心肺位居膈上，而肺尤高，天之分也，故属干金。肝肾位下，而肾尤下，为黄
泉之分，故属坎水。坎外阴而内阳，阳气潜藏于黄泉之中。静极复动，故冬至而一
阳生，惊蛰而雷出于地。肾水得命门之火所蒸，化气以上，肝受之而升腾，故肝于
时为春，于象为木，于卦为震雷、巽风。（肝之怒而气盛如之。）阳气上升，至心而盛，阳盛
则为火，故心属火。于卦为离。离，南方之卦也。圣人向明而治，心居肺下，乾卦
之九五也。实为君主，神明出焉。离、干中画之变也。兑、干上画之变也。肺
居心上，干之上画也。上画变而为兑，于时为秋，于象为金，金性沉降，秋气敛肃，
阳气升极而降，由肺而降，故肺又属兑金。（心火上炎，肾水下润，坎离之定位也。火在上而下降，
水在下而上升，坎离之交媾也。肾水上升，由肝木之汲引，地道左旋而上于天也。心火
下降，由肺金之敛抑，天道右旋而入于地也。）脾脏居中，为上下升降之枢纽。饮食入胃，
脾为行运其气于上下内外，犹土之布化于四时，故属土。于卦为坤、为艮。金、木、土皆配
两卦，而水、火各主一卦，故五行惟水火之用为独专也。
男女媾精以成胎，精即水也，精中之气即火也。水火精气，妙合而凝，是为胎
元。精以成形，气以成神，以其原于父母，故曰先天。然五官百骸，皆本此精以为
质，而无非此水所灌充也。呼吸运动，皆本此气以为机，而无非此火所流行也。其
独指肾为先天者，则以精气先结胞胎，中起一茎，形如莲蕊。一茎，即脐带也。莲
蕊，即两肾也。两肾为水，命门之火寓焉。一阳藏于二阴之中，于卦为坎，以脏腑
之始结在此，故独以肾中水火为先天也。先天水足，则儿肥盛而润泽；火足，则儿
强健而精明。水得火，则气常温而不至于寒，火得水，则形常润而不至于槁。
苟先天水火一有偏胜，则禀受失其中和，而后天培养之功，为不可少矣。人生一日不再
食则饥，故有资于饮食，则脾胃司之。胃主进纳，脾主运化，饮食之气味精华，
由脾胃以灌输周身。气日盛而体日充，先天之水火赖此滋养以生生不息，故以脾胃
为后天之本也。总之，人身中润泽之气即水也，温暖之气即火也。一有偏胜，其致
自饮食者，调之甚易，其禀于胎气者，治之甚难，故先天为重。然不以畏难而废治，
全赖饮食以救弊补偏，故后天为要也。
火根于肾，而属诸心，何也？曰∶肾于卦为坎，于令为冬，于位为北，本水之
宅也。而阳根于阴，则火生焉，下潜而上升。心于卦为离，于令为夏，于位为南，
则火之宅也。至其宅而后旺，故从其旺而属之心也。其曰∶心为君火，肾为相火。
又曰∶君火以明，相火以位，何也？曰∶君者主也，向明以治。心为一身之主，神
明出焉，故称君。相者竭其才能以奉君出治者也。肾位于下，输其火于心，以为
神明之用，犹相臣竭其才力以奉君出治，故称相。位以职掌言，明以功能言也。火
者，人身温和之气也。五脏六腑，皆有此温和之气，各归其部，则各有其位，各效
其能，则各有其明。肾中相火，非无明也，阳方潜藏，光未被乎四表，职
司封蛰，龙不离于深渊，故不言明而言位。失其位，则有飞扬僭越之患矣。心中君
火，非无位也，君主无为，不与臣下较职守，神明有觉，独从方寸着虚灵，故不言
位而言明也。失其明，则有昏惑晦昧之忧矣。然则君火、相火，皆吾身阳和之正气，
而不可无者。而或指之为邪，谓君火可直折，相火不可直折，何也？曰∶失其正则
为邪，失其和则为热。故谓君、相火为邪火者，乃指君火、相火之邪热者言，非君
火、相火之本为邪也。直折犹云正治，治热以寒，治之正也。君火属心，居于
上焦，其病无与于下。无与于下，则根本之真阳无恙，特炎于上者过乎赫曦，
故可以寒凉治其有余之邪，使归于正，无所损于本原也。若肾中相火，居于下
焦，病则必干乎上，无论下焦为寒鸟热，热固上僭，寒亦上浮。盖肾中水火同根，
本无偏胜，若热盛而水亏，则火必致上炎；寒盛而火虚，亦必火因寒逼，不安其宅
而上浮也。故言相火为病者，乃因其在上之热，而直探其在下之根言之。病既根于
下，则不可以治上者治之矣，何也？火虚而治以寒凉，是益助其下焦之寒，火愈被
逼而上浮矣。且为寒所逼之火，本无根之残焰，而又以寒折之，有不消灭者乎？水
虚而火炎，若无妨于寒凉，不知火炎本乎水虚，不用平润之剂以补水，而徒用苦寒
以制火，是何异因金银之缺少，而凿平马以相就，必致并伤其火而后已，
故曰不可直折也。相火静而藏则属肾，动而发则属肝胆，此火布KT 于三焦，
而心包络为三焦之脏，若肝之配胆，故又曰∶肝胆、三焦、心包络相火也。
心肺位于膈肌之上，其中肺的位置最高，对应天的部分，因此归属于金。肝和肾位于下方，其中肾的位置最低，对应黄泉的部分，因此归属于坎水。坎卦外阴而内阳，阳气潜藏于黄泉之中。静到极点就会复动，所以冬至时一阳生，惊蛰时雷从地下发出。肾水得到命门之火的蒸腾，化为气向上运行，肝脏接受这股气并升腾，所以肝在时令上对应春季，在形象上对应木，在卦象上对应震雷、巽风。（肝气愤怒时气势旺盛就像这样。）阳气上升，到达心脏时达到旺盛，阳气极盛就变成火，所以心归属于火。在卦象上对应离卦。离是南方的卦。圣人面向光明治理天下，心位于肺之下，对应乾卦的九五爻。心实际上是君主，神明由此产生。离卦是乾卦中间一画的变动。兑卦是乾卦最上面一画的变动。肺位于心的上方，对应乾卦的最上面一画。最上面一画变动成为兑卦，在时令上对应秋季，在形象上对应金，金的性质沉降，秋气收敛肃杀，阳气升到极点而降，由肺来下降，所以肺又归属于兑金。（心火向上炎，肾水向下润，这是坎卦和离卦的定位。火在上方向下下降，水在下方向上升起，这是坎卦和离卦的交媾。肾水上升，依靠肝木的汲引，地道向左旋转而上达于天。心火下降，依靠肺金的敛降抑制，天道向右旋转而入于地。）脾脏位于中央，是上下升降的枢纽。饮食进入胃中，脾负责将其气运送到上下内外，就像土在四季中分布化育一样，所以归属于土。在卦象上对应坤卦、艮卦。金、木、土都配两个卦，而水、火各主一个卦，所以五行中只有水火的作用最为专一。
