天地至大，人物至广，不外阴阳五行之理。五运，即五行也。六气，即三阴三阳也。故木、火、土、金、
水曰五运；厥阴、少阴、太阴、少阳、阳明、太阳曰六气。五运合五行，而六气亦合五行。天以此成四时而生
万物，
人以此成有形而合无形。是五运六气实医学之根源，神农本之而着药性，黄帝本之而着《内经》，仲师本之
而撰《伤寒》、《金匮》。今人但知风、热、湿、火、燥、寒为病，岂知厥阴主风，风，木也；少阴、少阳主
热，热，火也；太阴主湿，湿，土也；阳明主燥，燥，金也；太阳主寒，寒，水也。此风、热、湿、火、燥、
寒之病，而五运六气即主之，五脏六腑亦因之。其本末不可不察也！
六淫外感之说，世多不得其解，谓人外感天之六淫则为病，而孰知其非也。盖厥阴、少阴、太阴、少阳、
阳明、太阳曰六气，风、热、湿、火、燥、寒曰六淫。天有之，人亦有之。故居其内以通脏腑者，六气也；居
其外以通于天者，六淫也。天之六淫，与人之六淫，无时不感，讵必病也？《天元纪大论》云∶厥阴之上，
风气主之∶少阴之上，热气主之；太阴之上，湿气主之；少阳之上，相火主之；阳明之上，燥气主之；太阳
之上，寒气主之。所谓本也，是谓六元。由此例之，则三阴三阳之六气，在下为标，下即内也；而风、热、湿、
火、燥、寒之六淫，在上为本，上即外也。六淫在上而在外，故曰外感，感犹通也。故外感之说，其义有二∶
一言六淫外通于天；一
言六淫主外通于六气。义虽有二，总谓六淫在人而不在天，凡有所病，皆本人身之六淫，而非天之六淫也。且
独不观卒病论乎！发热，汗出，恶风，脉缓者，名为中风。是中风之名，从人身而定也。或已发热，或未发
热，必恶寒、体痛、呕逆，脉阴阳俱紧者，名为伤寒。是伤寒之名，从人身而定也，非外至也，若果外至，
胡不曰六淫外中，六淫外伤，而必曰外感也？世多不知此义，一遇病，辄云外感，岂无病时遂不感耶？甚矣！
其聩聩也。
Heaven and Earth are extremely vast, and all living things are numerous; none of them transcend the principles of Yin-Yang and the Five Elements. The Five Movements (Wuyun) refer to the Five Elements. The Six Qi (Liuqi) refer to the Three Yin and Three Yang. Therefore, Wood, Fire, Earth, Metal, and Water are called the Five Movements; Jueyin, Shaoyin, Taiyin, Shaoyang, Yangming, and Taiyang are called the Six Qi. The Five Movements correspond with the Five Elements, and the Six Qi also correspond with the Five Elements. Heaven utilizes these to form the four seasons and generate all things, while humans utilize these to form tangible bodies and align with intangible laws. Thus, the Five Movements and Six Qi are indeed the root of medicine. Shennong based his work on this principle to write the *Bencao* (Materia Medica); the Yellow Emperor based his work on this principle to write the *Huangdi Neijing* (Yellow Emperor's Inner Canon); and Zhang Zhongjing based his work on this principle to compose the *Shanghan Zabing Lun* (Treatise on Cold Pathogenic Diseases) and the *Jingui Yaolue* (Essential Prescriptions of the Golden Cabinet).
People today only know that Wind, Heat, Dampness, Fire, Dryness, and Cold are pathogenic factors, but how do they know that Jueyin governs Wind, and Wind belongs to Wood; Shaoyin and Shaoyang govern Heat, and Heat belongs to Fire; Taiyin governs Dampness, and Dampness belongs to Earth; Yangming governs Dryness, and Dryness belongs to Metal; Taiyang governs Cold, and Cold belongs to Water? These diseases caused by Wind, Heat, Dampness, Fire, Dryness, and Cold are actually governed by the Five Movements and Six Qi, and the Zang-Fu organs are consequently affected. The root and branches thereof must be carefully examined!
Regarding the theory of "Six Excesses (Liuyin) External Contraction," most people in the world fail to understand its true meaning. They believe that when a person is externally contracted by the Six Excesses of heaven, disease occurs; however, this is incorrect. Essentially, Jueyin, Shaoyin, Taiyin, Shaoyang, Yangming, and Taiyang are referred to as the Six Qi, while Wind, Heat, Dampness, Fire, Dryness, and Cold are referred to as the Six Excesses. These exist both in nature and within the human body. Therefore, what resides internally to connect with the Zang-Fu organs is the Six Qi; what resides externally to connect with Heaven is the Six Excesses. The Six Excesses of Heaven and the Six Excesses within humans are in constant interaction at all times; does this necessarily lead to disease? The *Suwen: Tianyuanji Dalun* states: "Above Jueyin, Wind Qi governs; above Shaoyin, Heat Qi governs; above Taiyin, Dampness Qi governs; above Shaoyang, Ministerial Fire governs; above Yangming, Dryness Qi governs; above Taiyang, Cold Qi governs." This is referred to as the "Root" (Ben), also known as the "Six Origins" (Liuyuan). By analogy, the Six Qi of the Three Yin and Three Yang are the "Branch" (Biao) located below, where "below" refers to the interior; whereas the Six Excesses of Wind, Heat, Dampness, Fire, Dryness, and Cold are the "Root" (Ben) located above, where "above" refers to the exterior. Since the Six Excesses are located above and outside, they are termed "External Contraction" (Waigan). "Contraction" here implies connection or resonance. Thus, the concept of "External Contraction" has two meanings: one is that the Six Excesses externally connect with Heaven; the other is that the Six Excesses govern the external connection with the internal Six Qi. Although there are two meanings, it ultimately asserts that the Six Excesses reside within the human body rather than in the external environment. Any disease that arises stems from the dysregulation of the Six Excesses within the person, not from external pathogenic factors.
Furthermore, have you not read the *Shanghan Lun*? When symptoms include fever, sweating, aversion to wind, and a slow pulse, it is named "Zhongfeng" (Wind Strike). This name for "Wind Strike" is determined based on the body's own response. If there is fever or no fever, accompanied by aversion to cold, body pain, vomiting, and a tight pulse in both Yin and Yang positions, it is named "Shanghan" (Cold Damage). This name for "Cold Damage" is also determined based on the body itself, not indicating an external invasion. If it truly indicated an external invasion, why would it not be called "Six Excesses External Strike" or "Six Excesses External Injury," but instead must be called "External Contraction"? Most people in the world do not understand this principle. Upon encountering illness, they immediately claim it is due to external contraction. Does this imply that without illness, there is no interaction? How ignorant this is!