Yangshan's Mind and Environment (BS32)

KOAN:

Yangshan asked a student, “Where are you from?”
The student said, “From Yu province.”
Yangshan said, “Do you think of that place?”
The student said, “I always think of it.”
Yangshan said, “The thinker is the mind and the thought-of is the enviroment. Therein are mountains, rivers, the land, buildings, towers, halls and chambers, people, animals, and so forth. Reverse your thought to think of the thinking mind—are there so many things there?”
The student said, “When I get here, I don’t see any existence at all.”
Yangshan said, “This is right for the stage of faith, but not yet right for the stage of the person.”
The student said, “Don’t you have any other particular way of guidance?” Yangshan said, “To say that I have anything particular or not would not be accurate. Based on your insight, you only get one mystery—you can take the seat and wear the robe. After this, see on your own.”

—Book of Serenity Case 32