The Yijing (The Book of Changes) incorporates sections that date from around the ninth century BCE. The older layer of the text, known as the “Basic Text” (Ben Jing), has traditionally been associated with divination. This older layer comprises:
1. 64 symbols of six lines each, with the broken lines (– –) signifying yin, or unbroken lines (—) signifying yang. Each of these six-lined symbols, called hexagrams (gua), bears a name which refers to phenomena or elements in the natural world
2. A hexagram statement (guaci) for each hexagram
3. A line statement (yaoci) for each of the six lines of every hexagram.
The broken line embodies the concept yin and represents a thematic cluster of characteristics associated with receptiveness and femininity, while the unbroken lines embody yang, representing a set of characteristics associated with firmness and masculinity. Each hexagram is a compilation of two trigrams (a combination of three broken or unbroken lines (see below), one set of three stacked on top of another). The eight trigrams are attributed to the Confucian culture hero, Fu Xi (c. 2800 BCE) (Legge, Yî King, 1899: 32).
In the Shang period (c. 1600–1046 BCE) preceding the Zhou, oracle bones (from bovine scapula) and turtle plastrons were used by the kings and their diviners to prognosticate on a wide range of subject matters including natural disasters, harvests, sickness, seasonal and climactic changes, military strategy, sorties and trips and childbearing (Keightley 1978: 33–5). It seems that, during the Zhou, divination was used to decipher cosmic processes and to interpret their correlations with and implications for the human world (Lynn, Classic of Changes, 1994: 1). In the use of the Yijing, the correct hexagram pertaining to a particular issue was identified and the prognosis made on the basis of the hexagram and line statements. Each hexagram name expresses its core meaning, together with a set of associated concepts. The terms associated with the hexagrams include, for example, Qian (heaven), Kun (earth), Pi (obstruction), Gu (corrupted or decayed), Fu (return), Heng (constancy), Huan (dispersion) and Sheng (ascendancy).