太阴当溽暑。六阳正盛。而曰太阴者。天道阴阳分治。时值夏至。干之六阳已极。而坤气见。故一阴生。一阴之所
以生。赖坤之全体也。又其时溽暑烦蒸。地气溢满。能大雨时行而湿物。是以谓之湿土。湿土为坤之全气。而居于西南。
故正位季夏。在司天则丑未主之。上为湿土。下为太阴。标本一同。唯湿之化乘于脾。故太阴所至。则湿重积。为不运。
为积饮。痞隔蓄满中。霍乱吐呕为重。 肿。及其太过。则懦积并 。皆脾气壅而不运。土壅则必水。故其脏脾肾。其
病腹满。四肢不举。脾主四肢。壅而不行。故不举也。是以土运太过之岁。肾水受邪。民病腹痛清厥。意不乐。体重烦
冤。此水土相汨。湿甚灭火之证也。甚则肌肉痿。足痿不收。行善螈胁下痛。土湿伤内。并伤于筋也。饮食中满食减。
燥则易化。湿则不化也。至其变生得位。则腹满溏泄肠鸣。及下甚。三焦土满。湿火不扬。故内蕴而证如是也。此皆杂
伤脾胃。然湿在中宫而已。至湿淫所胜。则微有异。为湿胜则湿之。浸淫所及。亦无不病。故病 肿骨痛阴痹。湿伤血
也。腰膝头项痛时眩。浸淫之至。木令不行。气与火两壅也。大便难。前云溏。此云难。以肺气阻绝。不得治节大肠也。
阴器不用。阴藏精而起亟。湿伤阴不能起亟。故不用也。饮不欲食。为胃有余。而浮火壅。咳唾则有血。为心火郁而刑
肺。心如悬。则并伤心之阴矣。此伤肾之至。与肾始受邪微有别耳。若夫土之不及。风乃大行。民病飧泄。霍乱体重腹
痛。风能胜湿。宜无飧泄霍乱。然土气为木所克制。风行其间。善行数变。则脾气有不及运者矣。筋骨繇复肌肉 善
怒。风气专行而燥。脾之散精皆所不及。不及则并不能养肝。故善怒也。至夫土郁。则病心腹胀。肠鸣而为数后。土壅
而陷下。气不得伸也。甚则心痛胁 呕吐土壅而逆上。气不得下也。霍乱饮发注下 肿身重。则上之郁也深矣。凡司天
在泉。为主为客。观之有余不足。或淫或郁。而其理尽矣。病机曰。诸湿肿满。皆属于脾。诸痉项强。皆属于湿。夫肿
满属太过与郁。则诚然矣。若痉一症。有出于少阴阴虚者。有起于阳明火劫者。今属太阴之湿壅而为痉。是太阳寒水所
乘。与厥阴风木所胜。于丑未之岁。土不堪水与木之侵。故有是症。此特从运气言之。而要不可例少阴阳明之痉也。
太阴湿土主令之时，正值溽暑季节。此时六阳之气正盛，但称为“太阴”，是因为天道中阴阳各有其主治之时。时间正值夏至，天干之六阳已至极点，而地气（坤气）开始显现，所以一阴始生。一阴之所以能够产生，是依赖于坤卦的完整体象。
又因当时气候湿热烦闷蒸腾，地气充盈弥漫，若能适时降下大雨以滋润万物，因此称之为“湿土”。湿土是坤卦的完整气化表现，居于西南方位，所以在季夏（农历六月）当正位。在司天在泉的理论中，丑年和未年由太阴湿土主事。上面是湿土之气，下面是太阴经气，标本一致。只有湿气化生影响脾脏，所以当太阴主令时，湿气就会沉重积聚，导致脾胃运化功能失常，形成停饮、痞塞、胸膈胀满等症状。若病情严重，则出现霍乱、呕吐等重症。身体浮肿，以及湿气太过导致的肌肉软弱、积滞并见，都是脾气壅滞而不能运化的结果。土气壅滞必然导致水液代谢障碍，所以病变涉及脾、肾两脏。病症表现为腹部胀满，四肢无力抬举。因为脾主四肢，脾气壅滞不能输布精微至四肢，所以四肢不能活动。
因此在土运太过的年份，肾水会受到邪气侵害，百姓会出现腹痛、四肢厥冷、心情不悦、身体沉重、烦闷不安等症状。这是水土相互干扰，湿气极盛抑制心火的表现。严重时会出现肌肉痿软、足部痿弱不能收持、行走时抽搐、胁下疼痛。这是因为土湿内伤，进而损伤了筋脉。饮食减少，腹部胀满，食物难以消化，是因为燥气容易消化食物，而湿气则使食物停滞不化。
等到湿气变化生成且得其正位时，会出现腹部胀满、大便稀溏、肠鸣，甚至腹泻严重，导致三焦土气壅满，湿火不得宣发，所以体内蕴结而出现上述证候。这些都是杂病损伤脾胃，但主要是湿气困阻在中焦（脾胃）。至于湿气淫胜的情况，则略有不同。如果湿气胜则表现为湿邪本身的症状，浸淫所及之处，没有不生病的。所以会出现水肿、骨痛、阴痹（发生在阴分的痹证），这是湿气损伤了血分。腰、膝、头、项疼痛，时常眩晕，这是湿气浸淫至极，导致肝木之气不能正常疏泄，气和火都发生壅滞。大便秘结，前文说大便稀溏，这里说困难，是因为肺气被阻绝，不能对大肠进行正常的治理和调节。生殖器功能减退，是因为肾藏精而起动频繁，湿气损伤阴精，使其不能正常起动，所以功能不用。想喝水但不想吃东西，是因为胃中有余邪，且浮火壅滞。咳嗽吐痰带血，是因为心火郁结而克制肺金。心中悬空感，则是同时损伤了心阴。这属于湿气伤肾的极致情况，与肾脏刚开始受邪时略有区别。
至于土气不及的年份，风气就会大行。百姓会出现完谷不化的泄泻、霍乱、身体沉重、腹痛。风能胜湿，按理说不应有完谷不化和霍乱，但因为土气被木气克制，风气流行其间，风性善行数变，导致脾气有不及运化的情况。筋骨松弛或拘急，肌肉跳动，容易发怒。因为风气专行且干燥，脾脏散精的功能都不足以应对。脾虚不能滋养肝脏，所以容易发怒。
