古称乙癸同源，肾肝同治，其说维何？盖火分君相。君火者，居于上而主静；相火
者，居乎下而主动。君火唯一心主是也，相火有二，乃肾与肝，肾应北方壬癸，于卦为
坎，于象为龙，龙潜海底，龙起而火随之；肝应东方甲乙，于卦为震，于象为雷，雷藏
泽中，雷起而火随之。泽也，海也，莫非水也，莫非下也，故曰乙癸同源。东方之木，
无虚不可补，补肾即所以补肝；北方之水，无实不可泻，泻肝即所以泻肾。至于春升，
龙不现则雷无声，及其秋降，雷未收则龙不藏，但使龙归海底，必无迅发之雷，但使雷
藏泽中，必无飞腾之龙，故曰肾肝同治。东方者，天地之春也，勾萌甲折，气满乾坤，
在人为怒，怒则气上，而居七情之升，在天为风，风则气鼓，而为百病之长，怒而补
之，将逆而有壅绝之忧，风而补之，将满而有胀闷之患矣。北方者，天地之冬也，草黄
米落，六字萧条，在人为恐，恐则气下，而居七情之降，在天为寒，寒则气惨，而为万
象之衰，恐而泻之，将怯而有颠仆之虞，寒而泻之，将空而有涸竭之害矣。然木既无
虚，又言补肝者，肝气不可犯，肝血自当养也。血不足者濡之，水之属也，肝木之源，
木赖以荣，水既无实，又言泻肾者，肾阴不可亏，而肾气不可亢也，气有余者，伐之木
之属也，伐木之干，水赖以安。夫一补一泄，气血攸分，即泄即补，水木向府，总
之，相火易上，身中所苦，泄木所以降气，补水所以制火，气即火，火即气，同物而异
名也。故知气有余，便是火者，愈知乙癸同源之义矣。然时医多执“肝常有余”之说，
举手便云平肝，殊不思《经》曰“东方木也，万物所以始生也。”《圣济经》云∶四时
之所化，始于木；十二经之所养，始于春。女子受娠一月，是厥阴肝经养之，肝者，乃
春阳发动之始，万物生化之源，故戒怒养阳，使先天之气相生于无穷，是摄生之切要
也。盖春属肝木，乃吾身升生之气，此气若有不充，则四脏何所禀，水如春无所生，则
夏长秋收冬藏者，将何物乎？五行之中，惟木有发荣畅茂之象，水火金土皆无是也。使
天地而无木，则世界黯淡，其无色矣。培之养之，犹恐不暇，而尚欲剪之、伐之乎！故
养血和肝，使火不上炎，则心气和平，而百骸皆理。况肾主闭藏，肝主疏泻，是一开一
合也。俗云∶肝有泻无补，不知六味地黄丸、七宝美髯丹等剂，皆补肝之药也。人特
习而不察耳。
古人称“乙癸同源，肾肝同治”，这种说法的依据是什么呢？大概是因为火分为君火和相火。君火居于上部而主静；相火居于下部而主动。君火只对应心主（心脏），相火有两个，分别是肾和肝。肾对应北方的壬癸水，在八卦中属于坎卦，在物象上象征龙，龙潜伏于海底，龙兴起时火便随之而起；肝对应东方的甲乙木，在八卦中属于震卦，在物象上象征雷，雷藏于沼泽之中，雷响起时火便随之而起。沼泽和海，无非都是水，都位于下方，所以称为“乙癸同源”。东方的木，没有虚证不可以用补法，补肾就是用来补肝的；北方的水，没有实证不可以用泻法，泻肝就是用来泻肾的。至于春季阳气升发，如果龙不出现，雷就没有声音；到了秋季阳气下降，如果雷未收敛，龙就不能潜藏。只要让龙回归海底，必然不会有迅猛爆发的雷；只要让雷藏在泽中，必然不会有飞腾的龙，所以说“肾肝同治”。
东方对应天地的春季，草木萌芽破壳，气充满天地之间，在人表现为怒，怒则气机上逆，位居七情（喜、怒、忧、思、悲、恐、惊）中的上升阶段；在天表现为风，风则鼓动气机，是百病之首。对怒气进行补益，将会导致气机逆乱而有壅塞断绝的忧患；对风气进行补益，将会导致胀满而有胀闷的病患。北方对应天地的冬季，草枯叶落，景象萧条，在人表现为恐，恐则气机下陷，位居七情中的下降阶段；在天表现为寒，寒则使气机惨烈，是万物衰败的原因。对恐惧进行泻法治疗，将会导致怯懦而有跌倒摔伤的忧虑；对寒气进行泻法治疗，将会导致空虚而有枯竭的危害。
然而既然说木没有虚证，又为何说要补肝呢？这是因为肝气不可被侵犯，但肝血自然应当滋养。血不足时要用濡润之法，这属于水的属性，是肝木的源头，木依靠它才能繁荣。既然说水没有实证，又为何说要泻肾呢？这是因为肾阴不可亏损，而肾气不可亢盛。气有余时，要采用伐除的方法，这属于木的属性，砍伐木的枝干，水才能安宁。这一补一泄，气血得以区分；边泄边补，水和木归于本源。总之，相火容易上炎，身体所痛苦的是气火失调，疏泄肝木是为了降气，滋补水液是为了制火。气和火，本质是同一种事物而名称不同。因此知道“气有余便是火”，就更明白“乙癸同源”的含义了。
