Koan

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A koan (pronounced /ko.an/ Japanese 公案) is a story, dialog, question, or statement from the history and lore of Chan (Zen) Buddhism, generally containing aspects that are inaccessible to rational understanding, yet that may be accessible to intuition. The mental effort of trying to “solve” a koan is intended to exhaust the analytic intellect and elevate the mind to a new level of intuitive awareness.

Some Zen practitioners concentrate on koans during meditation, and Zen teachers use them in training novices. Each koan represents both a communication of some aspect of Zen teaching, and a test of the student’s understanding; Zen teachers often recite and comment on koans. There are said to be 1,700 koans in all. 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).

What is a Koan?

In Chan (Zen) Buddhism, a koan is a succinct paradoxical statement or question, often used as a meditative discipline for novices. A koan can be a story, dialog, question, or statement from the history and lore of Chan (Zen) Buddhism, generally containing aspects that are inaccessible to rational understanding, yet that may be accessible to intuitive understanding. The mental effort of trying to “solve” a koan is intended to exhaust the analytic intellect and prepare the mind to entertain an appropriate intuitive response. Each koan represents both a communication of some aspect of Zen teaching, and a test of the student’s understanding.

Koans originate in the sayings and doings of Zen Buddhist sages and legendary figures, usually those authorized to teach in a lineage that regards Bodhidharma (c. fifth century – sixth 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.

There are said to be 1,700 koans in all. The two major collections are the Pi-yen lu (Chinese: “Blue Cliff Records”; Japanese: Hekigan-roku), consisting of 100 koans selected and commented on by a Chinese priest, Yüan-wu, in 1125 on the basis of an earlier compilation; and the Wu-men kuan (Japanese: Mumon-kan), a collection of 48 koans compiled in 1228 by the Chinese priest Hui-k'ai (known also as Wu-men).

English-speaking non-Zen practitioners sometimes use the term koan to refer to an unanswerable question or a meaningless statement. However, in Zen practice, a koan is not meaningless, and teachers often expect students to present an appropriate and timely response when asked about a koan. A koan is not a riddle or a puzzle.^[1][2][3][4] 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.

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, and sometimes by commentary on the commentary. Less formally, the term koan sometimes refers to any experience that accompanies awakening or spiritual insight.

Koan in the History of Dhyana (Ch'an, Zen)

The Dhyana (Chinese: Ch'an; Japanese: Zen) school of Buddhism emphasizes meditation as the way to immediate awareness of ultimate reality, a Buddhist practice which originated in India, and derives its name from the Sanskrit term for meditation, dhyana. Ch'an, which was influenced by Daoism and uses special training techniques and doctrines, developed in China.

Though fourth and fifth century Chinese Buddhist monks, such as Hui-yüan and Seng-chao, were teaching doctrines and practices similar to those of the Ch'an school before the traditional date of its arrival in China, Chinese texts name a South Indian monk, Bodhidharma, who came to China about 520 C.E., as its founder and first patriarch in China. Bodhidharma is held by Ch'an devotees to be the 28th patriarch of the Indian meditational school, which began with the monk Kasyapa, to whom the Buddha Sakyamuni revealed his supreme teaching. This teaching, that all beings possess a Buddha-nature (often equated with sunya (the void) in Ch'an), and that enlightenment (Chinese: Wu; Japanese: Satori) is the realization of this fact, is found in the Lankavatara-sutra. This ultimate truth, or reality, is beyond the ordinary duality of subject and object and cannot be explained by an enlightened one or conveyed by books, words, concepts, and teachers. It must be realized in immediate personal experience.

After the death of the fifth Chinese patriarch, Heng-jen, there was a schism between the Northern school founded by Shen-hsui, which held that enlightenment must be attained gradually, and the Southern school of Hui-neng, which taught that true wisdom, must be attained suddenly and spontaneously. The Southern school tended to neglect rituals and literature and to rely on teaching passed from master to pupil. Eventually the Southern school prevailed and Hui-neng's Platform Scripture (Chinese: T'an Ching) became a key text of the Ch'an school. During the ninth century, two branches of Ch'an Buddhism developed from the Southern school: Lin-chi (Japanese: Rinzai) and Ts'ao-tung (Japanese: Soto). Lin-chi relied heavily on the use of koan, often accompanied by shouts and slaps from the master to provoke anxiety which could bring about an instant realization of the truth. The Ts'ao-tung (Soto) school emphasized the practice of “silent illumination” or “just sitting” (Chinese: tso-ch'an; Japanese: zazen), sitting in silent meditation under the direction of a master and purging the mind of all notions and concepts.

Ch'an (Zen) Buddhism was introduced into Japan as early as the seventh century, but it did not flower until the twelfth century, under two monks, Eisai and Dogen. Eisai, founder of the Rinzai school, was a Tendai monk who visited China to study pure Buddhism. When he returned, he included a strict meditational system based on the use of the koan phrases as one element in the Tendai system.

Examples of Koan

• A monk asked Zhaozhou, "Does a dog have Buddha nature or not?" Zhaozhou said, "Wú (negative)."

  ("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 "non-being" in English. This is a fragment of Case #1 of the The Gateless Gate (Wu-Men Kuan). A similar koan records that on another occasion, Zhaozhou said "yes" in response [Case #18 of the Book of Serenity].)

• 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 The Gateless Gate (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 The Gateless Gate (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 The Gateless Gate (Wu-Men Kuan) as well as case #47 of the Book of Serenity.)

