The character “MU” can be translated as “has not”, “is without”, “without”, “lack of”, “absence”.

In this excerpt, Dogen explores various layers of meaning of the famous expression, recorded as a dialog between Master Joshu and one of his students.

A monk asks Great Master Shinsai of Joshu,

“Does even a dog have the Buddha-nature or not? ?

We should clarify the meaning of this question.

“A dog” is a dog. The question does not ask whether the Buddha-nature can or cannot exist in the dog; it asks whether even an iron man learns the truth. To happen upon such a poison hand may be a matter for deep regret, and at the same time the scene recalls the meeting, after thirty years, with half a sacred person.

Joshu says, “It is without.? (MU)

When we hear this expression, there are concrete paths by which to learn it: the “being without? with which the Buddha-nature describes itself may be expressed like this; the “not having ” which describes the dog itself may be expressed like this; and “there is nothing,” as exclaimed by an onlooker, may be expressed like this. There may come a day when this “being without” becomes merely the grinding away of a stone.

The monk says, “All living beings totally have the Buddha-nature. Why is the dog without?” The intention here is as follows: “If all living beings did not exist, then the Buddha-nature would not exist and the dog would not exist. How about this point? Why should the dog’s Buddha-nature depend on ‘non-existence?.?”

Joshu says, “Because it has karmic consciousness.?

The intention of this expression is that even though the reason it exists is karmic consciousness and to have karmic consciousness is the reason it exists, the dog is without anything, and the Buddha-nature is without anything. Karmic consciousness never understands intellectually what the dog is, so how could the dog meet the Buddha-nature? Whether we cast away duality or take up both sides, the state is just the constant working of karmic consciousness.

A monk asks Joshu, “Does the Buddha ?nature exist even in a dog or not?”

This question may be the fact that this monk is able to stand up to Joshu. Thus, assertions and questions about the Buddha-nature are the everyday tea and meals of Buddhist patriarchs.

Joshu says, “It exists.”

The situation of this “It exists” is beyond the “existence” of scholastic commentary teachers and the like, and beyond the dogmatic “existence” of the Existence School. We should move ahead and learn the Buddha’s Existence. The Buddha’s Existence is Joshu’s “It exists.” Joshu’s “it exists” is “the dog exists,” and “the dog exists” is “the Buddha-nature exists.”

The monk says, “It exists already?then why does it forcibly enter this concrete bag of skin?”

This monk’s expression of the truth poses the question of whether it is present existence, whether it is past existence, or whether it is Existence already; and although Existence already resembles the other “existences” Existence already clearly stands alone. Does Existence already need to force its way in? Or does Existence already not need to force its way in? The action of forcibly entering this concrete bag of skin does not accommodate idle heedless consideration.

Joshu says ?Because it knowingly commits a deliberate violation?