Wang, Zong-yue said:

What is taiji? It is generated from wuji, and is a pivotal function of movement and stillness. It is the mother of yin and yang. When it moves it divides. At rest it reunites." From this, it is known that taiji is not wuji, and is also not yin and yang. Instead an inclination of the natural pivotal function which makes the wuji derive into yin and yang also makes the yin and yang reunite into the state of wuji. This natural pivotal function of movement and stillness is called the 'Dao' or the 'rule' of great nature.

王宗岳云：〝太極者，無極而生，動靜之機，陰陽之母也。動之則分，靜之則合。〞由此可知太極並非無極，亦非陰陽，而是自然之機驅使無極演化為陰陽或陰陽復合為無極之勢。此自然動靜之機，即所謂道或大自然之理。

Wang, Zong-yue was a renowned taijiquan master who was born in Shan-You, Shanxi Province (山右 山西省), during the Chinese Qing Qian Long period (清乾隆) (a.d. 1736–1796). Taiji (太極) can be translated as "grand ultimate," or "grand extremity," and wuji (無極) is translated as "without ultimate," "without limit," or "no extremity." Wuji can also mean "no opposition." This means wuji is uniform and undifferentiated, a point in space or at the center of your physical, mental, and energetic bodies. For example, at the beginning of the universe, there was no differentiation, and this state was called wuji. Then it began its separation into complementary opposites, called yin (陰) and yang (陽). From the interaction of yin and yang, all things are created and grow.

Even though the theory of taiji (太極) originated from the Yi Jing (易經) (The Book of Changes) and has been studied and practiced for more than four thousand years in China, its applications in martial arts probably did not begin until several thousand years later. When taiji theory was adopted into the taiji ball qigong training in martial arts society, it significantly improved the health and martial aspect of martial artists. If we wish to understand the real meaning of taiji ball qigong practice, the first task is to comprehend the meaning of taiji.

From Wang, Zong-yue's statement, it is clear that taiji is neither wuji nor yin-yang, but is between them. It is the pivotal force or energy that causes the wuji state to divide into the yin and yang (i.e., two polarities) and also causes the yin-yang to reunite to the state of wuji. This natural pivotal force, energy, or function is called "taiji" (太極), "Dao" (道) (i.e., natural way), or "li" (理) (i.e., natural rules) of nature.

Tai Chi Ball and Wuji

Yin and yang, two polarities, originate from wuji through taiji's action or function. From these two polarities, again through taiji's action, four phases are derived. With the same theory, the variations continue until there are unlimited changes in the universe. From yin and yang's mutual interaction, millions of lives are born. From this, you can see that all life and all things are produced from the mutual interaction of yin and yang through the mediating function of taiji. Therefore, if you are interested in learning taiji ball qigong, you must understand yin and yang, and their relationship with taiji. Without knowing the theory and the Dao, your taiji ball qigong practice will be limited to the external forms and movements. In this case, you will have lost the real meaning of practicing taiji ball qigong.

Before the action of taiji ball qigong movement, the xin (i.e., emotional mind) is peaceful and the qi is harmonious, the xin and yi (wisdom mind) are at the (real) dan tian and the qi stays in its residence. This is the state of extreme calmness and is the state of wuji. However, when the xin and yi begin to act, the qi's circulation begins, the physical body's movement is thus initiated, and the yin and yang accordingly divides. From this (we) can see that xin and yi are what are called taiji in taiji ball qigong. That means the Dao of taiji ball qigong is the Dao of xin and yi (i.e., minds).

All objects, ideas, spirits, etc. can be classified as either yin or yang. Taiji ball qigong was created according to this theory. In the beginning posture of the taiji ball qigong practice, the mind is calm and empty, and the weight is evenly distributed on both feet. This state is wuji. When your mind starts to lead the body into the movement, internal (yin) and external (yang) aspects of taiji ball qigong features start to be discriminated. Moreover, the hands and feet are differentiated into insubstantial (yin) and substantial (yang). This is the state of two polarities.

