经曰∶亢则害，承乃制，制则生化，外列盛衰，害则败乱，生化大病。此数句，前人解说极多，能会经旨
者殊少。详其文意，当云∶亢则害，害则败乱，生化大病；承乃制，制则生化，外列盛衰。只作两下解之为是。
夫天地之间，五类生化，互有所胜，互有所制，地气制己胜，天气制胜己，此以地气之制己胜者言之也。夫六
气之用，各归其所不胜而为化，故太阴雨化施于太阳，太阳寒化施于少阴，少阴热化施于阳明，阳明燥化施于
厥阴，厥阴风化施于太阴，此地之四方，分为六步以应天外六节气令之治者也。天地之气，互为盈虚，恶所不
胜，归所同和，同者盛之，异者衰之，当其位则盛，非其位则衰。地气左迁于中，天气右行于外，内外相因，
盛衰相倚，故曰外列盛衰也。若夫亢则伤害，己胜不受胜己者之施化，于是有胜则有复，胜复更作，败乱生化
之常。故上胜则天气降而下，下胜则地气迁而上，甚则易位，气交易，则大变生而病作矣。所谓害则败乱，生
化大病者是也。此一胜一制，一正一变之异化也。河间云∶亢则害承者之母气，于是承者乃起而制之，是知有
非位之胜复，而不知制则生化外列盛衰，为当位之正化也。楼氏云∶火亢则害，水承乃制之，制生则化。至冬
着盛，是以夏之暑生冬之寒化，以冬之寒制夏之暑亢，恐不相反之甚，是知有当位之正化，而不知害则败乱，
生化大病，为非位之胜复也。安可即以今日既亢之乖气，复为后日得制之平气耶？殊不知亢制字义甚明，言亢
则非平，言制则非亢矣。生化盛衰，乃当位之常，败乱生化，乃非位之变也。二家全不分别，何也？
《黄帝内经》中说：气机亢盛就会造成危害，有制约才能维持平衡，有了制约才能正常生化，在外部表现出盛衰的变化；如果失去制约导致败坏混乱，就会产生严重的疾病。这几句话，前人解释非常多，但能真正领会经文主旨的人却很少。仔细推敲文意，应当理解为：“亢则害，害则败乱，生化大病”与“承乃制，制则生化，外列盛衰”。将其分为两层意思来理解才是正确的。
天地之间，五行各类事物的生化过程，互相有所克制，互相有所制约。“地气制约它所胜之气，天气制约克制它的气”，这是从地气制约其所胜之气的角度而言的。六气（风、寒、暑、湿、燥、火）的作用，各自归于它所不胜（即克我者）的位置而化生，所以太阴湿土之气施于太阳寒水，太阳寒水之气施于少阴君火，少阴君火之气施于阳明燥金，阳明燥金之气施于厥阴风木，厥阴风木之气施于太阴湿土。这是将地面的四方划分为六个阶段，以对应天外六节气令的治理。
天地之气，互为盈虚（消长），厌恶所不胜的力量，回归与之相和谐的状态，相同的力量就旺盛，不同的力量就衰退，处于其当位则旺盛，非其当位则衰退。地气在中部向左迁移，天气在外围向右运行，内外相互依存，盛衰相互倚靠，所以说“在外部表现出盛衰的变化”。
至于气机亢盛就会造成伤害，被胜之气不接受克制它之气的化生影响，于是就有胜气，随之就有复气，胜气和复气交替发作，破坏了生化正常的规律。所以，上面胜则天气下降，下面胜则地气上升，严重时位置互换，气机交换，就会产生巨大的变化而引发疾病。这就是所说的“如果失去制约导致败坏混乱，就会产生严重的疾病”。这是一胜一制、一正一变的不同气化现象。
刘河间（刘完素）说：“亢盛的是害，承袭的是母气，于是承袭者起来制约它。”这是只知道有非当位的胜复变化，却不知道“制则生化，外列盛衰”是当位的正常气化。
楼氏（作者自指）说：“火气亢盛则造成危害，水气承袭从而制约它，制约之后才产生生化。到了冬天寒气盛大，是以夏天的暑热生出冬天的寒气，用冬天的寒气制约夏天的暑热亢盛，恐怕不是相反得太过分吗？”这是只知道有当位的正常气化，却不知道“害则败乱，生化大病”是非当位的胜复变化。怎么可以把今天已经亢盛的乖戾之气，当作后天得到制约后的平和之气呢？
殊不知“亢”和“制”的字义非常明确，说“亢”就不是平和，说“制”就不是亢盛了。生化的盛衰，是当位的常态；败坏混乱生化，是非当位的变异。这两家完全不加区分，为什么呢？
The *Classic* states: "When qi is in a state of hyperactivity (Kang), it causes harm; when there is succession (Cheng), there is control (Zhi); when controlled, transformation and generation occur, manifesting externally as prosperity and decline; when harmed, disorder ensues, leading to severe disease from disrupted transformation." Regarding these sentences, predecessors have provided numerous interpretations, yet few can truly grasp the purport of the classic. Upon detailed examination of the textual meaning, it should be understood as: "Hyperactivity causes harm, harm leads to disorder, resulting in severe disease from disrupted transformation"; and "Succession brings control, control enables transformation, manifesting externally as prosperity and decline." It is correct to interpret this as two distinct aspects.
