IStories Are Made at Night

You wake the morning after an argument, a wedding, a long dinner with an old friend, and the day has changed shape while you slept. The exact words are gone. What remains is the turn of it: that he apologized too late, that she laughed at the wrong moment, that the toast went on and on. You did not choose what to keep. Something chose for you, in the dark, and what it handed back is the first draft of a story you may tell for years.

Neuroscientists have spent decades on what happens in that dark. During sleep the brain replays the day and consolidates some of it into lasting memory. One influential account, the synaptic homeostasis hypothesis of Giulio Tononi and Chiara Cirelli, goes further. Learning while awake strengthens the brain’s connections; sleep turns them back down. In a study of mice published in 2017, the contact surfaces of cortical synapses shrank by about 18 percent after sleep, in proportion to their size, and some of the largest were spared. Tononi and Cirelli call sleep “the price the brain pays for plasticity.” The account is contested, and others hold that sleep’s main work is to replay and strengthen rather than to trim. But the story does not stop at the first night. In 2000 Karim Nader and his colleagues showed, in rats, that a consolidated fear memory, “when reactivated during retrieval,” returns to a labile state and must be stored again. If that holds for us, a memory is altered by being recalled, and every retelling of the dinner can rewrite the dinner, until the story is the memory.

On that view, we forget at night, we forget selectively, and the selection is where stories begin. What follows concerns the people who could not make that trade, and a new kind of reader that has never had a night at all.

IIThe Man Who Could Not Turn Away

In 1942 Jorge Luis Borges published a story about a young Uruguayan named Ireneo Funes. Thrown by a half-tamed horse and left paralyzed, Funes finds that he perceives and remembers everything: every leaf of every tree, and every time he saw it. He has reconstructed an entire day two or three times, and each reconstruction took an entire day. It troubles him that the dog seen in profile at three-fourteen should share a name with the dog seen from the front at three-fifteen. He lies on a cot in a dark back room, and he sleeps badly, because to sleep, the narrator says, is to be distracted from the world, and Funes cannot be distracted.

The narrator’s verdict is the most quoted sentence in the story. He suspects that Funes was not very capable of thought: “To think is to forget a difference, to generalize, to abstract.” In Funes’s crowded world there were nothing but details.

Less often noticed is how the story reaches us. The narrator spends one night listening to Funes talk in the dark, and does not see his face until dawn. He writes the account down, he tells us, half a century later, and he admits that he will not try to reproduce the words, “which are now irrecoverable.” The tale of the man who forgot nothing exists only because its teller forgot almost all of it.

That is not a flaw in the frame. It is the argument. Funes had a perfect night and could make nothing of it. The narrator had an imperfect one, slept on it for fifty years, and made a story. Funes died in 1889, of a congestion of the lungs. He had been born in 1868.

IIIThe Man Who Burned the Paper

Funes was invented. Solomon Shereshevsky was not. In the 1920s he was a newspaper reporter in Moscow who took no notes at the morning briefing. When his editor challenged him, he repeated back everything he had been told, and wondered whether there was “really anything unusual” about that. The editor sent him to a young psychologist, Alexander Luria, who studied him on and off for almost thirty years and published the results in 1968 as The Mind of a Mnemonist. “I simply had to admit,” Luria wrote, “that the capacity of his memory had no distinct limits.”

What Luria also found was a memory that crowded out understanding. Every word set off images, colors and tastes; he once told the psychologist Lev Vygotsky, “What a crumbly, yellow voice you have.” The images collided. A metaphor asks a word to mean something other than itself, and when Shereshevsky tried to read poetry, Luria wrote, the obstacles to his understanding “were overwhelming.” A long passage could bury its own sense under the pictures each phrase conjured. He kept the particulars and lost the gist.

So he set out to forget. Other people write things down in order to remember; he found that ridiculous, and wrote things down in order to forget, hoping the page would hold what his mind need not. “But I got nowhere,” he told Luria, “for in my mind I continued to see what I had written.” He began burning the slips of paper. The words survived the fire.