男女交合精气以形成胚胎，精就是水，精中的气就是火。水和火的精气，奇妙结合而凝结，这就是胎元。精用来形成形体，气用来形成精神，因为它们源于父母，所以称为先天。然而五官百骸，都以这个精作为本质，而没有不是被这个水所灌充的。呼吸运动，都以这个气作为机制，而没有不是被这个火所流行的。之所以单独指肾为先天，是因为精气先结成胞胎，中间长出一根茎，形状像莲蕊。这一根茎，就是脐带。莲蕊，就是两肾。两肾属水，命门之火寓居在其中。一阳藏在二阴之中，在卦象上对应坎卦，因为脏腑的初始结缔在这里，所以单独以肾中的水火为先天。先天之水充足，则胎儿肥壮润泽；先天之火充足，则胎儿强健精明。水得到火，则气常温而不至于寒；火得到水，则形常润而不至于干枯。如果先天的水火有一方偏胜，那么禀受就失去了中和，后天的培养功夫就是不可少的了。人一天不再进食就会饥饿，所以需要依赖饮食，这由脾胃主管。胃主要负责接纳食物，脾主要负责运化，饮食的气味精华，通过脾胃灌输到全身。气日益旺盛而身体日益充实，先天的水火依赖这些滋养而生生不息，所以把脾胃作为后天之本。总之，人身中润泽的气就是水，温暖的气就是火。一旦有偏胜，其来源如果是饮食造成的，调理很容易；其来源如果是胎气（先天）造成的，治疗就很难，所以先天为重。然而不因为难治就放弃治疗，完全依赖饮食来补救弊端、纠正偏差，所以后天为要。
火的根源在肾，却归属于心，为什么呢？回答说：肾在卦象上对应坎，在时令上对应冬，在方位上对应北，本是水的宅舍。而阳根生于阴，所以火产生于此，向下潜藏而后上升。心在卦象上对应离，在时令上对应夏，在方位上对应南，则是火的宅舍。到了它的宅舍后才旺盛，所以顺着它旺盛的特性而归属于心。又说：心为君火，肾为相火。又说：君火以明，相火以位，为什么呢？回答说：君是主宰，面向光明进行治理。心是一身的主宰，神明由此产生，所以称为君。相是竭尽才能辅佐君主出来治理的人。肾位于下方，输送火给心，以供神明使用，就像相臣竭尽才力辅佐君主出来治理，所以称为相。“位”是从职掌角度说的，“明”是从功能角度说的。火，是人身上温和的气。五脏六腑，都有这种温和的气，各自归入其部位，就各有其位，各自发挥其功能，就各有其明。肾中的相火，并非没有“明”，只是阳气正在潜藏，光芒未遍布四方，职司封藏蛰伏，龙不离深渊，所以不说“明”而说“位”。失去其位，就有飞扬僭越的祸患了。心中的君火，并非没有“位”，君主无为，不与臣下计较职守，神明有知觉，独从方寸之间显现虚灵，所以不说“位”而说“明”。失去其明，就有昏惑晦暗的忧患了。既然如此，君火、相火，都是我们身上的阳和正气，是不可缺少的。但有人把它们指为邪火，说君火可以直接折损，相火不可以直接折损，为什么呢？回答说：失去正道就成为邪，失去和谐就成为热。所以说君、相火为邪火的，是指君火、相火的邪热而言，并非君火、相火的本质是邪。直折犹言正治，用寒凉治热，是正统的治疗。君火属于心，居于上焦，它的病与下部无关。与下部无关，那么根本的真阳就没有恙病，只是上面的火势过于猛烈，所以可以用寒凉药治疗其有余的邪气，使其归于正道，不会损伤本源。如果是肾中的相火，居于下焦，发病则必定波及上部，无论下焦是寒还是热，热固然是向上僭越，寒也会上浮。因为肾中水火同根，本来没有偏胜，如果热盛而水亏，火必然导致上炎；寒盛而火虚，也必然火因寒逼，不安于宅舍而上浮。所以说相火生病，是因其在上部的热，而直接探究其在下部的根源来说的。病既然根于下部，就不能用治上部的方法来治它，为什么呢？火虚而用寒凉药治疗，这是更加助长下焦的寒，火更加被逼而上浮。况且被寒所逼的火，本是没根的残焰，又用寒凉去折损它，有不熄灭的吗？水虚而火炎，看似不妨碍用寒凉药，不知道火炎本乎水虚，不用平润的药来补水，而只用苦寒药来制火，这何异于因为金银缺少，而凿平马匹来凑数，必定导致连火一起伤害才停止，所以说不可直折。相火静止而潜藏时属于肾，发动而发散时属于肝胆，此火散布于三焦，而心包络是三焦的脏，若肝配胆，所以又说：肝胆、三焦、心包络都是相火。
The Heart and Lung are located above the diaphragm, with the Lung being the highest, corresponding to the realm of Heaven, thus belonging to Metal. The Liver and Kidney are located below, with the Kidney being the lowest, corresponding to the realm of Yellow Springs (the underworld), thus belonging to Kan Water. Kan is Yin on the outside and Yang on the inside; Yang Qi hides within the Yellow Springs. When stillness reaches its extreme, it moves again; thus, at the Winter Solstice, one Yang is born, and at Jingzhe (Awakening of Insects), thunder