What the meaning of Taiji 太极？

Tai Chi (太极) expounds the process by which the universe evolves from Wuji (无极，the state of formlessness) to Tai Chi, and further to the creation and transformation of all things. I Ching·Xici (《易经・系辞》) states: "Thus, the Yi (the Book of Changes) has Tai Chi, which generates the Two Forms (两仪)." Tai Chi refers to the state before heaven and earth were separated, and chaos was undivided into yin and yang; the Two Forms are the yin and yang aspects derived from Tai Chi.

I Ching·Xici further says: "The Two Forms generate the Four Images (四象), and the Four Images generate the Eight Trigrams (八卦)." This means that all things and phenomena in the vast universe contain yin and yang, as well as external and internal aspects. They are in a relationship of both opposing and struggling against each other, and mutually nurturing and depending on each other. This is not only the general law of the material world, the guiding principle and origin of numerous things, but also the root cause of the generation and destruction of things.

The way of heaven and earth is to create all things through the qi (vital energy) of yin and yang. Heaven and earth, sun and moon, thunder and lightning, wind and rain, the four seasons, as well as male and female, firmness and softness, movement and stillness, manifestation and concealment—all things without exception are divided into yin and yang.

The principle of human life is that the qi of yin and yang nourishes the hundreds of bones and muscles. Channels and collaterals, bones and flesh, abdomen and back, the five zang-organs and six fu-organs, and even the "seven injuries and eight benefits" (a concept in traditional Chinese medicine related to health preservation)—within the human body, all conform to the principles of yin and yang.

Established over two to three thousand years ago, this theory still describes all phenomena for people today. Undoubtedly, concepts such as Tai Chi and yin and yang have exerted a profound influence on Taoism.