KoanA koan (pronounced /ko.an/) is a story, dialog, question, or statement in the history and lore of Chan (Zen) Buddhism, generally containing aspects that are inaccessible to rational understanding, yet that may be accessible to intuition. A famous koan is, “Two hands clap and there is a sound; what is the sound of one hand?” (oral tradition, attributed to Hakuin Ekaku, 1686-1769, considered a reviver of the koan tradition in Japan).

Koans originate in the sayings and doings of sages and legendary figures, usually those authorized to teach in a lineage that regards Bodhidharma (c. 5th-6th century) as its ancestor. Koans are said to reflect the enlightened or awakened state of such persons, and sometimes said to confound the habit of discursive thought or shock the mind into awareness. Zen teachers often recite and comment on koans, and some Zen practitioners concentrate on koans during meditation. Teachers may probe such students about their koan practice using “checking questions” to validate an experience of insight (kensho) or awakening. Responses by students have included actions or gestures, “capping phrases” (jakugo), and verses inspired by the koan.

As used by teachers, monks, and students in training, koan can refer to a story selected from sutras and historical records, a perplexing element of the story, a concise but critical word or phrase (話頭 hua-tou) extracted from the story, or to the story appended by poetry and commentary authored by later Zen teachers, sometimes layering commentary upon commentary. Less formally, the term koan sometimes refers to any experience that accompanies awakening or spiritual insight.

English-speaking non-Zen practitioners sometimes use koan to refer to an unanswerable question or a meaningless statement. However, in Zen practice, a koan is not meaningless, and teachers often do expect students to present an appropriate and timely response when asked about a koan. Even so, a koan is not a riddle or a puzzle1. Appropriate responses to a koan may vary according to circumstances; different teachers may demand different responses to a given koan, and not all teachers assume that a fixed answer is correct in every circumstance.

The word koan corresponds to the Chinese characters 公案 which can be rendered in various ways: gōng’àn (Chinese pinyin); kung-an (Chinese Wade-Giles); gong’an (Korean); cong-an (Vietnamese); kōan (Japanese Hepburn; often transliterated koan). Of these, “koan” is the most common in English. Just as Japanese Zen, Chinese Ch’an, Korean Son, and Vietnamese Thien, and Western Zen all share many features in common, likewise koans play similar roles in each, although significant cultural differences exist.



  • A monk asked Zhaozhou, “Does a dog have Buddha nature or not?” Zhaozhou said, “Wú”.
    (“Zhaozhou” is rendered as “Chao-chou” in Wade-Giles, and pronounced “Joshu” in Japanese. “Wu” appears as “mu” in archaic Japanese, meaning “no”, “not”, or “nonbeing” in English. This is a fragment of Case #1 of the Wu-Men Kuan. However, note that, a similar koan records that on another occasion, Zhaozhou said “yes” in response .)
  • Hui Neng asked Hui Ming, “Without thinking of good or evil, show me your original face before your mother and father were born”.
    (This is a fragment of case #23 of the Wu-Men Kuan.)
  • A monk asked Tung Shan, “What is Buddha?” Tung Shan said, “Three pounds of flax”.
    (This is a fragment of case #18 of the Wu-Men Kuan as well as case #12 of the Blue Cliff Record.)
  • A monk asked Zhaozhou, “What is the meaning of Bodhidharma‘s coming from the west?” Zhaozhou said, “The cypress tree in the courtyard”.
    (This is a fragment of case #37 of the Wu-Men Kuan as well as case #47 of the Book of Serenity.)

