A Course on Koans - Mu Part 1

The Koan Mu – Part One

This week’s koan is quite short: A monk once asked Master Joshu, “Has a dog Buddha Nature or not?” Joshu said, “Mu! (“No!”or “Not!”).

This koan is short but definitely not straightforward. The monk’s question and Joshu’s answer may strike you as irrelevant to our daily lives, and therefore of little interest.  If so, you may be surprised to learn that this is the most celebrated koan among the thousands that make up the vast koan literature. It has been used for centuries to introduce students to koan work, and even constitutes a kind of entrance test for koan practice.

Because of its importance, we will devote three installments to this koan. This first installment will give you a roadmap of the inner workings of this koan. The second installment will bear down on the importance of meditation in resolving this koan. The third installment will identify some implications of Mu that are meant to help you with koan work after Mu. 

As to “inner workings”, this koan is based on a bait and switch maneuver. As we shall see, the koan is not really about whether dogs have a certain property. Rather, it is about the relationship between you and Mu. By resolving for yourself what Mu is, you are given a chance to glimpse your own true nature for the first time. Because this koan is really about the voiced syllable Mu, American and Japanese teachers alike refer to this koan simply as “Mu” or “Muji”.

Mu is the first koan in “The Gateless Barrier, a 13th century koan collection by the Chinese Master Wumen (jap. “Mumon”). Mumon called this koan “the barrier of our sect”, giving the impression that beginners must “break through” this barrier before they can truly be called Zen practitioners. However, since the name “Wumen”, or “Mumon”, means “Gateless”, we are on notice that we are able to pass this barrier through an open gate. Accordingly, many teachers prefer to call Mumon’s collection “The Gateless Gate”.

​To track the bait and switch concealed in this koan, we need to understand its Buddhist terminology. “Buddha Nature” is the ultimate nature of reality as realized by the historical Buddha upon awakening. In his enlightenment under the tree, Buddha realized that all “sentient” (living) beings will ultimately realize that they themselves are Buddha and have always been so. Dogs are living beings, so Buddhist doctrine would seem to be clear; dogs “have” Buddha Nature. (“Have” is in quotes because Buddha Nature is not a property of a living thing; a living thing is Buddha Nature.)

Joshu’s reply of “Mu!” (chi.“Wu”, meaning “no” or “not”) is therefore surprising. Students may be tempted to think that their job is to decide whether Joshu’s answer was right or wrong and provide justification for their decision. However, as soon as the student begins to argue for a yes or no answer to the monk’s question, the teacher indicates that they are missing the point of the koan.  Instead, the teacher tells the student to ignore the monk’s question and just meditate on the question, “What is Mu?” In subsequent meetings, the teacher simply asks the student, “And so, what is Mu?”

After the teacher substitutes “What is Mu?” for the monk’s question, the student often tries to define Mu in words. The student may offer an answer based on the their own hazy ideas about Buddhism, such as, “Mu is everything and everywhere”.

To this, the teacher might say, “Yes that is true, but you need to show me this Mu directly, not tell me about it”. Flummoxed after attempts to define Mu in words, the student may humbly confess they are at an impasse and ask the teacher how they should proceed. This is fine. For Zen, going forward with something – anything – is always better than being stuck! The teacher’s reply to this request is always: “Just become one with Mu”. Though unclear, this advice is a pearl beyond price.

The admonition to become one with Mu, together with the abandonment of any attempt to define Mu in words, forces the student look inward. Rather than relying on knowledge in the form of words and concepts, the students must look to their own most primitive feelings, instincts and unexamined assumptions in search of an answer.
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You may have noticed that last week’s Introduction also called for us “to become one” with the koan. In that case, it was a distant temple bell; in this case it is Joshu’s “Mu”.
As I will explain in Part Two, people who “pass” Mu vary from those who have a “tip of the tongue taste” of enlightenment to those who have a deeper experience of Zen enlightenment. This depends on the effort you invest in the koan. So for now, just meditate steadfastly on Mu by whispering to yourself with each exhale, “Muuuuuuu”.