然而当时的医生多固执于“肝常有余”的说法，举手投足间就说要平肝，却不曾思考《内经》所说：“东方属木，是万物开始生长的地方。”《圣济经》说：四季的变化，始于木；十二经脉的滋养，始于春。女子怀孕一个月，由厥阴肝经滋养，肝是春阳发动的开始，也是万物化生的源头，所以告诫人们戒怒以养护阳气，使先天之气生生不息，这是养生的关键要点。因为春属于肝木，是我们身体中升发生发的元气，如果这股气不充足，其他四脏靠什么禀受呢？水如果没有春天的生发，那么夏天的生长、秋天的收获、冬天的收藏，又将凭借什么呢？五行之中，只有木具有发芽、繁荣、舒畅、茂盛的形象，水火金土都没有这样的特性。假使天地没有木，世界就会黯淡无光。培育它、滋养它，还怕时间不够，难道还要剪伐它吗！所以养血和肝，使火不上炎，那么心气平和，全身筋骨脏腑都能调理有序。况且肾主闭藏，肝主疏泄，这是一开一合的关系。世俗常说“肝有泻无补”，却不知道六味地黄丸、七宝美髯丹等方剂，都是补肝的药物。人们只是习以为常而没有仔细考察罢了。
The ancients referred to "Yi and Gui sharing the same source, Kidney and Liver treated together." What is the basis for this theory? It lies in the distinction between Ministerial Fire (Xiang Huo) and Sovereign Fire (Jun Huo). Sovereign Fire resides in the upper body and governs stillness; Ministerial Fire resides in the lower body and governs movement. Sovereign Fire corresponds solely to the Heart Master (Zang Zhi Jun Zhu); Ministerial Fire has two manifestations: the Kidney and the Liver. The Kidney corresponds to the Heavenly Stems Ren and Gui (North), belongs to the Kan trigram in the Eight Trigrams, and symbolizes the Dragon in imagery. When the dragon lurks at the bottom of the sea, its rising brings fire with it. The Liver corresponds to the Heavenly Stems Jia and Yi (East), belongs to the Zhen trigram, and symbolizes Thunder in imagery. When thunder hides in the marsh, its emergence brings fire with it. Marshes and seas are all water, all located below; hence, it is said that "Yi and Gui share the same source."
In the East, Wood cannot be tonified if there is no deficiency; tonifying the Kidney is a method to tonify the Liver. In the North, Water cannot be purged if there is no excess; purging the Liver is a method to purge the Kidney. Regarding the ascending energy of Spring, if the Dragon does not appear, Thunder makes no sound; during the descending phase of Autumn, if Thunder is not contained, the Dragon cannot hide. If the Dragon returns to the sea, there will be no sudden, explosive Thunder; if Thunder remains in the marsh, there will be no soaring Dragon. Thus, it is said that "Kidney and Liver are treated together."
