The Tuan Zhuan: the Commentary on the Judgment, explained

The Tuan Zhuan (彖傳, "Commentary on the Judgment") is the oldest systematic explanation of the I Ching's hexagram texts. For each of the 64 hexagrams it takes the terse Judgment and shows why it says what it says, by pointing to the two trigrams and to one or two decisive lines. When a Judgment seems cryptic, the Tuan Zhuan is usually the first place to look.

What the Tuan Zhuan is

The Zhouyi itself gives each hexagram a name, a short Judgment (卦辭, also called 彖辭) and six line texts. Around these grew the Ten Wings (十翼), a set of commentaries later attributed by tradition to Confucius; most modern scholars date them to the Warring States and early Han periods and see several hands at work. The Tuan Zhuan counts as two of the Wings, upper and lower, following the two halves of the classic. You can read how it fits with the others in our guide to the Ten Wings.

Originally the Tuan Zhuan circulated separately. In the received text you are most likely to meet, which goes back to the arrangement Wang Bi used, each section is printed directly after the Judgment it explains, introduced by 彖曰 ("the Commentary says"). Legge printed it as an appendix; Wilhelm placed it under each hexagram in his third book.

A small point of vocabulary: in the Great Treatise, 彖 means the Judgment itself — 彖者，言乎象者也, "the Judgment speaks of the image." The Tuan Zhuan is the commentary on that Judgment. Wang Bi summed up its job in one line: 夫彖者，何也？統論一卦之體，明其所由之主者也 — the Judgment discusses the hexagram as a whole and makes clear the "master" from which it proceeds.

The four tools it uses

Almost every Tuan section explains the Judgment with some mix of four moves:

• Trigram qualities. Each trigram has a character: ☰ strong (健), ☷ yielding (順), ☳ moving (動), ☵ dangerous (險), ☶ stopping (止), ☱ joyful (說), ☲ bright (明), ☴ penetrating (巽 / 入). The Tuan often names the hexagram by pairing them: "danger and stopping," "strength within, yielding without." See the eight trigrams and the trigram table.
• Trigram images. Heaven and earth, water and fire, thunder and wind, read as forces meeting or failing to meet.
• Central and corresponding lines. The second and fifth lines are central; a firm line in the fifth place or a yielding line answering it from the second (應) is often what makes a Judgment favourable. This is the language of correct place and central lines and of correspondence.
• A ruling line. When one line differs from the other five, the Tuan usually makes it the key. Of Hexagram 9, Xiao Chu it says 柔得位而上下應之，曰小畜: the single yielding line holds its proper place and everything above and below answers it. This idea became the doctrine of the ruler of the hexagram.

There is a fifth device, used more sparingly: the Tuan sometimes speaks of a line "coming" or "going," as in Hexagram 6, Song: 剛來而得中也, "the firm comes and attains the centre." Later commentators built the theory of hexagram changes (卦變) on such phrases, and argued over it for centuries; Cheng Yi and Zhu Xi did not agree on how to read them. You can use the Tuan without settling that debate.

Three worked examples

Meng, Youthful Folly

Hexagram 4, Meng has a famous Judgment: "It is not I who seek the young fool; the young fool seeks me. The first divination is answered. Asking two or three times is importunate; to the importunate no answer is given." The Tuan explains: 蒙，山下有險，險而止，蒙 — danger below a mountain, danger and then stopping: that is ignorance, a person who meets difficulty and halts. 童蒙求我，志應也 — the young one seeks me because their wills correspond (the yielding fifth line answers the firm second). 初筮告，以剛中也 — the first divination is answered because the second line is firm and central, a teacher who is solid and balanced. The cryptic oracle about divination becomes a picture of a learning relationship.

Tai, Peace

Hexagram 11, Tai puts ☷ earth above ☰ heaven, which looks upside down. The Judgment says only "the small departs, the great arrives: good fortune, success." The Tuan supplies the logic: 天地交而萬物通也 — heaven and earth intercourse and all things flow. Heaven's energy rises, earth's sinks, so they meet. Then it turns the trigrams into a social picture: 內陽而外陰，內健而外順，內君子而外小人 — yang within and yin without, strength within and yielding without, the noble within and the petty without. The odd-looking arrangement is explained in two sentences.

Ge, Revolution

Hexagram 49, Ge is ☱ the lake over ☲ fire. The Tuan: 水火相息，二女同居，其志不相得，曰革 — water and fire extinguish each other; two daughters (the youngest, ☱, and the middle, ☲) live together but their wills do not agree: that is revolution. It then reads the trigram qualities as the right manner of change: 文明以說, clarity and gladness, and 革而當，其悔乃亡 — when change is fitting, regret disappears. It ends by widening the view: 湯武革命，順乎天而應乎人 — the founders of Shang and Zhou changed the mandate in accord with heaven and in answer to people. 革之時大矣哉! "Great indeed is the time of revolution!"

That closing exclamation is a Tuan signature. About a dozen hexagrams get a line praising their time (時), their meaning in time (時義) or their use in time (時用) — a reminder that the Tuan reads each hexagram as a moment with its own demands.

How to use it when a Judgment is cryptic

The Judgments were written as divinatory formulas, and many are terse to the point of opacity. The Tuan Zhuan is the earliest reader to treat them as structured: name the trigrams, find the centre, find the line that rules. When a Judgment leaves you blank:

• Read the Tuan before any modern paraphrase. It is short, and it shows you which lines and trigrams the whole tradition will lean on.
• Look for the line it singles out. If the Tuan names a firm line "attaining the centre" or a yielding line "obtaining its place," that line is the hinge of the situation. If it is also one of your changing lines, give it extra weight.
• Translate the trigram qualities into your situation. "Danger and stopping" or "strength within, yielding without" are attitudes, not omens. Ask where in your own matter you see them.
• Notice the time exclamations. When the Tuan says "great is the time of…," the hexagram is less about outcome and more about recognising what this moment asks of you.

The Tuan is a commentary, not scripture. Zhu Xi stressed that the Zhouyi began as a divination text and that the Wings read moral philosophy into it; Wang Bi and Cheng Yi built their readings on it. Both views can sit together: the Tuan may not tell you what the Judgment originally meant, but it tells you how the I Ching has been read for two thousand years.

Putting it into practice

When you cast a hexagram, read the Judgment, then its Tuan, then the Great Image. On each hexagram page in our library of hexagrams you can then check whether the line the Tuan points to is one of your changing lines. Keep your note of the reading simple: the trigram pairing in one phrase, the key line in one phrase, and what that suggests you do next.