Koans are enigmatic spiritual formulas used for religious training in the Zen Buddhist tradition. Arguing that our understanding of the koan tradition has been extremely limited, contributors to this collection examine previously unrecognized factors in the formation of this tradition, and highlight the rich complexity and diversity of koan practice and literature.

he form and function of Koan literature: a historical overview / T. Griffith Foulk --
The antecedents of encounter dialogue in Chinese Chʻan Buddhism / John R. McRae --
Mahākāsyapa's smile: silent transmission and the Kung-an (Kōan) tradition / Albert Welter --
Kung-an Chʻan and the Tsung-men tʻung-yao chi / Ishii Shūdō --
Visions, divisions, revisions: the encounter between iconoclasm and supernaturalism in Kōan cases about Mount Wu-tʻai / Steven Heine --
"Before the empty eon" versus "A dog has no Buddha-nature": Kung-an use in the Tsʻao-tung tradition and Ta-hui's Kung-an introspection Chʻan / Morten Schlütter --
Kōan history: transformative language in Chinese Buddhist thought / Dale S. Wright --
Ikkyū and Kōans / Alexander Kabanoff --
Transmission of Kirigami (secret initiation documents): a Sōtō practice in medieval Japan / Ishikawa Rikizan --
Emerging from nonduality: Kōan practice in the Rinzai tradition since Hakuin / Michel Mohr --
Kōan and Kenshō in the Rinzai Zen curriculum / G. Victor Sōgen Hori.