湿者，太阴土气之所化也。在天为湿，在地为土，在人为脾。太阴以湿土主令，辛金从土而化湿。阳
明以燥金主令，戊土从金而化燥。己土之湿为本气，戊土之燥为子气，故胃家之燥，不敌脾家之湿，病则土
燥者少，而土湿者多也。太阴主升己土，升则癸水与乙木皆升，土之所以升者，脾阳之发生也。阳虚则土
湿而不升，己土不升，则水火陷矣。火金在上，水木在下，火金降于戊土，水木升于己土，戊土不降，则火
金上逆，己土不升，则水木下陷，其原总由于湿盛也。《子华子》“阴阳交则生湿”。湿者水火之中气，
上湿则化火而为热，下湿则化水而为寒。然上亦有湿寒，下亦有湿热。湿旺气郁，津液不行，火
盛者，熏蒸而生热痰，火衰者，泛滥而生寒饮，此湿寒之在上者。湿旺水郁，膀胱不利，火衰者，
流溢而为白淫，火盛者，梗涩而为赤浊，此湿热之在下者。便黄者，土色之下传。便赤者，木气之下陷。
缘相火在水，一线阳根，温升而化乙木，木中温气，生火之母，升则上达而化火，陷则下郁而生热
，木气不达，侵逼土位，
以其郁热，传于己土，己土受之，于是侵淫于膀胱。五行之性，病则传其所胜，其势然也。阴易盛而阳易
衰，故湿气恒长，而燥气恒消。阴盛则病，阳绝则死，理之至浅，未尝难知。后世庸愚，补阴助湿，泄火
伐阳，病家无不夭枉于滋润，此古今之大祸也。
湿，是由太阴脾土之气所化生的。在天象中表现为湿，在地形中表现为土，在人体中对应脾脏。太阴脾土主司湿气，辛金（肺）随土气而化为湿；阳明燥金主司燥气，戊土（胃）随金气而化为燥。己土（脾）的湿是本气，戊土（胃）的燥是子气，所以胃中的燥气，抵不过脾中的湿气，因此患病时，土燥的情况少，而土湿的情况多。
太阴主管升发己土（脾），脾土升发，则癸水（肾）与乙木（肝）随之升发。脾土之所以能升发，是因为脾阳的生发作用。如果阳气虚弱，则脾土湿滞而不能升发，己土不升，水火就会下陷。正常情况下，火和金在上，水和木在下，火金降于戊土（胃），水木升于己土（脾）。如果戊土不降，则火金上逆；如果己土不升，则水木下陷，其根本原因总归是由于湿气过盛。《子华子》说：“阴阳交合则生湿。”湿是水火的中间介质，上部的湿会化火变成热，下部的湿会化水变成寒。然而上部也有湿寒，下部也有湿热。
当湿气旺盛导致气机郁滞，津液运行不畅时：如果火势旺盛，熏蒸而生热痰；如果火势衰弱，泛滥而生寒饮，这是湿寒在上部的表现。当湿气旺盛导致水液郁滞，膀胱气化不利时：如果火势衰弱，流溢而成白淫（指小便浑浊或遗精滑泄等症）；如果火势旺盛，阻滞涩痛而成赤浊（指小便赤涩浑浊），这是湿热在下部的表现。大便发黄，是土色向下传导的表现；大便发红，是木气向下陷的表现。因为相火位于水中，一线阳根温升而化生乙木（肝），木中的温气温煦，是生火的母源，升发则上达化火，下陷则郁结生热。木气不达，侵逼土位，以其郁热传给己土（脾），己土受之，于是浸淫于膀胱。五行的特性是，生病时传变其所克制的脏腑，这是必然的趋势。
阴容易盛而阳容易衰，所以湿气常常增长，而燥气常常消退。阴盛则生病，阳绝则死亡，这是极浅显的道理，并不难知晓。后世庸医愚昧，补阴助湿，泻火伐阳，导致病人无不因过度滋润而夭折，这是古今的大祸患。
Dampness is transformed from the Qi of Taiyin Spleen-Earth. In Heaven it manifests as dampness, in Earth it manifests as soil, and in Man it corresponds to the Spleen. Taiyin Spleen-Earth governs dampness, and Xin Metal (Lung) transforms into dampness following Earth. Yangming Dry Metal governs dryness, and Wu Earth (Stomach) transforms into dryness following Metal. The dampness of Ji Earth (Spleen) is its original Qi, while the dryness of Wu Earth (Stomach) is its offspring Qi; therefore, the dryness in the Stomach cannot overcome the dampness in the Spleen. Consequently, in disease, cases of dry Earth are few, while cases of damp Earth are numerous.
Taiyin governs the ascending of Ji Earth (Spleen). When Ji Earth ascends, Gui Water (Kidney) and Yi Wood (Liver) also ascend. The reason Earth ascends is due to the generation of Spleen-Yang. If Yang is deficient, Earth becomes damp and fails to ascend. If Ji Earth does not ascend, Fire and Water sink. Normally, Fire and Metal are above, and Water and Wood are below. Fire and Metal descend into Wu Earth (Stomach), while Water and Wood ascend into Ji Earth (Spleen). If Wu Earth does not descend, Fire and Metal rebel upward; if Ji Earth does not ascend, Water and Wood sink downward. The root cause of all this is always excessive dampness. *Zihua Zi* states: "When Yin and Yang intersect, dampness is generated." Dampness is the medium between Water and Fire. Dampness above transforms into Fire and becomes heat; dampness below transforms into Water and becomes cold. However, there is also cold-damp above and damp-heat below.
When dampness is prosperous and Qi is stagnant, preventing the flow of body fluids: if Fire is vigorous, steaming generates hot-phlegm; if Fire is weak, overflowing generates cold-fluid retention. This constitutes cold-damp located above. When dampness is prosperous and Water is stagnant, leading to bladder dysfunction: if Fire is weak, leakage results in white turbidity (bai yin, referring to cloudy urine or seminal emission); if Fire is vigorous, obstruction and astringency result in red turbidity (chi zhuo, referring to red, turbid, and painful urination). This constitutes damp-heat located below. Yellow stool indicates the transmission of Earth's color downward. Red stool indicates the sinking of Wood Qi. Since ministerial fire resides within Water, a thread of Yang root warms and ascends to transform Yi Wood (Liver). The warmth within Wood is the mother of Fire; when ascending, it reaches above and transforms into Fire; when sinking, it stagnates below and generates heat. When Wood Qi fails to reach, it encroaches upon the Earth position, transmitting its stagnant heat to Ji Earth (Spleen). Upon receiving this, Ji Earth allows it to permeate into the Bladder. The nature of the Five Elements dictates that in disease, transmission occurs to the element it overcomes; this is the natural trend.
Yin easily prospers while Yang easily declines; thus, dampness often grows while dryness often diminishes. Yin prosperity leads to disease, and Yang extinction leads to death. This principle is extremely shallow and not difficult to understand. Later generations of mediocre and ignorant physicians have supplemented Yin to aid dampness and drained Fire to attack Yang, causing patients to invariably suffer premature death due to moistening treatments. This is a great calamity throughout history.