The I Ching (易經), or Book of Changes, is roughly three thousand years old and still in use. That is unusual for a divination text, and it is worth understanding why before you use it.
What it is
At its core it is a set of sixty-four six-line figures, each with a short oracle text. You generate a figure at random and read what it says. The oldest layer, the Zhouyi, contains just the hexagrams and their texts; the commentaries known as the Ten Wings were added later and shaped how the whole thing has been read ever since.
How the figures are built
- Two forces: a solid line (yang) and a broken line (yin).
- Three lines make a trigram — eight possible combinations.
- Two trigrams stacked make a hexagram — eight times eight, sixty-four.
The eight trigrams name natural forces: heaven, earth, water, fire, thunder, wind, mountain, lake. Every hexagram is read partly through the two trigrams composing it.
Where the text came from
Tradition credits King Wen with arranging the hexagrams and writing the judgments, and the Duke of Zhou with the line texts; Confucius was later held to have written the Ten Wings. Modern scholarship is more cautious — the core text is usually dated to the late Western Zhou or early Spring and Autumn period, with the commentaries added over the following centuries.
Archaeology matters here. The Mawangdui silk manuscripts, sealed in the second century BCE, contain the Book of Changes with a different hexagram order. The King Wen sequence is the one that survived, but it was not the only ancient arrangement.
What happens in a reading
You ask a question, generate the lines, and look up the figure. If any lines are moving — old yin or old yang — you also read their individual texts and derive a second, transformed hexagram. The first describes the situation; the second describes where it is going.
What it does not do
It does not predict the future, and it does not tell you what to do. The texts are closer to situation analysis than prophecy — they describe the shape of a configuration and how it tends to develop. Reading them as verdicts misunderstands the genre.
Two ways to read it
The classical approach reads the text — judgment, image and line texts — as commentary on your situation. The later Liu Yao approach instead assigns stems, branches, relatives and spirits to each line and judges their interactions. Same raw material, different method; most English-language books cover only the first.