The East corresponds to the Spring of Heaven and Earth, where buds sprout and break shells, filling the universe with Qi. In humans, this manifests as Anger (Nu); anger causes Qi to ascend, representing the rising aspect of the Seven Emotions (Qi Qing). In nature, it manifests as Wind (Feng); wind agitates Qi and is considered the chief of all diseases. Tonifying Anger would lead to rebellious Qi and the danger of obstruction and severance; tonifying Wind would lead to fullness and the risk of distension and oppression.
The North corresponds to the Winter of Heaven and Earth, where grass yellows and grains fall, presenting a desolate scene. In humans, this manifests as Fear (Kong); fear causes Qi to descend, representing the falling aspect of the Seven Emotions. In nature, it manifests as Cold (Han); cold makes Qi harsh and leads to the decline of all phenomena. Purging Fear would lead to timidity and the risk of fainting or falling; purging Cold would lead to emptiness and the harm of exhaustion.
However, although it is stated that Wood has no deficiency, why speak of tonifying the Liver? This is because Liver Qi should not be violated, but Liver Blood must be nourished. When Blood is insufficient, moistening methods are used, which belong to the Water element. Water is the source of Liver Wood; Wood relies on it to flourish. Although it is stated that Water has no excess, why speak of purging the Kidney? This is because Kidney Yin must not be deficient, while Kidney Qi must not be hyperactive. When Qi is excessive, it is subdued using methods belonging to the Wood element; cutting the trunk of the Wood allows Water to find peace. One tonification and one purging distinguish Qi and Blood; purging and tonifying simultaneously return Water and Wood to their origin. In summary, Ministerial Fire easily ascends; the suffering in the body stems from the imbalance of Qi and Fire. Purging Wood lowers Qi; supplementing Water controls Fire. Qi is Fire, and Fire is Qi; they are the same substance with different names. Therefore, understanding that "excess Qi is Fire" deepens the comprehension of "Yi and Gui sharing the same source."
However, contemporary physicians often adhere rigidly to the doctrine that "the Liver is often in excess," immediately resorting to pacifying the Liver without considering that the *Classic* states: "The East belongs to Wood, the beginning of the generation of all things." The *Shengji Jing* says: "The transformation of the four seasons begins with Wood; the nourishment of the twelve meridians begins with Spring." When a woman conceives, in the first month, the Jueyin Liver Meridian nourishes the fetus. The Liver is the beginning of the activation of Spring Yang and the source of the metabolism and generation of all things. Therefore, guarding against anger to nourish Yang, ensuring the infinite generation of congenital Qi, is crucial for health preservation. Spring belongs to Liver Wood, representing the ascending and generating Qi of our body. If this Qi is insufficient, what will the other four Zang organs rely upon? If Water lacks the generation of Spring, what will sustain the growth of Summer, the harvest of Autumn, and the storage of Winter? Among the Five Elements, only Wood exhibits the image of sprouting, flourishing, and thriving; Water, Fire, Metal, and Earth do not. If Heaven and Earth lacked Wood, the world would be dim and colorless. We cultivate and nourish it, yet fear we do not have enough time; how could we wish to prune or cut it down? Therefore, nourishing Blood and harmonizing the Liver prevents Fire from flaming upward, leading to peaceful Heart Qi and proper regulation of the entire body. Moreover, the Kidney governs closure and storage, while the Liver governs dispersion and drainage; this represents one opening and one closing. Common saying holds that "the Liver can only be purged, not tonified," unaware that formulas such as Liuwei Dihuang Wan (Six-Ingredient Rehmannia Pill) and Qibao Meiran Dan (Seven-Treasure Beard-Beautifying Pill) are indeed herbs for tonifying the Liver. People are simply accustomed to these views without careful examination.