For other uses, see Koan

The kōan (Chinese: 公案;^[1] Korean: 공안, romanized: kong'an) are groupings of related questions and answers which are a paradox.^[2] The kōan may be a story which cannot be understood or explained easily.

The kōan can be a special kind of metaphor with a hidden meaning,^[3] such as "the sound of one hand clapping".^[4]

Kōans originate in the sayings and events in the lives of wise men and legendary figures.

A kōan can refer to a story selected from Buddhist historical records and sutras.

The kōan is a fundamental part of the history and practice of Zen Buddhism.^[5]

• "Firewood becomes ash and it does not become firewood again".^[6]
• "The verbal and the nonverbal are like vines clinging to a tree".^[7]

• Blue Cliff Record or Account of the Blue Montains Chinese: 碧巖錄; Japanese: Hekigan-roku,^[2] is a collection of 100 kōans compiled in 1125 by Yuanwu Keqin (圜悟克勤 1063–1135).
• The Book of Equanimity or Book of Serenity Chinese: 從容録; Japanese: 従容録, romanized: Shōyōroku^[8] is a collection of 100 Kōans compiled in the 12th century by Hongzhi Zhengjue (宏智正覺 1091–1157)^[9]
• The Gateless Gate or the Gate with no Entrance Chinese: 無門關; Japanese: Mumonkan^[2] is a collection of 48 kōans and commentaries published in 1228 by Chinese monk Wumen (無門 1183–1260). The title may be more accurately rendered as Gateless Barrier or Gateless Checkpoint.

• The Gateless Gate 48 Zen kōans compiled in the early 13th century
• Book of Serenity Archived 2006-05-21 at the Wayback Machine A collection of 100 kōans, originally compiled in the 12th century
• Life at the Monastery Archived 2011-12-25 at the Wayback Machine – a humorous look at kōans
• Zen Buddhism Koan Study Pages
• Koan Collections and Studies
• Short Zen Poems, Koans^{[permanent dead link]} – Collection of modern koans.
• Zen Koans: Transcending Duality – a list of kōans
• What is the sound of one hand clapping?

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