I really like this old story about a Zen master.
A professor who wanted to discover what Zen was made an appointment to meet him. One morning he arrived at the Zen master’s house and was invited to sit down. As they sat, the professor went on and on about this theory and that theory, this hypothesis and that hypothesis.
The Zen master asked the professor if he would like some tea. The professor said yes. The master began to pour tea for him. The cup reached the top, and the Zen master continued to pour. The tea began to spill all over the table unto the floor.
The professor could not hold back any longer: “What’s wrong with you? Don’t you know that the cup is full?”
The Zen master replied, “Just like the cup. You are full of knowledge and information, and there is no room to add anything more. I cannot teach you Zen when you are so full of opinions. First empty the cup, and then return to me.”