emerges from the earth. Kidney Water, steamed by the Fire of the Gate of Life (Mingmen), transforms into Qi and ascends. The Liver receives this Qi and rises vigorously. Therefore, in terms of seasons, the Liver corresponds to Spring; in terms of imagery, it corresponds to Wood; and in terms of trigrams, it corresponds to Zhen Thunder and Xun Wind. (When the Liver is angry, its Qi becomes vigorous like this.) Yang Qi ascends and becomes vigorous upon reaching the Heart. Extreme Yang becomes Fire, so the Heart belongs to Fire. In terms of trigrams, it corresponds to Li. Li is the trigram of the South. Sages govern facing the brightness. The Heart is located below the Lung, corresponding to the Nine-Five line of the Qian trigram. It acts as the Sovereign, from which Divine Intelligence (Shenming) arises. The Li trigram is a variation of the middle line of the Qian trigram. The Dui trigram is a variation of the top line of the Qian trigram. The Lung is located above the Heart, corresponding to the top line of Qian. When the top line changes to Dui, it corresponds to Autumn in season, and Metal in imagery. Metal has the nature of sinking and descending; Autumn Qi is convergent and肃 (solemn/clear). Yang Qi rises to its peak and then descends, descending through the Lung; thus, the Lung also belongs to Dui Metal. (Heart Fire flares upward, Kidney Water moistens downward; this is the fixed position of Kan and Li. Fire descends from above, Water ascends from below; this is the intercourse of Kan and Li. Kidney Water ascends, drawn up by Liver Wood, following the Earthly Path rotating counter-clockwise to reach Heaven. Heart Fire descends, restrained by Lung Metal, following the Heavenly Path rotating clockwise to enter the Earth.) The Spleen is located in the center, serving as the pivot for ascending and descending. Food enters the Stomach, and the Spleen transports its Qi to the upper/lower and interior/exterior, just as Earth distributes and transforms throughout the four seasons; thus, it belongs to Earth. In terms of trigrams, it corresponds to Kun and Gen. Metal, Wood, and Earth each correspond to two trigrams, while Water and Fire each govern one trigram; therefore, among the Five Elements, only Water and Fire have exclusive functions.
