낮말은 새가 듣고 밤말은 쥐가 듣는다.
Nat-mareun saega deutgo bam-mareun jwiga deutneunda Daytime words are heard by birds; nighttime words are heard by mice. Whatever you say, something is listening — and what listens depends on when you speak.
The Korean proverb is one of the most cinematic warnings about discretion in any language. Most cultures have a way of saying the walls have ears — generic, ambient, architectural. The Korean version refuses the abstraction. There are two eavesdroppers, and they are on different shifts. In the daytime, when the windows are open and the sky is wide, the birds are listening from the eaves and the trees and the sky itself. At night, when the windows are closed and the household is still, the mice are listening from the gaps in the floorboards and the walls.
Whatever you say, something is taking it down. The proverb’s small joke is that you cannot even pick a quiet hour. Quiet hours have their own rodent staff.
What it means
Word for word the Korean is precise. 낮말은 — as for daytime words (the topic marker -eun makes daytime words the topic of the first clause). 새가 듣고 — birds hear, and. 밤말은 — as for nighttime words. 쥐가 듣는다 — mice hear. The grammar of the proverb is parallel and final-verb, which gives the saying a satisfying click as it ends. Each clause has its own subject (bird, mouse), its own verb (hear, hear), and the two clauses sit side by side as a complete observation.
Idiomatically, the proverb is a warning about the impossibility of fully private speech. The speaker is being told: do not say something here that you would not be willing to have travel. The proverb does not make this point abstractly. It points to the bird outside the window. It points to the mouse in the wall. The eavesdropping is physical. The proverb has located, exactly, who is going to overhear you.
There is a particular pleasure in the proverb’s bird/mouse split that other discretion proverbs lack. The bird is visible — high up, often within sight, the kind of thing you might have already noticed. The mouse is invisible — small, wall-bound, exactly the thing you would not see even if you tried. Together they cover the space of all possible overhearings. There is no time of day at which you are unobserved. There is no architecture in which you are alone.
Where it comes from
The proverb is well-attested in modern Korean proverb collections and is current across nearly all registers of Korean speech. The exact origin is less easy to date precisely; the saying belongs to the long oral tradition of Korean folk wisdom, and the agricultural world it presupposes — birds in the eaves of a hanok (traditional Korean house), mice in the wooden floors and grain stores — was a daily reality for most Koreans into the modern period.
What the proverb captures is a recognition that pre-modern village and small-town life made absolutely accurate: there were no truly private spaces. The thatched and wooden houses of pre-modern Korea were not soundproof. Birds nested in the eaves; mice lived in the walls; the lattice of family, neighbors, and household servants meant that any given spoken sentence had a real probability of being overheard. The proverb did not describe an unusual situation. It described the standard one.
The same situation produced parallel proverbs across most of East and Southeast Asia, and across Europe. What is distinctive about the Korean version is its taxonomic precision — the kind of eavesdropper specified by the time of speech. Other languages reach for a generic listener (the wall, the window, an unspecified ear). The Korean has done the entomological work.
How it gets used today
Today the proverb is current in Korean speech, particularly in family and workplace contexts where one person is warning another to be careful about what they say in a particular setting. A Korean mother, hearing her children gossip about a relative within earshot of an open window, may invoke the proverb with a small smile and a gesture toward the window — naetmareun saega deutgo. A colleague in a Korean office, asked to comment freely on a senior figure, may invoke the proverb to decline. The phrase functions as both warning and gentle refusal.
In modern usage the proverb has taken on additional life as a comment on digital communication. The same logic — that anything said anywhere is liable to be heard — applies even more to email, text messages, group chats, and social media than to the eaves of a hanok. Korean discussions of digital privacy and surveillance often invoke the proverb, sometimes with the wry update that the birds now use cell towers and the mice are now algorithms. The structural observation has aged unusually well.
The proverb is rarely used as harsh criticism. It is most often offered as a piece of friendly counsel, with the implication that the speaker would do well to take care — and with the slight comic flourish of imagining, for a moment, the bird and the mouse pricking up their tiny heads.
Cousins from other tongues
The closest structural cousin is also the proverb most likely to have shared cultural roots with the Korean.
In Japanese the saying is 壁に耳あり障子に目あり — kabe ni mimi ari, shōji ni me ari, “walls have ears, paper screens have eyes.” The Japanese shares the Korean’s two-category structure: the warning is built from two parallel observations rather than one general one. But the Japanese has done something the Korean did not: it has divided the eavesdropping by sense rather than by time. The walls listen. The paper screens see. The Japanese proverb invokes the specifically Japanese architectural element of the shōji — the translucent paper-and-wood sliding screen that defined room boundaries in pre-modern Japanese houses — and notes that, unlike a solid wall, the shōji leaks visual information as well as auditory. Where the Korean fears overhearing, the Japanese fears overhearing and being seen. The Korean covers daytime and nighttime. The Japanese covers ears and eyes. Both are taxonomic; they classify differently.
In English the cousin is the walls have ears, with the French les murs ont des oreilles as its near twin. The Western version has none of the East Asian taxonomic precision. The wall is a wall; ears are ears; one neither names the species of the listener nor specifies the time of day. The European saying is ambient in a way the Korean and Japanese sayings refuse to be. There is a popular tradition that the French phrase originated with Catherine de’ Medici, who is said to have had listening tubes installed in the walls of the Louvre to overhear courtiers’ conversations — the story is almost certainly apocryphal, but it captures something about how the European proverb wants to be understood: not as a general fact about the world but as a story about a specific architectural betrayal. The European saying assumes the listener has built the wall. The Korean assumes the listener has grown in it.
In Mandarin the cousin is 隔墙有耳 — gé qiáng yǒu ěr, “across the wall, there are ears.” The Mandarin proverb is interestingly different from the English: the ears are not in the wall but across it. The Mandarin treats the wall as a failed boundary — there is supposed to be silence on the other side, but there isn’t, because there are ears over there. The English treats the wall itself as the listener. The Mandarin treats the wall as a porous division. The Mandarin warning is therefore subtly more about the failure of architecture than about the malice of architecture. The wall is doing its best. It just isn’t enough.
Why it matters
A proverb about the impossibility of private speech is also a proverb about a culture’s preferred imagination of the eavesdropper. The Korean imagines a small ecosystem of overhearing creatures — the bird at noon, the mouse at midnight. The Japanese imagines walls and paper screens, sound and sight, the full sensorium of the household watching. The English imagines an architectural betrayal, perhaps with a court intrigue behind it. The Mandarin imagines a wall doing its best to be a wall and not quite managing.
Whatever you say, something will hear. The proverbs only disagree, very slightly, about who is on the listening end.