治肾水不足，虚火上炎，发热作渴，口舌生疮，牙龈溃烂，咽喉作痛，或形体憔
粹，寝汗发热。即六味丸加肉桂一两，临用去皮，忌火勿出气。
肾水不足，虚阳僭上，必用此方，以引火归原。夫五志之火，可以湿伏，可以直
折，龙雷之火，惟当从其性而伏之，肉桂性热，与火同性杂在下焦，壮水药中能引无根
虚火，降而归经，且肉桂之质，在中半以下，其性专走肾经，本乎地者亲下之义。况
相火寄于甲乙之间，肝胆水旺则巽风动而烈火焰明，古人谓北方不可泻，泻肝即所以泻
肾。《本草》曰∶木得桂而枯，取其义也。《经》曰∶热因热用，此之谓也。或者畏其
热而遗之，岂达造化降之微乎？黄柏、知母治相火，仅可施于壮实。若虚火而误用之，
则肾因泻而愈虚，愈虚而火愈炽矣。
治命门火衰，不能生土，以致脾胃虚
寒，饮食少思，大便不实，脐腹疼痛，夜多漩溺，或阴盛格阳，内真寒而外假热等证。
（张）按∶脾胃虚寒之至者，丹泽甚非所宜，减此二味，加牛膝、杜仲、鹿茸、五味子更
佳，即七味丸加熟附子一两，切片，微火焙。
肾有两枚，皆属于水，虽有左右之分，初无水火之别，考之《内经》，昭然可览。
《仙经》曰∶两个一般无二样，中间一点是真精；又曰∶两肾中间一点明。夫真精者，
明也。即命门相火也。命门乃穴名，而其穴在两肾中间，盖一阳生于二阴之间，所以成
乎坎，而象天之北也。《经》曰∶少火生气，人无此火生化之源几乎息矣。非附子雄健不
足以嘘既槁之阳春。王太仆曰∶益火之源，以消阴翳，此方是也。按∶六味地黄丸专补
左尺肾水，八味丸既补左尺肾水，兼补右肾相火。少年水亏火旺，宜服六味丸；老年水
火俱亏，宜服八味丸。况老年肾脏真水既虚，邪水乘之而为湿热，以作腰痛足痿，痰
唾消渴，小便不禁，淋闭等证，非桂附之温散而能治之乎？昧者畏其热，殊不知所补之
火乃真阳之元也。真阳之元一得，阴翳之火潜消矣。
治疗肾阴不足，虚火上炎，导致发热口渴，口腔和舌头生疮，牙龈溃烂，咽喉疼痛，或者身体消瘦憔悴，夜间盗汗并伴有发热。这就是在六味地黄丸的基础上加入一两肉桂，使用时需去除肉桂的粗皮，忌用猛火煎煮以免挥发掉药效。
肾阴不足，虚阳上浮僭越，必须使用此方，以引导浮火回归本源。五脏的情志之火，可以用湿法潜伏抑制，也可以直接折服；但龙雷之火（指下焦相火），只能顺应其本性来潜伏它。肉桂性热，与火同性，混杂在下焦，能在壮水（滋阴）的药物中引导无根的虚火下降并回归经脉。而且肉桂的药物质地作用部位在中下部，其药性专门走肾经，符合“本乎地者亲下”的道理。况且相火寄居于肝胆之间，如果肝胆之水旺盛，则巽风（肝风）发动而烈火燃烧更旺，古人说北方（肾）不可泻，泻肝实际上就是间接泻肾。《本草》说：“木材遇到肉桂就会枯萎”，取的就是这个意思。《内经》说：“用热药治疗热证（热因热用）”，说的就是这个道理。有人畏惧它的热性而不敢使用，这哪里能通达造化降伏邪火的微妙之处呢？黄柏、知母治疗相火，仅适用于体质强壮的人。如果是虚火却误用这些寒凉药，那么肾脏会因为被清泻而更加虚弱，越虚弱火势就越炽盛。
治疗命门火衰，不能温煦脾土，导致脾胃虚寒，食欲减退，大便不成形，脐腹部疼痛，夜间小便多，或者是阴寒内盛格拒阳气于外，出现内里真寒而外表假热的等症状。（张氏按语：对于脾胃虚寒极其严重的情况，熟地黄和山茱萸并不适宜，应减去这两味药，加入牛膝、杜仲、鹿茸、五味子效果更好。这就是七味丸加上一两熟附子，切片后，用微火焙干。）
肾脏有两个，都归属于水，虽然有左右之分，起初并没有水火的区别。考证《内经》，可以清楚地看到这一点。《仙经》说：“两个肾脏一般无二样，中间一点是真精”；又说：“两肾中间有一点光明”。所谓真精，就是光明。也就是命门的相火。命门是一个穴位名称，位于两肾中间，大概是一阳生于二阴之间，所以构成了坎卦，象征天的北方。《内经》说：“少火（正常的生理之火）产生元气，人如果没有这种火，生化之源就几乎停止了。”如果不是附子这样雄健有力的药物，不足以吹嘘起已经枯槁的阳春生机。王冰（王太仆）说：“补益火的源头，以消除阴寒的遮蔽”，这个方子正是如此。按语：六味地黄丸专门滋补左尺脉所主的肾水；八味地黄丸既滋补左尺肾水，又兼补右肾的相火。少年时期肾水亏虚而相火旺盛，适合服用六味地黄丸；老年时期水火俱亏，适合服用八味地黄丸。况且老年人肾脏的真水既然已经虚弱，邪水（病理之水）趁机侵犯而形成湿热，导致腰痛、足部痿软、痰多唾液粘稠、消渴、小便失禁、淋证闭塞等症状，如果不是桂枝和附子的温散作用，怎么能治愈呢？愚昧的人畏惧它的热性，殊不知所补充的火乃是真阳的根本。一旦获得了真阳的根本，阴寒遮蔽之火自然潜藏消退了。
Treats insufficiency of Kidney Water (Yin), with deficient fire flaming upward, causing fever and thirst, sores on the mouth and tongue, ulceration of the gums, pain in the throat, or emaciation and night sweats accompanied by fever. This is Liuwei Dihuang Wan (Six-Ingredient Rehmannia Pill) plus one liang of Rougui (Cortex Cinnamomi). When used, remove the bark; avoid strong fire to prevent volatilization of its qi.
