Zen students study with Zen masters for at least 10 years before they are allowed to teach others.
Tenno, who, having completed his apprenticeship, became a teacher, came to visit Nan-In. It was a rainy day, and Tenno put on his wooden shoes and took an umbrella.
After the greeting, Nan-In remarked:
- I think you left your shoes in the hallway. I would like to know whether your umbrella is to the right or left of your shoes?
The embarrassed Tenno could not give a decent answer. He realized that he could not realize Zen in himself every minute. He became Nan-In's student and studied for another 6 years to perfect his moment-to-moment Zen.