Zen Koans* deal with the absolute and the relative. What is the absolute and what
is the relative in the koan 'Mu'?
Generally, the one who asks the question asks from the point of view of the relative, and the Zen master’s response is usually couched in terms of the absolute. So the question, “Does a dog have Buddha Nature?” can be a relative question. And the answer, “Mu” is the absolute.
Why does Zhaozhou give different answers to the same question?
Why does he say, “Mu,” or “No,” at one point and, “U,” or “Yes” at another?
Are both “Mu” and “U” absolute? Here we must look carefully at the text.
Zhaozhou does not say, “A dog does not have Buddha Nature.” Nor does he
say, “A dog has Buddha Nature.” He says, “Mu.” He says, “U.” His response
to the question in each case is one word. The absolute, “No” and the
absolute, “Yes.”
In Zen there are no opposites. There is no duality. The
formula is found in the “Heart Sutra.” :
Form is emptiness
Emptiness is form
Form is contained in emptiness,
emptiness is contained in form.
Form interpenetrates emptiness,
emptiness interpenetrates form.
Good is contained in evil,
evil is contained in good.
Good interpenetrates evil,
evil interpenetrates good.
Light is contained in darkness,
darkness is contained in light.
Light interpenetrates darkness,
darkness interpenetrates light.
Mu interpenetrates U,
U interpenetrates Mu.
Yes interpenetrates No,
No interpenetrates Yes.
In the realm of the absolute, Yes and No
are the same, yet different.
In the realm of the absolute,
all experience is Yes and
all experience is No.
In the realm of the absolute,
everything is contained.
In the realm of the absolute,
there is nothing to be contained,
and there is no container.
There is no dog,
No monk,
No Zhaozhou,
No Buddha Nature!
No Mu.**
Mu.
******
http://www.treetopzencenter.org/Reflections on the Wumenkuan.pdf
*koans: a riddle presented in non-logical terms designed to short-circuit the rational mind, thereby triggering satori, or enlightenment, eg: "What is the sound of one hand clapping?"
**
Regarding this passage, there is a Zen story that goes like this:
Anger
When the Tesshu, a master of Zen, calligraphy and swordsmanship, was a young man he called on the Zen master Dokuon. Wishing to impress Dokuon he said, “The mind, the Buddha, and all sentient beings after all do not exist. The true nature of phenomenon is emptiness. There is no realisation, no delusion, no sagacity, no mediocrity, nothing to give and nothing to receive.
Dokuon promptly hit him with a bamboo stick. Tesshu became quite furious.
Dokuon said quietly: “If nothing exists, where did this anger come from?”
(That is, a few people have tried to build models of reality where space and time arise out of some other interaction. The universal wavefunction is a common, but rarely considered, aspect of known, mainstream quantum theory.)