A monk asked Joshu, a Chinese Zen master: “Has a dog Buddha-nature or not?”

Joshu answered: “Mu.” [Mu is the negative symbol in Chinese, meaning “No thing” or “Nay.”]

Mumon’s comment: To realize Zen one has to pass through the barrier of the patriarchs. Enlightenment always comes after the road of thinking is blocked. If you do not pass the barrier of the patriarchs or if your thinking road is not blocked, whatever you think, whatever you do, is like a tangling ghost. You may ask: What is a barrier of a patriarch? This one word, Mu, is it.

This is the barrier of Zen. If you pass through it you will see Joshu face to face. Then you can work hand in hand with the whole line of patriarchs. Is this not a pleasant thing to do?

If you want to pass this barrier, you must work through every bone in your body, through every pore of your skin, filled with this question: What is Mu? and carry it day and night. Do not believe it is the common negative symbol meaning nothing. It is not nothingness, the opposite of existence. If you really want to pass this barrier, you should feel like drinking a hot iron ball that you can neither swallow nor spit out.

Then your previous lesser knowledge disappears. As a fruit ripening in season, your subjectivity and objectivity naturally become one. It is like a dumb man who has had a dream. He knows about it but he cannot tell it.

When he enters this condition his ego-shell is crushed and he can shake the heaven and move the earth. He is like a great warrior with a sharp sword. If a Buddha stands in his way, he will cut him down; if a patriarch offers him any obstacle, he will kill him; and he will be free in his way of birth and death. He can enter any world as if it were his own playground. I will tell you how to do this with this koan:

Just concentrate your whole energy into this Mu, and do not allow any discontinuation. When you enter this Mu and there is no discontinuation, your attainment will be as a candle burning and illuminating the whole universe.

Has a dog Buddha-nature?
This is the most serious question of all.
If you say yes or no,
You lose your own Buddha-nature.

2.
Hyakujo’s Fox

Once when Hyakujo delivered some Zen lectures an old man attended them, unseen by the monks. At the end of each talk when the monks left so did he. But one day he remained after they had gone, and Hyakujo asked him: “Who are you?”

The old man replied: “I am not a human being, but I was a human being when the Kashapa Buddha preached in this world. I was a Zen master and lived on this mountain. At that time one of my students asked me whether or not the enlightened man is subject to the law of causation. I answered him: ‘The enlightened man is not subject to the law of causation.’ For this answer evidencing a clinging to absoluteness I became a fox for five hundred rebirths, and I am still a fox. Will you save me from this condition with your Zen words and let me get out of a fox’s body? Now may I ask you: Is the enlightened man subject to the law of causation?”

Hyakujo said: “The enlightened man is one with the law of causation.”

At the words of Hyakujo the old man was enlightened. “I am emancipated,” he said, paying homage with a deep bow. “I am no more a fox, but I have to leave my body in my dwelling place behind this mountain. Please perform my funeral as a monk.” Then he disappeared.

The next day Hyakujo gave an order through the chief monk to prepare to attend the funeral of a monk. “No one was sick in the infirmary,” wondered the monks. “What does our teacher mean?”

After dinner Hyakujo led the monks out and around the mountain. In a cave, with his staff he poked out the corpse of an old fox and then performed the ceremony of cremation.

That evening Hyakujo gave a talk to the monks and told them this story about the law of causation.

Obaku, upon hearing the story, asked Hyakujo: “I understand that a long time ago because a certain person gave a wrong Zen answer he became a fox for five hundred rebirths. Now I want to ask: If some modern master is asked many questions and he always gives the right answer, what will become of him?”