The hexagrams arise from a very simple yet profound structure. Each one is composed of six horizontal lines, read from bottom to top, and each line is either solid (yang) or broken (yin). Because each of the six positions can be yin or yang, there are 2⁶, or 64, possible line-patterns. These six lines are not treated as an undifferentiated stack: they are understood as two groups of three, known as trigrams. There are eight such trigrams—Heaven, Earth, Water, Fire, Thunder, Wind, Mountain, and Lake—each itself a particular configuration of yin and yang. By placing one trigram above another, an upper and a lower, the tradition generates 8 × 8, or 64, distinct hexagrams. In this way, the entire system rests on the interplay of the most basic duality, expressed through a rigorously ordered pattern.

What these 64 figures symbolize is not a set of static states, but a living tapestry of change. Each hexagram is taken to portray a characteristic configuration of forces, a recognizable situation in the cosmos and in human life, and at the same time a phase within an ongoing process. They are often read as archetypal situations or “moments” in the unfolding of events, each with its own tendencies, potentials, and appropriate responses. The hexagrams thus sketch universal principles of transformation, mapping how circumstances arise, mature, decline, and give way to something new. At their heart lies the ceaseless interaction of yin and yang—opposed yet complementary movements whose shifting balance gives shape to both nature and human affairs. Through this symbolic language, the hexagrams offer a way of contemplating how to move in accord with those patterns of change, aligning conduct and understanding with the larger order they reflect.