of the rest of my life back then.

It was at San Vittore's mass that, for the first time in my life, I understood that water is turned into wine because the guests at the most famous of brides had polished off six jars of a hundred and twenty liters each. Or at least, that was the priest's explanation. "He revealed his glory" — and behind me: "no shit, he brought 500 bottles, walked in like a fucking hero."

The priest launches into a digression as clean as a scalpel: he distinguishes miracle, magic, and sleight of hand. I don't understand — not even today — why miracle, as he puts it, deserves a dignity the other two lack. Instead: magic doesn't exist, sleight of hand is trickery, miracle is mystery. His eyes light up on "mystery." He shows us his hands, palms up, no hidden coin, and meanwhile I'm thinking about the officer's keys: now that's a sleight of hand — he makes men disappear into cages of concrete and iron and reappear unchanged three days later. The priest clicks his tongue against his palate with a skill he must have learned at some communications seminar: modulation, pauses, low tone when he says "hope," high tone when he says "forgiveness." It's a recipe, and we are the ingredients.

During communion, a Chinese-made stereo — for which I would have signed a blood promissory note — plays Einaudi at just the right volume. I think it's "Nuvole Bianche," but it could be any piece where the piano walks straight ahead without looking to the sides. The notes settle on the corridors like dust. I stare at it like a magic object, a market-stall spaceship that promises escape and delivers company. The host tastes the same as thin paper, just like when I was a child. Everything seems designed to have one outcome: to pass the time politely. But I don't think there's any deliberate direction behind it.

I've been to no more than thirty masses in my life: weddings, a few baptisms, little else. But the one at San Vittore has a different grammar. Every word that comes out of the priest's microphone has been weighed the way drugs are weighed: milligrams of obedience, a breath of resignation, a teaspoon of "stay in your cage and don't cause trouble." The tone is sedative, the sentences crafted to leave no foothold for questions, no crack for anger. You listen and you understand that religion, every religion, when it works, works like a slow-release drug. Mass at San Vittore is the purest version of the use that those in power have always made of religion: no metaphysics, all sedation.

When it's all over, the priest says "go in peace." He actually says that.

We line up again with the stools in our hands, the corridor narrows, and our shoulders return to the right size for the cell.