Roles of the koan in Zen practice

  • Koans collectively form a substantial body of literature studied by Zen practitioners and scholars worldwide. Koan collections commonly referenced in English include the Blue Cliff Record (Chinese: Pi-yen lu; Japanese: Hekiganroku), the Book of Equanimity (also known as the Book of Serenity; Chinese: Ts’ung-jung lu; Japanese Shoyoroku), both collected in their present forms during the 12th century); and Gateless Barrier (also known as Gateless Gate; Chinese: Wu-Men Kuan; Japanese Mumonkan) collected during the 13th century). In these and subsequent collections, a terse “main case” of a koan often accompanies prefatory remarks, commentary, poems, proverbs and other phrases, and further commentary, etc. about prior emendations. Koan literature typically derives from older texts and traditions, including texts that record the sayings and doings of sages; from Transmission of the Lamp records, which document the monastic tradition of certifying teachers; and from folklore and cultural reference points common among medieval Chinese. According to Victor Hori—a native English speaker who has experienced extensive koan training in Japanese monasteries—koan literature was also influenced by the pre-Zen Chinese tradition of the “literary game”—a competition involving improvised poetry2. Over centuries, contemporary collections continued to inspire commentary, and current koan collections contain modern commentaries. New koans on occasion are proposed and collected—sometimes seriously, sometimes in jest.
  • A koan or part of a koan may serve as a point of concentration during meditation and other activities, often called “koan practice” (as distinct from “koan study”, the study of koan literature). Generally, a qualified teacher provides instruction in koan practice to qualified students in private. In the Wu-Men Kuan, case #1, Wu-Men wrote “..concentrate yourself into this ‘Wu’..making your whole body one great inquiry. Day and night work intently at it. Do not attempt nihilistic or dualistic interpretations.”3 Beyond this, written instructions are rare.
  • A koan may be used as a test of a Zen student’s ability. For monks in formal training, and for some laypersons, a teacher invokes a koan and demands some definite response from a student during private interviews.
  • Koans are presented by teachers to students and other members of the community, often including the teacher’s unique commentary. A koan may seem to be the subject of a talk or private interview with a student. However, a koan is said to supersede subject-object duality and thus cannot necessarily be said to be the “subject” of such encounters. The dialog, lecture, or sermon may more resemble performance, ritual duty, or poetry reading.

Etymology and the evolving meaning of koan

Koan is a Japanese rendering of the Chinese term (公案), transliterated kung-an (Wade-Giles) or gōng’àn (Pinyin). Chung Feng Ming Pen (中峰明本 1263-1323) wrote that kung-an is an abbreviation for kung-fu an-tu (公府之案牘, Pinyin gōngfǔ àndú, pronounced in Japanese as ko-fu no an-toku), which referred to a “public record” or the “case records of a public law court”4 in Tang-dynasty China. Koan/kung-an thus serves as a metaphor for principles of reality that go beyond the private opinion of one person. A teacher’s test also resembles the judgement of a student’s ability to recognize and actualize that principle. Moreover, commentaries in koan collections bear some similarity to judicial decisions that cite and sometimes modify precedents. An article by T. Griffith Foulk claims “..Its literal meaning is the “table” or “bench” of a “magistrate” or “judge” ..”4. Apparently, kung-an was itself originally a metaphor—an article of furniture that came to denote legal precedents.

Before the tradition of meditating on koans was recorded, Huangbo Xiyun (720-814) and Yun Men (864-949) are both recorded to have uttered the line “Yours is a clear-cut case (chien-cheng kung-an) but I spare you thirty blows”, seeming to pass judgement over students’ feeble expressions of enlightenment. Xuedou Zhongxian (雪竇重顯 980-1052)—the original compiler of the 100 cases that later served as the basis for the Blue Cliff Record—used the term kung-an just once in that collection (according to Foulk4) in Case #64.

Yuanwu (圜悟克勤 1063-1135), compiler of the Blue Cliff Record (碧巌録) in its present form, “gained some insight” by contemplating (kan) koans5. Yuanwu may have been instructed to contemplate phrases by his teachers Chen-ju Mu-che (dates unknown) and Wu-tzu Fa-yen (五祖法演 ?-1104). Thus, by the Sung Dynasty, the term kung-an had apparently taken on roughly its present meaning from the legal jargon.

Subsequent interpreters have influenced the way the term koan is used. Dogen Zenji wrote of Genjokoan, which relates everyday life experiences to koans. Hakuin Ekaku recommended preparing for koan practice by concentrating on qi breathing and its effect on the body’s center of gravity, called the tanden or hara in Japanese—thereby associating koan practice with pre-existing Taoist and Yogic chakra meditative practices.

