Once, a long time ago, there was a wise Zen master called Nan-In. People from far and near would seek his counsel and ask for his wisdom. Many would come and ask him to teach them, enlighten them in the way of Zen. He seldom turned any away.
One day an important and learned man, a man used to command and who was used to being listened to came to visit the master. “I have come today to ask you to teach me about Zen. Open my mind to enlightenment.” The tone of the important man’s voice was one used to getting his own way.
The Zen master smiled and said that they should discuss the matter over a cup of tea. When the tea was served the master starting pouring tea in his visitor’s cup. While he was pouring the learned man started explaining everything he had read and knew about Zen philosophy. The Zen master listened quietly and he kept pouring the tea while the man kept talking and talking. He poured and he poured and the tea rose to the rim and began to spill over the table and finally onto the robes of the wealthy man. Finally the visitor shouted, “Enough. You are spilling the tea all over. Can’t you see the cup is full?”
The master stopped pouring and smiled at his guest. “You are like this tea cup, so full of knowledge and ideas that nothing more can be added. How could I possibly teach you about Zen when you are already full? Before you start to learn, you have to empty your cup.”