Taiji was a state in which the world became intelligible before creation. Taiji may be equated to the ''One'', ''Oneness'', Unity, as in ''attaining One or Unity'' and as stated in the Tao Te Ching.
Translated as "the great ultimate," the ''Taiji'' is understood to be the ideal of existence. Yin and yang represent the contrasting qualities within reality and experience. For example, light contrasts with darkness, providing them both with context and therefore meaning. ''Taiji'' is not perceived as a simple list of all things and potential things, but rather a complex interconnection of all things in all possible contexts. This concept is often used to illustrate the doctrine of unity. It is also used to explain the creation of the "myriad things" through the dialectical process of alternating polarity between yin and yang. Western proponents of Taoism sometimes conflate ''Taiji'' and the "myriad things," but ''Taiji'' is not only representative of what exists, but also that which has existed, will exist, and could potentially exist.
''Taiji'' in historical China
The concept of ''Taiji'' was introduced in the ''Zhuang Zi,'' showing its early place in Taoism. It also appears in the Xì Cí of the ''I Ching,'' a fundamental Taoist classic.
When Confucianism came to the fore again during the Song Dynasty as Neo-Confucianism, it synthesized aspects of Chinese Buddhism and Taoism, and drew them together using threads that traced back to the metaphysical discussions in the ''Book of Changes.''