Mumonkan = The Gateless Gate. Hekiganroku = Blue Cliff Records. Both are collections of classic and well worn Zen koans with layers of commentary by more contemporary, but still old for our time, teachers and thinkers - mostly, I believe, from China but with phonetic Japanese names. The function of the koan is to bring the mind to enlightenment by breaking through it's lifelong foundation in logic and linearity. They are deceptively brief and mundane, sometimes a bit perverse or violent, and frequently hilarious. I consider these stories to have something of a magical quality, something non-verbal and esoteric buried in the words that can teach me about my mind if I just commit enough time to it. They are impossibly impenetrable and function on many levels. These collections are wonderful because the comments are as poetic and difficult as the original story. To be clear, despite my experience with Japanese and Chinese culture, I'm not sure that I truly 'understand' any of these stories in the cultural context within which they were created. At the same time, the whole notion of 'understanding' is up for debate in Zen thought.
Does a dog have the Buddha nature?
Mu.