人禀阴阳五行之气以生，而阴阳之变化无尽。今以脏腑分阴阳者论之，是脏为阴主里，腑为阳主表，五脏
具五行之性，而五行又各具阴阳，故各脏之气为阳，血为阴也。如以腑配脏，则肝为乙木属阴，胆为甲木属
阳，木生火；心为丁火属阴，小肠为丙火属阳，火生土；脾为己土属阴，胃为戊土属阳，土生金；肺为辛金
属阴，大肠为庚金属阳，金生水；肾为癸水属阴，膀胱为壬水属阳，而水又生木，故阴阳五行之气生化不息
也。五行之生者，相长也。生气太过，则偏亢，故生中有克。克者，制也，如木克土，土克水，水克火，火克
金，金克木，互相节制也。是故不足，则以相生者助之，如补肝助心之类；太过，则以相克者制之，如滋水
制火之类，调之使平而后已。盖脏者，藏也，藏精气而不泻；腑者，器也，传化物而不藏。其能藏能化者，皆
由阴阳五行之气运用也。而脏腑各有所主，各有功能，各有所司，其或失司，则气化乖逆，而生百病矣。故如
肝藏魂与血而主筋，心藏神而主血脉，肺藏魄与气而主皮毛，脾藏意而主肌肉，肾藏精与志而主骨。肺又权衡
一身之气，脾又统领一身之血，而心为君主，一身气血随心所使，以各脏皆有系脉通心，故心定则神明，而五
脏皆安，心劳妄动，则五脏皆病。如忧则心气抑，怒则肝气逆，思则脾气结，悲则肺气消，恐则肾精伤。故凡
七情，皆由心发，而先伤各脏者也。如其功能所司，肝司疏泄，开窍于目；肾司闭藏，开窍于二便；脾司鼓
运，开窍于口；肺司呼吸，开窍于鼻；心司鉴察，开窍于舌；耳通心肾之气，又为心肾之窍也。脏腑之相配
者，以其部位相连而为表里，互相为用。腑本脏气以宣化，故脏虚则腑不转输；脏藉腑气以舒和，故腑实则
脏气厥逆。如肺与大肠为表里者，若肺气虚，则大肠失职，或泄泻，或闭塞；若大肠浊壅不行，则肺气逆满，
不能下降，余可例知，其互相为用者也。又如胃司纳谷，赖脾健运，以化饮食精微，上达于肺，敷布周身，
以充养各脏腑，故胃为水谷之海，六腑之大源也；其糟粕下传小肠，泌别清浊，清水渗入膀胱，浊滓下归大
肠，又必赖三焦气化宣畅，而水火均平，则二便通调，故曰∶气化则能出矣。然三焦气化，本于肾元之阴阳，
若肾元衰，则三焦无权，而脾胃因之升降不调，清浊淆混，则百病俱出，此脏腑之所以各有功用不同也。惟胆
附于肝为表里，其精汁有入无出，若受热邪，胆汁泄而口苦，则为病矣。又有心包络，居于膻中，为心脏之外
护，代心用事，凡邪之干心，皆包络受之，若心脏受
邪则神去，神去即死矣。心包经络与三焦连贯为表里，故五脏、六腑及心包络共成手足阴阳十二经，义详营卫
经络门中。必先熟脏腑生化之理、经络流行之道，方能辨病之表里虚实而治之，是故学人首当究心，而不可忽
者也。
人禀受阴阳五行之气而生成，但阴阳的变化是无穷无尽的。现在从脏腑角度来划分阴阳进行论述：脏属于阴，主要主管体内；腑属于阳，主要主管体表。五脏具备五行的特性，而五行中每一行又各自包含阴阳，所以各脏的气属于阳，血属于阴。
如果将腑与脏相配，那么肝为乙木，属性为阴，胆为甲木，属性为阳，木能生火；心为丁火，属性为阴，小肠为丙火，属性为阳，火能生土；脾为己土，属性为阴，胃为戊土，属性为阳，土能生金；肺为辛金，属性为阴，大肠为庚金，属性为阳，金能生水；肾为癸水，属性为阴，膀胱为壬水，属性为阳，水又能生木，因此阴阳五行之气的生化过程永不停息。
五行的相生关系，就是相互滋长。如果生气太过，就会偏盛亢进，所以在相生之中蕴含着相克。所谓“克”，就是制约的意思，如木克土、土克水、水克火、火克金、金克木，这是互相节制的关系。因此，当某一行不足时，就用相生的一方来资助它，例如补肝以助心（实则应为滋水涵木或补母生子，此处原文意指通过相生关系调节）；当某一行太过时，就用相克的一方来制约它，例如滋水以制火等，经过调理使其恢复平衡才停止。
所谓“脏”，就是藏的意思，贮藏精气而不外泄；所谓“腑”，就是器的意思，传导消化物而不贮藏。能够贮藏和转化的功能，都是依靠阴阳五行之气的运用来实现的。脏腑各有其主导的功能，各司其职，如果失职，就会导致气化逆乱，从而产生各种疾病。
例如：肝贮藏魂和血，并主管筋脉；心贮藏神，并主管血脉；肺贮藏魄和气，并主管皮毛；脾贮藏意，并主管肌肉；肾贮藏精和志，并主管骨骼。肺又权衡全身的气，脾又统领全身的血液，而心作为君主之官，全身的气血都随心所使，因为各脏都有经脉连通心脏，所以心神安定则神明清晰，五脏皆安；若心劳损妄动，则五脏都会生病。
例如：忧愁会使心气郁抑，愤怒会使肝气上逆，思虑会使脾气结滞，悲伤会使肺气消耗，恐惧会使肾精损伤。所以凡是七情（喜、怒、忧、思、悲、恐、惊），都是由心发起，并首先伤害各个脏腑。
至于它们的功能职责：肝主管疏泄，开窍于目；肾主管闭藏，开窍于前阴和后阴；脾主管运化，开窍于口；肺主管呼吸，开窍于鼻；心主管审视察知，开窍于舌；耳朵连通心肾之气，也是心肾的外窍。
脏腑之所以相互配合，是因为它们的部位相连，形成表里关系，互相为用。腑本于脏气来宣发转化，所以脏虚则腑不能正常转输；脏借助腑气来舒展调和，所以腑实（邪气盛）则脏气会厥逆。例如肺与大肠互为表里，如果肺气虚，则大肠失职，出现泄泻或闭塞；如果大肠浊气壅滞不通，则肺气上逆胀满，不能下降，其他脏腑的情况可以以此类推，这就是它们互相为用的体现。
又如：胃主管受纳食物，依赖脾的健运功能，来消化饮食中的精微物质，向上输送到肺，布散全身，以充养各个脏腑，所以胃被称为“水谷之海”，是六腑的大源头。食物的糟粕向下传入小肠，分别清浊，清液渗入膀胱，浊渣下归大肠，这又必须依赖三焦的气化功能宣通顺畅，使得水火平衡，二便才能通畅，所以说：“气化则能出矣”。然而三焦的气化，根本在于肾元的阴阳，如果肾元衰弱，则三焦失去职权，导致脾胃升降不调，清浊混淆，各种疾病就会发生，这就是脏腑各有不同功用的原因。