The role of koans in the Soto, Rinzai, and other sects

Koan practice—concentrating on koans during meditation and other activities—is particularly important among Japanese practictioners of the Rinzai sect of Zen. However, study of koan literature is common to both Soto and Rinzai Zen. There is a common misconception that Soto and related schools do not use koans at all, but while few Soto practictioners concentrate on koans while meditating, many Soto practitioners are indeed highly familiar with koans.

In fact, the Soto sect has a strong historical connection with koans. Many koan collections were compiled by Soto priests. During the 13th century, Dogen, founder of the Soto sect in Japan, compiled some 300 koans in the volumes known as the Greater Shobogenzo. Other koans collections compiled and annotated by Soto priests include The Iron Flute (Japanese: Tetteki Tosui, compiled by Genro in 1783) and Verses and Commentaries on One Hundred Old Cases of Tenchian (Japanese: Tenchian hyakusoku hyoju, compiled by Tetsumon in 1771.) However, according to Michael Mohr, “..koan practice was largely expunged from the Soto school through the efforts of Gento Sokuchu (1729-1807), the eleventh abbot of Entsuji, who in 1795 was nominated abbot of Eiheiji.”6, p245.

A significant number of people who meditate with koans are affiliated with Japan’s Sanbo Kyodan sect, and with various schools derived from that sect in North America, Europe, and Australia. Sanbo Kyodan was established in the 20th century, and has roots in both the Soto and Rinzai traditions.

Interpretation of koans

Zen teachers and practitioners insist that the meaning of a koan can only be demonstrated in a live experience. Texts (including koan collections and encyclopedia articles) cannot convey that meaning. Yet the Zen tradition has produced a great deal of literature, including thousands of koans and at least dozens of volumes of commentary. Nevertheless, teachers have long alerted students to the danger of confusing the interpretation of a koan with the realization of a koan. When teachers say “do not confuse the pointing finger with the moon”, they indicate that awakening is the standard — not ability to interpret.

Even so, koans emerge from a literary context, and understanding that context can often remove some — but presumably not all — of the mystery surrounding a koan. For example, evidence7 suggests that when a monk asked Zhaozhou “does a dog have Buddha-nature or not?”, the monk was asking a question that students had asked teachers for generations. The controversy over whether all beings have the potential for enlightment is even older8 — and in fact, vigorous controversy9 still surrounds the matter of Buddha nature.

No amount of interpretation seems to be able to exhaust a koan. So it’s unlikely that there can be a “definitive” interpretation. Teachers typically warn against over-intellectualizing koans, but the mysteries of koans compel some students to reduce (but not necessarily eliminate) the uncertainties — for example, by clarifying metaphors that were likely well-known to monks at the time the koans originally circulated. In that spirit, we present some interpretations that are certainly not the last word.

The sound of one hand

Two hands clap and there is a sound. What is the sound of one hand?
— Hakuin Ekaku
“..in the beginning a monk first thinks a koan is an inert object upon which to focus attention; after a long period of consecutive repetition, one realizes that the koan is also a dynamic activity, the very activity of seeking an answer to the koan. The koan is both the object being sought and the relentless seeking itself. In a koan, the self sees the self not directly but under the guise of the koan..When one realizes (“makes real”) this identity, then two hands have become one. The practitioner becomes the koan that he or she is trying to understand. That is the sound of one hand.” — G. Victor Sogen Hori, Translating the Zen Phrase Book 11

The Gateless Gate

Wumenguan (無門關, pronounced Mumonkan in Japanese, often translated into English as The Gateless Gate but more accurately rendered as Gateless Barrier) is a collection of 48 koans and commentaries published in 1228 by Chinese monk Wumen (無門). Five koans in the collection derive from the sayings and doings of Zhaozhou Congshen, (transliterated as Chao-chou in Wade-Giles and pronounced Jōshū in Japanese).

