In this koan the monastic is asking, given our original perfection, why do we need to practice? In the early years of Dogen's training, this question was uppermost in his mind. It is what drove him to study exhaustively and to travel to China. It's a question that many of my students ask me: "Since I'm already enlightened, why do I have to do anything?" Because it is through practice that realization and actualization ultimately take place. It is through practice that we must see for ourselves how Mayu's fanning himself is not only the wind reaching everywhere, but the fan, Mayu, the monastic, and us reaching everywhere.
To be "in the mountains" is the opening of flowers in the world. Those outside the mountains do not sense this, do not know this. Those without eyes to see the mountains do not sense, do not know, do not see, do not hear this truth.
"A flower opens and the world arises" is a line from a verse written by the Indian master Prajnatara. This phrase has also been translated as "opening within the world flowers," which means that mountains and the world are one reality. In Zen we use the expression: "In the marketplace, yet not having left the mountain; on the mountain, yet manifesting in the world."
Furthermore, nothing exists outside the mountains. Dogen refers to those "in the mountains" or "outside the mountains," but when he speaks of those "in the mountains," he is not discriminating between those "in the mountains" and the mountains themselves. He is in fact saying that the mountains are identical to those who are "in the mountains." "Those outside the mountains" are also the mountains themselves. The mountain reaches everywhere.
Then there is the line: "Those outside the mountains do not sense this, do not know this." There are two ways of understanding this. Those outside the mountains are not aware of the mountains walking because they are the mountains. They no longer have a reference system with which to see or sense or hear the mountains. Another interpretation is that "those without eyes to see" are suffering from the blindness of ignorance.
In Buddhism there are five kinds of blindness. The first is what we call the blindness of ignorance or separation. The second, the blindness of the heretic who denies the teachings of Buddhism. The third is the blindness of emptiness, where a person first perceives the absolute basis of reality. The fourth is the blindness of attaching to emptiness. The fifth is transcendental blindness, in which there is no distinction between seeing and not seeing.