At one time a monk asked Master Joshu, “Does a dog have Buddha Nature or not?” Master Joshu answered, “No.”
In the chapter of Shobogenzo titled Bussho or “Buddha Nature” Master Dogen talks about the meaning of this word “no” as it relates to a conversation between the fifth and sixth patriarchs. He says, “This ‘no’ is not the ‘no’ of ‘have’ or ‘have not.’ It is the no of no no.”
The no of no no is a way of expression that we do not often hear. The no of no no means that even no is denied.
In other words, this is not the kind of no which we conceive in our brains as the conclusion to the question of whether something exists or not. The meaning of no as it is used here does not require any kind of thinking at all.
In regards to this koan there is no shortage of explanations that this “no” represents the no of no in other words the absolute no, or that it represents the absolute void, or that it’s something that cannot possibly be understood, or other similar nonsense which even those who spout it don’t seem to understand.
But by slandering the Buddha’s truth with such nonsense, people who put out these kinds of explanations are really just floundering in the darkness, not knowing what is what and tasting the miseries of Hell.
In the chapter of Shobogenzo titled “Sutra of Mountains and Water” Master Dogen says that any koan has a superb theoretical meaning. The purpose of the koan stories is to make difficult points of Buddhist philosophy clear by using a concrete example. The tendency among many Chinese monks to view the koans as some kind of riddle whose original meaning was impenetrable was something Master Dogen scoffed at.
A dog which exists before your eyes is most certainly a dog. There is nothing extra added to that dog. And there is nothing lacking in the dog either, nothing apart from itself that it needs in order to be what it is — a dog. A dog is a dog. Joshu understood that to theorize about whether a dog has Buddha nature or not is just adding something extra. When dealing with any koan it is necessary to read it in this way on the basis of Buddhist philosophy.
I am an old monk of over 70 years who has spent the past fifty or more years studying Master Dogen’s Shobogenzo. Therefore I am an amateur when it comes to the koans included in Mumonkan and I have some misgivings. But on the basis of the Buddhist philosophy which I have absorbed through long years of studying Shobogenzo, there is no room for doubt about the meaning of this koan.