The 'Gateless Barrier' is generally acknowledged to be the fundamental koan collection in the literature of Zen. Gathered together by Wu-men (Mumon), a thirteenth-century master of the Lin-chi (Rinzai) school, it is composed of forty-eight koans, or cases, each accompanied by a brief comment and poem by Wu-men. | The Gateless Barrier by Robert Aitken, Paperback | Indigo Chapters