Kōan

A kōan (Chinese gong’an, “public case”) is a story, dialogue or saying from the Chan and Zen masters, presented to a student as a problem to be resolved not by reasoning but by awakening. Examples include Zhaozhou’s answer “Mu” (“no”) to the question whether a dog has buddha-nature, and Hakuin’s question about the sound of one hand.

The kōans were collected in the Song dynasty, with commentaries, in such works as the Blue Cliff Record and the Gateless Barrier. The master Dahui Zonggao taught students to concentrate on the critical phrase of a kōan (huatou), such as “Mu”, with great doubt, until the doubt shatters in awakening. In Japanese Rinzai practice, especially after Hakuin, students work through a long sequence of kōans, presenting their understanding to the teacher in private interviews.

The kōan is not a riddle with a hidden answer but a means of exhausting discursive thought and bringing the student to see directly. Critics within Zen, among them Dōgen, warned against treating kōans mechanically, though Dōgen himself commented on many.