Zen masters used to test their students by doing something particularly annoying. Then, when the student got upset, they felt the lesson rather than just hear or read about it. There is no better feeling than anger!
Here are two Zen stories that point to these matters:
One day Mara, the Evil One, was travelling through the villages of India with his attendants. he saw a man doing walking meditation whose face was lit up on wonder. The man had just discovered something on the ground in front of him. Mara’s attendant asked what that was and Mara replied, “A piece of truth.”
“Doesn’t this bother you when someone finds a piece of truth, O Evil One?” his attendant asked. “No,” Mara replied. “Right after this, they usually make a belief out of it.”
Yamaoka Tesshu, as a young student of Zen, visited one master after another. He called upon Dokuon of Shokoku.
Desiring to show his attainment, he said: “The mind, Buddha, and sentient beings, after all, do not exist. The true nature of phenomena is emptiness. There is no realization, no delusion, no sage, no mediocrity. There is no giving and nothing to be received.”
Dokuon, who was smoking quietly, said nothing. Suddenly he whacked Yamaoka with his bamboo pipe. This made the youth quite angry.
“If nothing exists,” inquired Dokuon, “where did this anger come from?”