Kotowaza: Japanese Proverbs
Japanese proverbs, called kotowaza (ことわざ), are short, complete sayings handed down from old times. They carry a lesson or a piece of social wisdom drawn from lived experience.1 They differ in form from four-character idioms (yojijukugo) and from phrasal idioms (慣用句): a kotowaza is a whole sentence with a moral, as in 七転び八起き ("fall seven times, rise eight") or 猿も木から落ちる ("even monkeys fall from trees").
This article draws the line between those three categories. It also explains which proverbs Japanese speakers actually say versus only recognize, and gives a curated reference of 50 essential kotowaza grouped by theme. Each entry includes a literal gloss and the nearest English equivalent.
Overview
What counts as a kotowaza
A kotowaza is a complete proverbial statement, not a single vocabulary word. The dictionary defines 諺 (ことわざ) as "a short saying handed down from old times, carrying a lesson or satire, often expressing social common sense drawn from lived experience."1
The dictionary's own examples of the category are full sentence-like sayings, such as 情けは人のためならず ("kindness is not for the other person's sake alone") and まかぬ種は生えぬ ("seeds you do not sow will not sprout").1 Hold onto that sentence shape: if it reads as a miniature sentence with a point to make, it is behaving like a kotowaza.
Where kotowaza come from
Kotowaza enter the language from three streams, all visible in the reference below. The first is native folk wisdom with no single source, such as 十人十色 ("ten people, ten colors") and 言わぬが花 ("not saying it is the flower," meaning some things are better left unsaid).
The second is Buddhist teaching. 塵も積もれば山となる ("even dust, piled up, becomes a mountain") comes from the treatise 大智度論,2 and 渡りに船 ("a boat at the crossing") from the Lotus Sutra.3
The third is 故事成語 (kojiseigo), sayings from Chinese classics and historical episodes. 千里の道も一歩から ("a journey of a thousand ri begins with one step") comes from the Laozi,4 and 良薬は口に苦し ("good medicine is bitter in the mouth," meaning good advice can be hard to hear) from the 孔子家語, a collection of Confucian material.5
Many proverbs were fixed in popular memory by iroha-karuta, a traditional card game. Each set pairs reading cards with picture cards. The reading cards bear a proverb that starts with one of the 48 iroha-plus-京 syllables, and the picture cards illustrate it. Regional sets exist for Edo, Kamigata, and Owari.6
The Edo set is nicknamed 犬棒かるた after its opening card, 犬も歩けば棒に当たる ("even a dog, walking about, runs into a stick"). This card fills the い slot at the head of the iroha sequence.7
Kotowaza, 慣用句, and yojijukugo: drawing the line
Three categories of set expression sit close together. The cleanest way to keep them apart is by form. A kotowaza is a full proverbial sentence with a lesson.1 A 慣用句 (kanyōku) is a phrasal idiom: "two or more words combining to express one specific meaning as a whole," with dictionary examples like 油を売る ("sell oil," to loaf) and あごを出す ("stick out one's chin," to be exhausted).8 A yojijukugo (四字熟語) is a set phrase built from four kanji, such as 以心伝心 (heart-to-heart understanding) and 不言実行 (acting without talking about it).9
The dividing question is whether the expression carries a standalone moral. A 慣用句 does not. The animal idiom 馬が合う ("the horses match," to get along well) is a phrasal idiom of exactly this kind. It has no lesson attached, so it belongs with the phrasal animal idioms rather than here.10
故事成語 is the category that does not fit on the same axis, because it is defined by origin rather than form. A 故事成語 is "a word formed from a 故事, especially a Chinese one," with examples 五十歩百歩 (a tiny difference) and 矛盾 (contradiction).11 A single Chinese-classic source can therefore surface as a sentence-shaped kotowaza (良薬は口に苦し) or as a four-kanji yojijukugo (五十歩百歩). The form decides which list it joins, while the 故事成語 label tracks where it came from.
The four-character side of this boundary is covered in depth by the articles Yojijukugo: Reading and Using Four-Character Idioms, Top 50 Yojijukugo for N2: Readings, Meanings, Examples, and Yojijukugo (四字熟語): The Japanese Four-Character Idioms Explained. This hub stays on the proverb side and links there instead of duplicating that material.
When modern speakers actually use them
Whether a proverb is genuinely spoken, mostly written, or merely recognized matters as much as its meaning. The split below is editorial judgment, treated as convention. The exception is the one dated survey figure, whose truth is tied to its year.
