Central to Chen Wangting's boxing method was the ancient concept of Yin and Yang, the all-encompassing notion of complementary opposites that underpins Chinese culture and philosophy to the present day. Yin and yang represent the perpetual process of change and flux in nature, such as night and day, female and male, decay and growth, etc. Whether a thing is classified as yin or yang depends on the role it plays in relation to other things, and not on its own intrinsic nature. Chinese philosophy is based on the concept of harmonizing with nature rather than dominating it in an effort to make it conform to human desires. Humanity, therefore, is part of nature to the Chinese, and as such, this theory underpins all aspects of life.
Within the parameters of Taijiquan, the yin and yang theory is applied in a practical way. The aim is to harmonize opposing elements until they reach a state of balance. This will allow the optimum benefits to accrue, be they physical or mental, for health or for martial skill. For example, movements that are slow and relaxed are yin, and movements that are fast and strong are yang; closing movements where energy is being stored are yin, and opening movements where energy is being released are yang; the non-weight-bearing side of the body is considered yin, and the weight-bearing side of the body is yang; and so on. Taijiquan demands that there is no violation of the principle; that there is a constant interchange of yin and yang; that there is always some yin in yang and vice versa; and that a balance of yin and yang energies is always present. An understanding of the underpinning philosophy can help one to grasp the fundamental aspect of the art, as well as to bridge the cultural gap between East and West.
Perhaps the greatest innovation of Chen Wangting was the assimilation into his martial art system of the ancient health method of daoyin (leading and guiding energy) and tu-na (expelling and drawing energy), in addition to Daoist theories on consciousness guiding movement. This unique synthesis represents the origin of all Taijiquan styles. The combination of the coordinated movements of the hands, body, eyes and footwork of the martial arts with the techniques of daoyin and tu-na led to Taijiquan's evolution into a comprehensive system of exercises. Characterized by a joining of inner and outer power, the correct practice is said to require "training the breath inwardly, and the muscles, bones and skin outwardly." By incorporating the practice of daoyin and tu-na into the martial exercises, Taijiquan became a holistic training system in which the practitioners' mental concentration, breathing and movements are intimately co-ordinated. This paved the way for Taijiquan's future use as an exercise system suitable for all, regardless of age and health status, and applicable to all aspects of health care.