Case 1: Zhaozhou’s dog

A monk asked Zhaozhou, “Does a dog have Buddha-nature or not?”
Zhaozhou replied, “Wú.”
Translators often render Zhaozhou’s answer as mu from Japanese retellings. Normally, wu and mu mean no, not, or nonexistence. Centuries earlier, the same Chinese character appeared at the end of verse 40 of Lao Zi’s Daodejing (Tao Te Ching) in a line sometimes translated as “existence emerges from nonexistence”. Mahayana Buddhist doctrine codified in the Nirvana Sutra held that all sentient beings, including animals, possess the capacity for enlightenment. However, the commentary of teachers in the Linji (Rinzai in Japanese) tradition tends to emphasize that this koan dialog consists of a challenge the monk posed to Zhaozhou to demonstrate Buddha-nature without becoming entangled in doctrine; and that this interpretation only has meaning to a meditator who contemplates the koan. Teachers routinely reject common speculations by students, including the assertion that wu signifies that “It is unknowable whether the dog has Buddha-nature”, that “The question has no meaning”, that Zhaozhou intended to convey the sound of a barking dog, the way we would say “woof!,” and other erroneous interpretations. However, some teachers have accepted prefabricated responses such as shouting “mu!” or barking like a dog. Nevertheless, students offering such canned responses may not withstand the “checking questions” that such teachers pose in further inquiry. Moreover, many other teachers demand an entirely improvised response.

A related koan in the Book of Serenity reinforces the teaching that Zhaozhou’s response does not refer to affirmation or negation:

One time a monk asked Zhaozhou, “Does a dog have Buddha-nature or not?”
Zhaozhou answered, “No.”
Another time, a monk asked Zhaozhou, “Does a dog have Buddha-nature or not?”
Zhaozhou answered, “Yes.”

Case 6: Buddha holds out a flower

When Shakyamuni Buddha was at Mount Grdhrakuta, he held out a flower to his listeners.
Everyone was silent.
Only Mahakashyapa broke into a broad smile.
The Buddha said, “I have the True Dharma Eye, the Marvelous Mind of Nirvana, the True Form of the Formless, and the Subtle Dharma Gate, independent of words and transmitted beyond doctrine. This I have entrusted to Mahakashyapa.”
From Wu-Men’s comment about this koan: “Gautama insolently insults noble people. He sells dog meat labeled as mutton and thinks it commendable.” Wu-Men actually intends his scathing insult as a form of high praise, thwarting any student’s attempt to rationally explain the koan as feeble.

Case 7: Zhaozhou washes the bowl

A monk asked Zhaozhou to teach him.
Zhaozhou asked, “Have you eaten your meal?”
The monk replied, “Yes, I have.”
“Then go wash your bowl,” said Zhaozhou.
At that moment, the monk was enlightened.
This koan is beloved of students, perhaps because it seems to negate the need to understand obscure doctrines. Wu-Men comments in verse “Because it’s so clear / it takes long to realize”, and straightforward it may seem, but this koan is an idiom and the student is assumed to be aware of its cultural context. If one does not know this context, the koan cannot be understood.
The meal of consideration is a traditional meal of rice. It was customary for monks to maintain samadhi while eating this meal, and so Zhaozhou is not asking whether the monk has eaten: he asks instead whether the monk was able to remain in samadhi throughout the meal. The monk affirms, and then realizes he has already received the teaching.

Case 8: Keichu’s wheel

Getsuan said to his students, “Keichu, the first wheel-maker in China, made two wheels having fifty spokes each. Suppose you took a wheel and removed the nave uniting the spokes. What would become of the wheel? If Keichu had done so, could he be called the master wheel-maker?”
This koan alludes to the Tao Te Ching, one of the main texts of Taoism:
We put thirty spokes together and call it a wheel;
But it is on the space where there is nothing that the usefulness of the wheel depends.

