The Gateless Barrier
The Gateless Barrier (Mandarin: 無門關 "Wúménguān"; Japanese: 無門関 "Mumonkan"), sometimes translated as The Gateless Gate, is a collection of 48 Chan (Zen) koans compiled in the early 13th century by the Chinese Zen master Wumen Huikai (無門慧開; Japanese: "Mumon Ekai"; 1183–1260). The title has a double meaning and can also be understood as Wumen's Barrier; the compiler's name, which literally means "No Gate", is the same as the title's first two characters. Wumen's preface indicates that the volume was published in 1228. Each koan is accompanied by a commentary and verse by Wumen . A classic edition includes a 49th case composed by Anwan (pen name for Cheng Ch'ing-Chih) in 1246. Wu-liang Tsung-shou also supplemented the volume with a verse of four stanzas composed in 1230 about the three checkpoints of Zen master Huanglong. These three checkpoints of Huanglong should not be confused with Doushuai's Three Checkpoints found in Case 47. Along with the "Blue Cliff Record" and the oral tradition of Hakuin Ekaku, "The Gateless Gate" is a central work much used in Rinzai School practice. Five of the koans in the work concern the sayings and doings of  Zhaozhou; four concern Ummon. The common theme of the koans of the Wumen Guan and of Wumen's comments is the inquiry and introspection of dualistic conceptualization. Each koan epitomizes one or more of the polarities of consciousness that act like an obstacle or wall to the insight. The student is challenged to transcend the polarity that the koan represents and demonstrate or show that transcendence to the Zen teacher. Structure and contents. The text was originally prepared by Wumen as a record of his teaching during a monastic training period held at "Longxiang" (Soaring Dragon) monastery in the summer  of 1228. Wumen selected the 48 koans and commented on and added a verse for each koan. His teachings were transcribed and after the training period were compiled into the collection called the Wumen Guan. As was customary in China at the time, an edition might have additions of text inserted by a subsequent owner or publisher. The most well known version of the text is from the Japanese wood block edition made from the 1246 manuscript edition that contains the following sections. Zen Caveats. The Wumen Guan has an appendix titled "Zen Caveats" (禪箴) with one-line aphorisms dealing  with Zen practice The word "zhēn" (箴) means "caveat", "warning", or "admonition", but it also has the meaning of "needle" or "probe" (as in acupuncture needles) and is sometimes translated as "Zen Needles". As with the main koans, each caveat challenges the Zen student's attachment to dualistic concepts, here those especially related to Zen practice.