TL;DR: A koan is an old Zen story or question, used as an object for practitioners to contemplate until ordinary reasoning is blocked. The Gateless Gate (1228) collects 48 koans compiled by Zen master Wumen Huikai, while the Blue Cliff Record collects 100 koans with verses by Xuedou and commentary by Yuanwu. Both are texts of Chinese Zen from the Song dynasty, not of Vietnamese Buddhism, and should not be read as riddles with fixed answers.
What is a koan?
A koan is a story, a question, or a short exchange between master and student in the Zen tradition, recorded and used as an object of contemplation for the practitioner. The word "koan" (公案) was originally a legal term meaning a "public case", that is, a magistrate's ruling, and Zen later borrowed it to refer to the spiritual "cases" a practitioner must break through personally. The essential point is that a koan is not meant to test knowledge, and it has no correct answer to memorize; it is meant to push the reader to the point where ordinary reasoning is stopped.
What is the Gateless Gate and why is it named that way?
The Gateless Gate (無門關) is a collection of 48 koans compiled by Zen master Wumen Huikai in 1228 during the Song dynasty, each case consisting of the original koan, Huikai's own comment, and a closing verse[1]. The title comes from the opening line of the work itself: taking "no gate" as the dharma gate, because "entering through a gate is not the treasure in the house"[1]. In other words, the book declares itself to have no gate to enter by, and that gatelessness is itself the gate.
According to Huikai's preface, he gathered the koans during the time he taught students at Dongjia Longxiang, at first only to "knock on the door" and guide learners, then gradually wrote them down into a collection, not arranged in any order of before and after, gathered into 48 cases[1]. The printing was done in early 1229 to wish the emperor long life, as recorded in the text itself[1].
The first case and the word "Wu"
The opening case is the famous question: a monk asked Zen master Zhaozhou whether a dog has Buddha-nature, and Zhaozhou answered "Wu" (無, literally "no")[1]. What is notable is that in Buddhist scripture all sentient beings have Buddha-nature, so the answer "no" runs directly against the familiar teaching. That very paradox is where the work lies.
Huikai comments that one who wants to practice Zen must pass through the "gate of the ancestral teachers", and that gate is precisely the word Wu; he warns the practitioner not to understand it in the sense of "nothingness" or in the sense of "being and non-being", but to make the whole body rise up as one mass of doubt, like swallowing a red-hot iron ball that can neither be swallowed nor spat out[1]. This is a description of method, not a definition of a concept.
What is the Blue Cliff Record and how does it differ from the Gateless Gate?
The Blue Cliff Record (碧巖錄) is a collection of 100 koans selected and "versified" (commented on in verse) by Zen master Xuedou Chongxian of the Song dynasty, after which Yuanwu Keqin added the commentary, explanation, and introduction to each case, completing it around 1125[3].
The fundamental difference between the two books lies in scale and density of commentary. The Gateless Gate is compact with 48 cases, each having a short comment and one verse[1]. The Blue Cliff Record runs to 100 cases, Yuanwu's commentary is usually longer and more layered, and its printing blocks were once destroyed by Dahui and then recut, as recorded in the postscripts of the book[3].
| Criterion | Gateless Gate | Blue Cliff Record |
|---|---|---|
| Main compiler | Wumen Huikai | Xuedou Chongxian, with commentary by Yuanwu Keqin |
| Number of cases | 48 | 100 |
| Date | 1228, Song dynasty | Around 1125, Song dynasty |
| Structure of each case | Original koan, comment, verse | Original koan, Xuedou's verse, Yuanwu's commentary |
| Textual character | Compact, sharp comments | Long, layered, once burned and reprinted |
How does a koan work?
A koan does not work by supplying information, but by making the familiar mechanism of reasoning get stuck. In Zhaozhou's case, the practitioner is placed between the teaching "all beings have Buddha-nature" on one side and the answer "no" on the other; the two cannot be reconciled by ordinary reasoning, so the practitioner is forced to let go of the usual way of understanding[1].
Should a beginner read the Gateless Gate or the Blue Cliff Record first?
In form, the Gateless Gate is more compact: the number of cases is small, each case has a short comment and verse, and it states clearly its purpose of "knocking on the door" to guide learners[1]. The Blue Cliff Record is twice as long and Yuanwu's commentary is layered, requiring a reader already familiar with Zen language.
Even so, neither is a textbook for looking up answers. Reading a koan as one reads a riddle goes against the very declaration of the Gateless Gate: understanding it in the sense of "being" or "non-being" is rejected by Huikai himself[1].
Is the koan part of Vietnamese Buddhism?
No. Both the Gateless Gate and the Blue Cliff Record are texts of Chinese Zen of the Song dynasty, written in Chinese characters. Modern Vietnamese translations are only a means of reading; they do not turn these into texts of Vietnamese Buddhism.
Phan Van Hum, in Phat giao triet hoc (1942), describes Zen as the school transmitted by Bodhidharma that advances the doctrine of "not establishing words and letters"[2].
What is the use of reading a koan today?
Gợi ý của Nhật Nguyệt: for a modern reader who does not practice Zen, the value of a koan lies in the fact that it is a record of a method of training cognition different from ordinary logical method. Read it to see how a tradition handles the limits of language, not to draw a moral lesson or advice on conduct. Assigning to a koan messages about work, love, or money is the reader's interpretation, not what the text says.
A few points to note when researching
- A koan has no "correct answer" to look up; the collections only record the comment of one specific master, and that comment belongs to that master.
- The Gateless Gate and the Blue Cliff Record are not two versions of the same collection; they are two independent collections with different numbers of cases and structures[1].
- Words such as "Wu" in Zhaozhou's case are an object of practice, not a philosophical assertion about nothingness[1].
