renowned Zen master said that his greatest teaching was this:

Buddha is your own mind.

So impressed by how profound this idea was, one monk decided to leave the monastery and retreat to the wilderness to meditate on this insight. There he spent 20 years as a hermit probing the great teaching. One day he met another  monk who was traveling through the forest. Quickly the hermit monk learned that the traveler also had studied under the same Zen master. "Please, tell me what you know of the master's greatest teaching."
The traveler's eyes lit up, "Ah, the master has been very clear about this. He says that his greatest teaching is this:

"Buddha is NOT your own mind."