应天为天符，承岁为岁直，三合为治。天，谓司天；岁，谓岁支；曰应、曰承，谓岁运
也。
司天行天之气，岁支行地之气，岁营运气交之化，三者其气不必皆同，而亦有时而同者。如
戊寅、戊申岁，戊为火运，寅、申又为相火，是以岁运而同司天之气，谓之天符。符者，同
也，同于天也。如甲辰，甲戌岁，甲为土运，辰、戌又为土，是以岁运而同岁支之气，谓之
岁直。直者，值也，值其岁也。又曰岁会，会者，合也，合于岁也。若己丑、己未岁，岁运
之土，既同天气，又同岁支，谓之太乙天符，即经所谓三气并合为治也。夫气同者，其化同
；其气异者，其化异。化同则有相助为虐之害，化异则有互相克贼之忧。然以不及之运，而
得司天岁支之助，则不及之气转为平气，而气反治；若岁运太过，其气已盛，而复得司天、
岁支之合，三气并治，其亢而害物，有不可言喻者矣。故曰∶中执法者，其病速而危；中行
令者，其病徐而持；中贵人者，其病暴而死。
《素问·六元正纪大论》分列六十年运气、病治之纪，统论六气司天在泉之政，可谓详
且尽
矣。然而验之于事，合之于时，往往不能相符。且也一年之间，九州之内，有东南旱干而西
北淫雨者，有西北焦槁而东南大水者，则九州分野，上应九宫，为地气之不齐也。且有宋元
丰四年，岁在辛酉，涸流之纪，而河决大水，则气化胜复之异，胡源所谓岁水不及，侮而乘
之
者土也。土不务德，故以湿胜，寒时则有泉涌河衍涸流生鱼，其变为骤注，为霖溃，名为少
羽，而实与太宫之岁同者是也。是故五运六气之理，不可不知也，亦不易知也。而况古今度
数之有差等，天人感召之有休咎。执而泥之，刻舟而求剑者也；废而弃之，亡筌而求者也。
非沉潜之士，而具圆机之智者，乌足以误此！
应合司天之气称为“天符”，承接岁支之气称为“岁直”（又称“岁会”），这三者相合共同主导当年的气候与疾病变化。这里所说的“天”，指的是司天之气；“岁”，指的是岁支；所谓“应”和“承”，是指岁运（中运）与司天、岁支的关系。
司天主管天之阳气，岁支主管地之阴气，而岁运则负责交感化生万物，这三者的气机并不一定完全相同，但有时也会相同。例如戊寅年、戊申年，戊属火运，寅年和申年又对应相火，因此岁运与司天之气相同，这叫做“天符”。符，就是相同的意思，即与司天之气相同。又如甲辰年、甲戌年，甲属土运，辰年和戌年又对应土，因此岁运与岁支之气相同，这叫做“岁直”。直，就是值遇的意思，即值遇该年的地支之气。这也叫作“岁会”，会，就是相合的意思，即与岁支相合。如果是己丑年、己未年，岁运的土气，既同于司天之土气，又同于岁支的土气，这叫做“太乙天符”，也就是《内经》所说的三气并合来主治一年。
凡是气机相同的，其气化表现也相同；气机不同的，其气化表现也不同。气化相同就会产生相互助长为虐的危害，气化不同则会有互相克制伤害的忧虑。然而，如果是岁运不及（虚弱），得到了司天和岁支的帮助，那么不及的气就会转化为平气（平和之气），气机反而能够正常治理；如果岁运太过（强盛），气已经旺盛，又再得到司天和岁支的聚合，三气并治，其亢盛而伤害万物的程度，就有不可言喻的了。所以说：侵犯执法之位（少阳相火司天）的病，发病迅速且危险；侵犯行令之位（阳明燥金、太阳寒水等）的病，发病缓慢且持久；侵犯贵人位（太乙天符）的病，发病暴烈且致死。
《素问·六元正纪大论》分列了六十年的运气及相应的病症与治疗规律，总论六气在司天和在泉时的政令特点，可以说是详细且完备了。然而，用事实去验证，与时令去对照，往往不能完全相符。况且在一年之中，九州之内，有东南干旱而西北多雨的，也有西北焦枯而东南洪水的，这说明九州分野之上对应九宫，是地气不均匀造成的。还有宋神宗元丰四年，岁在辛酉，本应是“涸流之纪”（水运不及之年），却发生了黄河决口大水泛滥的情况，这就是气化胜复（有余与不足相互报复）的差异。正如胡源所说，这是岁水不及，被土气侮乘（反克）的结果。土气不修其德，所以湿气偏胜。在寒冷时节，就会出现泉水涌出、河水漫延、干涸河流中生出鱼类的现象，其变化表现为暴雨倾注、霖雨溃决，名义上属于“少羽”（水运不及），但实际上与“太宫”（土运太过）年份的情况相同。因此，五运六气的道理，不能不知道，但也难以轻易掌握。更何况古今历法度数存在差异，天人感应也有吉凶休咎的不同。拘泥固执地套用，就像刻舟求剑一样愚蠢；废弃抛弃不用，就像得鱼忘筌一样片面。如果不是深沉潜修之士，且具备圆融机智智慧的人，怎么能够真正领悟其中的奥妙呢！
The term "Tianfu" (Heavenly符/Alignment) refers to the alignment with the Si Tian (Sitting Heaven, the ruling Qi of the upper half of the year), while "Suizhi" (Year Direct) or "Suihui" (Year Meeting) refers to the alignment with the Sui Zhi (Earthly Branch of the year). The combination of these three constitutes the governing pattern. Here, "Tian" denotes the Si Tian Qi; "Sui" denotes the Sui Zhi; and the terms "Ying" (respond) and "Cheng" (succeed/align) refer to the relationship between the Sui Yun (Central Movement/Qi of the year) and the Si Tian and Sui Zhi.
