In the theory of Chen Xin, it is stated: “Opening and closing, void and solid, are the essence of boxing; ‘one opens and one closes, there are changes and constants, both void and solid are present, sometimes appearing and sometimes hiding’; ‘there is closing within opening, and opening within closing’; ‘there is void within solid, and solid within void’; ‘one opening and one closing encapsulate the essence of boxing techniques.’ He places the concepts of opening and closing, void and solid in a primary position and discusses them comprehensively.
1. Opening and closing are from the inside out, drawing the outside in, achieving unity of the internal and external.
If Tai Chi only emphasizes the external forms of opening and closing without focusing on the internal movements, then whether practicing boxing or push hands, it will diminish its therapeutic, health-preserving, and skill-enhancing effects, and it cannot be called a martial art that unifies the internal and external. Tai Chi has always been referred to as an internal martial art, which means that movements and breathing must be coordinated under the guidance of consciousness. This involves a close integration of consciousness, breathing, and movement, requiring the muscles, joints, and internal organs to work internally to coordinate the external movements of the limbs.
The emphasis of opening and closing lies in the internal changes rather than the external forms of movement. The internal movement of opening and closing still operates under the principles of “spiral force” and “force like pulling silk,” which is referred to as “force transformed from within” or “internal energy subtly shifting.” Opening signifies expansion and magnification, while closing signifies contraction and reduction. The opening and closing in Tai Chi, due to the spiral nature of the movements, implies adherence and connection, allowing one to open without colliding and to close without evading, especially enabling one to combine their strength while dispersing the opponent’s strength. Through long-term training in push hands, one can fully utilize the special techniques of “using light to control heavy,” “using softness to overcome hardness,” “using small force to defeat large force,” and “taking advantage of the opponent’s momentum and borrowing their strength.” When practicing the unity of internal and external opening and closing, one should contemplate the phrases “the internal does not move, the external does not act.” Each movement requires “initially moving the intention, then moving internally, and finally moving externally.”
When the movement opens, both the internal and external open; when the movement closes, both the internal and external close, with spirit and energy interwoven, the whole body complete and seamless, transitions should be executed in one breath, with concentrated force directed to a single point, and able to flexibly change at any time.
2. There is closing within opening, and opening within closing.
Within each opening and closing, there is a further requirement for “closing within opening and opening within closing,” “opening within opening and closing within closing.” “Closing within opening and opening within closing” is the central function of “force like pulling silk.” The movement of energy in Tai Chi is governed by the waist and spine, with the spiral movements directed outward called “opening,” and the return to the dantian from the extremities called “closing.” In Tai Chi, the outward peng (ward-off) is considered opening, while the inward lu (rollback) is considered closing. Peng is a forward spiral, while lu is a reverse spiral; “reverse” comes from “forward,” and opposites complement each other. Due to the “force like pulling silk” and the spiral nature of the movements, when the arms close, the area below the elbows is already opening, and when the arms open, the area below the elbows is already closing. For example, the fixed posture of ’embracing the knee and stepping back’ is opening, and when transitioning to ‘hand waving the pipa,’ retracting the right hand is closing, while the area below the elbows is already opening, which is “opening within closing”; then, when the right hand makes half a circle outward, it is opening, while the area below the elbows is already closing, which is “closing within opening.” Finally, when the hand waving the pipa is completed, both hands embrace left front and right back, becoming closing again, but the chest slightly contains inward, expanding the chest muscles, becoming external closing and internal opening, which is “closing within opening.” “Opening within opening and closing within closing” means that when opening, one continues to extend and lengthen, and when closing, one continues to contract and reduce, cycling endlessly. “Opening within opening” in push hands manifests as I advance and lengthen, while the opponent retreats and shortens; I advance in steps to gain opportunity and momentum. “Closing within closing” manifests as the opponent repeatedly advances in an arc, while I follow the movement to adhere and continue to arc in contraction; I leap back in steps while the opponent cannot adhere, and my counterattack’s explosive power becomes stronger. “Opening within opening and closing within closing” is an advanced skill achieved after deep practice in Tai Chi, characterized by extreme softness and agility, with spiral movements being very subtle, “the whole body soft as if without bones” while maintaining a centered and upright posture, “suddenly releasing is all hands.”
Masters of Tai Chi can achieve the level of “others do not know me, but I alone know others” in push hands techniques, primarily due to the internal movement of “force transformed from within” and “internal energy subtly shifting,” where the route, direction, and force point of one’s own energy are first transformed internally, synchronizing with the opponent’s movements like glue, yet the intention and energy always lead the opponent, making it difficult for them to perceive. Because this practice is advanced and detailed, it yields good results whether applied in therapeutic health, enhancing physical fitness, or improving skills. The reason Tai Chi can attract people to practice continuously, becoming increasingly interesting and addictive, lies in the depth of intention and interest, which has no limits. In the current widespread practice of Tai Chi, to improve the effectiveness of training, it is essential to emphasize the combination of internal and external movements, especially after becoming proficient in the forms, one must always pay attention to “the internal does not move, the external does not act.”