In speech
A core set of kotowaza is genuinely conversational. Speakers use them for real-time encouragement, gentle warning, or self-deprecation. 七転び八起き, 猿も木から落ちる, 出る杭は打たれる, 知らぬが仏, 失敗は成功のもと, 急がば回れ, and 案ずるより産むが易し all make a clear social move and are heard in everyday speech.
Each does a specific job. 七転び八起き consoles someone after a setback. 猿も木から落ちる laughs off your own slip, and 出る杭は打たれる warns against standing out.
The same proverb can read as wise or slightly preachy depending on delivery and direction. It is safest when aimed at yourself (self-deprecation) or at someone you are encouraging. It is riskiest aimed upward at a superior, where it can sound like a lecture. This is a convention of polite use, not a measured rule.
In writing, speeches, and set phrases
Proverbs appear heavily in essays, graduation and New Year speeches, advertising copy, and book and song titles. Several read as 書き言葉 (written-style language) and sound stiff when spoken aloud. These include 禍福は糾える縄の如し, 過ぎたるはなお及ばざるがごとし, 雨垂れ石を穿つ, and 人事を尽くして天命を待つ.
What marks these as literary is their classical grammar. Forms like 〜の如し ("is like"), 〜ざるがごとし ("is like not..."), and other kanbun-derived endings signal an older register. It carries weight on the page but feels formal in casual conversation.
Recognized but rarely said
A real portion of "famous" proverbs are understood by nearly everyone yet seldom uttered in casual speech. Treat these as reading and listening comprehension targets, not phrases to force into your own production. 待てば海路の日和あり, 沈む瀬あれば浮かぶ瀬あり, and 門前の小僧習わぬ経を読む sit in this group.
Living proverbs also carry surface variation, and one survey puts a number on it. In the 文化庁 (Agency for Cultural Affairs) 2006 『国語に関する世論調査』, for 出る杭は打たれる, 73.1% of respondents used the 杭 (stake) form. By contrast, 19.0% used the 釘 (nail) form 出る釘は打たれる.12 The figure both confirms 杭 as the canonical surface and shows the kind of drift a frequently spoken proverb accumulates.
A curated reference of essential kotowaza
The 50 proverbs below are grouped into five themes of ten. The grouping is thematic, not alphabetical or by origin. Origin appears inline only where the proverb is a 故事成語 with a named classical source.
How to read this reference
Each entry gives the proverb with its reading, a literal gloss of the surface image, the dictionary's idiomatic meaning, and the nearest English equivalent. For some proverbs, the literal and idiomatic senses nearly coincide. For others, such as 河童の川流れ, they diverge sharply.
The English equivalent is an editorial approximation: the closest English proverb rather than a translation of the dictionary line. Treat it as a bridge to a meaning you already know, not as an exact rendering. Where a verbatim example sentence exists, it follows the entry. Not every proverb has one.
Several proverbs preserve old grammar: the classical negative 〜ぬ／〜ず (知らぬが仏, 後悔先に立たず), the classical adjective ending 〜し (良薬は口に苦し), and fixed structures like こそ…なれ (好きこそ物の上手なれ). This is why proverbs read older than their everyday vocabulary. It is also why the readings sometimes differ from how the same kanji are read in modern prose.
Effort, perseverance, and patience
七転び八起き ・ ななころびやおき Literal: "fall seven times, rise eight." Meaning: rising again after every failure, and by extension that life is full of ups and downs.13 English equivalent: "fall down seven times, get up eight." A highly conversational staple of encouragement.
継続は力なり ・ けいぞくはちからなり Literal: "continuation is power." Meaning: even small efforts, kept up, eventually show as results.14 English equivalent: "slow and steady wins." Very common in speeches and 書き初め (New Year calligraphy); sourced to Weblio's 実用日本語表現辞典.
石の上にも三年 ・ いしのうえにもさんねん Literal: "three years even on a [cold] stone." Meaning: endure patiently and you will succeed.15 English equivalent: "perseverance prevails." Common, encouraging patience.
石の上にも三年、というじゃない。もう少し辛抱しなさいよ。16
"They say good things take time. Be a little more patient."
急がば回れ ・ いそがばまわれ Literal: "if you hurry, go around." Meaning: the safe long way reaches the goal sooner than a risky shortcut.17 English equivalent: "more haste, less speed." Common and conversational.
急がば回れ。18
"More haste, less speed."
