Yamaoka Tesshu, a samurai and student of Zen, traveled around Japan studying from various Zen masters. One day, he wandered into the Shokoku Temple and happened upon the monk Dokuon.In a desire to show his comprehension of Zen, Tesshu stated to the Master, "The mind, the Buddha and all beings are empty. The true nature of all things is emptiness. There is no enlightenment, no delusion; no sages, no commoners; no toil, no reward."
Master Dokuon remained quiet for some time and then banged him on the head.
Tesshu fumed in anger and asked, "What did you do that for?"
Master Dokuon replied, "If everything is empty, where did the temper come from?"