Attention!
A monk asked Zen Master Joshu: "Does a dog have Buddha Nature [the potential for enlightenment]?"
Master Joshu replied: "Yes."
Then the monk said: "Since it has, how did it get into that bag of skin?"
Master Joshu answered: "Because knowingly, he intentionally offends."
On another occasion a monk asked Master Joshu: "Does a dog have Buddha Nature?"
Master Joshu answered: "No!" [Mu, which means "no-thing" in Chinese, non-thing-ness, non-identity, impersonal.]
Then the monk asked: "If all beings have Buddha Nature, why doesn't the dog have it?"
Master Joshu answered: "It is because of his having karmic consciousness."
APPRECIATORY VERSE
A dog's Buddha Nature, yes.
A dog's Buddha Nature, no.
From the first a straight hook [spear] seeks fish with abandon.
Chasing the breeze, seeking the fragrance -- a cloud and water mingle.
Pattering and chattering to make debates and excuses, it is evenly revealed, grandly displayed.
Don't worry that he is not careful at the start.
Pointing to the fault, he snatched the jewel away.
King Shin did not know Shojo Rin.