On Mu & Buddha Nature: A Reflection on Zen & Koan Introspection

Mu & Buddha Nature
A Reflection on Zen & Koan Introspection

By Josh Bartok

Josh Bartok is a Soto Zen Buddhist priest, and a teacher of the Soto reformed koan system developed by Master Daiun Sogaku Harada, based on the master’s years studying the Takujo Hakuin koan curriculum at the turn of the nineteenth & twentieth centuries.  Bartok Osho is abbot & senior teacher at the Greater Boston Zen Center in Cambridge, Massachusetts.

The Koan Mu, also known as Zhaozhou’s Dog, is the first koan in the Boundless Way School and in a number of koan systems. The koan goes like this:

A monk asked Master Zhaozhou, “Does a dog have Buddha nature?”
Zhaozhou answered, “Mu.”

This Mu in Japanese means “no”, “not,” “un-.” In Chinese, the same word is pronounced “Wu”, which some people feel in this particular case is echoic of a dog’s bark.
What is this Buddha nature that the monk is inquiring about? Dogen offers a beautiful depiction of it:

“Mountains, rivers, and the great earth all depend on it. Various samadhis and the six miraculous powers emerge from it.” Thus, mountains, rivers, and the great earth are all the ocean of Buddha nature. In the very moment they depend on it, they are mountains, rivers, and the great earth. Know that the form of the ocean of Buddha nature is like this. It is not concerned with inside, outside or in between. This being so, to see mountains and rivers is to see Buddha nature; to see Buddha nature is to see the fins of a donkey and the beak of a horse. Thus, you understand and go beyond understanding. Even though you may be limited, you are in the vast ocean of Buddha nature.

When Shakyamuni Buddha first awakened, upon seeing the morning star he said, “How wonderful! All beings and I simultaneously awaken to what always was.” This is awakening to Buddha nature. It is original awakening, original enoughness. This Buddha nature is not accomplished or earned, it is not deserved or achieved. Being part of the vast ocean of Buddha nature is simply the fact of the matter; it is simply what is. “What is” is expressed by mountains, and rivers, and the great earth. Isn’t it wonderful that mountains, and rivers, and the great earth depend on it? They take refuge in it, entrusting themselves to it. Thus they manifest as mountains, rivers, and the great earth.

Dogen says mountains, rivers, and the great earth are all the ocean of Buddha nature. This is an image throughout the Buddhist scriptures, and is especially emphasized by Dogen. This ocean of Buddha nature is a way of describing the entirety of the universe. Everything in it arises as ripples, waves, and undercurrents; jellyfish, sharks, and anemones, all manifesting as the ocean of Buddha nature. Nothing is separate.

The ocean of Buddha nature is not concerned with distinguishing inside or outside, with has or has not. It is not concerned with mountains or rivers, dogs or monks, clarity or confusion. This being so, to see mountains and rivers is to see Buddha nature. To see hedges, and walls, and rocks, and trees, and suffering, and fear, and grief, and sadness is to see Buddha nature. These are what the universe of Buddha nature is doing in this place and this moment, manifesting the form of mountain, manifesting the form of grief.

Dogen continues, “To see Buddha nature is to see the fins of a donkey and the beak of a horse.” If you’re seeing a thing that you call Buddha nature, this distinguishing is a concept you’ve totally made up. Understanding this, you can go beyond understanding. Kaz Tanahashi translates Mu as a prefix meaning “beyond.” There is understanding, and there is beyond understanding. You understand, and you realize that you don’t understand. Not-understanding means not limiting Buddha nature to our mere ideas about what it is or should be or how we can tell if we have it or are manifesting it well.

One belief that can arise is that beyond-understanding should feel totally different. But grief and fear are not ecstatic, or even vaguely enthusiastic. This is it too. Sometimes ecstatic arises. Sometimes ecstatic does not arise. Early on in my practice I was working with Mu with my teacher, and had some experience of clarity. Then I got really obsessed with that, and was tortured by the question of, “So, where is Mu when I don’t see it?” The thing that I was looking for was the fins of a donkey and the beak of a horse. Mu itself was never for a moment hidden, from the beginning.

Dogen lovingly encourages us, “Even though you may be limited, you are in the vast ocean of Buddha nature.” Your mind, your stories, your content of consciousness are only ever limited because that is the nature of contents of consciousness. This limitedness is also included in the vast ocean of Buddha nature. Dogen invites us to go beyond understanding contents of consciousness, with I-me-mine, what I feel right now.

