A scholar in the Han dynasty could expect to spend the better part of an hour casting a single hexagram: dividing stalks, counting them off by threes, setting remainders aside, doing it again. A shopkeeper in the Ming dynasty could get the same six lines with three coins and six throws, in under a minute. Same book, same four possible lines, wildly different amounts of ceremony. The story of that change is really a story about who the I Ching (易经, Yìjīng) was for.
The old way: fifty yarrow stalks
The classical casting method uses fifty dried stalks of yarrow — a common plant with straight, sturdy stems that Chinese tradition associated with the spiritual. The procedure opens, poetically, by setting one stalk aside: the number of the great expansion is fifty, of which forty-nine are used (大衍之数五十，其用四十九). That unused stalk isn't waste; various commentators read it as the unchanging origin, the still point the whole process revolves around.
What follows is a sequence of random divisions and countings. You split the bundle of forty-nine into two heaps — a genuine free choice, which is where the randomness enters. You take one stalk from the right heap, count the left heap off in groups of four, set aside the remainder, do the same to the right heap, and combine the set-aside stalks. That is one round. You do three rounds per line, and the total count of the three rounds tells you which of the four possible lines you have drawn.
Each line takes minutes. Six lines take a while — long enough, traditionalists would argue, to actually think about your question. The slowness was the point: the procedure gave the asker time to hold the problem in mind, the way a long walk helps before a difficult conversation.
The four lines both methods produce
However you cast, each of the six lines of a hexagram is one of four things, identified by the numbers 6, 7, 8, and 9:
- 9 — old yang: a solid line that is about to change into a broken one. A moving line.
- 8 — young yin: a broken line at rest. Stable.
- 7 — young yang: a solid line at rest. Stable.
- 6 — old yin: a broken line about to change into a solid one. Also moving.
This is worth internalizing, because every description of I Ching casting — stalks, coins, dice, or the reader on this site — comes down to generating those four outcomes with roughly the right frequencies. The yarrow method and the coin method do not produce identical odds (the stalk method makes moving lines rarer, which classical readers considered a feature: change should be special). But both produce the same four kinds of line, and both build the hexagram from the bottom up.
The shortcut: three coins
The coin method keeps only the random heart of the procedure and throws away the counting. You take three coins, assign heads 3 points and tails 2 points, throw all three, and add up what you see. With heads = 3 and tails = 2:
- Three heads makes 9 — old yang, a moving line.
- Two heads and one tail makes 8 — young yin, stable.
- One head and two tails makes 7 — young yang, stable.
- Three tails makes 6 — old yin, a moving line.
Throw six times, record each line from the bottom up, and you have your hexagram — plus, if any of your lines are 6s or 9s, a second "becoming" hexagram showing where the situation is heading. Our I Ching reader implements exactly this: it casts, stacks, marks the moving lines, and flips them for you, so you can watch the change happen instead of doing the bookkeeping.
A historical aside that surprises many readers: the coins traditionally used were often bronze coins with square holes, and some practitioners insisted on coins with a particular emperor's reign mark. Other practitioners insisted the opposite — that a well-worn everyday coin, saturated with ordinary life, made a better instrument. The argument nicely captures the whole tradition: is the power in the tool, or in the person holding it?
Why the shortcut won
Coins were what people had. Yarrow stalks needed gathering, drying, storing, and careful handling; three coins fit in a sleeve. As literacy spread and the I Ching moved from the court diviner's desk to the market fortune-teller's mat, the method that anyone's hands could do became the method everyone used. By late imperial times the stalk procedure was mostly preserved by scholars and ceremonial purists — kept alive partly because of a belief that the slower method's line frequencies were the correct ones, and partly, one suspects, because some questions deserve an hour of sitting with the stalks.
There is an honest tension here and the tradition itself names it. The fast method democratized the book. The slow method protects a kind of attention. Neither camp abolished the other: for the last several centuries, both have simply coexisted, used by the same people on different occasions, the way the same cook might make noodles by hand on Sunday and buy them cut on Tuesday.
Casting today — and a note on randomness
Modern readers add dice, card decks, calibrated apps, and web tools (like ours) to the old menu. The underlying act never changed: introduce genuine randomness, translate it into one of four line types, build six lines, read. If anything, software has quietly settled an old argument — a good random number generator is at least as unpredictable as any coin, and rather more so than a tired human shuffling stalks at midnight.
What no method can automate is the part that comes before the throw: holding a real question, of the kind you actually have to answer. The classical writers were blunt that a cast made carelessly, about a question half-formed, produces noise. The coins are the easy part. They always were.