至于土气郁结，则会出现心腹胀满，肠鸣且多次排便。这是土气壅滞而下陷，气机不能舒展。严重时心痛、胁痛、呕吐，这是土气壅滞而逆上，气机不能下行。霍乱、饮水即吐、腹泻如水、身体浮肿沉重，这说明上面的郁结已经很深了。凡是司天和在泉的主客之气，观察其有余和不足，或是淫胜或是郁结，其中的道理就穷尽了。《病机十九条》中说：“诸湿肿满，皆属于脾。”“诸痉项强，皆属于湿。”对于肿满属于太过和郁结来说，确实如此。但对于“痉”这一症状，有的出于少阴阴虚，有的起于阳明火劫。现在将其归为太阴湿壅导致的痉证，是因为太阳寒水乘虚侵袭，以及厥阴风木相克。在丑未之年，土气不堪受水和木的侵凌，所以出现这种症状。这只是从五运六气的角度来论述，但不能以此类推少阴和阳明的痉证。
During the period governed by Taiyin (Great Yin) damp-earth, it is the season of muggy heat. At this time, the six yang energies are at their peak, yet it is called "Taiyin" because in the Heavenly Dao, yin and yang each have their respective periods of governance. The time coincides with the Summer Solstice; the six yangs of the Heavenly Stems have reached their extreme, while the Earthly Qi (Kun energy) begins to manifest, thus generating one yin. The reason for the generation of one yin relies on the complete form of Kun.
Furthermore, during this time, the climate is humid, hot, and steaming, with Earthly Qi filling the space. If heavy rains occur timely to moisten all things, it is therefore termed "Damp-Earth." Damp-Earth is the complete qi manifestation of Kun, residing in the southwest direction. Thus, it holds its proper position in the late summer (the sixth lunar month). In the theory of Si Tian (Chief Qi) and Zai Quan (Subordinate Qi), the years of Chou and Wei are governed by Taiyin Damp-Earth. Above is the Qi of Damp-Earth, and below is the Qi of the Taiyin Meridian; the root and branch are identical. Only when the transformation of dampness affects the Spleen does dampness become heavy and accumulate when Taiyin governs. This leads to impaired transport and transformation, retention of fluids, epigastric fullness, chest obstruction, and abdominal distension. When severe, it manifests as cholera-like vomiting and diarrhea. Edema occurs, and if dampness is excessive, it results in muscle weakness and accumulation stagnation. All these are due to the stagnation of Spleen Qi and failure of transport. When Earth Qi stagnates, Water metabolism must be affected; thus, the organs involved are the Spleen and Kidney. The symptoms include abdominal fullness and inability to move the four limbs. Since the Spleen governs the four limbs, its stagnation prevents the distribution of essence, leading to immobility.