Within heaven and earth, the transformation and generation of the five categories of things involve mutual overcoming and mutual restraint. "Earthly qi restrains what it overcomes; Heavenly qi restrains what overcomes it." This statement refers to earthly qi restraining what it overcomes. The functions of the Six Qi (Wind, Cold, Summer-Heat, Dampness, Dryness, Fire) each return to their position of being overcome (the element that controls them) for transformation. Thus, Taiyin's damp transformation acts upon Taiyang; Taiyang's cold transformation acts upon Shaoyin; Shaoyin's heat transformation acts upon Yangming; Yangming's dry transformation acts upon Jueyin; Jueyin's wind transformation acts upon Taiyin. This divides the four directions of the earth into six steps to correspond with the governance of the six seasonal qi commands outside heaven.
Heavenly and earthly qi mutually wax and wane. They abhor what they cannot overcome and return to what harmonizes with them. What is similar prospers; what is different declines. When in its proper position, it prospers; when not in its proper position, it declines. Earthly qi migrates leftward within the center, while heavenly qi moves rightward on the exterior. Interior and exterior cause each other; prosperity and decline rely on each other. Hence, it is said that "prosperity and decline are manifested externally."
As for hyperactivity causing harm: if the overcome qi does not accept the transformative influence of the qi that overcomes it, then there is an excess (Sheng), followed by a counteraction (Fu). Excess and counteraction alternate, disrupting the normal order of transformation and generation. Therefore, if the upper part has excess, heavenly qi descends; if the lower part has excess, earthly qi ascends. In severe cases, positions are exchanged. When qi exchanges positions, major changes arise, and disease occurs. This is what is meant by "when harmed, disorder ensues, leading to severe disease from disrupted transformation." This represents the difference between one excess and one control, or one normal and one aberrant transformation.
Liu Hejian (Liu Wansu) stated: "Hyperactivity is harm; the successor is the mother qi of the successor. Thus, the successor arises to control it." This understanding recognizes non-proper positional excess and counteraction but fails to recognize that "controlled transformation generates, manifesting externally as prosperity and decline," which constitutes proper positional normal transformation.
Lou Ying (the author) stated: "If fire is hyperactive, it causes harm; water succeeds and controls it. Control generates transformation. By winter, cold is abundant. Thus, summer heat generates winter cold, using winter cold to control summer heat hyperactivity. Is this not excessively contrary?" This understanding recognizes proper positional normal transformation but fails to recognize that "harm leads to disorder, leading to severe disease from disrupted transformation," which constitutes non-proper positional excess and counteraction. How can one equate today's already hyperactive and deviant qi with tomorrow's balanced qi after control? One must not fail to realize that the meanings of "hyperactivity" and "control" are clear: "Hyperactivity" implies imbalance, while "Control" implies the cessation of hyperactivity. Prosperity and decline in transformation are the norms of proper positioning; disorder and disruption of transformation are the variations of improper positioning. Why do these two schools completely fail to distinguish between them?