Through interaction of substantial (yang) and insubstantial (yin), all of taiji ball qigong moving patterns are generated. From this, you can see that the taiji (i.e., the Dao) in taiji ball qigong is actually the mind. It is the mind that makes the body move and divides the wuji state into yin and yang two polarities. We can conclude from this that taiji ball qigong is actually a qigong practice of the mind (i.e., taiji).

Though a human body is bonded between the heaven and the earth, (its) xin and yi are able to reach (anywhere) unlimitedly in the universe without being restricted by time and space. From xin and yi, the yin and yang are initiated and (continue to) move into unlimited variations. This is the theory of millions of divisions and creations of taiji. Therefore, those who practice taiji ball qigong must begin from the (training of) xin and yi.

人身雖束於天地之間，然心意可達無窮於宇宙，並不為時間、空間所限。由心意，陰陽生而演變分化無窮。此為太極萬象衍生創造之理。因此，學太極氣功者，必須從心意著手。

Though our physical bodies are restricted by our three-dimensional reality, our minds are free to travel and reach anywhere in the universe, or even beyond this universe, unrestricted by time (i.e., the mind is grand ultimate). All human creations, from shovels to airplanes, arose first in our imaginations. From our thoughts, new ideas are created. It is the same for taiji ball qigong. It was created from the mind, and its creation will continue without an end. Since it is an active, living, and creative art, taiji ball qigong is a product of spiritual enlightenment and an understanding of life.

Xin (i.e., emotional mind) and yi (i.e., wisdom mind) are contained internally, which belongs to yin. The movements (actions) of taiji ball qigong are manifested externally, which belongs to yang. When the functions of xin and yi are applied to our spiritual feeling, they direct us into the correct Dao of cultivating our human nature through efforts toward strengthening the mind, raise up the spirit to comprehend the real meaning of human life, and from this, further to comprehend the meaning and relationship among humans, between humans and objects around us, and also to search for the truth of nature in heaven and earth. When the function of xin and yi is applied to our physical body, it is the great Dao of cultivating the physical life for self-defense, nourishing the physical life, and strengthening the physical body. This is the foundation for extending our lives and establishing a firm root of health.

心意者，內含也，陰也。太極球氣功之動作，外顯也，陽也。心意活動於己身之精神內感，即強心、提神、領悟人生之養性正道。由之去瞭解人與人、人與事物關係之真諦並尋求天地自然之真理。心意活動於己身物理之造化，即防身、養生、與強身之修命大道。此為延命立基之本。

As mentioned earlier, xin and yi are the taiji in taiji ball qigong. This internal thinking is yin. When this yin is manifested externally, then yang is demonstrated. When xin and yi are acting on internal spiritual feeling, it serves to cultivate our human temperaments and helps us to understand the meaning of our lives. When xin and yi are acting and manifested externally, it promotes physical health and self-defense. Therefore, when we practice taiji ball qigong, we should cultivate both our spiritual beings (yin) and train our physical bodies (yang).

Taiji ball qigong originated from the Daoist family. Its ultimate goal is to reach enlightenment and so as to achieve the Dao of unification between heaven and human. Therefore, the final goal of practicing taiji ball qigong is to reach the unified harmonious wuji world (i.e., state) of the heaven and human. From practicing taiji ball qigong, (we are able) to further comprehend the meaning of human life and the universe.

太極球氣功始於道家，其終的在通乎神明以臻天人合一之道。因而習太極球氣功之終的亦即在於天人合一大合諧之無極世界，由習太極球氣功而領悟人生宇宙之理也。

Taiji ball qigong was created in the religious (Daoist) school of qigong. The goal of Daoist cultivation is to reach enlightenment, to unify the human spirit with the natural spirit. This is the wuji harmonious state. To reach this destination, the first step is to appreciate the meaning of life and to understand natural truth.

The above is an excerpt from Tai Chi Ball Qigong: For Health and Martial Arts by Dr. Yang, Jwing-Ming and David Grantham