Roles of the Koan in Zen Practice

Zen Literature

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 twelfth century); and The Gateless Gate (also known as Gateless Gate; Chinese: Wu-Men Kuan; Japanese Mumonkan) collected during the thirteenth 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 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 poetry.^[5][6] Over centuries, contemporary collections continued to inspire commentary, and current koan collections contain modern commentaries. Occasionally new koans are proposed and collected, sometimes seriously, sometimes in jest.

Meditation

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."^[7] Beyond this, written instructions are rare.

Examination of students

A koan may be used as a test of a Zen student's ability. For monks in formal training, and for some lay-persons, 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 a 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"^[8][9][10] 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. When a teacher tests a student using a koan, it resembles the judgment of a student's ability to recognize and actualize that particular principle. 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" (an) of a "magistrate" or "judge" (kung) …."^[8]. Apparently, kung-an was itself originally a metaphor in which an article of furniture that came to denote legal precedents.

Before the tradition of meditating on koans was recorded, Huangbo Xiyun (720-814) and Yunmen Wenyan (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," a seeming judgment of 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 Foulk^[8].) 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) koans^[11]. 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 acquired its present meaning from the legal term.

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 associated koan practice with pre-existing Taoist and Yogic chakra meditative practices by recommending preparation 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.

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); 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 tradition, although significant cultural differences exist.

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 practitioners 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 practitioners concentrate on koans while meditating, many Soto practitioners are thoroughly familiar with koans.

The Soto sect has a strong historical connection with koans; many koan collections were compiled by Soto priests. During the thirteenth 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."^[12]

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 twentieth century, and has roots in both the Soto and Rinzai traditions.

Interpretation of Koans

Though Zen teachers and practitioners insist that the meaning of a koan can only be demonstrated in a live experience, and that it cannot be conveyed by texts, the Zen tradition has produced a great deal of literature, including thousands of koans and 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 the ability to interpret koans should not be equated with enlightenment.

Understanding the literary and historical context of a koan can often remove some of the mystery surrounding it. For example, evidence^[13] 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 enlightenment is even older^[14]—and in fact, vigorous controversy^[15] still surrounds the matter of Buddha nature.

No amount of interpretation seems to be able to exhaust a koan; there can be no "definitive" interpretation. Teachers typically warn against over-intellectualizing koans, but some of the mystery can be dispelled by clarifying metaphors that were probably well known to monks at the time the koans originally circulated. The following interpretations are presented in that spirit:

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^[16]

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 the year 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 (negative)"

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 Lin-chi (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. Students offering such responses may not be able to withstand the "checking questions" that such teachers pose in further inquiry. Other teachers demand an entirely improvised response.

A related koan in the Book of Serenity^[17]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 as it may seem, 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 (the practice which produces complete meditation) 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".^[18]

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.

—Linji

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?"

See also

• Dharma

Notes

References

ISBN links support NWE through referral fees

• Aitken, Robert. 1990. The Gateless barrier: the Wu-men kuan (Mumonkan). San Francisco: North Point Press. ISBN 0865474419 Book of Serenity
• Cleary, Thomas, (Translator). Book of Serenity: One Hundred Zen Dialogues. Shambhala, 1998. ISBN 1570623813
• Gregory, Peter N. Sudden and Gradual. (Approaches to Enlightenment in Chinese Thought) Motilal Books, 1991. ISBN 8120808193
• Heine, Steven, and Dale Stuart Wright. 2000. The Koan: texts and contexts in Zen Buddhism. New York: Oxford University Press. ISBN0195117484
• Hori, G. Victor Sogen. "Translating the Zen Phrase Book," Nanzan Bulletin 23, 1999, 44-58
• Hori, Victor Sōgen. 2003. Zen sand: the book of capping phrases for kōan practice. Nanzan library of Asian religion and culture. Honolulu: University of Hawai'i. ISBN 0824822846
• Hubbard, Jamie, and Paul L. Swanson. 1997. Pruning the bodhi tree: the storm over critical Buddhism. Nanzan library of Asian religion and culture. Honolulu: University of Hawaiʻi Press. ISBN 082481908X
• Kudo, Sumiko. (translator). The Gateless Barrier: Zen Comments on the Mumonkan, Zenkei Shibayama. Shambhala Publications, 1974.
• Loori, John Daido, Bonnie Myotai Treace, and Konrad Ryushin Marchaj. 1994. Two arrows meeting in mid-air the Zen koan. Tuttle library of enlightenment. Boston: C.E. Tuttle Co. ISBN 0585068240
• MacRae, John R. Seeing Through Zen: Encounter, Transformation, and Genealogy in Chinese Chan Buddhism. Berkeley: University of California Press, 2003, ISBN 0520237986
• McCandless, Ruth Strout, Genro Oryu, Fugai and Steve Hagen. The Iron Flute: 100 Zen Koans, Nyogen Senzaki (Translator). (original 1961) reprint Tuttle Publishing, 2000. ISBN 080483248X.

• Miura, Isshū, and Ruth Fuller Sasaki. 1965. The Zen Koan; its history and use in Rinzai Zen. New York: Harcourt, Brace & World.
• Shibayama, Zenkei, and Huikai. 1974. Zen comments on the Mumonkan. New York: Harper & Row. ISBN 006067279X
• Zen Letters: Teachings of Yuanwu, Yuanwu Kequin (1063-1135), translated into English by J. C. Cleary and Thomas Cleary. Shambhala Publications, 1994,

External links

All links retrieved April 21, 2018.

• Zen Koans.
• The Gateless Gate by Ekai, called Mumon. 48 Zen koans compiled in the early thirteenth century. Shoyoroku A collection of 100 koans, originally compiled in the twelfth century.
• T. Matthew Ciolek. Zen Buddhism Koan Study Pages. World Wide Web Virtual Library.