A University Professor went to see Nan-in, a Zen Master, to find out more about Zen.
As their meeting continued Nan-in was pouring Tea and continued to pour even though the cup was overflowing.
The Professor cried. "Enough! No more will go in!"
Nan-in replied "Like this cup you are full of your own opinions and speculations. How can I show you Zen unless you first empty your cup?"