Si Tian governs the Qi of Heaven, Sui Zhi governs the Qi of Earth, and Sui Yun manages the transformative interaction that nurtures all things. The Qi of these three factors does not necessarily always coincide, but there are times when they do. For instance, in the years of Wu Yin and Wu Shen, Wu corresponds to Fire Yun (Fire Central Movement), and both Yin and Shen correspond to Xiang Huo (Ministerial Fire). Thus, the Sui Yun aligns with the Si Tian Qi, which is called "Tianfu." Fu means alignment, specifically alignment with Heaven. Similarly, in the years of Jia Chen and Jia Xu, Jia corresponds to Earth Yun, and both Chen and Xu correspond to Earth. Thus, the Sui Yun aligns with the Sui Zhi Qi, which is called "Suizhi." Zhi means encountering or matching, i.e., matching the Qi of the specific year's branch. This is also referred to as "Suihui," where Hui means convergence, i.e., convergence with the Sui Zhi. In the years of Ji Chou and Ji Wei, the Earth Yun converges with both the Si Tian Qi and the Sui Zhi Qi; this is called "Taiyi Tianfu" (Supreme Heavenly Alignment), which corresponds to the classic statement that the convergence of the three Qi modes governs the year.
When the Qi is identical, its transformation is identical; when the Qi differs, its transformation differs. Identical transformations lead to mutual reinforcement and exacerbation of harm, while differing transformations lead to concerns of mutual overcoming and injury. However, if a Sui Yun that is deficient (Bu Ji) receives assistance from the Si Tian and Sui Zhi, the deficient Qi transforms into Ping Qi (Balanced Qi), and the pathological process is mitigated. Conversely, if the Sui Yun is excessive (Tai Guo) and already vigorous, and it further converges with the Si Tian and Sui Zhi, resulting in the governance of three aligned Qi modes, the resulting exuberance and damage to living things are beyond description. Therefore, it is said: When invading the position of the Law Enforcer (Shao Yang Ministerial Fire), the disease is rapid and critical; when invading the position of the Order Executor (Yang Ming Dryness or Tai Yang Cold), the disease is slow and persistent; when invading the position of the Noble Person (Tai Yi Tianfu), the disease is violent and fatal.
*Su Wen: Chapter on the Great Treatise of the Six Sources and Correct Records* categorizes the patterns of Yun Qi and corresponding diseases/treatments for sixty years, comprehensively discussing the policies of the Six Qi in their roles of Si Tian (ruling the upper heaven) and Zai Quan (ruling the lower earth). This can be considered detailed and exhaustive. However, when verified against actual events and aligned with seasonal timing, discrepancies often arise. Within a single year across the Nine Provinces, there may be drought in the southeast and excessive rain in the northwest, or scorched earth in the northwest and flooding in the southeast. This indicates that the correspondence between the Nine Provinces and the Nine Palaces results from uneven Earth Qi. Furthermore, in the fourth year of Yuanfeng during the Song Dynasty (Xin You year), which should have been a "He Liu" (Dried Stream) record due to Water Yun deficiency, the Yellow River burst its banks causing massive floods. This illustrates the anomaly of Sheng Fu (Victory and Repayment/Rebound in Qi dynamics). As Hu Yuan explained, this was caused by Earth Qi usurping and attacking Water Qi due to Water Yun deficiency. Since Earth failed to cultivate its virtue (moistening/nourishing aspect appropriately), Dampness became excessive. During cold periods, this manifested as spring water surging, river overflow, and fish appearing in dried streams. Its transformation appeared as sudden torrential rains and prolonged inundating showers. Although nominally classified as "Shao Yu" (Water Yun Deficiency), it essentially resembled the conditions of a "Tai Gong" (Earth Yun Excess) year. Therefore, the principles of Wu Yun Liu Qi (Five Movements and Six Qi) must be understood, yet they are not easily grasped. Moreover, given the discrepancies in calendrical calculations between ancient and modern times and the varying auspicious or inauspicious outcomes of Heaven-Human resonance, rigid adherence to these theories is like carving a mark on a moving boat to find a lost sword; conversely, abandoning them entirely is like discarding the fishing trap after catching the fish. Only those who are deeply contemplative and possess flexible wisdom can truly comprehend these subtleties!