Therefore, in years where the Earth Transport is excessive, Kidney Water suffers from pathogenic influence. The people suffer from abdominal pain, cold extremities, depression, heavy body, and vexation. This is a condition where Earth and Water interfere with each other, and excessive dampness extinguishes Heart Fire. In severe cases, muscle flaccidity, foot weakness and inability to hold, frequent cramps during walking, and hypochondriac pain occur. This is because internal injury by Earth-Dampness also damages the sinews. There is dietary stagnation with abdominal fullness and reduced appetite; dryness facilitates digestion, whereas dampness hinders it.
When the variation of dampness generates and attains its proper position, symptoms such as abdominal fullness, loose stools, and borborygmus appear. If the downward flow is severe, the San Jiao (Triple Burner) becomes full of Earth Qi, and Damp-Fire cannot rise. Thus, internal entrapment leads to such manifestations. These are all miscellaneous injuries to the Spleen and Stomach, specifically dampness obstructing the Middle Jiao. However, when dampness overcomes and dominates, there are slight differences. If dampness prevails, it presents as dampness itself; wherever it infiltrates, disease arises. Thus, edema, bone pain, and Yin Bi (bi-syndrome affecting the yin aspects) occur, indicating that dampness has injured the Blood. Pain in the waist, knees, head, and neck, along with frequent dizziness, indicates that dampness has infiltrated to an extreme, preventing the Wood phase from functioning normally, causing both Qi and Fire to stagnate. Difficulty in defecation occurs; previously mentioned was loose stool, here difficulty is noted, because Lung Qi is obstructed and cannot regulate the Large Intestine. Impotence or dysfunction of the genitalia occurs because the Kidney stores essence and initiates movement frequently; dampness injures Yin, preventing this initiation, hence dysfunction. Desire to drink but lack of appetite indicates excess in the Stomach and stagnation of floating Fire. Coughing up blood-stained sputum indicates that depressed Heart Fire attacks Lung Metal. A sensation of the heart hanging indicates simultaneous injury to Heart Yin. This represents the extreme of Kidney injury by dampness, slightly different from the initial stage of Kidney pathogenic invasion.
In years where Earth Qi is deficient, Wind acts excessively. The people suffer from undigested food in stool (sun-xie), cholera, heavy body, and abdominal pain. Although Wind can overcome dampness and theoretically should not cause sun-xie or cholera, because Earth Qi is controlled by Wood, and Wind moves among them, being agile and changeable, the Spleen Qi fails to transport adequately. Flaccidity or spasticity of sinews and bones, muscle twitching, and irritability occur. Because Wind moves exclusively and is dry, the Spleen's function of dispersing essence is insufficient. Deficiency leads to an inability to nourish the Liver, hence irritability.
Regarding Earth Qi stagnation (Yu), diseases include abdominal and chest fullness, borborygmus, and frequent defecation. This is due to Earth Qi stagnation sinking down, preventing Qi from extending. In severe cases, heart pain, hypochondriac pain, and vomiting occur, as Earth Qi stagnation causes rebellion upward, preventing Qi from descending. Cholera, vomiting after drinking, profuse watery diarrhea, edema, and heavy body indicate deep stagnation above. Regarding Si Tian and Zai Quan, whether as host or guest, observing surplus and deficiency, or overacting and stagnation, the principles are exhausted. The Pathogenesis states: "All dampness-related edema and fullness belong to the Spleen." "All spasms and neck stiffness belong to dampness." It is indeed true that edema and fullness belong to excess and stagnation. However, regarding spasms, some arise from Shaoyin Yin deficiency, and others from Yangming fire coercion. Now attributing spasms to Taiyin damp-stagnation implies that Taiyang Cold-Water is invading, and Jueyin Wind-Wood is overcoming. In Chou and Wei years, Earth cannot withstand the invasion of Water and Wood, hence these symptoms. This is discussed specifically from the perspective of Yun Qi (Five Movements and Six Qi), and one must not generalize this to Shaoyin and Yangming spasms.