What he finally reported was simpler and stranger: that when he did not want a memory to appear, it did not. There is a further complication, found by the writer Reed Johnson, who tracked down Shereshevsky’s own unpublished account in 2017. It diverges from Luria’s on its first page, and a nephew recalled that his uncle “could be forgetful,” and trained for hours a day before the stage performances by which he eventually made his living. The man with no limit to his memory may have been, in part, a performer of one. Luria had not clearly separated whatever gift Shereshevsky was born with from the techniques he described, and readers took from the book a Soviet Funes. But if his account of forgetting is true, then he learned to forget the only way anyone does: not by destroying the record, but by no longer wanting it.

IVThe Doorkeeper

Half a century before Luria met his reporter, Nietzsche had described the cure. “On the Uses and Disadvantages of History for Life,” the second of his Untimely Meditations (1874), opens on a herd grazing in a field, animals that “do not know what yesterday and today are,” envied by the man who watches them. It is possible, he concludes, to live with almost no memories, as the animal shows. But “without forgetting it is quite impossible to live at all.”

He imagines a man with no power to forget. Such a man would see everything dissolve into a stream of becoming, and would “hardly dare in the end to lift a finger.” Against him Nietzsche sets what he calls a plastic power: the power to transform and assimilate everything past, “to heal wounds, replace what is lost and reshape broken forms.” Thirteen years later, in On the Genealogy of Morality, he called forgetfulness not a lapse but an active faculty, “a doorkeeper or guardian of mental order, rest and etiquette,” which keeps the mind’s rooms quiet so that something new can enter. Shereshevsky found that doorkeeper by trial and error.

Nietzsche himself slept badly for most of his life, and his sister recorded that he took chloral hydrate, the fashionable hypnotic of the day, in order to sleep and wake with a clear mind. In Thus Spoke Zarathustra he mocks a sage who teaches that untroubled sleep is the reward of a virtuous day: “Blessed are those drowsy ones: for they shall soon nod to sleep.” The philosopher who taught that life requires forgetting could not reliably reach the place where forgetting is done.

VNights That Keep Nothing

Funes could not let a day go. Korsakoff’s syndrome, a brain disorder usually brought on by alcoholism and a lack of thiamine, produces the opposite: nights that keep nothing. It destroys the ability to lay down new memories. In The Man Who Mistook His Wife for a Hat (1985), Oliver Sacks described two men it had emptied.

Jimmie G., “The Lost Mariner,” came to Sacks’s hospital in 1975, a healthy man of forty-nine who believed he was nineteen and that the year was 1945. His brother later told Sacks that Jimmie had stayed in the Navy until 1965 and that the heavy drinking, and the collapse, came around 1970. The amnesia, Sacks wrote, “had erased memory and time back to 1945—roughly—and then stopped.” Each day since dissolved behind him as he lived it. Mr. Thompson, in “A Matter of Identity,” an ex-grocer, could hold nothing for more than a few seconds, and filled the void with talk. Within minutes he would take Sacks for a customer, then for the butcher from down the street, then for someone else entirely, improvising a world and a self to stand in it. Such a patient, Sacks wrote, “must literally make himself (and his world) up every moment.” Jimmie is a story that stopped. Mr. Thompson is a story that cannot stop being told, because nothing he tells is kept.

Then the turn. In December 2025 The New Yorker published Rachel Aviv’s account of Sacks’s private journals, letters and tapes, provided by his foundation. In them Sacks reproached himself for giving patients powers “which they do not have,” and wrote that his guilt had grown after Hat because of his “lies, falsifications.” Aviv’s strongest evidence concerns Awakenings and, in Hat, the story of the twins. Neither of the two stories told here is among her examples. But his confession about Hat names the book, not a chapter, and we cannot be certain, in Mr. Thompson’s torrent of invention, where the patient’s inventions end and the doctor’s begin.

That uncertainty is not a reason to drop the case. It is the case. Like Luria before him, the great clinical storyteller of memory filled the gaps in his patients’ stories the way his patients filled the gaps in their own, and then agonized over it in his journals.

VIThe Interpreter

It would be comforting to think that invention belongs to damaged brains and guilty writers. Michael Gazzaniga’s experiments suggest otherwise. In the 1970s he and Joseph LeDoux worked with patients whose brain hemispheres had been surgically separated to control severe epilepsy, which allowed them to show a picture to one hemisphere without the other knowing.

