The Yijing (The Book of Changes) is an old text incorporating sections that date from around the ninth century BCE. The older section of the text includes symbols comprised by six lines each, called ‘hexagrams’. It also includes interpretations of each hexagram (guaci: hexagram statement) and statements on each of a hexagram's six lines (yaoci: line statement). The six lines of a hexagram are either broken (–), signifying yin, or unbroken (–), signifying yang. The concept yin represents a set of characteristics associated with receptiveness, while yang a set of characteristics associated with firmness. Each line statement provided an individual prognosis as well as recommendations for action (Cheng 2003: 517). The hexagram and line statements are attributed to King Wen of Zhou (1099–1050 BCE), the founder of the Zhou Dynasty. Together with the hexagrams, sixty-four in total, these statements are the earliest layer of the Yijing. There are two other layers which are later additions to the text. The idea of using hexagrams for representing clusters of concepts and in divination precedes the composition of the Yijing. The two previous dynasties, the Xia (c. 2070–1600 BCE) and the Shang (c. 1600–1046 BCE), had their respective divination manuals called Yi of Xia and the Yi of Shang (Cheng 2003: 517). The hexagrams are each a compilation of two trigrams, symbols which consist of some combination of three broken and unbroken lines.