Case 29: Huineng’s flag

Two monks were watching a flag flapping in the wind. One said to the other, “The flag is moving.”
The other replied, “The wind is moving.”
Huineng overheard this. He said, “Not the flag, not the wind; mind is moving.”
Of the two monks, Wumen says they were trying to buy iron; Huineng, out of compassion, gave them gold instead. This koan demonstrates the realization that in naming an object one may cloud one’s understanding of the true nature of mind by falling into externalization and believing that the true nature of the flag, the wind, and the mind are different. Hui Neng always taught the One Vehicle Buddhism of One Mind which teaches that wisdom (sanskrit: prajna) comes from the Essence of Mind and not from an exterior source.

Case 37: Zhaozhou’s cypress

A monk asked Zhaozhou, “Why did Bodhidharma come to China?”
Zhaozhou replied, “The cypress in the courtyard.”
After Zhaozhou’s death, a monk asked Huijiao (a disciple of Zhaozhou’s) about the cypress koan. Huijiao denied that Zhaozhou ever said it. The disciple did indeed know Zhaozhou’s koan (it was very famous already), but felt it would be better to retire the koan for this particular monk. This denial has become a koan itself.
Reportedly, Chinese translators have tended to render the type of tree in the koan as “cypress” while Japanese translators have rendered it as “the oak tree in the courtyard”.10

Other traditional koans

What is the Buddha?

Zen teachers asked this question have given various answers. Here are some of them:

  • Three pounds of flax (Dongshan Shouchou’s (910-990, pronounced Tosan Shusho in Japanese) response in case 18 of The Gateless Gate)
  • Dried dung. (Yunmen Wenyan’s response in case 21)

Killing the Buddha

If you meet the Buddha, kill him.
If you are thinking about Buddha, this is thinking and delusion, not awakening. One must destroy preconceptions of the Buddha. Zen master Shunryu Suzuki wrote in Zen Mind, Beginner’s Mind during an introduction to Zazen, “Kill the Buddha if the Buddha exists somewhere else. Kill the Buddha, because you should resume your own Buddha nature.”

The abbot’s gift

A Zen monk, early in his training, is preparing to leave the monastery and switch locations, for that is common in the Zen practice. Before he leaves he goes to the abbot of the monastery to say goodbye. He does so, but the abbot says he has a gift for him. Now, it is part of the Japanese way to accept gifts and be appreciative; to do otherwise is rude and, therefore, wrong. The abbot takes a pair of tongs and picks up a red hot coal from the adjacent fire pit on which he has a tea kettle.
The young monk starts to contemplate what he should do, and after a few moments, runs out of the hall distressed, for he cannot figure out what he is supposed to do. He can take the coal and be burned, or he can refuse the gift of the abbot. Both, in his mind, are things he cannot do.
He meditates on the problem for the next week, and comes back to say goodbye. However, the same scene is played again, and the same frustration is found when he tries to figure out what the abbot wants him to do.
He meditates further on the subject and feels he has discovered how to respond to the abbot’s gift. He returns, for the third time, to say goodbye to the abbot, and as before the abbot picks up a red hot coal and presents it as a gift to the young monk. The young monk simply replies, “Thank you.”
The abbot breaks a grin, nods his head, and returns the coal to the fire pit. “You may go now,” he says.

Contemporary koans

Anecdotes of recent zen teachers have started to make their way into zen lore as koans, for example:

One day, a student of Shunryu Suzuki Roshi confronted him at Sokoji, in his office, and said, “if you believe in freedom why do you keep your bird locked up in a cage?” Suzuki Roshi went over and opened the door of the cage and the bird flew out and flew out the window.

An introductory koan used by several Diamond Sangha teachers is, “Who hears?”

Hacker culture has invented a number of humorous koans which do not fit the normal definition of koan. See hacker koan.

See also


See Ruth Fuller Sasaki’s introduction on page xi of The Zen Koan, Isshu Miura and Ruth Fuller Sasaki, Harvest/HBJ, 1965; see also Steve Hagen’s introduction on page vii of the 2000 edition of The Iron Flute (subtitle) 100 Zen Koans, translated into English by Nyogen Senzaki and Ruth Stout McCandless, originally Tetteki Tosui, Genro, 1783; see also pp xiii, 26, and 212 of The Gateless Barrier (subtitle) The Wu-Men Kuan (Mumonkan), Robert Aitken, North Point Press/Farrar, Strauss and Giroux, New York, 1991, incorporates Wu-Men Kuan (J. Mumonkan), Wu-Men, 1228); see also p64 of Two Arrows Meeting in Mid Air (subtitle) The Zen Koan, John Daido Loori, Charles E. Tuttle, Vermont/Tokyo, 1994.

