Mumonkan - Case 1: Joshu's "Mu."

A koan is simply a historical case, an example of a master at work.  They're often constructed to confound and mentally trap students such that there is no way to solve them aside from setting aside thinking, but that doesn't mean you can't derive an intellectual understanding from them that might help you direct yourself toward goals.  Just keep in mind that the intellectual understanding is not the goal, and doesn't show the kind of understanding that we're after.  

I'm going to begin with the Mumonkan (Katsuki Sekida translation), which is a collection of 48 koan, assembled and commented on by Zen master Mumon Ekai, for use as a tool for teaching students.  Mumon chose to begin his collection with the case of Joshu's "Mu," which is one of the simplest and most direct, but also one of the most daunting cases for a beginner to grasp.

The Case:

 A monk asked Jõshû, "Has a dog the Buddha Nature?" Jõshû answered, "Mu (no)."

Mumon's Comment:

In order to master Zen, you must pass the barrier of the patriarchs. To attain this subtle realization, you must completely cut off the way of thinking. If you do not pass the barrier, and do not cut off the way of thinking, then you will be like a ghost clinging to the bushes and weeds.  Now, I want to ask you, what is the barrier of the patriarchs?  Why, it is this single word "Mu." That is the front gate to Zen.  Why, it is this single word "Mu." That is the front gate to Zen.  Therefore it is called the "Mumonkan of Zen."  If you pass through it, you will not only see Jõshû face to face, but you will also go hand in hand with the successive patriarchs, entangling your eyebrows with theirs, seeing with the same eyes, hearing with the same ears. 

Isn't that a delightful prospect?  Wouldn't you like to pass this barrier?  Arouse your entire body with its three hundred and sixty bones and joints and its eighty-four thousand pores of the skin; summon up a spirit of great doubt and concentrate on this word "Mu."  Carry it continuously day and night. Do not form a nihilistic conception of vacancy, or a relative conception of "has" or "has not."  It will be just as if you swallow a red-hot iron ball, which you cannot spit out even if you try.  All the illusory ideas and delusive thoughts accumulated up to the present will be exterminated, and when the time comes, internal and external will be spontaneously united. You will know this, but for yourself only, like a dumb man who has had a dream. Then all of a sudden an explosive conversion will occur, and you will astonish the heavens and shake the earth.  It will be as if you snatch away the great sword of the valiant general Kan'u and hold it in your hand. When you meet the Buddha, you kill him; when you meet the patriarchs, you kill them. On the brink of life and death, you command perfect freedom; among the sixfold worlds and four modes of existence, you enjoy a merry and playful samadhi.

Now, I want to ask you again, "How will you carry it out?"  Employ every ounce of your energy to work on this "Mu."  If you hold on without interruption, behold: a single spark, and the holy candle is lit!

Mumon's Verse:

The dog, the Buddha Nature,

The pronouncement, perfect and final.
Before you say it has or has not,
You are a dead man on the spot.

My Analysis:  

This is a remarkably difficult starting point, even just from a perspective of linguistics.  The western student approaching this koan probably has already heard several, and conflicting things about what the word "Mu" means.  Some will say "nothingness," or that it is a means of refusing to answer the question.  You can make an argument for lots of different interpretations, but it's easiest if you simply take "mu" as a contextual "no."  He is delivering a flat, and simple answer to the monk's question:  "No, the dog does not have Buddha nature."  

Only that isn't simple at all.  "Buddha Nature" in Zen is seen as the essential nature of all beings, or even at times as the nature of reality, and it is said that every being possesses Buddha Nature.  So we're faced with a yes or no question which has as close to a prescribed "correct" answer you could expect to find, and the master responds flatly with what we understand to be the incorrect answer.  His mastery of the subject isn't in question, so as the reader, you're left with the unenviable task of making sense of this.  

Heads up: you can't.  If the goal of Zen is to become free from the attachment to your own thoughts and your concept of self, that isn't going to happen by stumbling upon an intellectual understanding of the koan and patting yourself on the back.  That kind of freedom only comes when you break things.  When Joshu responds with the answer that is fundamentally incorrect, "Mu" becomes a wrecking ball, demolishing his own authority as a teacher, demolishing the concepts of "correct" and "incorrect," "has" or "doesn't have," demolishing the idea of pressing the world into a shape that we understand, demolishing all of the accumulated knowledge that gave rise to the question in the first place.  He hasn't dismissed the question, he has effectively erased it by giving an answer that it wasn't designed to accommodate.  He tossed Mu out into the world, and it began breaking things.  

When Mumon suggests that you grasp this "Mu" with all of your being, this is his intent.  He wants you to hold on to that wrecking ball and allow it to destroy all of your established knowledge, all of your beliefs, all of your concepts, including the concept of a self, all of the things that you're clinging to like "a ghost clinging to the bushes and weeds."  What he describes is an effort, and that is no mistake.  Imagine you're trapped inside a room and the door is locked.  You have a baseball bat with which you can break the window and climb out.  Understanding that you can break the glass does not get you free.  You still need to do the work of breaking that glass.  Understanding that that these things need to break for you to be free is one thing; actually breaking them is quite another.  So don't sit on this realization and accept it as the goal.  All you've done is found a way; you haven't broken out yet.