五脏生克，须实从气机病情讲明，若徒作五行套语，茫然不知的，实多致错误。
今略着其概如左。饮食入胃，脾为营运其精英之气，虽曰周布诸脏，实先上输于肺，
（气亲上也。）肺先受其益，是为脾土生肺金。肺受脾之益，则气愈旺，化水下降，
泽及百体，是为肺金生肾水。肾受肺之生，则水愈足，为命门之火所蒸，化气上升，
肝先受其益，是为肾水生肝木。肝受肾之益，则气愈旺，上资心阳，发为光明，是
为肝木生心火。脾之所以能运化饮食者，气也。气寒则凝滞而不行，得心火以温之，
乃健运而不息，是为心火生脾土。此五脏相生之气机也。肺在心上，心火上炎，肺
受其伤，此为心火克肺金也。若由脾胃积热，或由肝肾相火，或由本经郁热，皆与
心无涉。肾阴太盛，寒气上冲，心为之悸；或肾寒甚，而逼其龙火上乘，心为之烦，
皆肾水克心火也。若饮水过多，停蓄不行，心火被逼不安而悸者，与肾无涉。脾气
过燥，则肾水为其所涸而失润；或过湿，则肾水为其所壅而不流，皆脾土克肾水也。
若他脏之燥，外感之湿，与脾无涉。肝木 泄太过，则脾胃因之而气虚；或肝气郁
结太甚，则脾胃因之而气滞，皆肝木克脾土也。若自致耗散，自致凝滞，及由
他脏腑所致者，与肝无涉。气有降则有升，无降则无升，纯降则不升，何则？
浊阴从肺右降，则胸中旷若太虚，无有窒塞，清阳得以从肝左升，是谓有降有
升。若浊阴壅满胸中，不肯下降，则肝气被遏，欲升不能，是谓无降无升。
（东垣谓食填太阴，为金克木，即此说。详见伤饮食门。）肺金肃敛太过，有秋无春，
是谓纯降不升。无降无升，纯降不升，皆肺金克肝木也。若肝木自沉，或因他脏之寒郁，
与肺无涉。此五脏相克之病情也。不足，则欲其生；太过，则欲其克。故木疏
土而脾滞以行，金得火而肺寒以解，肾得脾之健运而水无泛滥之虞，肝得金之
敛抑而木无 散之患。人但知生之为生，而不知克之为生。心火偏胜，则克肺
金，若肾水充足，则火有所制，不但不克金，且温脾以生金，余脏同此论之。
此平人之无病，实由五脏互相克制，故不至偏胜为灾。即《经》所谓∶亢则害，
（亢，太盛也；害，克也。）承乃制，（承，相承也。水之承金，如子之承父，火耒克金，水乃制之也。）
制生化。（火受水制，则不特不克金，且益土以生金。化，犹生也。）若已病之人，则火盛者，不
但刑金，且复涸水，肝脾皆被焚灼矣。不治之，而望其自然承制，有此理乎？乃
医者见其热极血瘀而舌黑也，热伏于内而外反寒 也，谓黑为水色，寒 为水象，
是火极而反兼水化，乃金之子水，为母报火之仇，即亢害承制之理。其说虽本前人，
终欠的当。《医贯》曰∶人皆曰水克火，予独曰水养火。盖水克火者，后天有形之
水火也。水养火者，先天无形之水火也。（先天水火，互相为根，故水养火，如灯得油而愈明也。）人
皆曰金生水，予独曰水生金。盖肺气，夜卧则归藏于肾水之中，肾中火炎，则金为
火刑而不能归；无火则水冷金寒，亦不能归。凡气从脐下逆奔而上者，肾虚不能纳
气归元也。毋徒治肺，或壮水之主，（此即承制之理，肾水心火一也。）或益火之元，（所谓水
冷金寒用丙丁也，即制生化以克为生之理。）金向水中生矣。人皆曰土克水，予独于水中补土。
八味丸从水中补火，以蒸腐水谷是也。（寻常土寒，止须补脾胃之阳，若命门火衰，犹釜底无薪，必
须八味丸。）人皆曰木克土，予独升木以培土。盖木者，春生之气也，与胃气同出异名。
