Mu

A monk asked the master,

"Does a dog have Buddha Nature?"

The master said, "Mu."

Zen Buddhism is known for its koans-- paradoxical anecdotes or riddles that are used to provoke enlightenment. Mu is a popular first koan. In Zen Buddhism, everyone and everything has buddha nature. So, why did the master answer no (mu) to the question from the monk?

Koans are meant to jostle the mind, to awaken the practitioner. The discrepancy of all beings having Buddha nature, but the master saying no, provides a sense of being unsure-- to cut through the typical way of thinking. It shuts off the analytic way of thinking and allows us to just live in the moment. No interpretation, no busy mind trying to interpret the world for us.

This isn't an interpretation. I can't do that for you. I can't even claim to have mastered it myself, but it is a start for fellow seekers.