Filled to the Brim

An American professor who had made a lifetime's study of the Japanese tea ceremony heard about an old man living in Japan who was a master of the tea ceremony. He decided to make a special trip to Japan to meet up with the tea expert.

He found the master living in a small house on the outskirts of Tokyo and they sat down to have tea together. The professor immediately started talking about the tea ceremony, his studies, all he knew about it and how he was looking forward to sharing his learning with the old man.

The old man said nothing and started to pour tea into the professor's cup. While the professor talked, the old man continued to pour the tea. The cup was filled to the brim but the old man kept pouring. The tea overflowed and spilled down the sides of the cup in a stream onto the floor. 

"Stop!" yelled the professor. "You are crazy. You can't fit any more tea in that cup. It's full!"

"I was just practising," replied the old man, "for the task of attempting to pass learning to a mind that is already full."