当遂其发生之性，木气升发，即胃气升发也。及其发达既久，生意已竭，又当敛归
水土之中，以为来春发生之本，（明此则金之克木，正所以敛聚其生意，不使散也，亦以克为生之理。）
焉有伐之之理？此东垣《脾胃论》用升、柴以升木气，谆谆言之详也。（土性中和，有升有
降。郁而不升，虽曰木病，亦即土病。故升木即是培土。由是言之，若有升无降
，则降金亦未始非培土矣。）愚按赵
氏之说甚有理，诚能触类引伸，则五脏互相关系之故，无不了然矣。赵氏又论五行各有
五，其说颇凿，未甚的当。予谓五脏无一脏无血液，是皆有水也；无一脏无气，
是皆有火也；无一脏不发生，是皆有木也；无一脏不藏敛，是皆有金也。有气、有
血、有发、有敛，是无一脏不和平，则皆有土也。知五脏各具五行，则其互相关涉
之故，愈推愈觉无穷，而生克之妙，不愈可见哉。
五脏之间的相生相克关系，必须从气机运行和病情实际的角度来阐明。如果只是机械地套用五行理论，茫然不知其所以然，实在容易导致错误。
现在简要概括如下：饮食进入胃中，脾脏负责运化其中的精微之气，虽然这些气会周遍分布到各个脏腑，但实际上先上输于肺脏。（因为气性轻清，亲向上行。）肺脏首先受到滋养，这就是脾土生肺金。肺脏接受了脾脏的滋养，则肺气更加旺盛，将津液化为水液下降，滋润全身百体，这就是肺金生肾水。肾脏接受了肺脏的滋生，则肾水更加充足，被命门之火蒸腾，化为气上升，肝脏首先受到滋养，这就是肾水生肝木。肝脏接受了肾脏的滋养，则肝气更加旺盛，向上资助心阳，表现为光明（指精神焕发、目明等），这就是肝木生心火。脾脏之所以能够运化饮食，依靠的是气。如果气寒，就会凝滞而不运行，得到心火的温煦，才能健运而不停止，这就是心火生脾土。这是五脏相生的气机规律。
肺脏位于心脏之上，如果心火向上炎灼，肺脏受到损伤，这就是心火克肺金。如果是由于脾胃积热，或者肝肾相火妄动，或者本经郁热所致，都与心脏无关。如果肾阴太盛，寒气上冲，心脏就会悸动；或者肾寒严重，逼迫龙雷之火上乘于心，心脏就会烦躁，这都是肾水克心火的表现。如果是饮水过多，停蓄不行，导致心火被逼不安而心悸，这与肾脏无关。脾气过于燥热，则肾水会被它吸干而失去滋润；或者脾气过于湿盛，则肾水会被它壅塞而不能流动，这都是脾土克肾水的表现。如果是其他脏腑导致的燥，或者外感引起的湿，与脾脏无关。肝木疏泄太过，则脾胃因此气虚；或者肝气郁结太甚，则脾胃因此气滞，这都是肝木克脾土的表现。如果是自身耗散、自身凝滞，以及由其他脏腑引起的问题，与肝脏无关。
气有降就有升，没有降就没有升，只降不升是怎么回事呢？浊阴之气从肺右侧下降，则胸中空旷如太虚，没有窒塞，清阳之气得以从肝脏左侧上升，这叫有降有升。如果浊阴壅满胸中，不肯下降，则肝气被遏制，想要升发却不能，这叫无降无升。（李东垣说食物填塞太阴脾土，造成金克木，就是这个说法。详见伤饮食章节。）肺金肃敛太过，只有秋天的肃杀而没有春天的生发，这叫纯降不升。无降无升、纯降不升，都是肺金克肝木的表现。如果是肝木自身下沉，或者因其他脏腑的寒邪郁闭所致，与肺脏无关。这是五脏相克的病情规律。
