Because Yin and Yang depend on each other (each exists as a precondition for the other), pure Yin does not last, and pure Yang does not endure. Hence, in martial arts, there is no absolute relaxation or tension. Complete relaxation is slackness, and complete tension is stiffness. There is relaxation within tension, and tension within relaxation, the transformations of Yin and Yang are infinitely profound.
Ancient Tai Chi manuals clearly state that all movements in Tai Chi are formed in response to the opponent's actions, thus lacking the fancy, bizarre, and complex proactive skills found in some external martial arts. In this sense, Tai Chi is actually simple and easy to learn. However, even the simplest actions can be challenging. For example, who can't walk? Everyone thinks walking is simple, but tightrope walking is essentially walking. How many people in the world can walk on a tightrope hundreds of meters high above a canyon? Hence, walking also involves difficulty and tricks. Indeed, no matter how clear and straightforward the principles and techniques of any skill in the world, learning it involves difficulty and tricks; mastering any skill to a high level is even more challenging. Learning Tai Chi is naturally difficult and requires tricks, and for the average person, the difficulty can be quite substantial, even insurmountable for some, hence the saying, "Many practice, but few succeed." Can this situation be changed? Of course.
The term "缠法" (Chán Fǎ) was proposed by Chen Xin, also known as Chen Xinyi, in his book "Illustrated Explanation of Chen-Style Taijiquan." He stated, "Taijiquan also involves 'Chán Fǎ' (Entwining Techniques)." He further emphasized, "Without understanding this, one cannot comprehend the essence of the martial art." Chen Xin affirmed the significant position of "Chán Fǎ" in the Chen-style Taijiquan routines and elaborated on its various forms: "there are 'Jin Chán' (Advancing Entwining), 'Tui Chán' (Retreating Entwining), 'Zuo Chán' (Left Entwining), 'You Chán' (Right Entwining), 'Shang Chán' (Upward Entwining), 'Xia Chán' (Downward Entwining), 'Li Chán' (Inward Entwining), 'Wai Chán' (Outward Entwining), 'Shùn Chán' (Clockwise Entwining), 'Nì Chán' (Counterclockwise Entwining), 'Dà Chán' (Large Entwining), and 'Xiǎo Chán' (Small Entwining)."
Traditional Tai Chi Chuan and modern Tai Chi exercises are completely different. Their principles and training methods maintain the unique characteristics of early Tai Chi Chuan. This includes their requirements in practice and application. The training and application of traditional Tai Chi Chuan are primarily based on the principles outlined in the "Tai Chi Chuan Theory." It revolves closely around the traditional principles and techniques, integrating the practice and application of Tai Chi Chuan.