Insufficiency of Kidney Water leads to deficient Yang usurping the upper position; this formula must be used to guide the fire back to its source. The fire of the Five Emotions can be subdued by dampness or directly suppressed; however, the Dragon and Thunder Fire (Ministerial Fire of the Lower Jiao) should only be subdued by following its nature. Rougui is hot in nature, sharing the same nature as fire; mixed in the Lower Jiao, it can guide rootless deficient fire downward and return it to its meridians within formulas that nourish Water (Yin). Moreover, the quality of Rougui acts in the middle and lower parts; its nature specifically enters the Kidney Meridian, adhering to the principle that "what is grounded by Earth tends toward the lower." Furthermore, Ministerial Fire resides between the Liver and Gallbladder (Wood elements); if Liver-Gallbladder Water is abundant, Xun Wind (Liver Wind) moves, and the fierce flame burns brightly. Ancients stated that the North (Kidney) should not be purged; purging the Liver is essentially purging the Kidney. *Bencao* states: "Wood withers when encountering Cinnamon," taking this meaning. *Jing* states: "Use heat to treat heat" (treating heat patterns with hot herbs), which refers to this. Some fear its heat and omit it; how can they understand the subtlety of Creation's method of subduing? Huangbai (Phellodendri Cortex) and Zhimu (Anemarrhenae Rhizoma) treat Ministerial Fire but are only applicable to robust constitutions. If mistaken for deficient fire, they will cause the Kidney to become more deficient through purging; the more deficient it becomes, the fiercer the fire burns.
Treats decline of Mingmen Fire (Gate of Life Fire), unable to generate Earth, resulting in Spleen-Stomach deficiency-cold, lack of appetite, loose stools, pain in the umbilical and abdominal regions, frequent urination at night, or conditions such as Yin excess repelling Yang outward, presenting with true cold inside and false heat outside. (Commentary by Zhang: For extreme cases of Spleen-Stomach deficiency-cold, Shudihuang (Prepared Rehmanniae Radix) and Shanzhuyu (Corni Fructus) are not suitable. Reduce these two ingredients, add Niuxi (Achyranthis Bidentatae Radix), Duzhong (Eucommiae Cortex), Lurong (Cornu Cervi Pantotrichum), and Wuweizi (Schisandrae Fructus) for better effect. This is Qiwei Wan (Seven-Ingredient Pill) plus one liang of Shufuzi (Prepared Aconiti Lateralis Radix), sliced and lightly roasted over mild fire.)
The Kidneys are two in number, both belonging to Water. Although there is a distinction between left and right, originally there is no difference between Water and Fire. Examining *Neijing*, this is clear. *Xianjing* says: "The two kidneys are identical; the single point in the center is True Essence"; again: "There is a brightness in the center of the two kidneys." This True Essence is brightness, which is the Ministerial Fire of the Mingmen. Mingmen is an acupoint name, located between the two kidneys, representing one Yang born between two Yins, thus forming the Kan trigram, symbolizing the North of Heaven. *Jing* states: "Minor Fire generates Qi; without this fire, the source of transformation and generation would almost cease." Only the vigorous nature of Fuzi (Aconiti Lateralis Radix Praeparata) is sufficient to blow upon the dried-up spring warmth. Wang Taipu (Wang Bing) said: "Benefit the source of Fire to eliminate Yin shadows," and this formula is exactly that. Commentary: Liuwei Dihuang Wan specifically tonifies the Kidney Water of the Left Chi pulse; Bawei Dihuang Wan (Eight-Ingredient Rehmannia Pill) tonifies both the Left Chi Kidney Water and the Ministerial Fire of the Right Kidney. In youth, with Water deficiency and Fire hyperactivity, Liuwei Dihuang Wan is appropriate; in old age, with both Water and Fire deficiency, Bawei Dihuang Wan is appropriate. Furthermore, since the True Water of the Kidneys in the elderly is already deficient, pathogenic Water takes advantage to create Damp-Heat, leading to symptoms like lower back pain, flaccidity of the legs, profuse phlegm/saliva, Xiao Ke (Wasting-Thirst), urinary incontinence, strangury, and obstruction. Can these be treated without the warming and dispersing action of Guizhi (Cinnamomi Ramulus) and Fuzi? Ignorant people fear its heat, not realizing that the Fire being supplemented is the origin of True Yang. Once the origin of True Yang is obtained, the Fire of Yin shadows naturally subsides.