See chapter 4 of Zen Sand (subtitle) The Book of Capping Phrases for Koan Practice, Victor Sogen Hori, 2003, University of Hawai’i Press.

The Gateless Barrier (subtitle) Zen comments on the Mumonkan, Zenkei Shibayama (1894-1974), Translated from Chinese and Japanese into English by Sumiko Kudo, Shambhala Publications, 1974; incorporates Wu-Men Kuan (J. Mumonkan), Wu-Men, 1228).

See The Zen Koan (see note ) p4-6, and also “The form and function of koan literature” (subtitle) “A historical overview”, T. Griffith Foulk, in The Koan (subtitle) Texts and contexts in Zen Buddhism, Steven Heine and Dale S. Wright, eds., 2000, Oxford University Press, p21-22. Assertions that the literal meaning of kung-an is the table, desk, or bench of a magistrate appear on page 18 of the article by Foulk, and also in Seeing Through Zen, (subtitle) Encounter, Transformation, and Genealogy in Chinese Chan Buddhism, John R. MacRae, 2003, University of California Press, p172-173 note 16.

See Zen Letters (subtitle) Teachings of Yuanwu, Yuanwu Kequin (1063-1135), translated into English by J. C. Cleary and Thomas Cleary, 1994, Shambhala Publications, p16, and “Before the empty eon versus A dog has no Buddha-nature” (subtitle) “Kung-an use in the Ts’ao-tung tradition and Ta-hui’s Kung-an introspction Ch’an”, Morten Schlutter, in The Koan (subtitle) Texts and contexts in Zen Buddhism, Steven Heine and Dale S. Wright, eds., 2000, Oxford University Press, p185-186.

“Emerging from Nonduality” (subtitle) “Koan Practice in the Rinzai tradition since Hakuin”, Michael Mohr, in The Koan (subtitle) Texts and contexts in Zen Buddhism, Steven Heine and Dale S. Wright, eds., 2000, Oxford University Press, p245.

See the commentary on case #1 in The Gateless Barrier (subtitle) Zen Comments on the Mumonkan, Zenkei Shibayama, translated in English by Sumiko Kudo, 1974, Shambhala Publications.

See “Tao-sheng’s Theory of Sudden Enlightenment”, Whalen Lai, in Sudden and Gradual (subtitle) Approaches to Enlightenment in Chinese Thought, p173 and 191. The latter page documents how in 429 or thereabouts (more than 400 years before Zhaozhou), Tao-sheng was expelled from the Buddhist monastic community for defending the idea that incorrigible persons (icchantika) do indeed have Buddha-nature (fo-hsing).

Pruning the Bodhi Tree (subtitle) The Storm over Critical Buddhism Jamie Hubbard and Paul L. Swanson, eds, 1997, University of Hawaii Press; for example see Chapter 1, “Why They Say Zen Is Not Buddhism” (subtitle) “Recent Japanese Critiques of Buddha-Nature”, Paul L. Swanson.

The Gateless Barrier (subtitle) The Wu-Men Kuan (Mumonkan), Robert Aitken, North Point Press/Farrar, Strauss and Giroux, New York, 1991, incorporates Wu-Men Kuan (J. Mumonkan), Wu-Men, 1228); see p306, footnote 1 for Case #37.

Translating the Zen Phrase Book, G. Victor Sogen Hori, Nanzan Bulletin 23, 1999, p44-58.

Dates are as per Zen’s Chinese Heritage, subtitled The masters and their teachings by Andy Ferguson, published in 2000 by Wisdom Publications. Koan Koan Koan Koan (Zen) 公案 Koan Koan Công án

buddha monk

buddha monk