The Japanese master

A great Japanese master received a university professor who came to enquire about wisdom. The master served tea. He poured his visitor's cup full, and then kept on pouring. The professor watched the overflow until he could no longer restrain himself. 'It is overfull. No more will go in!' 'Like this cup,' the master said, 'you are full of your own opinions and speculations. How can I show you wisdom unless you first empty your cup?'