A university professor went to visit a famous Zen master. While the master quietly served tea, the professor talked about Zen.
The master poured the visitor’s cup to the brim, and then kept pouring.
The professor watched the overflowing cup until he could no longer restrain himself. “It’s overfull! No more will go in!” the professor blurted.
“You are like this cup,” the master replied, “You are full of ideas. You come and ask for teaching, but your cup is full; I can’t put anything in. Before I can teach you, you’ll have to empty your cup.”
Moral: keep an open mind.