火有人火。有相火。人火者。所谓燎原之火也。遇草而 。得木而燔。可以湿伏。可以水灭。可以直折。
黄连之属可以制之。相火者。龙火也。雷火也。得湿则 。遇水则燔。不知其性而
以水折之。以湿攻之。适足以光焰烛天。物穷方止矣。识其性者。以火逐之。则焰灼自消。炎光扑灭。古书
泻火之法。意盖如此。今人率以黄柏治相火。殊不知此相火者。寄于肝肾之间。此乃水中之火。龙雷之火也。
若用黄柏苦寒之药。又是水灭湿伏。龙雷之火愈发矣。龙雷之火。每当浓阴骤雨之时。火焰愈炽。或
烧毁房屋。或击碎木石。其势诚不可抗。惟太阳一照。火自消灭。此得水则炽。得火则灭之一验也。
又问龙雷何以五六月而启发。九十月而归藏。盖冬时阳气在水土之下。龙雷就其火气而居于下。夏时阴气
在下。龙雷不能安其身而出于上。明于此义。故惟八味丸桂附与相火同气。直入肾中。据其窟宅而招之。同气相
求。相火安得不引之而归原。即人非此火不能有生。世人皆曰降火。而予独以地黄滋养水中之火。世人皆曰灭
火。而予独以桂附温补天真之火。千载不明之论。予独表而出之。高明以为何如。
震本坤体。阳自外来交之。有动乎情欲之象。是以圣人于。卦中。凡涉乎震体者。取义尤严。 雷震。君子
以恐惧修省。在复则曰先王以至日闭关。欲其复之静也。在随则曰向晦入晏。
意欲其居之安也。在颐则曰慎言语。节饮食。欲其养之正也。明乎此义。而相火不药自伏矣。
火分为人火和相火。人火，就是所说的燎原大火。它遇到草就会蔓延，遇到木头就会燃烧，可以用湿气压制，可以用水扑灭，可以直接用苦寒药折服。黄连这类药物就可以制约它。相火，就是龙火，也是雷火。它遇到湿气反而更旺，遇到水反而燃烧得更烈。如果不了解它的本性，而用水去灭它，用湿去攻它，恰恰会让火势光焰冲天，直到物体烧尽才会停止。懂得它本性的人，用火去驱逐它，那么火焰灼热自然消退，炎光也就扑灭了。古书中记载的泻火方法，意思大概就是这样。现在的人普遍用黄柏来治疗相火，却不知道这相火寄居在肝肾之间，这是水中的火，是龙雷之火。如果使用黄柏这种苦寒的药物，又是用水灭、用湿伏的方法，龙雷之火反而会更加旺盛。龙雷之火，每当浓云密布骤雨来临的时候，火焰会更加炽盛，有时烧毁房屋，有时击碎木石，其气势确实不可抵挡。只有太阳一出来，火自然就消灭了。这就是得水则炽、得火则灭的一个验证。
又有人问：龙雷之火为什么在五六月激发，而在九十月归藏？大概是因为冬天时阳气在水土之下，龙雷依附于火气而居于下方；夏天时阴气在下，龙雷不能安身而出现在上方。明白了这个道理，所以只有八味丸中的肉桂、附子与相火同气，能直接入肾中，占据其巢穴来招引它。同气相求，相火怎么能不被引导回归本源呢？即人如果没有这火就不能生存。世人都说降火，而我唯独主张用地黄滋养水中的火；世人都说灭火，而我唯独主张用肉桂、附子温补天真的火。这是千年来没有阐明的理论，我独自将其揭示出来。高明之士认为如何？
震卦的本体是坤体，阳气从外进入交合其中，有动于情欲的象征。因此圣人在《易经》中，凡是涉及震卦体的，取义尤为严格。如“震”卦中说：“君子以恐惧修省。”在“复”卦中说：“先王以至日闭关”，是想让它恢复宁静。在“随”卦中说：“向晦入晏”，是想让它安居。在“颐”卦中说：“慎言语，节饮食”，是想让它修养端正。明白了这个道理，那么相火不用药也能自然潜藏了。
Fire is divided into human fire (Ren Huo) and ministerial fire (Xiang Huo). Human fire refers to the so-called prairie fire. It spreads when encountering grass and burns when encountering wood; it can be subdued by dampness, extinguished by water, or directly suppressed by bitter-cold herbs. Herbs such as Coptidis Rhizoma (Huanglian) can control it. Ministerial fire is dragon fire and thunder fire. It becomes more vigorous when encountering dampness and burns fiercer when encountering water. If one does not understand its nature and attempts to extinguish it with water or attack it with dampness, it will only cause flames to reach the sky until the fuel is exhausted. Those who understand its nature drive it away with fire, causing the scorching heat to dissipate naturally and the blazing light to be extinguished. The methods of purging fire recorded in ancient texts are likely based on this principle. Nowadays, people generally use Phellodendri Cortex (Huangbai) to treat ministerial fire, unaware that this ministerial fire resides between the Liver and Kidney. It is fire within water, namely dragon and thunder fire. If one uses bitter-cold herbs like Phellodendri Cortex, employing the method of extinguishing with water and subduing with dampness, the dragon and thunder fire will become even more vigorous. Dragon and thunder fire, during times of dense clouds and sudden rain, becomes extremely intense, sometimes burning houses or shattering wood and stone; its momentum is indeed irresistible. Only when the sun shines does the fire vanish. This is a verification of "becoming vigorous with water and vanishing with fire."
It is further asked: Why does dragon and thunder fire emerge in the fifth and sixth lunar months and hide in the ninth and tenth? Generally, in winter, Yang Qi is below the water and earth, and dragon and thunder reside below, attaching to the fire energy. In summer, Yin Qi is below, and dragon and thunder cannot settle there, thus emerging above. Understanding this principle, only the eight-ingredient pill (Ba Wei Wan) containing Cinnamomi Ramulus (Guizhi) and Aconiti Lateralis Radix Praeparata (Fuzi), which share the same qi as ministerial fire, can enter the Kidney directly, occupy its lair, and attract it. Like attracts like; how could ministerial fire not be guided back to its origin? Indeed, without this fire, humans cannot have life. While the world speaks of lowering fire, I alone advocate nourishing the fire within water using Rehmanniae Radix (Dihuang); while the world speaks of extinguishing fire, I alone advocate warming and tonifying the innate fire using Cinnamomi Ramulus and Prepared Aconite Root. This is a theory unclear for a millennium, which I alone bring to light. What do the wise think?
The Zhen trigram has the structure of Kun, with Yang Qi entering from outside to interact, symbolizing movement arising from desires. Therefore, the Sages took strict meanings from any hexagram involving the Zhen trigram. In the Zhen hexagram, it says: "The superior person, in fear, cultivates self-reflection." In the Fu hexagram, it says: "The former kings closed the passes at the winter solstice," intending to restore stillness. In the Sui hexagram, it says: "Entering peace at dusk," intending to ensure safe dwelling. In the Yi hexagram, it says: "Be cautious in speech and moderate in diet," intending to cultivate righteousness. Understanding this meaning, ministerial fire will naturally subside without medication.