What Is the I Ching? Yijing & Book of Changes
ZHOU YI 周易 · THE CLASSIC OF CHANGES
KEY TAKEAWAYS / TL;DR
- ◈The I Ching (c. 1000 BCE) is one of the oldest surviving divination and philosophical texts, and one of Confucianism's Five Classics.
- ◈Its architecture is binary: Yin and Yang lines combine into 8 trigrams, which stack into 64 hexagrams for reading changing situations.
- ◈Leibniz noted in 1703 that the I Ching's hexagram system can be compared with binary arithmetic, an important but debated historical correspondence.
By the Numbers
- 2
- Line States
- Yin and Yang are the smallest units of the system.
- 8
- Trigrams
- Three-line figures represent eight natural forces.
- 64
- Hexagrams
- Two stacked trigrams create the complete matrix.
What does I Ching mean?
“I Ching” is the common English spelling of Yijing (易經), usually translated as “Book of Changes.” The name points to change as the subject of the tradition: lines combine into trigrams and hexagrams, while judgments, line texts, and later commentaries offer symbolic ways to reflect on a situation.
The core text, the Zhou Yi (周易) ("Changes of Zhou"), dates back to the Western Zhou dynasty (1000 to 750 BCE). By the 3rd century BCE, the "Ten Wings" (十翼) commentaries had added later philosophical and ethical readings to the earlier divination text. In 136 BCE, Emperor Wu of Han placed it among the Five Classics.
Tradition credits King Wen of Zhou (周文王) with organizing the 64 hexagrams into their canonical order while imprisoned in the 12th century BCE, and composing the "judgments" (卦辞). His son, the Duke of Zhou (周公), is said to have written the line texts (爻辞).
TEXTUAL SOURCE NOTES
- Zhou Yi core text
- Used for the named hexagrams, judgments, and line-text framework. The page separates this early divination layer from later philosophical commentary; the linked edition provides a direct text reference.
- Primary layer: 《周易》卦辞 and 爻辞 tradition · Chinese Text Project, Book of Changes
- Ten Wings and later reception
- Used for the philosophical vocabulary around change, yin-yang, and moral cultivation. Later commentaries extend the system and form a separate layer in its reception history.
- Commentarial layer: 《十翼》 plus later Chinese and Western reception history.
BINARY ARCHITECTURE
Yin and Yang lines are the smallest units of the hexagram system
The German mathematician Gottfried Wilhelm Leibniz noted a striking correspondence between the I Ching's hexagram system and his own binary arithmetic in 1703. Later scholars still debate how far that comparison should be taken historically.
THE EIGHT TRIGRAMS
Yin and Yang lines grouped into sets of three, representing the fundamental forces of nature
Creative, strong, initiating
Receptive, yielding, nurturing
Arousing, shocking, movement
Gentle, penetrating, gradual
Abysmal, dangerous, flowing
Clinging, luminous, clarity
Keeping still, meditative, stable
Joyous, open, communicative
64 HEXAGRAMS
When two trigrams stack, they form a symbolic matrix of changing situations
Each hexagram is a figure of six stacked lines (爻 yao), read from bottom to top. The lower three lines form the Inner Trigram (representing the internal situation), while the upper three lines form the Outer Trigram (representing the external situation).
Since there are 8 possible trigrams, stacking any two yields 8 x 8 = 64 unique hexagrams. Each hexagram has a name, a Judgment (卦辞) attributed to King Wen, and six Line Texts (爻辞) traditionally attributed to the Duke of Zhou.
The King Wen Sequence (文王序卦) arranges the 64 hexagrams in a deliberate narrative order. Hexagrams are typically paired: the second in each pair is usually the first inverted.
DIVINATION
The art of consulting the Changes through yarrow stalks or coins
Yarrow Stalk Method
THE CLASSICAL APPROACH
The classical yarrow method involves sorting 50 yarrow stalks through a ritualized process of division and counting. One stalk is set aside, and the remaining 49 are repeatedly divided into groups to determine each line.
This process is repeated six times (once per line), building the hexagram from bottom to top. The yarrow stalk method produces a different probability distribution than coins, especially between Old Yin and Old Yang.
Three-Coin Method
THE POPULAR APPROACH
Three coins are tossed simultaneously six times. Each toss produces a line: heads = 3, tails = 2. The sum determines the line type:
- 6 — Old Yin ⚋ (changing → becomes Yang)
- 7 — Young Yang ⚊ (static)
- 8 — Young Yin ⚋ (static)
- 9 — Old Yang ⚊ (changing → becomes Yin)
Changing Lines
HOW MOVING LINES CHANGE A READING
Changing Lines (变爻) are lines marked as "old" values, 6 or 9. Old Yang (9) changes to Yin, and Old Yin (6) changes to Yang, creating a second hexagram for comparison.
The second hexagram is often called the "relating" or "changed" hexagram. Readers compare it with the first hexagram to describe how the situation may be shifting.
A reading with no changing lines often points to a steadier situation. A reading with several changing lines usually asks for more care because more factors are moving at once.
Global Influence
FROM CHINA TO THE WORLD
The I Ching gained widespread attention in the West through Richard Wilhelm's influential 1923 German translation, rendered into English by Cary F. Baynes in 1950. The Swiss psychologist Carl Gustav Jung wrote a famous foreword to the English edition, connecting the I Ching's logic to his theory of synchronicity.
The mathematician Gottfried Leibniz discussed the I Ching's binary-looking structure in 1703 while developing binary arithmetic. The comparison belongs to intellectual history and shows how later readers placed the hexagram sequence alongside binary thought.
Sources: Chinese Text Project, Book of Changes; Wikipedia — I Ching, §History and textual origins & §Hexagrams & §Divination; King Wen Sequence; Stanford Encyclopedia of Philosophy, §Chinese Philosophy