The Xici (Great Treatise): the I Ching's philosophy of change

The Xici (繫辭傳, "Commentary on the Appended Statements"), which Wilhelm called the Great Treatise, is the I Ching's philosophical essay. It does not comment on one hexagram after another; it steps back and asks what the book is, why it works, and how a person should use it. Most of the famous sayings people quote "from the I Ching" — about yin and yang, the Supreme Ultimate, change that leads to continuity — actually come from here.

What kind of text it is

The Xici is counted as two of the Ten Wings, an upper and a lower part. Tradition attributed it to Confucius; its passages quote "the Master said" (子曰), which shows at least that its compilers saw themselves as writing in his school. Modern scholars generally date it to the late Warring States or early Han and treat it as a compilation rather than a single essay. A version of it was found among the Mawangdui silk manuscripts, differing from the received text in places — see Mawangdui and the excavated I Ching.

Editions divide it into chapters differently; Zhu Xi's division into twelve chapters per part is the one most often cited. Because of that, the safest way to find a passage is by its words, which is how we quote below.

Change as the nature of things

The treatise opens by aligning the book with the world: 天尊地卑，乾坤定矣 — heaven is high, earth is low, and so Qian and Kun are fixed. Movement and rest, firm and yielding, follow. Its central claim is that the hexagrams are not arbitrary symbols but a model of how things actually move.

Three short sentences carry most of its philosophy:

• 一陰一陽之謂道 — "One yin, one yang: this is called the Way." Reality is the alternation of the two, not either one alone. See yin and yang.
• 生生之謂易 — "Producing and reproducing: this is called change." Change is generative, not mere instability.
• 易窮則變，變則通，通則久 — "When change reaches its limit, it transforms; transforming, it gets through; getting through, it endures." This is perhaps the most quoted line of the whole book, and the logic behind every changing line: a situation pushed to its extreme turns over.

The Xici also warns that people see the Way partially: 仁者見之謂之仁，知者見之謂之知，百姓日用而不知 — the humane see it and call it humaneness, the wise see it and call it wisdom, and ordinary people use it every day without knowing it.

The Taiji passage

The best-known cosmological sentence in Chinese thought is a short passage in the upper Xici:

易有太極，是生兩儀，兩儀生四象，四象生八卦，八卦定吉凶，吉凶生大業.

"In change there is the Supreme Ultimate (太極). This generates the two modes; the two modes generate the four images; the four images generate the eight trigrams; the eight trigrams determine good fortune and misfortune; good fortune and misfortune give rise to the great enterprise."

Read in context, the passage is about how the figures of the book unfold: one becomes two (yin and yang lines), two become four (the paired lines), four become eight (the trigrams). Song thinkers, above all Zhou Dunyi and Zhu Xi, made it the foundation of a whole cosmology, and Shao Yong's binary arrangement of the trigrams — the Early Heaven order — grew from reading it as a doubling process. Whether the original authors meant a cosmology or a description of the hexagram system is still debated.

"The sages set up the images"

Why use pictures at all? The Xici answers with a famous exchange:

子曰：「書不盡言，言不盡意。」…聖人立象以盡意，設卦以盡情偽，繫辭焉以盡其言.

"Writing does not exhaust speech, and speech does not exhaust meaning." So the sages set up the images to exhaust meaning, arranged the hexagrams to exhaust the true and the false, and appended statements to exhaust what could be said. Images say more than words can. This is the root of a long argument: Wang Bi later held that once you grasp the meaning you may forget the image, while image-and-number scholars insisted the images themselves carry the meaning (see image and number versus meaning and principle).

The lower Xici tells how the trigrams began: Fu Xi 仰則觀象於天，俯則觀法於地 — looking up he contemplated the images in the heavens, looking down the patterns on the earth; he observed birds and beasts, took from his own body near at hand and from things far off, and so made the eight trigrams. It is a story about attention, and it is why the trigrams are always read as images drawn from nature.

The passages on divination

The Xici is also the earliest text that tells you how to consult the book:

• How to sit with it. 君子居則觀其象而玩其辭，動則觀其變而玩其占 — at rest, the superior person contemplates the images and savours the words; when about to act, they contemplate the changes and savour the divination. Study when calm, consult when facing a decision.
• How it answers. 君子將有為也，將有行也，問焉而以言，其受命也如響 — when about to act, one asks it in words, and it receives the charge like an echo.
• How it works. 易無思也，無為也，寂然不動，感而遂通天下之故 — the Changes has no thought and no action; still and unmoving, when stirred it penetrates all situations.
• The yarrow procedure. The passage beginning 大衍之數五十，其用四十有九 ("the number of the great expansion is fifty; forty-nine are used") is the only classical description of the yarrow-stalk method.
• How to read the lines. 二多譽，四多懼…三多凶，五多功 — the second place has much praise, the fourth much apprehension, the third much misfortune, the fifth much merit. A whole theory of line positions in a sentence.

Lines readers still quote

Some Xici sentences have lived far outside the I Ching:

• 二人同心，其利斷金；同心之言，其臭如蘭 — "When two people are of one heart, their sharpness can cut metal; words from one heart are fragrant as orchids." (A comment on Hexagram 13, Tong Ren.)
• 天下同歸而殊塗，一致而百慮 — the world comes home to the same place by different roads, to one end by a hundred thoughts.
• 君子藏器於身，待時而動 — the superior person keeps their tools on their person and waits for the moment to act.
• 作易者，其有憂患乎 — "Did those who made the Changes not know anxiety and hardship?" A reminder that the book was written for difficult times.

Putting it into practice

The Xici will not tell you what your hexagram means, but it tells you how to hold a reading:

• Ask before acting, not after. Its model consultation is "when about to act."
• Expect turning, not fixity. A hexagram at its extreme is about to change; read the changed hexagram as the way through.
• Let the image work. If the words of a line feel thin, return to the picture — the Xici says the image holds more than the words.

Then cast your question, and read the result in that spirit.