Here’s a thought experiment for those of us who live in cities and spend far too much mental energy on our neighbors: Let’s say that an apartment is opening up in your building, one floor below yours, and by some miraculous breach of the urban space-time continuum, you’re allowed to pick the new tenant. But, because your city’s new mayor wants to establish some liberal cred and distinguish himself from the market-driven ruthlessness of his predecessor’s real-estate policies, a new law stipulates that the apartment be set aside for an artist: a dancer, a musician, a painter, a fashion designer, an actor, or a writer. You’re all for supporting creativity, but you’re also for your own peace and quiet. The dancer is out, as is a musician of any kind. A painter might be nice, but what if his work consists of shooting paint cans, like William Burroughs, or he has noisy affairs with his models? The designer might cast sideways glances at your Birkenstocks when you cross paths by the mailboxes. Actors like to practice their lines in the mirror, plus there’s the risk of Method shenanigans.

So you choose the writer and go about your business, blissfully unbothered. Some days pass, without a sound. Then the letters start coming. They are winsome and solicitous and erudite, but they have a consistent, definite point. “Madame,” they begin. “I hope you won’t find me too indiscreet. There’s been a lot of noise these past few days and as I’m not well, I’m more sensitive to it.” “If the hammering must be done in the morning, might it be done in the part of your apartment that is above my kitchen, not my bedroom.” “If there’s too much noise on Sunday morning I won’t be able to get out of bed until the afternoon.” The problem in the building isn’t him. The problem is you.

In the London Review of Books a few weeks ago, Michael Wood brought to the attention of the English-speaking world “Lettres à sa voisine,” a book of the recently discovered cache of letters that Marcel Proust sent to his upstairs neighbors at 102 Boulevard Haussmann, where he lived from late 1906 through the spring of 1919. (The book was published in France last fall; New Directions is working on an English translation.) Proust, who lived in his parents’ home until after his mother died, when he came into enough money to get his own place, moved into the building when he was thirty-five. His apartment had belonged to his great-uncle; as Edmund White notes in his biography of the writer, he had inherited a quarter of the building but foolishly let his aunt buy out his share, leaving him a renter. Proust had once been a man about town, but by the time he moved to Boulevard Haussmann his terrible asthma kept him inside. He worked in his bedroom, which he eventually soundproofed with squares of cork, and kept the windows closed and the curtains drawn to keep out the dust and hubbub of the avenue below. Still, these measures weren’t sufficient to block the intrusions of Charles Williams, an American dentist who kept his office on the third floor, directly above Proust’s apartment, and Marie Williams, who lived with her husband and son upstairs.

It seems almost too perfect that Proust, the bedridden invalid, would have sent notes upstairs, sometimes by messenger, sometimes through the post, to implore the Williamses to nail shut the crates containing their summer luggage in the evening, rather than in the morning, so that they could be better timed around his asthma attacks. (Is there a trove somewhere of Baudelaire’s letters to his pharmacist, begging for a remedy for absinthe hangovers?) But such is life in the city: things outside force their way in. As I’m writing this, the kid upstairs is practicing his jump shot, and I can tell you what time he leaves for school in the morning, and what his mother yells at him to get him out the door. I know that the little dog downstairs gets walked at nine in the morning and at midnight. When the guy in the next building over pulls out his electric guitar, the vibrations shake my bed.

This stuff can drive you to insanity, and often does, but Proust’s letters to the Williamses are full of wit and playful decorum, inspired by the necessity of nagging yet hardly disgruntled in tone or spirit. Practical requests are folded in with winning pleasantries. The word “noise” appears often, though so does the word charmant, as in, “Alas on coming home in the grip of the most violent attack I find your charming letter,” or “If your charming son, innocent of the noise that martyrizes me, is nearby, please give him my best wishes.” Proust doesn’t date his letters (the editors give approximations), but he does note, pointedly, that he’s writing at one in the morning. He sends up little gifts to apologize for making so many demands: “I hope that you will accept these four pheasants with the same ease with which I offer them to you as a neighbor.” This graceful flourish, accompanied by some articles of his that he hopes M. Williams might find interesting, is followed by a new demand: Could the next round of hammering happen the day after tomorrow after seven in the evening, because if it goes on in the morning there’s no chance of getting any rest during the day and going out will be impossible?

It was Marie, as the book’s title indicates, with whom Proust carried on the bulk of the correspondence; twenty-three of the twenty-six letters in the volume are addressed to her. Spread out from 1908 to 1916, this doesn’t seem like all that many, though maybe the two had other ways of communicating. Proust kept a telephone in his bedroom until the First World War broke out, and had a separate contraption called a théâtrophone that allowed him to listen to live concerts through the receiver. Marie played the harp; did he sometimes call her up when insomnia struck to ask her to hold the receiver in her lap as she gently plucked the strings?

There is a warmth and affection, plus a sprinkling of flirtatious flattery, in Proust’s letters to Marie, and, it seems, in her letters to him, though we have only his half of the exchange. The noise almost seems like an excuse to drop her a line. He writes to her of his work—La Nouvelle Revue Française was publishing extracts of “In Search of Lost Time,” which he sent her—and of her music. In a letter that the editors of the collection have dated to March 1915, he tells her that his close friend Bertrand de Fénelon has been killed in combat. Marie’s brother, too, has just died. “I didn’t think that God could add to my pain, when I learned of yours,” Proust writes. “And I’ve so fallen into the habit, without knowing you, of sympathizing with your sorrows and your joys, through the partition where I feel you invisible and present, that the news of the death of Monsieur your brother has deeply distressed me.” This subtle crossing of partitions, physical and mental, this delicate art of sympathetic spying, is vital to any novelist’s work. Certainly it is vital to Proust’s, and his condolence note is also a kind of confession. Proust is telling Marie that, during their eight years of living next to one another, she has come to occupy real space in his imagination. That is where he knows her best.