A university professor came to a Zen master to find out something about Zen. Nin-in, the Zen master, offered him some tea. He poured the tea into his cup and kept pouring even when the cup overflowed.
When he saw what was happening, the professor remarked, “The cup is flowing over. You cannot pour any more into it.”
“You’re right; and you are just like this cup. You are full to overflowing with your own insights and speculations. How can I tell you anything about Zen before you empty your cup?”
– “Spielend Leben”
Only an unbiased mind – and for that matter, to that extent empty – can seek after or acquire truth . So first empty your mind of the prejudices that are filling it already.