I keep seeing the following koan:

A monk asked Zhàozhōu, "Does a dog have Buddha nature or not?" Zhaozhou said, "Wú".

What does this mean and why is it important?

More specifically: Does "Wú" mean "no" in this context, or does it mean "the question doesn't make sense and therefore cannot be answered"? I've seen both interpretations, which one is correct?

  • It is supposed to be spelled, Woof!
    – user2341
    Commented Jun 29, 2017 at 2:24

3 Answers 3


We should really have a rule on here not to provide koan answers! It's so important that you figure them out for yourself! Written out, the answers become hollow and never approach their true 'meaning'. That said (and no spoilers follow!)...

Mu does mean no, but it also can translate as blankness, voidness, or absence. That should ring a bell regarding the concept of emptiness or shunyata. The koan really doesn't have anything to do with dogs or whether or not they have a Buddha nature. It has more to do with this idea of emptiness - what it is and the initial experience of it. The monk in this koan is all caught up in scholasticism and conceptualism. He's using his small mind to try and understand a concept that it's just not capable of of apprehending. Zhaozhou's answer is an attempt to shake that monk out of his smaller way of thinking and point him instead to mu - the true essence of Zen.

  • 1
    PS - mu is Japanese. Same word, though.
    – user698
    Commented Sep 2, 2014 at 16:08
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    Does it mean that a dialogue involving any random question, e.g. "What time is it?" "Wú" would be just as good a koan?
    – kami
    Commented Sep 2, 2014 at 16:13
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    Not providing koan answers seems like one for meta so I've asked the question there meta.buddhism.stackexchange.com/q/271/157 Commented Sep 2, 2014 at 16:56
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    @michau - Possibly, but that's actually a whole other topic - namely how the hua-t'ou (repeated phrase) operates in Zen meditation. While the important part of the koan is the hua-t'ou mu/wu, I doubt that another random yes/no question would have the impact as the original or garnered the same reputation.
    – user698
    Commented Sep 2, 2014 at 17:42
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    @michau - there's a reason why we talk more about the negative version rather than the positive version! I think the koans are getting at two slightly different ideas. The positive version kind of gets me thinking of the Heart Sutra, but that just speculation on my part. Also, when I say 'important part', I mean wu serves as the hua-t'ou if you are going to meditate on the koan.
    – user698
    Commented Sep 3, 2014 at 13:16

People often report this koan with out explaining the surface meaning. Chinese at the time considered dogs nasty dirty animals, that hold the same position as pigs in the western mind. Pigs or cockroaches or those parasites that burrow into your eyes. So the surface question is can the most contemptible being become enlightened.

The surface meaning of the most common answer, Mu is Buddhist jargon, meaning emptiness, sunyata. In the Mahayana system, you are enlightened when you realize the truth of sunyata, i.e. that you have no self (no atman), everything changes over time and various other things that I don't have space for here.

In my opinion, koan practice is a practice. You think about a question and always are told that your answer is wrong. During this process, many people report flashes of insight where they subjectively feel that they have grasped the answer, i.e. satori or sudden enlightenment. Reasoning takes time, so sudden enlightenment can't be done in step by step reasoning.

In China, there was a huge multiyear (multi decade?) discussion on if enlightenment was a matter of following steps or if it was something that happened to you in a flash. In China and Japan, the sudden enlightenment proponents won.

Some modern critics say that especially in Japan with a new funerary and post mortem outlook, have moved onto a form of Zen where sunyata is a sudden realization that you do have an immortal self, which contradicts early Buddhist thought.

  • sounds like you are describing incubation. Is it correct to say that koans are designed to prolong the experience of sudden insight as long as possible?
    – Ooker
    Commented Feb 25, 2019 at 15:00

I have always found koans to be useful tools for thought. Through study of the dharma, interaction with the sangha and a variety of other means we reach new insights that are much like dull tools. Through their use applied against the situations in various koan we find their true worth. There is no right answer to a grinding wheel.

    – user698
    Commented Jun 29, 2017 at 14:00

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