The Gateless Barrier, translated as The Gateless Gate, is a collection of 48 Zen Koans compiled in the early 13th century by the Chinese Zen master Wumen Huikai. The title can also be translated as Wumen’s Barrier (the author’s name, which literally means “No Gate”, is the same as the title’s first two characters).

Wumen’s preface says the volume was published in 1228. Each koan is accompanied by an analysis and from the author. A classic edition includes a 49th case composed by Anwan and four stanzas from Wu-liang Tsung-shou about the three checkpoints of Zen master Huanglong. These three checkpoints of Huanglong are different from 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 teaching much used in Rinzai School of Zen. Five of the koans in the The Gateless Gate concern the sayings and doings of Zhaozhou; four concern Ummon.

The common theme of much of the work is dualistic conceptualization. Each koan epitomizes one or more of the polarities of consciousness that act as an obstacle or wall to insight, or “don’t know mind”. The student is challenged to transcend the polarity the koan represents and demonstrate that transcendence to the Zen teacher.

Koans are a Zen Buddhist spiritual technique which use word-play to achieve enlightenment. They frequently involve absurd or contradictory statements, which are intended to create extreme cognitive dissonance in the mind of the pupil. As such, their actual content or structure is not as important as the mental state which they induce.