只有胆附着在肝脏，互为表里，其分泌的精汁有入无出，如果受到热邪，胆汁外泄导致口苦，这就生病了。还有心包络，位于膻中穴处，作为心脏的外部保护，代替心脏行使职能，凡是邪气侵犯心脏，都由心包络承受，如果心脏直接受邪，则神气离去，神去即死亡。心包络的经络与三焦连贯，互为表里，所以五脏、六腑及心包络共同构成了手足阴阳十二经脉，详细义理参见《营卫经络》章节。
Human beings are generated by inheriting the Qi of Yin, Yang, and the Five Elements (Wu Xing), yet the transformations of Yin and Yang are endless. Now, discussing the division of Zang-Fu organs into Yin and Yang: the Zang organs belong to Yin and primarily govern the interior; the Fu organs belong to Yang and primarily govern the exterior. The five Zang organs possess the characteristics of the Five Elements, and each of the Five Elements further contains both Yin and Yang. Therefore, the Qi of each Zang organ is Yang, while its Blood is Yin.
If we pair the Fu organs with the Zang organs: the Liver is Yi Wood, belonging to Yin; the Gallbladder is Jia Wood, belonging to Yang; Wood generates Fire. The Heart is Ding Fire, belonging to Yin; the Small Intestine is Bing Fire, belonging to Yang; Fire generates Earth. The Spleen is Ji Earth, belonging to Yin; the Stomach is Wu Earth, belonging to Yang; Earth generates Metal. The Lung is Xin Metal, belonging to Yin; the Large Intestine is Geng Metal, belonging to Yang; Metal generates Water. The Kidney is Gui Water, belonging to Yin; the Bladder is Ren Water, belonging to Yang; and Water generates Wood again. Thus, the generation and transformation of the Qi of Yin, Yang, and the Five Elements ceaselessly continue.
The mutual generation among the Five Elements refers to mutual growth. If the generating Qi is excessive, it becomes hyperactive; therefore, within generation lies restriction (Ke). "Restriction" means control or restraint, such as Wood controlling Earth, Earth controlling Water, Water controlling Fire, Fire controlling Metal, and Metal controlling Wood, which act as mutual checks. Consequently, when a certain element is deficient, it is assisted by the element that generates it, such as tonifying the Liver to aid the Heart (note: text implies using generative relationships for regulation); when an element is excessive, it is restrained by the element that controls it, such as nourishing Water to restrain Fire. Treatment continues until balance is restored.
