How to Read an I Ching Hexagram: Trigrams, Lines, and Changing Lines

The I Ching, or Book of Changes, is one of the oldest Chinese classics. Its core is a set of 64 figures called hexagrams, each made of six stacked lines, with a short text attached to the whole figure and to each line. For many first-time readers the book is baffling, not because the ideas are obscure but because nobody explains how a hexagram is built and in what order the texts are meant to be read.

This guide explains the mechanics: trigrams, lines, changing lines, how the texts are layered, how the traditional three-coin method works, and how to get from a first hexagram to a second, "relating" one. We approach the I Ching as a classic text for reflection. Whatever you think of divination, the structure is worth understanding, because it shaped two thousand years of Chinese thought about change and timing.

Lines: yin and yang

Every hexagram is built from two kinds of line:

a solid line (⚊), called yang, associated with the firm and active;
a broken line (⚋), called yin, associated with the yielding and receptive.

Lines are counted from the bottom up. The bottom line is line one and the top line is line six. This matters, because the line texts follow that order, and position carries meaning: the lowest line usually describes the beginning of a situation, the top line its end or its excess.

The traditional line names combine number and position. A yang line is called "nine" and a yin line "six", so the bottom line of a hexagram might be 初九 (Nine at the beginning) or 初六 (Six at the beginning), and the top line 上九 or 上六. The middle lines are named by number, for example 九二 (Nine in the second) or 六五 (Six in the fifth).

The eight trigrams

Each hexagram can be seen as two three-line figures, or trigrams, one stacked on the other. There are eight possible trigrams, and each has a name and a set of associated images. The most common image for each is:

Trigram	Name	Image	Lines, bottom to top
☰	Qian 乾	Heaven	yang, yang, yang
☷	Kun 坤	Earth	yin, yin, yin
☳	Zhen 震	Thunder	yang, yin, yin
☵	Kan 坎	Water	yin, yang, yin
☶	Gen 艮	Mountain	yin, yin, yang
☴	Xun 巽	Wind, wood	yin, yang, yang
☲	Li 离	Fire	yang, yin, yang
☱	Dui 兑	Lake	yang, yang, yin

A useful pattern for memorizing: in Zhen, Kan, and Gen, a single yang line moves from bottom to middle to top; in Xun, Li, and Dui, a single yin line does the same.

The lower trigram is sometimes called the inner trigram and the upper the outer. Eight possible lower trigrams times eight possible upper trigrams gives the 64 hexagrams. For example, hexagram 11, Tai (Peace), has Qian (Heaven) below and Kun (Earth) above. The traditional commentary reads this as heaven's energy rising and earth's settling, so the two meet, which is why the figure is associated with harmony and flow.

The layers of text

A hexagram page in a traditional edition contains several layers written at different times. The main ones are:

The Judgment (卦辞): a short text for the hexagram as a whole. For hexagram 1, Qian, it is just four characters, 元亨利贞, often read as "fundamental, prevailing, beneficial, steadfast".
The line texts (爻辞): one short text for each of the six lines. These are often vivid and specific, with images of dragons, foxes crossing rivers, or wells being cleaned.
The commentaries: later layers traditionally grouped as the Ten Wings. Two are printed with each hexagram in most editions: the Tuan (彖), which explains the Judgment, and the Image (象), which interprets the hexagram through its two trigrams and comments on each line.

The Judgment and line texts form the oldest part, the Zhouyi proper. The commentaries came centuries later and represent an early tradition of interpretation. Keeping the layers distinct helps: when a passage seems to say something oddly moralistic, check whether it is from the old text or from the commentary. Our reader I Ching, Plainly presents the Judgment, Tuan, Image, and all six lines of every hexagram in the original Chinese, a literal translation, and a plain reading, so you can see each layer separately.

Changing lines: what 6 and 9 mean

Traditional casting does not just produce yin or yang lines. It produces one of four numbers for each line:

Number	Name	Line	Changes?
6	Old yin	broken	yes, becomes yang
7	Young yang	solid	no
8	Young yin	broken	no
9	Old yang	solid	yes, becomes yin

Old lines are "changing" or "moving" lines. The idea is that a situation at its extreme turns into its opposite: yang at its fullest begins to yield, and yin at its fullest begins to firm. This is also why line names use "nine" and "six": they are the numbers of the changing lines.

The three-coin method

The oldest documented method uses yarrow stalks and is slow. The common modern method uses three coins:

Assign a value to each side. The usual convention is heads = 3 and tails = 2.
Toss three coins together and add the values. The total is always 6, 7, 8, or 9.
Write down the resulting line. The first toss gives the bottom line.
Repeat five more times, building the hexagram upward.

With three coins, 6 and 9 each have a 1 in 8 chance, and 7 and 8 each have 3 in 8. (The yarrow method gives different odds, making old yin rarer than old yang, which is one reason some readers prefer it.)

A worked example

Suppose your six tosses, from the first to the sixth, give: 7, 9, 8, 8, 8, 8.

Step 1: draw the primary hexagram. Bottom to top that is yang, yang, yin, yin, yin, yin.

Step 2: find the trigrams. The lower three lines are yang, yang, yin, which is Dui (Lake). The upper three are yin, yin, yin, which is Kun (Earth). Earth over Lake is hexagram 19, Lin (Approach).

Step 3: identify changing lines. Only the second line is a 9, so it is changing.

Step 4: build the relating hexagram. Flip the changing line. The lower trigram becomes yang, yin, yin, which is Zhen (Thunder). Earth over Thunder is hexagram 24, Fu (Return).

Step 5: read in order. Read the Judgment of Lin for the overall situation. Then read the line text for its second line, which is the most specific part of the reading. Finally, read the Judgment of Fu as the direction the situation is moving in.

How to read the texts

A practical sequence many readers use:

Look at the two trigrams and their images before reading anything. What picture do they make?
Read the Judgment of the primary hexagram.
Read the Image commentary, which often draws a lesson from the trigram picture.
If there are changing lines, read those line texts, from the bottom up. If there are none, the Judgment carries the reading.
If there are changing lines, read the Judgment of the relating hexagram.
Write down, in your own words, what the texts suggest about the question or situation you were reflecting on.

Traditions differ on what to emphasize when there are many changing lines. Some commentators give rules for each case, from one changing line up to six. As a beginner, it is enough to read all the changing lines and notice which one resonates most clearly.

Reading it as a classic

You do not have to believe that coins reveal the future to get value from this. The line texts are, among other things, a catalogue of situations: beginnings that are difficult, moments to wait, times when advancing brings regret. Reading a hexagram slowly, and writing your own response, is a structured way to look at a situation from an unfamiliar angle. Treat the text as a prompt for thought, not as a verdict, and make real decisions with the same care you would use anyway.

If you want to go further, read the hexagrams in order rather than only when you cast them, starting with 1 and 2, Qian and Kun, which set out the logic of the whole book. Hexagrams 63 and 64, After Completion and Before Completion, are a good place to see how the book ends on an unfinished note.