It happened once that a certain man came to visit a Zen Roshi. After exchanging greetings, the man said, “Roshi, I have studied philosophy for many years, learning from many sources, and I would like now to hear what Zen can teach about several important themes that are the subject of a book I wish to write.”

The Roshi said, “Shall we have tea?”

In a short time a teapot and two cups stood on the table. Silently, the Zen master picked up the teapot and began to pour – but when the cup was full, he did not stop. He continued to pour, so that tea began to spread over the table.

The visitor stared at this in astonishment, and then said, “Roshi, the cup is full! No more will go in!”

The Roshi set the teapot down, and said, “And so it is with your mind. It is full of so many thing, there is no room for anything more. To know about Zen you must empty your mind.”