正气不足，就需要相生来补益；正气太过，就需要相克来制约。所以木能疏土，使脾滞得以运行；金得火温，使肺寒得以解除；肾得到脾的健运，则水液没有泛滥的忧虑；肝得到金的敛抑，则木气没有耗散的隐患。人们只知道相生是生养，却不知道相克也是生养。心火偏胜，就会克制肺金；如果肾水充足，则火有所制约，不仅不克金，而且温脾以生金，其他脏腑也同理推论。这是健康人无病的原因，确实是由于五脏互相克制，所以不至于偏胜为灾。正如《内经》所说：“亢则害”，（亢，太盛的意思；害，克制的意思。）“承乃制”，（承，相承接的意思。水承接金，如同儿子承接父亲，火来克金，水便制约它。）“制生化”。（火受水制约，则不仅不克金，而且益土以生金。化，犹生的意思。）
如果已经生病的人，火气盛者，不但刑克肺金，而且又会耗竭肾水，肝脾都被焚灼了。如果不治疗，却希望它们自然承制，有这样的道理吗？然而医生见到热极血瘀而舌苔黑，热伏于内而体表反寒，就说黑色是水色，寒象是水象，认为这是火极而反兼水化，是金之子水，为母报火之仇，即亢害承制的原理。这种说法虽然源于前人，终究不够确切。《医贯》说：人都说水克火，我独说水养火。所谓水克火，是指后天有形的水火。所谓水养火，是指先天无形的水火。（先天水火，互为根本，所以水养火，就像灯得到油而更明亮一样。）人都说金生水，我独说水生金。盖肺气，夜间卧睡时归藏于肾水中，肾中火炎，则金被火刑而不能归藏；如果没有火，则水冷金寒，也不能归藏。凡是气从脐下逆奔而上的人，是肾虚不能纳气归元。不要仅仅治疗肺，或者壮水之主（这就是承制的原理，肾水心火是一体的），或者益火之元（所谓水冷金寒用丙丁火，即制生化以克为生的原理），金就能在水中生了。人都说土克水，我独说在水中补土。八味丸就是从水中补火，以蒸腐水谷的方法。（寻常脾胃寒冷，只需补脾胃之阳，如果命门火衰，犹如釜底无薪，必须用八味丸。）人都说木克土，我独说升木以培土。盖木，是春生之气，与胃气同出而异名。应当顺遂其发生之性，木气升发，就是胃气升发。等到发达久了，生意已尽，又应当收敛归入水土之中，作为来年春天发生的根本（明白这一点，就知道金的克木，正是为了敛聚其生意，不使其散失，这也是以克为生的原理），哪有伐木的道理？这就是李东垣《脾胃论》中使用升麻、柴胡以升发木气，反复详尽论述的原因。（土性中和，有升有降。郁而不升，虽然说是木的病，也就是土的病。所以升木即是培土。由此而言，如果有升无降，那么降金也未尝不是培土啊。）
我认为赵献可的说法很有道理，如果能触类旁通，那么五脏互相关系的缘故，就没有不明白了。赵氏又论述五行各有五，这种说法比较穿凿，不太确切。我认为五脏没有一脏没有血液，所以都有水；没有一脏没有气，所以都有火；没有一脏不发生长，所以都有木；没有一脏不藏敛，所以都有金。有气、有血、有生发、有敛藏，是没有一脏不和平，所以都有土。知道五脏各具五行，那么它们互相关涉的缘故，越推究越觉得无穷无尽，而生克的奥妙，不是更加明显了吗？
The mutual generation and restriction among the Five Zang Organs must be explained from the perspective of Qi mechanism and clinical conditions. If one merely applies the clichés of the Five Elements without understanding the essence, it often leads to errors.
