Koans are enigmatic spiritual formulas used for religious training in the Zen Buddhist tradition. This innovative religious practice is one of the most distinctive elements of this tradition, which originated in medieval China and spread to Japan and Korea. Perhaps no dimension of Asian religous has attracted so much interest in the West, and its influence is apparent from beat poetry to deconstructive literary critisism. The essays collected in this volume, all previously unpublished, argue that our understanding of the koan tradition has been severely limited. The authors try to undermine stereotypes and problematic interpretations by examining previously unrecognized factors in the formation of the tradition, and by highlighting the rich complexity and remarkable diversity of koan practice and literature.