A monk asked Joshu: `Has a dog Buddha-nature or not?'
Joshu answered: "Mu
(Myrmidion's note, Mu, or Wu in Chinese is a character that means nothing, non-being, not, negation)
Mumon's comments: To come to enlightenment, you have to pass the barrier of the patriarchs. It always comes after your way is blocked. If you do not pass the barrier, you are entangled, clinging to grass. You ask, what is a barrier? It is this word: Mu.
This is barrier of meditation. If you pass it, you will see Joushu, and work with all the patriarchs. The hair of your eyebrows entangled with theirs, and see with the same eyes, and hear with the same ears. Is this not good? Wouldn't you like to pass the barrier?
To pass the barrier, you must work with every bone, with every hair follicle, to answer this question. What is Mu? Think on it all day and all night. It is not the word meaning nothing. Do not think of existence. To pass this barrier, it will be like eating a hot iron, that you cannot spit out. When you reach enlightenment, your previous thoughts disappear. As the ripening of fruit, your knowledge of things, and external knowledge come together. It is like mute who has dreamt a dream, because he knows it, but cannot speak of it.
When you know this, your self is crushed, and you can move heaven and earth. You are like a warrior (General Guan) with a sharpened sword. If Buddha stands in your way, cut him down, and if a patriarch obstructs your way, kill him. Thus will you be free of samsara, and enter any world.
Does a dog have Buddha nature?
This is the greatest question of all.
If you say yes or no,
You lose your own Buddha-nature.