Even if we discover the fins of the donkey, we have only discovered Buddha nature. Even if we may be limited, feel confused, have certainty that this can’t be it or that I am not enough—even so, this is the vast ocean of Buddha nature. As the Song of the Precious Mirror samadhi says, “You are not It, but in truth It is you.”

When the monk asks, “That dog? That dog over there? Licking its butt right now? Does that dog have Buddha nature?” Zhaozhou says, “No.” What is this No? What is this Mu? What is it that this monk is asking? “When I feel like this, do I have Buddha nature? I’m pretty sure that I am the one being alone in the universe lacking Buddha nature.” Kind of like a birth defect. I was born without it—I know because I can’t see it.

The invitation of Mu is to investigate for yourself this matter of have and have not, this matter of Buddha nature and no Buddha nature, of understanding and beyond understanding. We are invited to investigate, to look deeply, deeply, deeply into Mu, every moment breathing Mu, Mu breathing. Letting Mu lift the feet in kinhin walking meditation, and receive the body’s weight. Sit as Mu. Really become intimate with Mu.
Dogen continues:

Learn and study what kind of moment it is when there is no Buddha nature. Is it no Buddha nature on the top of the Buddha’s head, or is it no Buddha nature that is going beyond? No Buddha nature is sometimes understood as the samadhi of this one moment.

No Buddha nature as the samadhi of this moment, the full entrusting to this moment, absorption into this moment. Samadhi is sometimes translated as absorption, and meditation is often spoken of as cultivating samadhi. But don’t imagine samadhi is some kind of special state. Don’t imagine samadhi as stilling the mind, quieting the mind or emptying the mind. There is samadhi of a still mind. There is samadhi of a quiet mind. There is samadhi of a racing mind, samadhi of cacophony arising. There is samadhi of stillness and of motion. All of that can arise as the samadhi of this moment exactly as it is. Not this moment as you wish it were, as you think it should be, as it was a moment ago, as you’re sure it’ll be later. It’s not this moment as it would be if only you had more sleep or better parents or more time to practice. It is the samadhi of this moment.

This is Mu. This is no Buddha nature. This is beyond Buddha nature. Practicing Mu, investigate deeply: what is it? What is Mu? What is no Buddha nature? Dogen suggests, “Ask whether there is no Buddha nature when Buddha attains Buddhahood.” We might say, “Ask whether there is no Buddha nature when Buddha fails to attain Buddhahood.” The scroll in our Zen Center says, “The non-attained Buddha.” This is a reference to the Buddha who sat for three eons on the Bodhi seat meditating his utmost, and did not realize Buddha nature at all. “Why?” the monk asks. “Why didn’t that guy get it? He was Buddha and he was sitting there on the Bodhi seat meditating his utmost. Why didn’t he attain Buddha nature?” “Because he was a non-attained Buddha.”

Dogen continues, “Ask whether there is no Buddha nature when Buddha nature attains Buddhahood.” Ask whether there is no Buddha nature when calm is attained, when there is certainty that this cannot be it. When there is certainty that you are lacking. Ask whether there is no Buddha nature, and if it comes back with a resounding, “Yes, absolutely! I can firmly clearly see no Buddha nature.”—how about the no Buddha nature of that yes? Buddha nature and no Buddha nature: how many things is that?

“Ask whether there is no Buddha nature that arouses the aspiration of enlightenment.” This is raising the Bodhi mind. Dogen comes back to this repeatedly. Attaining awakening, saving all beings—these are not things you can do, and the aspiration to do them is utterly essential to the Zen way. It is the aspiration to practice this no Buddha nature, to actualize that which is not actualized even in three kalpas. Utterly indispensable. That doesn’t mean that this is a thing that can be done, but get on with doing it.

Then Dogen suggests, “Have a pillar ask this question, or ask pillars this question.” This is a clear pointer to one way of working with Mu off the cushion. Whatever is encountered in daily life, ask it, “What is no Buddha nature? What is Buddha nature? Where is the ocean of Buddha nature? What is Mu?” Ask everything that is encountered. This is one way to bring Mu into your life, for your life to be Mu’s life.

Ask everything this question, and listen for the answer. Ask-and-receive the answer. Have a pillar ask these questions. Let everything you encounter ask that of you. And, Dogen says, have Buddha nature itself ask this question. Mu asking Mu, Mu responding.