I Ching divination is a method of divination using lots or random symbols to interpret the I Ching. The I Ching contains 64 hexagrams, which are symbols made of six lines. Each line is either yin (broken) or yang (solid), and each hexagram has explanations. There are two main ways to create the lines of a hexagram: by using 50 yarrow stalks or by tossing three coins. Some lines may be labeled as "old" lines, which then change to form a second hexagram. The text related to the hexagram(s) and any old lines is studied, and the meanings from this study are interpreted as guidance or a message.
Methods
Each hexagram has six lines, written one above the other. Each line is either yīn (dark, feminine, shown as a broken line) or yáng (light, masculine, shown as a solid line). Lines can also be old (changing, marked with an "X" on a yīn line or a circle on a yáng line) or young (unchanging). When using the I Ching as an oracle, each line gets a number: 6 for an old yīn line, 7 for a young yáng line, 8 for a young yīn line, or 9 for an old yáng line. The six lines are created in order, starting with the first (lowest) line and moving upward to the sixth (top) line. After the hexagram is formed, its commentaries are studied. If there are no old lines, the reading ends. If there are old lines, their specific commentaries are also studied. Then, the old lines change: old yīn lines become young yáng lines, and old yáng lines become young yīn lines. This creates a second hexagram, and its commentaries are studied as well.
The method used to create the hexagram depends on the diviner’s beliefs and needs. The yarrow-stalk method is traditional and complex, requiring time to manipulate the stalks. It allows for 0 to 6 moving lines and favors static lines over moving ones in a 3:1 ratio. Coin methods are faster and often used by fortune-tellers who need quick results. Other methods, like interpreting time or direction, may also be used. Some methods ensure exactly one or no moving lines, while the yarrow-stalk method allows for any number of moving lines.
Plastromancy, or turtle-shell divination, is one of the earliest recorded forms of fortune-telling. A diviner would heat a turtle shell, causing cracks to form. These cracks were sometimes marked with ancient Chinese writing. This practice was used long before the Zhou Yi (around 1100 BC). A similar method, scapulimancy, used ox shoulder bones. The bones were carved to thin them before heating to create cracks.
Hexagrams can also be made using yarrow stalks, which are usually real yarrow plant stalks or wooden sticks. When using real yarrow, local varieties or those from spiritual places, like Confucian temples, are preferred. The stalks are stored in cloth bags or wooden boxes when not in use.
The yarrow-stalk method uses 50 stalks, with one set aside. The remaining 49 are divided into two piles. One stalk is set aside from the right pile, and the pile is grouped into sets of four. The remainders are combined and set aside, and the process is repeated twice more. After three rounds, the total number of stalks in the remainder pile is either 9 or 5 (first count), and 8 or 4 (second count). These numbers are assigned values of 2 or 3, and the total of the three counts gives the number for the first line (6, 7, 8, or 9). This process is repeated five more times to complete the hexagram.
The yarrow-stalk method gives different probabilities for each line number compared to the three-coin method. The three-coin method is faster and more popular but produces different results. Three coins are tossed, with heads (2) and tails (3) assigned values. Six tosses create the hexagram. Some fortune-tellers use an empty turtle shell to shake the coins before tossing them.
To match the yarrow-stalk method’s probabilities, the three-coin method can be modified by using a special coin. If the special coin is tails and the others are tails (normally a 6), it is re-flipped. If it stays tails, it remains a 6 (moving yīn); otherwise, it becomes an 8 (static yīn). This makes moving yīn less likely. If the special coin is heads and the others are tails (normally a 7), it is re-flipped. If it stays heads, it remains a 7 (static yáng); otherwise, it becomes a 9 (moving yáng). This makes static yáng less likely and moving yáng more likely.
The two-coin method involves tossing two coins twice. The first toss gives a value of 2 (two heads) or 3 (anything else). The second toss assigns values to each coin individually, adding them for a total of 6 to 9. This matches the yarrow-stalk method’s probabilities. A modified version of this method simplifies the process while keeping the same probabilities.
Probability analysis ofI Chingdivination
Most studies about the chances of using the coin method or the yarrow-stalk method agree on the probabilities for each method. The coin method is very different from the yarrow-stalk method because it gives the same chance for both moving lines and both static lines, which is not true for the yarrow-stalk method.
However, the way to calculate how often each outcome happens in the yarrow-stalk method—usually thought to be the same as the simplified method using sixteen objects—has an error, according to Andrew Kennedy. This error is including the number zero as a possible choice for either hand. The yarrow-stalk method clearly requires that the four numbers be chosen without using zero. Kennedy explains that if the user is not allowed to choose zero for either hand, or if a single stalk is moved from the right hand to the left hand before counting by fours (which also leaves zero in the right hand), the number of times each hexagram appears changes greatly for someone who uses the oracle regularly. To fix this, Kennedy changed the simplified method using sixteen colored objects described in this article. He suggests using 38 objects, with the following arrangement:
This setup produces the frequencies that Kennedy calculated, with less than 0.1% difference.