Nan-in, a Japanese Zen master, received a visiting teacher who came to inquire about Zen.
The man came inside and sat down, Nan-in served tea. He poured his visitor’s cup until it was full, but then kept pouring.
The visitor watched his teacup overflow until he no longer could restrain himself. “It is completely full. No more tea will go in!”
“Like this cup,” Nan-in said, “you are full of your own opinions and speculations. How can you begin to learn unless you have first emptied your cup?”