塵も積もれば山となる ・ ちりもつもればやまとなる Literal: "even dust, piled up, becomes a mountain." Meaning: tiny things, accumulated, become something great.2 English equivalent: "many a little makes a mickle." A 故事成語 from the Buddhist treatise 大智度論.2
塵も積もれば山となる。19
"Many a little makes a mickle."
雨垂れ石を穿つ ・ あまだれいしをうがつ Literal: "raindrops bore through stone." Meaning: persistent small effort eventually succeeds.20 English equivalent: "constant dripping wears away the stone." A 故事成語 from the 漢書; literary, more written than spoken.
失敗は成功のもと ・ しっぱいはせいこうのもと Literal: "failure is the root of success." Meaning: reflecting on a failure and fixing its causes leads to later success.21 English equivalent: "failure is the mother of success." Very common and motivational.
失敗は成功のもと。22
"We learn by trial and error."
急いては事を仕損じる ・ せいてはことをしそんじる Literal: "hurry, and you bungle the matter." Meaning: acting in haste invites failure. Proceed calmly.23 English equivalent: "haste makes waste." Pairs with 急がば回れ; sourced to 実用日本語表現辞典.
苦あれば楽あり ・ くあればらくあり Literal: "if there is hardship, there is ease." Meaning: ease follows hardship, and effort is rewarded.24 English equivalent: "no pain, no gain." Common and consoling. It is the mirror of 楽あれば苦あり in the fate group.
為せば成る ・ なせばなる Literal: "if you do it, it gets done." Meaning: with the will to act, you can accomplish it.25 English equivalent: "where there's a will, there's a way." From a verse attributed to 上杉鷹山; sourced to 実用日本語表現辞典.
Caution, risk, and humility
猿も木から落ちる ・ さるもきからおちる Literal: "even monkeys fall from trees." Meaning: even someone expert in their field sometimes fails.26 English equivalent: "even Homer nods." Highly conversational and a classic for self-deprecation. This is a full proverbial sentence (a kotowaza), not a phrasal animal idiom.
猿も木から落ちる。27
"Even monkeys fall from trees."
弘法にも筆の誤り ・ こうぼうにもふでのあやまり Literal: "even Kōbō [Daishi] makes a brush slip." Meaning: even a master of the craft errs.28 English equivalent: "even Homer nods." Widely recognized, with a learned flavor.
河童の川流れ ・ かっぱのかわながれ Literal: "a kappa swept down the river." Meaning: even a master in their own element can fail.29 English equivalent: "even the best slip up." Well recognized, conversational but slightly folksy; another proverb-form animal saying that belongs here.
転ばぬ先の杖 ・ ころばぬさきのつえ Literal: "a walking-stick before you fall." Meaning: precaution taken in advance prevents failure.30 English equivalent: "an ounce of prevention is worth a pound of cure." Common as advice; note the classical negative 〜ぬ.
出る杭は打たれる ・ でるくいはうたれる Literal: "the stake that sticks out gets hammered." Meaning: those who stand out draw resentment, and those who push forward get struck down.31 English equivalent: "the nail that sticks out gets hammered down." Highly conversational, and often truncated to 出る杭は…. For the 杭 / 釘 variation, see the 2006 survey figure above.
出る杭は打たれる。32
"The stake that sticks out gets hammered down."
後悔先に立たず ・ こうかいさきにたたず Literal: "regret does not stand ahead." Meaning: what is already done cannot be undone by regretting it later.33 English equivalent: "no use crying over spilt milk." Common and conversational; classical negative 〜ず.
後悔先に立たず。34
"What is done cannot be undone."
良薬は口に苦し ・ りょうやくはくちににがし Literal: "good medicine is bitter in the mouth." Meaning: good advice is hard to hear but does you good.5 English equivalent: "the truth hurts." A 故事成語 from the 孔子家語. Recognized and advisory, with the classical adjective ending 〜し.
良薬は口に苦し。35
"Good medicine tastes bitter."
過ぎたるはなお及ばざるがごとし ・ すぎたるはなおおよばざるがごとし Literal: "going too far is like not reaching far enough." Meaning: excess is as bad as deficiency.36 English equivalent: "moderation in all things." A 故事成語 from the Analects. Literary 書き言葉, with classical 〜ざる and 〜がごとし.
言うは易く行うは難し ・ いうはやすくおこなうはかたし Literal: "to say is easy, to do is hard." Meaning: talking about something is easy, but carrying it out is difficult.37 English equivalent: "easier said than done." A 故事成語 from the 塩鉄論. Semi-literary, with classical 〜く and 〜し.
言うは易く行うは難し。38
"Easier said than done."
