When a scholar of Zen Buddhism has a dog called Mu, as I do, people think they know why. But things are not always what they seem, and my black lab’s name does not come from the famous koan “Mu.” It derives, rather, from Mustafa—the name given him at the humane society when he was picked up as a stray puppy. Mustafa soon became Musty and then just Mu. . . his Buddha-nature was never in question.

The koan “Mu,” a.k.a. “Chao-chou’s Dog,” also has a pedigree that is rather different from what one might imagine. Today this koan is regarded as an ideal device for cutting off discursive, conceptual thought and for leading Zen trainees to an initial experience of enlightenment; yet it actually derived from a highly intellectual, scholastic debate over the presence of Buddha-nature in sentient and insentient beings that continued for centuries during medieval Chinese Buddhism. Readers who want a taste of the arcane details of that debate, and a lucid interpretation of the koan in its original philosophical context, are advised to check out an article by Robert Sharf entitled “On the Buddha-nature of Insentient Things.”

As Sharf points out (the following translations are all his), the discourse records of the Ch’an master Chao-chou Ts’ung-shen (778-897) contain three dialogues in which the master responds to questions about Buddha-nature. The first such exchange reads as follows:

[A student] asked: “Does a dog also have buddha-nature or not?” The master said: “It does not” [in Chinese, “wu”; pronounced “mu” in Japanese]. [The student] said: “Everything has buddha-nature, from the buddhas above to the ants below. Why does a dog not have it?” The master said: “Because it has the nature of karmically conditioned consciousness.”

Here the student expressed what all Chinese Buddhists from about the seventh century on took for granted: that all sentient beings are innately possessed of Buddha-nature (or Buddha-mind). Chao-chou’s “wu” was thus unexpected and perhaps intended to shock, but it was not necessarily enigmatic. He may simply have wished to stress the point that although living beings have Buddha-nature, unless they realize that fact by “seeing the nature” they remain caught up in delusion and continue to suffer in the karmically conditioned round of rebirth.

The second relevant exchange in Chao-chou’s record reads:

[A student] asked: “Does an oak tree also have buddha-nature or not?” The master said: “It has.” [The student] said: “Then when will it become a buddha?” The master said: “When the sky falls to the earth.” [The student] said: “When will the sky fall to the earth?” The master said: “When the oak tree becomes a buddha.”

Here the question concerns the presence of Buddha-nature in an insentient thing, a tree. Chao-chou is willing to concede that, in a certain sense, all of existence is coextensive with Buddha-nature or Buddha-mind (for nothing could exist “outside” of it). He wants to argue, however, that only sentient beings can “become” buddhas by waking up to or seeing the Buddha-nature within them; such an epistemological transformation is impossible for insentient beings, at least until the end of the world.

The third exchange reads:

[A student] asked: “Does a dog also have buddha-nature or not?” The master said: “The [road] in front of every house leads to Ch’ang-an [the capital].”

Here Chao-chou affirms that all sentient beings do in fact have Buddha-nature, dogs included, but again he implies that they need to wake up to that fact if it is to do them any good. The “road that leads to Ch’ang-an” may run in front of every house, but unless one actually travels it, the sights and smells of the capital can only be imagined.

Some of the dog lovers who have contributed to this issue suggest that their own pooches have not only gone for walks around their neighborhood streets, but actually have made the trip to Ch’ang-an. It is unlikely, however, that Chao-chou had such a fond view of the species: Dogs in medieval China were more likely viewed as filthy curs, or as sources of protein, than as “man’s best friend.” They were, on occasion, identified in Buddhist morality tales as bodhisattvas in disguise, as were beggars and pregnant women, but such stories gained their edifying force precisely from the ordinarily low, polluted state of the beings in question.

My Mu is a beloved pet, but he surely has not glimpsed his own Buddha-nature. Nor does he recognize that of squirrels: The mere sight of one, and all of his bad karma, born of beginningless greed, hatred, and delusion, comes rushing out in an eye-popping, hackle-raising snarl. And when it comes to oak trees, lamp posts, and other insentient things, not even their Buddha-nature can save them from the indignity of being his territorial markers.

Chao-chou’s dog eventually strayed from the master’s discourse record and was adopted by Wu-men Hui-k’ai (1183-1260) as the first case of his koan collection entitled Gateless Barrier (Wu-men-kuan). According to that text:

A monk asked master Chao-chou: “Does a dog also have buddha-nature or not?” The master said: “It does not.”

The exchange was shortened in this context, eliminating the follow-up question about buddhas and ants, and Wu-men added a comment that instructs us not to think about the meaning of Chao-chou’s “wu,” but simply to break the bonds of intellect and directly penetrate its deep meaning. The way of philosophy being thus cut off, people ever since have been without a clue as to what the master meant. I, for one, can do little more than leave my mark on the oak tree and hope that some of you may sniff it out.

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