The wild fox kōan, also known as "Pai-chang 's fox" and "Hyakujō and a Fox", is an influential kōan story in the Zen tradition dating back as early as 1036, when it appeared in the Chinese biographical history T'ien-sheng kuang-teng lu. It was also in The Gateless Gate (Mandarin: 無門關 Wúménguān; Japanese: 無門関 Mumonkan), a 13th-century collection of 48 kōans compiled by the Chinese monk Wumen, as case two. Overview The koan tells the story of a monk who, after denying that an enlightened person falls into cause and effect, was turned into a wild fox for five hundred lifetimes. He appears to Zen Master Baizhang (Wade-Giles: Pai-chang; Japanese: Hyakujō) and demands a "turning word," a phrase intended to prompt one to realization, to be freed from his animal form. After Baizhang tells him not to ignore cause and effect, the monk confirms that he has been released from his wild fox body and asks to be given a monk's funeral rites. Later, when Baizhang's disciple Huangbo (Wade-Giles: Huang-po; Japanese: Ōbaku) asks what would have happened had the monk not denied cause and effect, Baizhang tells Huangbo to come close so he can answer him. Huangbo steps forward and slaps Baizhang, ostensibly in the awareness that Baizhang had intended to strike him. Baizhang laughs approvingly and compares Huangbo to the Indian monk and Zen patriarch Bodhidharma. The kōan Main case Tanahashi gives the following rendering of the koan: Wumen's commentary and poem Shibayama gives the following translation of Wumen's commentary and verse: Interpretation The meaning of the kōan has been the object of intense debate and scrutiny within Zen due to its complexity and multi-layered themes. It was rated by Zen Master Hakuin (1686–1769) as a nantō kōan, one that is "difficult to pass through" but has the ability to facilitate "postenlightenment cultivation" or "realization beyond realization" (shōtaichōyō). Important themes include causality (karma in Buddhism), the power of language, reincarnation, and the folklore elements involved in the insertion of the fox into the tale. Traditionally, interpretations since the time of the Mumonkan have stressed the nonduality of the two understandings of causality expressed within the case. Dōgen, regarded by Sōtō adherents as the founder of their practice, recast the kōan in the later part of his life as an affirmation of the fundamental importance of acknowledging cause and effect. The significance of this debate goes to fundamental issues in Buddhist