能ある鷹は爪を隠す ・ のうあるたかはつめをかくす Literal: "the able hawk hides its talons." Meaning: the truly capable do not show off their ability.39 English equivalent: "still waters run deep." Common, complimentary, and conversational.
Human nature and society
十人十色 ・ じゅうにんといろ Literal: "ten people, ten colors." Meaning: tastes and views differ from person to person.40 English equivalent: "to each their own." Very common and conversational; four kanji in form but used as a proverbial saying, not treated here as a yojijukugo.
十人十色。41
"To each their own."
蛙の子は蛙 ・ かえるのこはかえる Literal: "a frog's child is a frog." Meaning: children follow their parents' path, and ordinary parents tend to have ordinary children.42 English equivalent: "like father, like son." Common and conversational, sometimes with a resigned or self-deprecating tone. A proverb-form animal saying.
蛙の子は蛙。43
"Like father, like son."
鬼に金棒 ・ おににかなぼう Literal: "an iron club for an ogre." Meaning: adding still more strength to something already strong.44 English equivalent: "making the strong stronger." Common, conversational, and positive.
知らぬが仏 ・ しらぬがほとけ Literal: "not knowing is [being a] Buddha." Meaning: ignorance keeps you calm. It can also be a wry jab at the one person left in the dark.45 English equivalent: "ignorance is bliss." Highly conversational and often wry; classical negative 〜ぬ.
知らぬが仏。46
"Ignorance is bliss."
言わぬが花 ・ いわぬがはな Literal: "not saying it is the flower." Meaning: leaving something unsaid is more tasteful and avoids trouble.47 English equivalent: "some things are better left unsaid." Recognized and mildly refined. Classical negative 〜ぬ.
井の中の蛙大海を知らず ・ いのなかのかわずたいかいをしらず Literal: "a frog in a well does not know the great ocean." Meaning: narrow experience leaves one blind to the wider world.48 English equivalent: "a big fish in a small pond." A 故事成語 from the Zhuangzi. The short form 井の中の蛙 is the more spoken truncation. Classical negative 〜ず.
類は友を呼ぶ ・ るいはともをよぶ Literal: "[the same] kind calls [its] friends." Meaning: like-minded and similar people naturally gather together.49 English equivalent: "birds of a feather flock together." A 故事成語 rooted in the I Ching; very common and conversational.
類は友を呼ぶ。50
"Birds of a feather flock together."
親しき仲にも礼儀あり ・ したしきなかにもれいぎあり Literal: "even between close friends, there is courtesy." Meaning: keep courtesy even with intimates, since too much familiarity breeds discord.51 English equivalent: "good fences make good neighbors." Common and advisory. Classical 親しき and 〜あり.
郷に入っては郷に従え ・ ごうにいってはごうにしたがえ Literal: "entering a village, follow the village." Meaning: when you live somewhere, follow its customs.52 English equivalent: "when in Rome, do as the Romans do." Common and advisory, traced through 童子教 to the Chinese 入郷随俗.
二兎を追う者は一兎をも得ず ・ にとをおうものはいっとをもえず Literal: "one who chases two hares catches not even one." Meaning: attempting two different things at once leaves you succeeding at neither.53 English equivalent: "if you chase two rabbits, you catch neither." A Western proverb that entered Japanese in the Meiji era. Classical negative 〜ず.
二兎を追う者は一兎をも得ず。54
"If you run after two hares, you will catch neither."
Fate, luck, and timing
棚から牡丹餅 ・ たなからぼたもち Literal: "a botamochi [sweet] from the shelf." Meaning: unexpected good luck gained without effort.55 English equivalent: "a windfall." Very common, often shortened to たなぼた.
棚からぼた餅とはこのことだ。56
"This is what they call a lucky break."
The dictionary headword spells the second half 牡丹餅, while the Tatoeba sentence above spells it ぼた餅. It is the same proverb. Only the kana-versus-kanji spelling of botamochi differs.56
渡りに船 ・ わたりにふね Literal: "a boat at the crossing." Meaning: just what is needed arriving at just the right moment.3 English equivalent: "a godsend." A 故事成語 from the Lotus Sutra; common, often in the narrative phrase 渡りに船とばかりに.
待てば海路の日和あり ・ まてばかいろのひよりあり Literal: "if you wait, there comes fair weather for the sea route." Meaning: wait, and a favorable chance will come.57 English equivalent: "everything comes to those who wait." Recognized but not heavily spoken, with a literary flavor. Classical 〜あり.
