How to Read the I Ching: Which Changing Line Counts

A three-coin cast gives you six numbers, one for each line, counted from the bottom up. Sevens and eights are stable lines. Sixes and nines are changing lines: a nine is old yang, a six is old yin, and each one flips into its opposite. Flip them all and the hexagram you cast becomes a second hexagram, the relating hexagram, which Chinese texts call the zhi gua, the hexagram it goes to.

How many lines changed decides which text you read, and it is the step where a first reading tends to drift. It is tempting to read every changing line, or whichever paragraph catches the eye. The rules below are the ones the twelfth-century scholar Zhu Xi set out in his Yixue Qimeng, and they are the rules the I Ching tool on this site uses to mark the text to read.

The seven rules

With few changes the matter still sits in the hexagram you cast, so you read its own words. As more lines change, the weight moves across to the hexagram it is becoming. Three changing lines sit in the middle, and both judgments are read together, the primary one first. Zhu Xi adds a further refinement for the three-line case that the tool here does not apply, and a switch on the page shows every changing line for readers who follow another method.

How often each case comes up

With three fair coins, a line comes up 6 one time in eight and 9 one time in eight, so any single line changes one time in four. The six lines are independent of each other, which makes the number of changing lines easy to compute.

About two casts in three are read from one or two line texts. Roughly three in ten are read from judgments, because nothing changed or because exactly three lines did. Reading a line of the relating hexagram, the four- and five-line cases, happens in fewer than four casts in a hundred, and all six lines change once in 4,096.

Yarrow stalks give the same overall rate. Each line changes one time in four under the stalks too, so the count of changing lines follows the same table. What differs is which kind of line changes: under the stalks old yang comes up three times as often as old yin, and under the coins the two are equally likely. How to cast the I Ching sets the two procedures side by side.

A worked example

Suppose the six tosses, from the bottom line up, come to 9, 8, 7, 8, 6, 8. The first line is a nine and the fifth is a six, so two lines change. The primary hexagram is Ming Yi, hexagram 36. Turn the first line to yin and the fifth to yang and you have Jian, hexagram 39.

Two changing lines means you read both changing lines of the primary hexagram, with the upper one leading. The fifth line comes first. In Chinese it is 箕子之明夷，利貞, which Legge closes with "It will be advantageous to be firm and correct." The first line follows, with its image of Ming Yi "flying, but with drooping wings". In a two-line case Jian's judgment stays in the background, where it shows the direction the movement is taking.

Anyone who applies the rule to these six numbers will land on the same two lines. What those lines mean for the question you asked is still yours to work out, or the work of a reading.

How the six-line method reads a moving line

Reading the text treats a changing line as a pointer to a paragraph. The six-line method, liu yao, also called najia or wen wang gua, treats it as a force. Every line is given a stem, a branch and an element, and a moving line acts on the other lines, producing or controlling them. The chart printed under each cast on this site is built that way, and the paid reading follows its rules.

Those rules come from Zeng Shan Bu Yi (增刪卜易), a Qing dynasty manual attributed to Ye He Lao Ren. It is exact about what a changed line can do. The line a moving line turns into acts only back on its own moving line. The book puts it as 變出之爻能生克沖合本位之動爻, which in our translation reads: the line that comes out of a change can produce, control, clash with or combine with the moving line in its own place. No other line in the chart reaches it, and only the month and the day act on it. The book calls the change the end of the matter, 變爻爲事之終.

So the first thing to check on a moving line is how the line it changes into treats it. If the changed line produces it, the manual calls that turning back to feed it (回頭生). If it controls it, that is turning back to check it (回頭克). A branch that steps forward is an advancing change (化進神), and one that steps back is a retreating change (化退神). The manual lists seven forward steps, hai to zi, yin to mao, si to wu, shen to you, chou to chen, chen to wei and wei to xu, and the reverse of each is a retreating change. It does not count xu to chou in either direction.

When many lines move in both trigrams, the two methods part ways. Zhu Xi's rules still point to a text. The manual says the outcome cannot be judged from such a cast and asks for a second cast to read with it, 須再占一卦.

What the tool marks

After a cast, I Ching Online marks the changing lines on the figure, names the relating hexagram, and says which rule applies and which text to read first. Switch on Show every changing line to read each moving line in turn. The six-line chart under the texts lists what each moving line turns into, and whether it turns back to feed it, turns back to check it, advances or retreats.

To check the example yourself, open Ming Yi and Jian. The texts for all six lines changing are on the Qian and Kun pages, and every hexagram is listed in the 64 hexagrams. Plum Blossom divination is the number method that always gives exactly one moving line, Kau Cim vs I Ching compares a hexagram with a temple fortune stick, and Chinese divination methods places both among the other systems.