In Yang-style Tai Chi, relaxing the waist is emphasized as a crucial point: "The waist is the master of the whole body. Only when the waist is relaxed, then the feet are powerful, and the lower stance is stable. Changes between solidity and emptiness all come from the turning of the waist, thus it's said that the source of command is in the space of the waist. Any lack of strength must be sought in the waist and legs."
Yang Chengfu summarized the practice of Yang-style Tai Chi Chuan into ten essentials: "Empty the mind and top up the energy, contain the chest and pull up the back, relax the waist, distinguish between solid and empty, sink the shoulders and drop the elbows, use intent not force, coordinate the upper and lower body, harmonize the inside and outside, continue movements without interruption, and find stillness in motion.
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.
The postscript explains that to understand the Four Characters Secret, one must first understand the energy; without this understanding and reaching a highly refined level of practice, it's impossible to fully grasp it. This might sound mysterious, but practicing push hands involves a process of 'gradually understanding the energy from familiarity and progressing to a divine level of understanding.' Only after passing the initial stage can one gradually understand the "Four Characters Secret." Of course, due to individual differences in insight, even with the same effort, comprehension can vary in timing.
In Tai Chi pan jia, every posture and even every small movement is permeated with Tai Chi Yin Yang philosophy. Otherwise, even practice for decades, just stay in physical fitness stage, cannot reach martial arts high level. For martial artists, not only know how it works but also why it works, then can keep improving. Purpose of pan jia must be clear: only through pan jia, can really grasp the whole body movement rules, achieve coordination of hand, eye, body, method, step; spirit, energy, intention, strength, mind, whole body as one family.
Why standing post (Zhan Zhuang) can make bone marrow full and body strong? Secret is in stretching tendons and pulling bones! Post deep in ground, very stable, no matter wind or rain, it not move! Big sky and universe, stand alone, look down on everything! Stand between heaven and earth, fill the gaps of universe! Standing post is way to make body's qi channels fully stretch. It let essence, energy, spirit go back into marrow. People who do standing post often have strong bones and tendons. One sign of this strength is person look not fat, but weight is not light, this show body healthy. Some people look fat, but is soft fat, lots of flesh, when weigh, very light, this actually show essence not stay in bones.
"The highest martial achievement is the way to peace the world; the intermediate martial achievement brings peace to the mind and body; the lowest martial achievement refines techniques to prevent harm...
In practicing Tai Chi, wanting to delve deeper into the art, the biggest obstacle encountered is the challenge of one's inherent force, which is the stiffness throughout the body, both inside and out. This inherent force affects the light and agile application of Tai Chi, presenting practitioners with the task of overcoming this barrier.