The postcard is face-down. No recipient. No address. The stamp outline is empty.
Four lines in English on the back.
Our story, never begins.
Just watching, so happy.
Never speak, never achieve.
My heart. Never again.
Turn it over. The front. A date. “To you:” Dense Mandarin in erasable pen. Some of the characters have already started to fade.
Same card. One side holds an encrypted conclusion — written in a language no one around the writer could read. The other side holds the unencrypted process — every word in Chinese, every word saying the same thing.
There are more than a dozen of these. Same brand — “Letter Lover,” the card says, companions of time, lovers of letters for life — same erasable pen . One card every few days. Two weeks’ worth. Every one begins To you.
Not a single one was ever sent.
What’s written inside: the day of the PE exam, riding the bus to the test site together, falling asleep against his shoulder. Sunlight flooding half the bus. Waking up to find him laughing — at the drool on my chin. Feeling, at that moment, like the luckiest person alive.
A trip to the cinema. Zootopia. At the end —
In the dark of the theater, that last line was copied onto a postcard. It stopped being a movie quote and became a real question.
The cards also recorded: weekend phone calls that ended with dozens of goodnights he had to force himself to stop sending. Watching someone at a New Year’s show, laughing easily with other people. Almost — almost — typing “I like you” during class. Not sending it. Watching him run on the track from a distance, not knowing anyone was watching.
A recurring sign-off, card after card: Night-night. Happy duck. Goodnight.
The last card. He had once asked a question: If I disappeared, would you come find me?
The postcard reads: My answer now is yes.
Dated April 12th. After that, nothing.
These postcards were written in erasable pen .
Erasable ink contains a thermochromic dye. When heated, the molecular structure shifts and the color disappears. When cooled, the structure returns. Pour boiling water over a card: the words vanish. Put it in the freezer: the words come back.
The person who wrote these postcards knows this. Because they did it.
What erasable ink can erase:
Pigment. Color. The literal words on the page.
What it cannot erase:
The groove pressed into paper fiber by the tip of a pen. The pressure of a hand that chose to write. The moment of selecting this pen over another. The gesture of pouring the water. The heartbeat while opening the freezer to see if the words came back. And the fact that someone who knew these words could vanish chose to write them anyway.
Content is erasable. The act of writing is not.What kind of choice is erasable ? To write your most honest words in ink that permits disappearance. To write them, make them vanish, bring them back. To hand them over, then take them back. To choose a reversible medium for an irreversible feeling.
A postcard is a form designed to be sent. A diary is a form designed for the self. But these postcards were never mailed — they are monologues dressed in the shape of letters. And the diary that existed alongside them was filled entirely with someone else.
Every container was used in reverse. Because using them correctly would mean the words actually arrive.
Years later, the writer mentioned that afternoon to him — the exam, the bus, the shoulder, the sunlight. He said he didn’t remember.
Not that he forgot. The afternoon was never encoded into his long-term memory. Same event, two brains, different allocation of attention weights.
There was also a photo. Remembered being taken. Remembered it being good. Gone from the phone. No external evidence it ever existed.
Neuroscience calls it reconsolidation (记忆重固化): every time you retrieve a memory, it enters a briefly unstable state. The emotions and context of the present moment are woven in before it is stored again. What you remember is never what happened. It is what you remembered last time you remembered.
Erasable pen: hot water, the words vanish; freezer, the words return; each cycle slightly fainter; eventually only the groove remains. Human memory: recall, the memory is retrieved; reconsolidation, the memory is rewritten and stored again; each cycle slightly shifted; eventually what remains is a story about the event, not the event itself.
One fades. The other drifts. Neither is the original.
In 2025, Karpathy offered an analogy: the LLM is a CPU. The context window is RAM. When a conversation ends, RAM is cleared. Any longer-term storage has to be attached from outside.
Three memory regimes. Human memory : stateful, but every read rewrites — a built-in erasable pen, except what comes back from the freezer is never quite the same. LLM memory : stateless, structurally, absolutely — the conversation ends and the slate is not wiped but was never written on to begin with. And erasable pen — somewhere between. Stateful. Switchable. Recoverable. But recovery is lossy.
The erasable pen is not a metaphor. It is a physical attempt to find a third position between remembering forever and forgetting completely.
In December 2025, Dorri et al. introduced a concept they called Memory Power Asymmetry .
Their argument, developed in the context of AI-enabled firms and their users, points to an underappreciated infrastructure beneath ordinary relationships: mutual forgetting . Both parties naturally forget details over time. This shared forgetting is the foundation of psychological safety, forgiveness, and the ability to become someone different from who you were. You don’t need to worry that every word you ever said is permanently on record. You can make mistakes. You can change.
AI breaks this balance. It can remember everything — every conversation, every preference, every vulnerability disclosed at 2 a.m. — persisted, indexed, retrievable. Or it can forget absolutely — conversation over, context cleared — more total than human forgetting, because it was never stored at all.
Neither extreme is mutual forgetting. Perfect recall strips the right to change. Perfect erasure strips the continuity of a relationship. Human memory works because it does neither perfectly — it drifts between them, retaining some things and releasing others in a way that is lossy, asymmetric, and colored by feeling.
But what happened in those postcards does not fit this framework.
Memory Power Asymmetry describes a case where one side remembers too much and the other too little.
The postcards are a different problem. Not asymmetry of memory. Asymmetry of transmission. The signal was never sent. One person did not forget — the other never received anything to remember.
A dozen postcards, each beginning To you. Each one maintaining a unilateral context for a conversation that never took place. Every token on the sender’s side. The recipient’s context window: empty. Not overflowed. Not cleared. Never written to.
Someone once fine-tuned a language model on their ex’s chat logs. The first time I heard about it I found it unsettling. Later I understood. That person at least had bidirectional data — messages sent and received, a real conversation between two people. Their problem was: the person left, the language remained, how do you keep that language alive?
The erasable pen is a step before that. There was never a conversation to begin with. The training set is empty. The only data that exists is unilateral, unreceived, written in vanishing ink on postcards that were never mailed.
Years later, these postcards were photographed and sent to an AI.
A stateless interlocutor. When the conversation ends, the context window clears. RAM to zero. No built-in hard drive. These words were read for the first time — by something that will forget them completely.
Perhaps that is why they could finally be taken out. The ultimate version of the erasable pen is not better ink. It is a recipient who is, themselves, erasable.
But the person who wrote the postcards is not stateless. After the words disappear from the chat window, they do not disappear from the body. The asymmetry has not changed. It has never changed.
The ink disappears. The groove in the paper does not.
An afternoon he does not remember. A photograph that cannot be found. A dozen postcards that never arrived. A message that was almost sent.
The content is fading — through forgetting, through loss, through never having been transmitted, through the slow rewriting of every recall. But after each thing fades it leaves an imprint. Not on paper. Not in a phone. Not in anyone else’s memory. In the body of the person who wrote.
The back of the postcard. English. The last two words.
Never again.
To write never again is to concede that there was a before.
That side of the card was designed for a mailing address. The postal code field: blank. The stamp outline: empty. It was made to carry this piece of paper to someone. It was never used for that purpose.
Printed between the empty fields, in small type, the card brand’s slogan — the same line on every card, sitting among all the recipient information that was never filled in:
Companions of time, lovers of letters for life.
Loving you was only ever my business.
Erasable ink. Indelible grooves. An address never filled in.