An Unanswerable Question
"What is the sound of one hand clapping?"
This question hangs in the air, seeming like a nonsense riddle meant to confuse us. It shows how most people in the West misunderstand what a Zen koan really is.
Many of us think we need to find a clever answer. In koan zen buddhism, finding an answer isn't the goal at all. The koan works more like a tool for surgery than a simple brain teaser.
I want to take you deeper than just the surface puzzle. We'll explore what a koan truly is - a powerful tool that wears out your logical mind, breaks down either/or thinking, and opens a direct path to insight through experience.
What is a Koan?
Let's first look at the name. The word kōan (公案) comes from Japanese, which came from the Chinese term gōng'àn.
This term originally meant "public case" in ancient China - like a legal case that set standards for future judgments. Zen masters chose this term very carefully.
In Zen practice, a koan serves as a "public case" showing an enlightened mind. It records a moment of awakening through a question, dialogue, or action. This record becomes a standard that students can use to check their own understanding.
It's not something to debate philosophically. A koan points directly to ultimate reality by going around the thinking filters we normally use to understand the world.
The difference between koans and riddles is total, not slight. They work in completely different ways toward completely different ends.
| Logical Puzzle / Riddle | Zen Koan |
|---|---|
| Goal: Find a single, clever, logical answer. | Goal: Exhaust the logical mind to arrive at a non-conceptual insight (kensho). |
| Tool: Uses intellect, reason, and analysis. | Tool: Uses the entire being—body, breath, and consciousness. |
| Result: A feeling of intellectual satisfaction ("I solved it!"). | Result: A shift in perception; a direct, personal experience of reality. |
| Nature: A closed system with a defined solution. | Nature: An open pointer to a reality that cannot be captured in words. |
The True Purpose
Why use a tool designed to be so confusing? The purpose is to starve the part of our mind that causes us the most trouble: the judging mind.
In Sanskrit, this is called vikalpa. It works like our mind's default operating system. This mind works by constantly cutting reality into pairs of opposites.
It labels everything: good or bad, right or wrong, sacred or ordinary, self or other, subject or object.
We live our entire lives inside this grid of judgments. "I like this feeling, I hate that one." "This is me; that is the world." "This is success; that is failure."
Zen practice suggests this constant dividing causes our anxiety and suffering, what Buddhism calls dukkha. We get stuck chasing what we label "good" and running from what we label "bad."
The koan throws a wrench into this machine.
It gives the judging mind data it cannot process. It's like asking a calculator, "What color is the number seven?" The system has no way to handle the question. It gets stuck.
A koan is built to be impossible for logic to digest. It shows a situation where concepts we think can't both be true - like "is" and "is not," or "moving" and "still" - are shown as true at the same time.
When someone works with a koan with deep focus, it creates a state called "Great Doubt" (daigi).
This isn't the doubt of someone who doesn't believe. It's a deep, energetic, all-consuming state of questioning. The mind becomes like a pressure cooker of inquiry.
The process is meant to be very frustrating. The person will turn the koan over and over, using all their brain power. They will try clever answers, philosophical ideas, and poetic images.
Each attempt fails. This failure is exactly the point.
The constant effort, combined with the koan's illogical nature, eventually leads to complete mental exhaustion. The thinking mind finally gives up. It surrenders.
In that moment of letting go, when the busy intellect falls quiet, something else can emerge. A different kind of knowing—direct, intuitive, beyond concepts—can flash into awareness.
This is called kensho or satori. It's the "Aha!" moment that the whole practice aims to create.
How to Work With a Koan
Understanding the theory is one thing. The practice is another matter entirely. How does someone actually "work with" a koan?
First, we must understand: we don't think about the koan. We try to become one with it. This process involves absorption, not analysis.
While a teacher in a formal koan zen buddhism tradition guides the specifics, the inner process follows a general path.
First, you receive the koan. Traditionally, a Zen master gives a specific koan to a student when they seem ready for this intense practice.
Next, you learn to "hold" the question. During seated meditation (zazen), and later during all daily activities, you gently keep the koan's central question at the front of your mind.
For the koan "Mu," the question is simply, "Mu." Not "What does Mu mean?" but just the sound and feeling of "Mu." For "the sound of one hand," the question is, "What is this sound?"
The third stage is living with the koan. It becomes the quiet hum beneath your daily life. While washing dishes, walking to work, or talking with friends, the question stays with you.
When your intellect tries to solve it—"The sound of one hand is silence!" or "Mu means emptiness!"—you simply notice that thought, let it go, and return to the raw question itself.
This is where the felt experience begins. It starts with curiosity, which soon turns into growing frustration.
You feel pressed against a wall that won't move. Your mind races, looking for an exit, a solution, any relief from the pressure of the question. You may strongly want to give up or dismiss it as nonsense.
This intense struggle doesn't mean you're doing it wrong. This struggle is the path. The heat from this inner friction burns away layers of thought.
The breakthrough, the kensho, isn't an "answer" as we normally think of answers. It's a sudden, complete shift in perspective. It often comes not during hard effort, but in a moment of total exhaustion, when the mind finally lets go of the problem.
It's like a "pop." The tension resolves not into a new thought, but into seeing reality directly as it is, without the labels the mind had placed on it. It's an experience, not a conclusion.
Two Famous Koans
To make this clearer, let's look at how this process works with two famous koans.
Our first example is a common starting koan called "Joshu's Dog."
The koan goes: A monk once asked Master Zhaozhou (J. Joshu), "Does a dog have Buddha-nature or not?" Zhaozhou replied, "Mu!"
(In Chinese, "Mu" or "Wu" means "no" or "not," but here it's used to cut through the very basis of the question.)
The mind trap springs immediately. Buddhist teaching says all beings have Buddha-nature. So why did the master say "no"? The mind gets caught between yes and no, between teaching and the master's word. This is exactly the dual-thinking trap the koan sets.
The real work has nothing to do with dogs or Buddhist ideas. The practice is to forget the monk, forget the dog, and forget Buddha-nature. The practice is to become Mu.
The person breathes in "Mu." They breathe out "Mu." They let the single sound "Mu" fill their whole awareness, pushing out all other thoughts. The sound "Mu" becomes a sword cutting away the endless stream of mental chatter until the question itself dissolves.
Our second example is Hakuin's "Sound of One Hand."
The koan asks: "You know the sound of two hands clapping. Now, what is the sound of one hand?"
The mind trap is trying to imagine a physical sound one hand could make. Is it the whoosh of air? The sound of blood in your ear? Is it silence? These are all clever products of the rational mind trying to solve what it sees as an outside problem.
The real work is seeing that the koan isn't asking about something you perceive. It points directly at the perceiver. It forces you to find the very source of hearing itself, the silent, aware space where both the sound of two hands and the "sound" of one hand appear.
The koan turns your attention completely around, away from objects in the world and toward the subject that is aware of them. The "answer" isn't a sound, but a direct recognition of this always-present, silent awareness.
A Finger Pointing at the Moon
In the end, a koan isn't a riddle to solve. It's an experience tool designed to short-circuit the logical mind and break down the illusion of a separate self.
A classic Zen saying captures this perfectly: "The teaching is a finger pointing at the moon. Do not mistake the finger for the moon."
The koan is that finger.
Its purpose isn't to be admired, analyzed, or intellectually understood. Its only function is to direct your gaze away from the finger itself—away from words and concepts—and toward the direct, bright, and always-present reality of your own true nature.