楽あれば苦あり ・ らくあればくあり Literal: "if there is ease, there is hardship." Meaning: pleasure is followed by hardship, and the two go together.58 English equivalent: "take the bad with the good." Common, both consoling and cautioning. It is the mirror of 苦あれば楽あり.
禍福は糾える縄の如し ・ かふくはあざなえるなわのごとし Literal: "fortune and misfortune are like a twisted rope." Meaning: good and bad luck alternate like the strands of a twisted rope.59 English equivalent: "fortune's wheel turns." A 故事成語 from the 漢書. Literary 書き言葉, with classical 〜の如し.
人事を尽くして天命を待つ ・ じんじをつくしててんめいをまつ Literal: "exhaust human effort, then await heaven's will." Meaning: do everything within your power, then leave the rest to fate.60 English equivalent: "man proposes, God disposes." A 故事成語 from 読史管見. Semi-literary, but said before exams and contests.
犬も歩けば棒に当たる ・ いぬもあるけばぼうにあたる Literal: "even a dog, if it walks about, runs into a stick." Meaning: acting can court trouble, or, in the other sense, going out can bring unexpected luck.7 English equivalent: "every dog has its day" (luck sense). The opening card of the Edo iroha-karuta. Well known and slightly folksy.
残り物には福がある ・ のこりものにはふくがある Literal: "in the leftovers there is fortune." Meaning: what is left over can hold unexpected good.61 English equivalent: "there's luck in leftovers." Very common, light, and conversational.
果報は寝て待て ・ かほうはねてまて Literal: "for good fortune, sleep and wait." Meaning: you cannot force luck, so wait calmly for the right time.62 English equivalent: "good things come to those who wait." Common and reassuring.
沈む瀬あれば浮かぶ瀬あり ・ しずむせあればうかぶせあり Literal: "if there is a sinking shoal, there is a rising shoal." Meaning: life holds both bad times and good, and misfortune does not last forever.63 English equivalent: "every cloud has a silver lining." Recognized but more literary, and consoling. Classical 〜あり.
Practice, learning, and skill
習うより慣れろ ・ ならうよりなれろ Literal: "rather than being taught, get used to it." Meaning: you learn faster through experience than through instruction.64 English equivalent: "practice makes perfect." Very common and conversational. Sourced to 実用日本語表現辞典.
習うより慣れろ。65
"Practice makes perfect."
好きこそ物の上手なれ ・ すきこそもののじょうずなれ Literal: "it is fondness that makes one skilled." Meaning: you improve quickly at what you love, because you throw yourself into it.66 English equivalent: "what one likes, one will do well." Common and encouraging; the こそ…なれ structure is fixed and old.
聞くは一時の恥聞かぬは一生の恥 ・ きくはいっときのはじきかぬはいっしょうのはじ Literal: "to ask is a moment's shame; not to ask is a lifetime's shame." Meaning: staying silent about what you do not know leaves you ashamed for life.67 English equivalent: "better to ask the way than go astray." Common and advisory. Classical negative 〜ぬ.
聞くは一時の恥、聞かぬは一生の恥。68
"It doesn't hurt to ask."
千里の道も一歩から ・ せんりのみちもいっぽから Literal: "even a thousand-ri road starts from one step." Meaning: any great undertaking begins with a first step.4 English equivalent: "a journey of a thousand miles begins with a single step." A 故事成語 from the Laozi; common and motivational.
千里の道も一歩から。69
"A journey of a thousand miles begins with a single step."
門前の小僧習わぬ経を読む ・ もんぜんのこぞうならわぬきょうをよむ Literal: "the boy at the temple gate reads sutras he was never taught." Meaning: constant exposure teaches you without instruction, since environment shapes a person.70 English equivalent: "a saint's neighbor learns the prayers." Recognized but somewhat literary. Classical negative 〜ぬ.
三人寄れば文殊の知恵 ・ さんにんよればもんじゅのちえ Literal: "three people gathered, the wisdom of Monju." Meaning: even ordinary people, putting their heads together, produce excellent ideas.71 English equivalent: "two heads are better than one." Common and conversational, used in teamwork contexts. Monju (文殊) is the bodhisattva of wisdom.
三人寄れば文殊の知恵って言うだろ。みんなで考えれば、いい案が浮かぶかもしれないよ。72
"They say two heads are better than one. If we all think together, we might come up with a good idea."
案ずるより産むが易し ・ あんずるよりうむがやすし Literal: "giving birth is easier than worrying about it." Meaning: doing a thing often turns out easier than the worrying beforehand.73 English equivalent: "fear is worse than the danger." Common and reassuring. Classical adjective 〜し.