3. There is void within solid, and solid within void.
The concepts of void and solid, from the perspective of intention, can be illustrated with the hands; for example, if the intention is concentrated on the right hand, then the right hand is solid, and the left hand is void; if the intention is concentrated on the left hand, then the left hand is solid, and the right hand is void. This distinction clarifies the void and solid of the two hands. After a period of training, based on the clear distinction of void and solid, one must further require that the void contains solid, and the solid contains void. Again, using the hands as an example, the previously distinguished hands must now further clarify void and solid; the void hand must contain solid, and the solid hand must contain void. For instance, the forward pushing hand is solid, the side pushing forward is solid, while the back side is void. This concept of solid within void is to concentrate force at a single point, ensuring that areas not requiring force are relaxed, adhering to the principle of economical force. The side pushing forward is solid, likened to the edge of a knife, while the back side is void, likened to the back of the knife, indicating that the force point must be concentrated on the edge. The back hand is void, but it is also required to have intention concentrated within it. This concept of void within solid is to balance the center of gravity and ensure that the forward hand exerts more force.
Each movement in Tai Chi is a circle, and within the turning of the circle, the void and solid are constantly changing. For example, when the hand draws a circle, the upper half is void, while the lower half is solid; if the internal energy in peng is void, then the lower lu is solid. This represents one void and one solid within a circle. Within one void and one solid, there must still be the principle of “force like looseness, not looseness, yet to be extended and not yet extended,” further achieving void within solid and solid within void. In push hands, within one circle, there are countless flexible changes of void and solid, yin transforming into yang, yang transforming into yin, seeming yin yet not yin, seeming yang yet not yang, appearing and disappearing, making it difficult for the opponent to grasp; “the whole body is Tai Chi everywhere” illustrates this subtle change.
The distinction of void and solid in the legs, whether front void and back solid or front solid and back void, or left void and right solid or left solid and right void, further requires void within solid and solid within void; void is not entirely without strength, and solid is not entirely rigid. This is essential for making footwork flexible and swift. When first practicing Tai Chi, the footwork must clearly distinguish between large void and large solid; after practicing for a while, as the skill becomes refined, the ratio of void to solid should gradually decrease, for example, from 8:2 to 7:3, 6:4, etc. The shorter the distance between void and solid, the more flexible and rapid the changes become. The ancients represented the practical use of opening and closing, void and solid with the terms yin and yang: closing and void are yin, opening and solid are yang. Yin transforms into yang, yang transforms into yin, “yin extreme gives birth to yang, yang extreme gives birth to yin,” “yin does not leave yang, and yang does not leave yin,” which means “yin and yang mutually root each other.” “There is yang within yin, and there is yin within yang,” which means “opening within closing, closing within opening; void within solid, solid within void.” Void and solid must permeate each other, subtly influencing one another, and also require “sometimes appearing and sometimes hiding,” with changes being very flexible. To achieve this, the intention and energy must be flexible in all directions, up and down, front and back, left and right. Only with flexible changes in intention and energy can void and solid “sometimes appear and sometimes hide.” Each posture must be able to support from “eight directions” while also requiring “eight directional transformations”; when the intention shifts, the whole body moves, and when the intention moves, the gaze leads, thus “with a turn of the eye, the whole body moves.” This is the wonderful application of void and solid.
The transformation of void and solid, like opening and closing, is also guided by consciousness, first moving internally and then externally, achieving unity of the internal and external, and still relying on the “spiral-like movement of force” as the central function.
The concepts of opening and closing, void and solid are integrated into every movement of Tai Chi, alternating with the changes in movements, always opening and closing, void and solid, with opening within closing, closing within opening, void within solid, and solid within void. If the intention continuously concentrates on one hand or both hands moving in the same direction, then the transformation of void and solid should change with the opening and closing of the movements, that is, solid when opening and void when closing.
4. Opening and closing, void and solid are gradual changes, coordinating the internal and external.
From opening to closing, from closing to opening, from solid to void, and from void to solid, these are gradual changes, not abrupt changes. The process of transformation corresponds to the initiation, cessation, and speed of the movement. This gradual practice, akin to static strength training, is most effective in developing endurance and strength, not only involving a significant amount of movement but also allowing the actions to become increasingly refined, with internal strength gradually enhanced, achieving a state where softness contains firmness, and the whole body remains calm and relaxed.