Here is a brief summary: When food enters the Stomach, the Spleen transports and transforms its essence (Jingqi). Although this Qi distributes throughout all organs, it actually first ascends to the Lung. (Qi has a light nature and tends to ascend.) The Lung receives this benefit first, which represents Earth generating Metal. Once the Lung is nourished by the Spleen, its Qi becomes vigorous, transforming fluids into water that descends to moisten the entire body, which represents Metal generating Water. The Kidney, nourished by the Lung, has sufficient Water, which is steamed by the Fire of the Mingmen (Gate of Vitality) to transform into Qi ascending upward. The Liver receives this benefit first, representing Water generating Wood. The Liver, nourished by the Kidney, has vigorous Qi that assists Heart Yang upward, manifesting as brightness (spiritual vitality and clear vision), representing Wood generating Fire. The ability of the Spleen to transport and transform food relies on Qi. If Qi is cold, it stagnates and fails to move; receiving warmth from Heart Fire allows it to function vigorously and ceaselessly, representing Fire generating Earth. This is the Qi mechanism of mutual generation among the Five Zang Organs.
The Lung is located above the Heart. If Heart Fire flares upward, damaging the Lung, this represents Fire restricting Metal. However, if the cause is heat accumulation in the Spleen and Stomach, or ministerial fire from the Liver and Kidney, or depression-heat in the meridian itself, it is unrelated to the Heart. If Kidney Yin is excessive, causing cold Qi to rush upward, palpitations occur in the Heart; or if Kidney Cold is severe, forcing Dragon Fire (Ministerial Fire) to ascend, causing irritability in the Heart, these represent Water restricting Fire. However, if palpitations result from excessive water intake leading to fluid retention and pressing down on Heart Fire, it is unrelated to the Kidney. If Spleen Qi is too dry, it depletes Kidney Water, causing loss of moisture; or if Spleen Qi is too damp, it obstructs Kidney Water, preventing flow; these represent Earth restricting Water. Dryness from other organs or dampness from external pathogens are unrelated to the Spleen. If Liver Wood over-excretes, Spleen and Stomach become Qi-deficient due to it; or if Liver Qi depression is too severe, Spleen and Stomach experience Qi stagnation due to it; these represent Wood restricting Earth. Self-consumption, self-stagnation, or issues caused by other Zang-Fu organs are unrelated to the Liver.
Qi involves both descending and ascending; without descending, there is no ascending. What does pure descending without ascending mean? When turbid Yin descends via the right side of the Lung, the chest becomes empty like the Great Void, free of obstruction, allowing Clear Yang to ascend via the left side of the Liver. This is having both descending and ascending. If turbid Yin fills the chest and refuses to descend, Liver Qi is suppressed and cannot ascend. This is neither descending nor ascending. (Li Dongyuan stated that food filling the Taiyin causes Metal to restrict Wood, which is this principle. See the chapter on Food Injury.) If Lung Metal restricts too much, having only Autumn's肃敛 (descending/contracting) without Spring's growth, this is pure descending without ascending. Neither descending nor ascending, or pure descending without ascending, both represent Metal restricting Wood. If Liver Wood sinks internally, or is constrained by cold from other organs, it is unrelated to the Lung. This is the pathology of mutual restriction among the Five Zang Organs.
When deficient, one desires generation; when excessive, one desires restriction. Thus, Wood loosens Earth, allowing Spleen stagnation to move; Metal receives Fire, resolving Lung cold; the Kidney receives Spleen's vigorous transport, avoiding water flooding; the Liver receives Metal's restraint, avoiding Wood scattering. People know generation as nurturing, but do not know that restriction also nurtures. If Heart Fire is excessive, it restricts Lung Metal; but if Kidney Water is sufficient, Fire is controlled. It not only fails to restrict Metal but also warms the Spleen to generate Metal. The same logic applies to other organs. Health arises precisely because the Five Zang Organs mutually restrict each other, preventing any single one from becoming excessive and causing disaster. As the *Classic* states: "Excess leads to harm," (Excess means too strong; Harm means restriction.) "Succession brings control," (Succession means following. Water follows Metal; just as a son follows a father, Fire comes to restrict Metal, so Water controls it.) "Control generates transformation." (When Fire is controlled by Water, it not only stops restricting Metal but benefits Earth to generate Metal. Transformation implies generation.)
