Too full to learn - a story

A scholar visited the monk Nanyin to ask him about Zen. Nanyin offered some tea to his guest, but he continued pouring even after the cup was full. After a short while, the scholar could not stand it any longer and said "the cup is already full! Stop pouring!". Nanyin replied "You are just like this cup, full of your views and opinions. If you do not empty your cup first, how can I tell you about Zen?"