Void and solid cannot be understood merely as the distinction of hands and feet; in reality, the muscles, joints, and internal organs of the chest, abdomen, and back must also distinguish between void and solid, and this is the main part of the movement. Therefore, the boxing theory states: “The key lies in the transformation of the chest and waist,” “each part has its own void and solid, and everywhere is a void and solid,” “force transformed from within,” “all of this is intention, not external.” If there is only the void and solid of the hands and feet, without the void and solid of the chest, abdomen, and back, then there is no internal movement to govern the external movement, and it cannot be a holistic, internal and external unified movement; in combat, it is impossible to achieve “internal movement without being perceived by others.” Additionally, one should not think that merely coordinating breathing with the movements of the limbs constitutes an internal martial art or internal power. This is not comprehensive, as breathing only utilizes the diaphragm’s up and down movement to provide slight self-massage to the internal organs, lacking the conscious guidance of the muscles, joints, and internal organs of the chest and abdomen to engage in activity, thus failing to meet the requirement of “one movement leads to all movements.” Only with the practice of “force like pulling silk,” where intention and energy change flexibly, and “moving energy like a string of pearls, reaching every detail,” can the internal organs, muscles, blood vessels, and meridians all be exercised simultaneously, achieving the state of “one movement leads to all movements.”
5. The overall void and solid of the body lie in the transformation of the waist gap.
Tai Chi emphasizes the need to clearly distinguish void and solid everywhere, but there must be a primary and secondary distinction. Which part’s void and solid governs the overall internal and external, up and down, front and back, left and right void and solid, allowing for “the main line to lead the details”? In classical Tai Chi theory, this key answer can be found. Wang Zongyue’s “Thirteen Postures and Their Applications” states: “The source of intention lies in the waist gap; pay attention to the transformation of void and solid.” Wu Yuxiang said: “It is governed by the waist.” Li Yiyu said: “The key lies in the transformation of the chest and waist, not externally.” Chen Xin said: “The waist is the key to the upper and lower body; above the waist, energy moves upward, below the waist, energy moves downward, resembling the dual forces of up and down, yet in reality, it is one energy flowing through, not conflicting.” All these clearly indicate that the overall pivot for distinguishing void and solid in all parts of the body lies in the “waist gap.” Some people mistakenly change “waist gap” to “waist,” which is incorrect. The “waist gap” is commonly known as the “waist eye,” referring to the two kidneys; in Traditional Chinese Medicine, the kidneys are called “the source of life and vitality,” and “the source of true energy,” believing that “when the kidneys are strong, essence is sufficient and energy is abundant,” leading to clarity of mind and vision. Chen Xin said: “Where does the central energy return? It returns to the two kidneys.” Hao Yue Ru said: “The transformation occurs as the steps follow the body; the source of intention lies between the waist eyes; when turning left, the left waist eye slightly lifts upward, using the right waist eye to support the left waist eye; when turning right, the right waist eye slightly lifts upward, using the left waist eye to support the right waist eye. This is what is meant by ‘the source of intention lies in the waist gap.'” This means that the overall void and solid of the body lie in the waist, and secondarily in the chest, which is the practice of transforming void and solid through the waist gap.
The waist gap governs the transformation of the two legs and footwork, which is directed by the internal movement of the waist gap, known as the steps following the body. When the waist gap is engaged on one side, the leg on the lower side is also engaged, while the other side’s void leg steps lightly. The void leg and the solid leg on one side have a mutual connection; the void leg prevents it from becoming too light, hence Li Yiyu said: “The upper body connects at the shoulders, while the lower body follows the legs.” But where is the pivot for the transformation of the waist gap? Chen Xin’s boxing theory points out: “The key lies between the two waists, between the two kidneys, as the key pivot for the upper and lower body.” This vividly indicates the role of the waist under the control of the mingmen (Gate of Life) in the spine governing the two kidneys. Whenever the hands and legs move forward, the two kidneys first transform, the energy sinks to the dantian, the mingmen slightly pushes backward, and the waist’s strength relaxes downward, hence those who practice Tai Chi for a long time develop a strong and full daimai (the belt vessel surrounding the waist).
Each inhalation and exhalation, the diaphragm’s rise and fall, relates to the stability of the center of gravity; the transformation of void and solid in the waist gap relates to the movement of the center of gravity.
The transformation of the chest’s void and solid: the collarbone relaxes downward, fixed by intention, the chest slightly contains inward; when the lower side of the waist gap is engaged, the upper chest muscles relax and sink along the arc, moving outward and forward (as referred to in Wu Yuxiang’s “Ten Essentials of Body Mechanics” as “protecting the chest”). Thus, with the clear distinction of void and solid in the waist gap, the left and right chest muscles also clarify their void and solid in the arc’s relaxation.
The distinction of void and solid in the waist gap and chest must still adhere to the principle of “void within solid, solid within void”; the void side must have the intention of mobility to prevent it from becoming too light; the solid side must concentrate intention to prevent it from becoming too heavy. The void of the chest governs the two hands, with the collarbone fixed, and the left and right chest muscles alternating between void and solid (also an internal folding), which can govern the transformation of the void and solid of the two hands (the transformation of the two hands’ void and solid is also called folding, governed by internal movement).