For those already ill, excessive Fire not only punishes Metal but also dries up Water, burning the Liver and Spleen. If untreated, expecting natural succession and control—is this reasonable? Physicians seeing extreme heat with blood stasis and black tongue, or internal heat with external cold, might say black is the color of Water, and cold is the image of Water, arguing that extreme Fire mimics Water transformation. They claim Water (child of Metal) avenges its mother (Metal) against Fire, citing the principle of excess-harm-succession-control. Although based on predecessors' theories, this is ultimately imprecise. *Yi Guan* states: Everyone says Water restricts Fire; I alone say Water nourishes Fire. Water restricting Fire refers to postnatal, tangible Water and Fire. Water nourishing Fire refers to prenatal, intangible Water and Fire. (Prenatal Water and Fire root each other; thus Water nourishes Fire, like oil making a lamp burn brighter.) Everyone says Metal generates Water; I alone say Water generates Metal. Lung Qi returns to store within Kidney Water during sleep. If Kidney Fire flares, Metal is punished by Fire and cannot return; without Fire, Water is cold and Metal is cold, also unable to return. Any Qi rushing upward from below the navel indicates Kidney deficiency failing to grasp Qi and return it to the source. Do not merely treat the Lung; either strengthen the master of Water (this is the principle of succession-control, where Kidney Water and Heart Fire are one), or benefit the origin of Fire (using Bing-Ding Fire for cold Water and cold Metal, i.e., controlling transformation to use restriction as generation), and Metal will be generated within Water. Everyone says Earth restricts Water; I alone supplement Earth within Water. Ba Wei Wan (Eight-Ingredient Pill) supplements Fire within Water to steam and rot food and drink. (For ordinary Spleen-Stomach cold, tonifying Spleen-Stomach Yang suffices; but for Mingmen Fire decline, like a pot without fuel, Ba Wei Wan is necessary.) Everyone says Wood restricts Earth; I alone raise Wood to cultivate Earth. Wood is the Qi of Spring birth, sharing the same origin as Stomach Qi but differing in name. One should follow its nature of emergence. When Wood Qi rises, Stomach Qi rises. After prolonged development, when life energy is exhausted, it should contract and return to Water and Earth to serve as the root for next spring's emergence. (Understanding this reveals that Metal restricting Wood is precisely to gather its life energy, preventing scatter, again using restriction as generation.) How could there be a reason to destroy it? This is why Li Dongyuan's *Pi Wei Lun* (Treatise on the Spleen and Stomach) earnestly discusses using Sheng Ma (Cimicifugae Rhizoma) and Chai Hu (Bupleuri Radix) to raise Wood Qi. (Earth nature is neutral, involving both rising and falling. Depression preventing rise, though called a Wood disease, is also an Earth disease. Thus raising Wood is cultivating Earth. From this perspective, if there is rising without falling, then lowering Metal is also cultivating Earth.)
I consider Zhao Xianke's theory very reasonable. If one can extend it by analogy, the relationships among the Five Zang Organs will become clear. Zhao further argued that each of the Five Elements has five aspects, a view that is somewhat forced and imprecise. I believe each of the Five Zang Organs contains Blood, thus possessing Water; each has Qi, thus possessing Fire; each has growth/emergence, thus possessing Wood; each has storage/restriction, thus possessing Metal. Having Qi, Blood, Emergence, and Restriction means no organ lacks harmony, thus possessing Earth. Knowing that each Zang organ embodies the Five Elements makes their interrelationships infinitely profound, revealing the subtleties of generation and restriction even more clearly.