案ずるより産むが易し。74
"Fear often exaggerates danger."
鉄は熱いうちに打て ・ てつはあついうちにうて Literal: "strike the iron while it is hot." Meaning: train while young and receptive, and act while enthusiasm still runs high.75 English equivalent: "strike while the iron is hot." A Western proverb. Common and conversational.
鉄は熱いうちに打て。76
"Strike while the iron is hot."
餅は餅屋 ・ もちはもちや Literal: "for mochi, the mochi shop." Meaning: in any field, the specialist is best.77 English equivalent: "leave it to the experts." Common and conversational.
百聞は一見に如かず ・ ひゃくぶんはいっけんにしかず Literal: "a hundred hearings do not equal one seeing." Meaning: one direct look tells you more reliably than many secondhand reports.78 English equivalent: "seeing is believing." A 故事成語 from the 漢書. Very common and conversational, with the classical negative 如かず.
百聞は一見に如かず。79
"Seeing is believing."
How to study and use kotowaza
Learn for recognition first, production second
Prioritize understanding the proverbs you meet in reading and listening before trying to use them yourself. Most learners overreach by inserting proverbs into their own speech too early. A mistimed proverb can read as preachy.
Move a proverb into active use only after you have actually heard a native speaker use it. The "recognized but rarely said" group, such as 待てば海路の日和あり and 沈む瀬あれば浮かぶ瀬あり, is comprehension-target material. Learn to recognize it, but do not force it into production.
Anchor each proverb to a situation
Memorize the trigger situation, not just the gloss. 七転び八起き fits consoling someone after a setback. 猿も木から落ちる fits laughing off your own slip. 出る杭は打たれる fits warning against standing out, and 急がば回れ fits resisting a risky shortcut.
One proverb tied to one clear situation is far more usable than a long undifferentiated list. Pair a spaced-repetition system with the verbatim example sentences above. This gives each proverb the trigger context that makes it recallable in the moment, the same approach as sentence mining.
Good to know
"Even monkeys fall from trees" is a proverb, not an animal idiom
猿も木から落ちる is a full proverbial sentence carrying a complete lesson, "even experts fail." That is exactly the dictionary definition of a kotowaza.261 馬が合う ("the horses match," to get along well) is a phrasal 慣用句: two or more words combining into one meaning, with no standalone moral.108
Same animal-vocabulary surface, different category. Phrasal animal idioms like 馬が合う are catalogued with the other phrasal idioms, such as the body-part 慣用句. They are not listed here, where every entry is a complete proverbial sentence.
Proverbs can sound preachy if mistimed
Dropping a moralizing proverb into the wrong moment, or aiming one upward at a superior, can read as lecturing. The safest uses are self-deprecation and encouragement. For self-deprecation, use 猿も木から落ちる about your own slip. For encouragement, use 七転び八起き or 失敗は成功のもと.
This is a convention of polite use rather than a measured rule, but it is a reliable one. When in doubt, point the proverb at yourself.
Many proverbs are deliberately incomplete in speech
Speakers often utter only the first half of a proverb and let the listener finish it. Examples include 出る杭は…, 猿も木から…, and 井の中の蛙…. The dictionary itself records some of these short forms as sub-entries, such as 井の中の蛙.
Recognizing the truncation is a comprehension skill. A trailing-off 出る杭は… is not an unfinished thought. It is the whole proverb, with the obvious second half left for you to supply.
The same Chinese saying can be a proverb or a four-kanji idiom
故事成語 is defined by origin, not form: "a word formed from a 故事, especially a Chinese one."11 A single Chinese-classic source can therefore yield both a sentence-shaped kotowaza, such as 良薬は口に苦し from the 孔子家語, and a four-kanji yojijukugo.
This is why the three-way boundary is drawn by form, sentence versus phrase versus four-kanji, while 故事成語 cuts across all three by source. The label tells you where an expression came from, not which shelf it sits on.
See also
- Classical Grammar Survivals in Modern Japanese
- Bungo (文語) Grammar Primer for Modern Readers
- Yojijukugo: Reading and Using Four-Character Idioms
- Animal Idioms: 馬, 犬, 猫, 虎
- Japanese Body-Part Idioms: 手, 目, 口, 心 Expressions
- How Japanese Slang Works: Semantic Shift, Clipping, and Net-Speak
- Passive vs. Active Vocabulary in Japanese: The Two-Speed Problem