Zen Koan #8: Hakuin’s “What Is the Sound of One Hand?”
Zen Koan #8: Hakuin’s “What Is the Sound of One Hand?”
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Context: Hakuin Ekaku (1686–1769) was a Japanese Zen master who revitalized Rinzai Zen. He created many koans.
His most famous: “Two hands clap and there is a sound; what is the sound of one hand?”onehandspeaks.com. This koan, often shortened to “What is the sound of one hand clapping?”, is usually the first koan assigned to novice monks in Rinzai Zen.
Commentary: Hakuin intended this koan to arouse great doubt and concentration. At first glance, it sounds like a riddle or nonsense: one hand alone makes no sound – or does it? The student might be tempted to answer with a joke (“silence!” or by clapping one hand on their body or a table). But any quick answer misses the point.
The “sound of one hand” is not a literal noise; it is sometimes called the “sound of one hand washing”, meaning it washes away delusion. In some accounts, Hakuin came up with this koan after a neighbor asked him why he meditated – he answered it was so he could hear the sound of one hand.
The neighbor was mystified, but Hakuin promised him that if he died without hearing it, Hakuin would listen at his grave and tell him. This dramatic tale underscores Hakuin’s flair – he wanted to plant a question that would consume the student’s whole mind. In koan training, “one-hand sound” can’t be solved by reasoning. The student must turn hearing back on itself – what is the “sound” of the mind when all duality (two hands) is collapsed into unity (one hand)? The “one hand” can symbolize the One Mind.
Hakuin’s koan drives the student to a precipice: trying to “hear” the unhearable eventually forces a leap to a new mode of perception. Zen lore is full of stories of monks struggling with this koan for days, weeks, months – until in deep fatigue or despair they suddenly catch an inner sound (or insight) and experience kenshō (an initial awakening). Hakuin himself stressed that one must “become one with the sound.” Some say when you truly hear the one-hand sound, the whole universe is ringing. Interestingly, Hakuin gave this koan to laypeople as well – it appears in his writings that even village women practiced it and gained clarity. Its wording has entered pop culture and everyday idioms. Yet its true purpose remains what Hakuin intended: to baffle the ordinary mind. The koan is not asking for an answer like “It is the sound of silence” – it is inviting you to experience the soundless sound. One Zen verse about it says: “If you hear it, all affairs are settled.” Perhaps it is the same sound poet Basho heard as a “old pond / a frog jumps in – / plop.” Perhaps it is what you hear right now, if you really listen. What is the sound of one hand? Listen…
Zen Koans: The Gateless Gate to Insight
Zen koans are short, paradoxical anecdotes or questions used in Zen Buddhism to provoke deep reflection and awaken insight beyond logical reasoning. A classic koan often features an encounter between a student and a master where the master’s response is unexpected or seemingly nonsensical. Koans are not riddles with trick answers; instead, each koan is a “Gateless Gate” – a barrier that the logical mind cannot pass. Only by dropping analytical thinking and engaging one’s whole being can one penetrate a koan and experience a shift in consciousness. As 18th-century master Hakuin Ekaku described, “From the very beginning all beings are Buddha... It is like water and ice... Stop the movement to grasp or reject and behold: the water flows clear and freely” – a poetic summary of the koan spirit of letting go and directly seeing reality.
Koans emerged within the Chán/Zen tradition of China during the Tang and Song dynasties (7th–13th centuries) and were later transmitted to Japan, Korea, and Vietnam. Koan practice involves contemplating these stories during meditation or daily activities, often under guidance of a teacher. The seemingly illogical responses of the masters are designed to frustrate the discursive mind and force the student to turn inward, smashing conventional dualistic thinking. The great Zen teacher Wumen (Mumon) said one must “pass through the barrier of the ancients” to realize enlightenmentsacred-texts.com. In koan practice, great doubt and great faith work together – as the student’s habitual thinking gets tied in knots, a breakthrough becomes possible.
