The sensei picked up the teapot and began to pour tea into one of the cups.  Soon the cup was full, but the sensei kept pouring and tea was running down the sides of the cup and into the tray.  She finally shouted, “Stop, can’t you see the cup is full and no more will fit into the cup?”
The sensei smiled and said, “Like this cup, your mind is full of what you believe and don’t believe.  Before you can learn more, you must empty your cup to make room for more.