Male and female essence combine to form the embryo. Essence is Water, and the Qi within essence is Fire. Water and Fire essence and Qi miraculously combine and condense, forming the Fetal Origin (Taiyuan). Essence forms the physical structure, and Qi forms the Spirit. Since they originate from parents, they are called Pre-heaven (Xiantian). However, all five senses and hundred bones are based on this essence as substance, and none are not filled by this Water. Respiration and movement are based on this Qi as mechanism, and none are not circulated by this Fire. The reason the Kidney alone is designated as Pre-heaven is that essence and Qi first knot to form the placenta, growing a single stem in the middle, shaped like a lotus stamen. This single stem is the umbilical cord. The lotus stamen refers to the two Kidneys. The two Kidneys are Water, wherein the Fire of the Gate of Life resides. One Yang hides within two Yins, corresponding to the Kan trigram. Because the initial formation of the zang-fu organs occurs here, the Water and Fire within the Kidney alone are considered Pre-heaven. If Pre-heaven Water is sufficient, the fetus is plump and lustrous; if Pre-heaven Fire is sufficient, the fetus is strong and sharp. Water receiving Fire keeps Qi warm and prevents cold; Fire receiving Water keeps form moist and prevents dryness. If Pre-heaven Water or Fire has any excess, the endowment loses its harmony, making Post-heaven cultivation indispensable. A person who does not eat for a day feels hunger, thus relying on diet, which is managed by the Spleen and Stomach. The Stomach primarily accepts and receives, while the Spleen primarily transforms and transports. The flavors and essences of food are distributed throughout the body by the Spleen and Stomach. As Qi grows daily and the body fills out, Pre-heaven Water and Fire rely on this nourishment to generate endlessly; thus, the Spleen and Stomach are regarded as the Root of Post-heaven. In summary, the moistening Qi in the human body is Water, and the warming Qi is Fire. Once there is an imbalance, if it stems from diet, regulation is easy; if it stems from fetal Qi (Pre-heaven), treatment is difficult, hence Pre-heaven is prioritized. However, one should not abandon treatment due to difficulty; relying entirely on diet to remedy defects and correct deviations makes Post-heaven essential.
