Koan PracticeSome Zen Buddhists practice meditation on koans during zazen. A koan (literally "public case") is a story or dialog, generally related to Zen or other Buddhist history; the most typical form is an anecdote involving early Chinese Zen masters. Koan practice is particularly emphasized by the Japanese Rinzai schools, but it also occurs in other forms of Zen.
According to one view, a koan embodies a realized principle, or law of reality. Koans often appear paradoxical or linguistically meaningless dialogs or questions. The 'answer' to the koan involves a transformation of perspective or consciousness, which may be either radical or subtle, possibly akin to the experience of metanoia in Christianity. They are a tool to allow the student to approach enlightenment by essentially 'short-circuiting' the logical way we order the world. In order to try to answer these often unanswerable problems, the thinker may be forced to create new mental pathways. Those pathways then may be useful for other problems, thus producing a "mind expansion" effect.
The Zen student's mastery of a given koan is presented to the teacher in a private interview, referred to as dokusan (独参), daisan (代参), or sanzen (参禅). Zen teachers advise that the problem posed by a koan is to be taken quite seriously, and to be approached as literally a matter of life and death. Koans do not have "no answer". There is a sharp distinction between right and wrong ways of answering a koan—although there may be many "right answers", practitioners are expected to demonstrate their understanding of the koan and of Zen through their answers.
While there is no single correct answer for any given koan, there are compilations of accepted answers to koans that serve as references for teachers. These collections are of great value to modern scholarship on the subject.