Trigrams / Hexagrams and Component Lines

A gua (trigram/hexagram) is a system of symbols consisting of undivided lines (—) and divided lines (- -). The undivided line (—) is a yang line while the divided one (- -) a yin line. Three lines make a trigram, and there are eight such trigrams. When six lines are put together, they together make 64 hexagram combinations. Trigrams / hexagrams and component lines were created partly for the purpose of divination. Ancient Chinese people used yarrow stalks to make hexagrams, calculated the variations they suggested, and consulted them for the purpose of divination. Later on, people used trigrams / hexagrams and component lines symbolically to explain the changes and the laws regulating the changes that occurred in people and everything else, and why and how these changes took place.

When the eight trigrams were invented, they embodied the images of all things. When the eight trigrams were multiplied by eight trigrams and permuted into the 64 hexagrams, all the 384 lines were included.
When sages saw the changes or events happening under heaven, they observed the similarities of the events and responded with appropriate rites and rituals. They judged their implications of the changes by obtaining explanations from the yao.