Fire originates in the Kidney but is attributed to the Heart. Why? The answer is: The Kidney corresponds to the Kan trigram, Winter season, and North direction, being the residence of Water. Yet Yang roots in Yin, generating Fire, which sinks and then ascends. The Heart corresponds to the Li trigram, Summer season, and South direction, being the residence of Fire. It flourishes once it reaches its residence, so it is attributed to the Heart based on its flourishing nature. It is said: The Heart is Ministerial Fire (Jun Huo), and the Kidney is Assistant Fire (Xiang Huo). It is also said: Ministerial Fire manifests as clarity (Ming), and Assistant Fire manifests as position (Wei). Why? The answer is: The "Minister" (Jun) is the ruler, governing facing the brightness. The Heart is the master of the body, from which Divine Intelligence arises, hence called Minister. The "Assistant" (Xiang) exhausts their talent to serve the Minister in governance. The Kidney is located below, transmitting Fire to the Heart for the use of Divine Intelligence, just as an assistant minister exhausts their ability to serve the ruler; hence called Assistant. "Position" refers to official duties, while "Clarity" refers to function. Fire is the mild/warm Qi in the human body. All five zang and six fu organs possess this mild Qi. Each returns to its region, having its own position; each performs its function, having its own clarity. The Assistant Fire in the Kidney is not without clarity, but because Yang is hiding, its light has not yet spread to the four directions. Its duty is sealing and storing; the dragon does not leave the deep abyss. Thus, it speaks of "Position" rather than "Clarity." Losing its position leads to the danger of soaring and usurping. The Ministerial Fire in the Heart is not without position, but the sovereign acts without action, not competing with ministers over duties. Divine Intelligence has awareness, manifesting emptiness and spirituality from the heart/mind. Thus, it speaks of "Clarity" rather than "Position." Losing clarity leads to the worry of confusion and obscurity. Therefore, both Ministerial and Assistant Fires are the righteous Qi of Yang and warmth in our bodies and cannot be absent. Some point to them as pathogenic fire, saying Ministerial Fire can be directly suppressed, but Assistant Fire cannot. Why? The answer is: Losing righteousness becomes pathogenic; losing harmony becomes heat. Thus, when referring to Ministerial/Assistant Fire as pathogenic fire, it refers to the pathogenic heat of these fires, not that their essence is pathogenic. "Direct suppression" implies orthodox treatment: treating heat with cold is orthodox. Ministerial Fire belongs to the Heart, residing in the Upper Jiao. Its pathology does not affect the lower part. Not affecting the lower part means the True Yang of the root is unharmed; only the fire flaring above is excessively intense. Thus, cooling herbs can treat the excess pathogenic factor, returning it to orthodoxy without damaging the origin. If it is the Assistant Fire in the Kidney, residing in the Lower Jiao, pathology must affect the upper part. Regardless of whether the Lower Jiao is cold or hot, heat certainly flares upward, and cold also floats up. Since Water and Fire in the Kidney share the same root and originally have no excess, if Heat is excessive and Water is deficient, Fire will inevitably flare upward; if Cold is excessive and Fire is deficient, Fire will be forced by Cold, unable to remain in its residence, and float upward. Therefore, speaking of Assistant Fire disease involves probing the root below due to the heat above. Since the disease roots in the lower part, one cannot treat it using methods for the upper part. Why? Treating deficient Fire with cold herbs further aids the cold in the Lower Jiao, forcing Fire to float higher. Moreover, Fire forced by cold is a rootless remnant flame; suppressing it with cold will surely extinguish it. If Water is deficient and Fire flares, it may seem unaffected by cold herbs. However, Fire flaring stems from Water deficiency. Without using moistening agents to tonify Water, and merely using bitter-cold to control Fire, is this not like flattening a horse to match missing gold/silver? It will inevitably damage the Fire itself. Hence, it is said that Assistant Fire cannot be directly suppressed. When Assistant Fire is quiet and stored, it belongs to the Kidney; when active and emitted, it belongs to the Liver and Gallbladder. This Fire spreads through the Sanjiao (Triple Burner), and the Pericardium is the zang organ of the Sanjiao. Since the Liver pairs with the Gallbladder, it is also said: Liver, Gallbladder, Sanjiao, and Pericardium constitute Assistant Fire.