The term "Zang" (Viscera) implies storing; they store Essence-Qi without draining. The term "Fu" (Cavities) implies vessels; they transmit and transform substances without storing. The abilities to store and transform are all achieved through the operation of the Qi of Yin, Yang, and the Five Elements. Each Zang-Fu organ has its specific dominance, functions, and responsibilities. If these duties fail, the Qi transformation will become disordered, leading to various diseases.
For example: The Liver stores Hun (Ethereal Soul) and Blood, and governs the sinews/tendons. The Heart stores Shen (Spirit), and governs the blood vessels. The Lung stores Po (Corporeal Soul) and Qi, and governs the skin and body hair. The Spleen stores Yi (Intellect), and governs the muscles. The Kidney stores Jing (Essence) and Zhi (Willpower), and governs the bones. The Lung also weighs and regulates the Qi of the whole body, and the Spleen commands the Blood of the whole body. The Heart acts as the Monarch, directing the Qi and Blood of the entire body, because all Zang organs have meridians connecting to the Heart. Therefore, if the Heart is stable, the Spirit is clear, and the five Zang organs are at peace; if the Heart is overworked and moves recklessly, all five Zang organs will become diseased.
For instance: Worry suppresses Heart Qi; Anger causes Liver Qi to rebel upwards; Overthinking causes Spleen Qi to knot; Grief consumes Lung Qi; Fear injures Kidney Essence. Thus, all Seven Emotions originate from the Heart and first injure the respective Zang organs.
Regarding their functional responsibilities: The Liver governs free flow and drainage, opening into the eyes. The Kidney governs closure and storage, opening into the two lower orifices (urethra and anus). The Spleen governs transportation and transformation, opening into the mouth. The Lung governs respiration, opening into the nose. The Heart governs discernment and inspection, opening into the tongue. The ears connect the Qi of the Heart and Kidney and serve as the external orifices for both.
The pairing of Zang and Fu organs is based on their connected anatomical locations forming Exterior-Interior relationships, where they mutually support each other. The Fu organs rely on Zang Qi to disseminate and transform; thus, if the Zang is deficient, the Fu cannot transport effectively. The Zang organs rely on Fu Qi to relax and harmonize; thus, if the Fu is full of pathogenic factors, the Zang Qi may rebel. For example, the Lung and Large Intestine are exterior-interior pairs. If Lung Qi is deficient, the Large Intestine loses its function, resulting in diarrhea or constipation. If turbid stagnation in the Large Intestine fails to move, Lung Qi rebels causing fullness and inability to descend. The rest can be inferred similarly, demonstrating their mutual utility.
Furthermore, the Stomach governs the reception of food, relying on the Spleen's robust transportation to digest dietary essences, sending them upward to the Lung to distribute throughout the body, thereby nourishing all Zang-Fu organs. Thus, the Stomach is called the "Sea of Water and Grain" and the great source of the six Fu organs. The dregs pass down to the Small Intestine, which separates the clear from the turbid. Clear fluids seep into the Bladder, while turbid residues go to the Large Intestine. This process relies on the smooth Qi transformation of the Sanjiao (Triple Burner) to balance Water and Fire, ensuring the unobstructed passage of urine and feces. Hence it is said: "Qi transformation allows for excretion." However, Sanjiao Qi transformation originates from the Yin and Yang of the Kidney Yuan (Original Qi). If Kidney Yuan declines, the Sanjiao loses authority, causing disorder in Spleen-Stomach ascending and descending, mixing clear and turbid, leading to myriad diseases. This explains why Zang-Fu organs have different functions.
Only the Gallbladder attaches to the Liver as an exterior-interior pair. Its essence juice (bile) enters but does not exit normally. If affected by Heat Pathogens, bile leaks out causing bitter taste in the mouth, resulting in disease. There is also the Pericardium (Xin Bao Luo), located in the Danzhong region, serving as the outer protection for the Heart, acting on behalf of the Heart. Whenever pathogens invade the Heart, the Pericardium receives them. If the Heart itself is invaded, the Spirit departs, and departure of the Spirit means death. The Pericardium meridian connects with the Sanjiao meridian, forming an exterior-interior relationship. Thus, the five Zang, six Fu, and the Pericardium together constitute the twelve Hand-Foot Yin-Yang meridians. Detailed explanations are found in the chapter on Ying-Wei (Nutritive and Defensive) and Meridians.
One must thoroughly understand the principles of Zang-Fu generation/transformation and the pathways of meridian circulation before being able to differentiate the exterior-interior and deficiency-excess nature of diseases for treatment. Therefore, students must prioritize this study and cannot neglect it.