Classic Collections of Koans
Over generations, Zen teachers compiled koan collections with commentary to aid students. Three of the most famous are The Gateless Gate (Mumonkan), The Blue Cliff Record (Hekiganroku), and The Book of Equanimity (Shōyōroku):
The Gateless Gate – compiled in 1228 by Chinese master Wumen Huikai (Mumon Ekai). It contains 48 koans (plus one added later), each with Wumen’s commentary and verse. The title “Gateless Gate” indicates that the only barriers to enlightenment are our own attachments. Wumen’s cases include famous dialogues like “Joshu’s Dog”, “Mu”, and “Nansen Cuts the Cat”. Wumen’s brief commentaries are often wry or poetic, designed to jolt the reader’s mind into a new perspective.
The Blue Cliff Record – a 12th-century collection of 100 koans, expanded from earlier compilations by master Yuanwu Keqin. The Blue Cliff Record includes extensive commentary and verse for each casebluecliffrecord.ca. These koans are drawn from the golden age of Zen in Tang/Song China and feature many renowned masters. The Blue Cliff is known for its literary elegance and subtle, layered analysis – in fact, it was once suppressed for fear monks would intellectualize its poetry instead of directly realize the truth. Nevertheless, it remains a treasure trove of Zen wisdom, including koans like “Every Day Is a Good Day”, “The Highest Meaning of the Holy Truths” (Bodhidharma’s encounter with Emperor Wu), and Layman Pang’s stories.
The Book of Equanimity – also known as the Book of Serenity, compiled by Wansong Xingxiu in the 12th century. It contains 100 koans (with some overlap with the Blue Cliff) and emphasizes balanced, peaceful reflection – hence “equanimity.” Each case is accompanied by verses by earlier master Hongzhi. The Book of Equanimity includes cases such as “The World Honored One (Buddha) Points to the Ground”, “Jizo’s Most Intimate”, and “Rinzai’s True Person”. It is valued in the Sōtō Zen school for its gentle yet profound approach.
Each of these collections became a classic, studied by monks and lay practitioners alike. In the Rinzai Zen tradition (especially in Japan), a teacher might assign koans sequentially to trainees – starting with a “first barrier” koan like Mu or “What is the sound of one hand?”, then moving through dozens or even hundreds of koans over years of training. In Sōtō Zen, koans are not assigned in the same way, but they still inform teachings and are reflected upon during zazen (sitting meditation) or in daily life stories.
Koans are “alive” – not mere texts to be parsed, but encounters to be experienced anew by each practitioner. There is a saying that “a koan is not answered, it answers you.” In working with koans, one isn’t solving a puzzle so much as allowing the koan to work on one’s own tightly held perspectives. A genuine response to a koan comes not from the intellect but from one’s whole being, often spontaneously. It could manifest as a word, a gesture, a deep bow – or simply a fundamental shift in understanding. The commentaries and verses provided by the classic koan collections are there not to explain the koan’s “solution” (indeed, any such explanation could spoil it), but to point towards the state of mind of the masters and to inspire the adept. They often use allusions, poetry, or humor to hint at the deeper meaning.
Below, we explore 100 traditional Zen koans drawn from the Mumonkan, Blue Cliff Record, Book of Equanimity, and other classic Zen lore. For each koan, we present the original story or exchange (in English translation), give a bit of historical/spiritual context about the teachers or setting, and offer a brief commentary or interpretation to illuminate the key insight or paradox. These koans are not meant to be “understood” in a conventional way – rather, let their images and words resonate beyond reason. As Wumen said in his preface to The Gateless Gate, “If you do not pass the barrier and do not shatter your illusions, you will remain a ghost clinging to bushes and grasses.” But if you step through the gateless gate, even the most ordinary moment – hearing the rain drip, seeing a flower bloom, washing your bowl – can reveal ultimate truth.
One Hundred Zen Koans (with Context and Commentary)
Below is a curated list of 100 classic Zen koans. They span the early Chinese masters (6th–10th century), the golden age of Zen (Tang/Song dynasties), and a few later and modern anecdotes that have entered Zen teaching. Each koan is titled by a distinguishing phrase or subject. The context notes the protagonist master (and era, if known) or source, and the commentary highlights the paradox or insight. Many of these koans appear in the aforementioned collections, indicated in parentheses for reference (GG = Gateless Gate, BCR = Blue Cliff Record, EQ = Book of Equanimity). Whether a koan is encountered in formal practice or casual reading, it can serve as a “finger pointing at the moon” – do not fixate on the finger (the words), but look to the moon (your own direct experience)!
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