A university professor went to visit a famous Zen master. While the master quietly served tea, the professor talked about Zen, asking many, many questions. 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, "Full of your own opinions and speculations. How can I show you Zen unless you first empty your cup."
Comment: I've read many variations on this parable, this is the shortest. Other's make a point to note the professor is prideful in his intellectual accomplishments and either secretly wonders if the master can teach him anything or has so many questions for the master that he cannot possibly be contemplating any of the answers. This reinforces a basic Buddhist tenet of "relinquishing". Parables will have a permanent home in the Wisdom section.