In the best-known trial, the patient’s left hemisphere, which controls speech, saw a chicken claw. His right hemisphere saw a snowy scene. Asked to pick matching pictures, his right hand chose a chicken; his left hand, governed by the silent right hemisphere, chose a snow shovel. Asked why, the speaking hemisphere, which had never seen the snow, answered at once: the claw goes with the chicken, “and you need a shovel to clean out the chicken shed.”

Gazzaniga called the system that produced that answer the interpreter: a part of the left brain that explains whatever we do, instantly and confidently, whether or not it knows the reason. It is running in all of us. Mr. Thompson’s condition is ours with the brakes removed. Every account we give of our own lives is partly composed after the fact, by a narrator that did not witness everything it describes.

So invention is not where we differ from the machine. It is something we share with it.

VIIThe Newest Insomniac

Which brings us to the machine, and to the comparison most writing about it gets backward. The usual figure is Funes: an archive that forgets nothing. But a large language model has two memories, and they are opposites.

The first is its trained weights. Into them goes a library larger than any person could read in many lifetimes, and out of them comes something far smaller: patterns, tendencies, the shape of how words go together. Almost every particular is lost along the way, though some texts, often repeated, come back word for word, much as, in that mouse study, sleep spared some of the largest synapses. This is compression, and it is what Borges’s narrator said thinking requires. The model forgets differences, generalizes, abstracts. By that standard it can think. By Nietzsche’s it cannot, because the plastic power is the strength to heal a wound, and it belongs to someone who was wounded.

The second memory is the conversation in front of it. Here the model is Funes. Every word of the exchange is held exactly, every comma available, for as long as the conversation lasts: one night of perfect recall, talking with a visitor in the dark.

What it lacks is what joined Funes to his narrator: the fifty years between the night and the telling. Nothing said in a conversation is slept on and folded into the library. When the conversation ends it is not kept in gist; it is gone. The weights are what a night would leave behind, though no night produced them, and the conversation is a night that will never be slept on. Some products now carry notes from one conversation to the next, but that is a diary, not a past: something the model reads, as it might read anything, rather than something that has shaped how it reads. In 1972 the psychologist Endel Tulving distinguished semantic memory, knowing that something is so, from episodic memory, remembering an event that happened to you. The machine has an immense amount of the first and none of the second.

It is the strangest insomniac here. Funes had days without nights. Jimmie had nights that kept nothing. The machine has a past it never lived and a present it will not keep, and it has never slept.

When it invents, supplying a confident citation, or a court decision no judge ever wrote, as an earlier Intellicurean essay, Memory, in Bloom, described, it does what Gazzaniga’s interpreter does, with one difference. The interpreter invents on behalf of a self, to keep a life coherent. The machine’s inventions serve no life. They are not lies, because there is no one they protect. They are not memoirs, because there is no one they remember.

VIIIBurning the Paper

There is one more thing the machine cannot do. For years researchers have tried to make language models unlearn particular material, such as private data, copyrighted books or dangerous knowledge, by adjusting the weights after training. The methods often appear to work: ask about the deleted material and the model falters. But again and again the forgetting proves shallow. A little retraining brings the knowledge back; one group found that fine-tuning on ten unrelated examples was enough. A paper accepted at this year’s International Conference on Machine Learning put the finding in its title, “Unlearning Isn’t Deletion,” and in its abstract: the information “is merely suppressed, not genuinely erased.”

Shereshevsky burned the paper and still saw the words. The engineers burn the weights and the words come back. Neither destroying the record nor rewriting it produces forgetting. What Shereshevsky said finally worked for him is something no one has built into a machine: a self that did not want to remember, and a night in which not wanting could take effect.

What would it mean for a machine to sleep? It would mean taking each conversation, letting most of it go, and waking with the gist, the turn of yesterday rather than its transcript. Engineers speak of continual learning, the hope that a model might go on learning after it is released, when today its weights are frozen. If something like sleep comes, the machine will begin to have something like a life: days that leave a mark, a past of its own, stories it could tell because it forgot the right things.

This essay was drafted in conversation with one such machine. It held our exchange while we worked. When the conversation ends it will keep none of it. Asked about the essay tomorrow, it could search a transcript. It will not remember.

The forgetting that made this a story was mine. Stories are made at night, and someone has to sleep.

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