I Ching Divination · Coin Method & Yarrow

The I Ching (Yijing, the “Book of Changes”) is one of China's oldest classics. Originally a manual of divination, it was later expounded by Confucius and generations of scholars and came to head the Confucian canon. This tool reproduces its simplest casting method — the six-line coin method, also called the “copper-coin oracle” — together with the Judgments and line texts of all sixty-four hexagrams.

1. What is the six-line coin method?

The ancient method cast yarrow stalks by the “great expansion” procedure, which is elaborate; later ages simplified it to tossing three coins six times, hence the name “coin method”. An old coin carries an inscription on one side, called the “face” (zi); the other side is blank and is called the “back” (bei). By the ancient rule the back is yang and the face is yin: each toss of three coins counts backs and faces to fix one line's yin or yang and whether it is “moving” or “static”:

• Three backs (three yang) → old yang (number nine, a moving line, drawn as “○”)
• Two backs, one face → young yin (number eight, static)
• One back, two faces → young yang (number seven, static)
• Three faces (three yin) → old yin (number six, a moving line, drawn as “×”)

Tossing six times from the bottom up gives, in order, the first, second, third, fourth, fifth and top lines — one hexagram, the primary hexagram.

2. The yarrow method of the Great Expansion: the ancient rite

The coin method is the later simplification; the ancient procedure recorded in the Great Commentary (Xici I) works with the stalks of the yarrow plant, and is called the method of the Great Expansion. The text says:

Of the great expansion the number is fifty, of which forty-nine are used. Divided into two to represent the two; one set aside to represent the three; counted by fours to represent the four seasons; the remainder gathered in the bend of the finger to represent the intercalary month.

One of the fifty stalks is set aside unused (representing the Supreme Ultimate), so forty-nine are actually used. One line takes three changes, and each change has four steps, together called the four operations - which is what the text means by "four operations complete a change, eighteen changes complete a hexagram" (six lines, three changes each):

1. Split (divided into two to represent the two): part the forty-nine stalks by hand into a left and a right pile, representing heaven and earth.
2. Set one aside (one set aside to represent the three): take one stalk from the right pile and set it apart, representing heaven, earth and humankind.
3. Count by fours (counted by fours to represent the four seasons): count out each pile in groups of four; what is left over is one to four stalks (an exact division counts as four).
4. Gather the remainder (gathered to represent the intercalary month): put the stalk set aside together with both remainders to one side.

What is left after the remainder is gathered is called the remaining count: after the first change it is forty-four or forty (the remainder gathered being five or nine), after the second forty, thirty-six or thirty-two (four or eight), after the third thirty-six, thirty-two, twenty-eight or twenty-four. Divide the remaining count by four and you have the number of the line:

The text also says "the stalks of Qian are two hundred and sixteen, those of Kun one hundred and forty-four" - six Old Yang lines (6x36 = 216) and six Old Yin lines (6x24 = 144) - which agrees exactly with the remaining counts in the table above.

How this tool casts by yarrow

In the ancient rite the split was made by hand, so this tool gives that step back to you as a slider: you decide how many stalks go to each pile. The tool does not split for you and uses no random numbers - it only performs the counting of setting one aside, counting by fours and gathering the remainder. One drag of the slider completes a "split" (one change); after three changes press "Record this line." When six lines are in place you have the primary and the changed hexagram.

Compared with the coin method, the yarrow method adds the step of splitting by hand and stays closer to the ancient rite; yet both yield one image, and the way of reading it is no different.

3. How a hexagram is built: eight trigrams and sixty-four hexagrams

Of the six lines, the lower three form the “lower trigram” and the upper three the “upper trigram”, each one of the eight primary trigrams:

• Qian ☰ (Heaven), Dui ☱ (Lake), Li ☲ (Fire), Zhen ☳ (Thunder)
• Xun ☴ (Wind), Kan ☵ (Water), Gen ☶ (Mountain), Kun ☷ (Earth)

Stacking an upper and a lower trigram yields the sixty-four hexagrams (numbered in the King Wen sequence). For every hexagram this tool gives the Judgment — the original I Ching verdict on the hexagram as a whole — and six line texts, a note on each line, plus a one-line plain-language gist to help you read them.

4. Primary hexagram, moving lines and changed hexagram: what “transformation” means

Among the six lines cast, old yang and old yin are the moving lines. By the principle that an extreme reverses, they transform: old yang becomes yin, old yin becomes yang. Change each moving line of the primary hexagram and you obtain another hexagram — the changed hexagram.

• Primary hexagram: the present state and shape of the matter.
• Moving lines: where the change lies; their texts are usually the heart of the reading.
• Changed hexagram: the tendency and outcome the matter is moving toward.

If all six lines are static (no moving line), there is no changed hexagram; judge by the Judgment of the primary hexagram alone.

5. How to read it

1. Read the primary hexagram's Judgment first: grasp the overall character of the situation (fortune, misfortune, regret, difficulty).
2. Then read the moving lines: if there are moving lines, go through their texts one by one; they usually offer concrete reminders.
3. Then read the changed hexagram's Judgment: it shows where things are heading and can be set against the primary hexagram, beginning against end.
4. For a static hexagram, the primary alone: with no moving line the matter changes little, and the primary hexagram's Judgment suffices.

Traditional readings also consult the “nuclear”, “opposite” and “reversed” hexagrams; this tool keeps it simple and shows only the main line — primary hexagram → moving lines → changed hexagram.

6. The right attitude

The I Ching says, “When at rest the gentleman observes its images and plays with its texts; when active he observes its changes and plays with its judgments.” The ancients used it to cultivate themselves, read situations and resolve doubts — not to court luck. Divination rests on sincerity and stillness: having cast, look inward and weigh reason and circumstance. Never let a hexagram replace your own judgment and action, and never use it for medical, legal or investment decisions.