火于八卦居一。于六气司天独居二。人之脏腑亦二。盖天之帝人之心。皆以照临为德。其居神之物。有火象焉。此
所谓君火也。是故在天之君火。本不以火用。特以明乎帝德。故主十二辰而首出之。在人之君火。亦非以火用。特以建
极广明。故主十二官而临照之。初非以灼燔为令也。经曰。君火以明。明者。明其为照也。天之君火。临于卯。位于午。
而于司火不无热人者。以午在夏。正令自热也。人之君火。正于广明。广明之地膻中也。膻中为神明喜乐之官。清明广
大之地。为生之本。营之居。唯无精以养。则或有神飞而自焚之患。否则。清静宁谧。何 爆之有。而君火之不用。从
可知矣。相火者、在天则生巳午。其官为火。正奉行天职以立暑令。不得同于君火。故谓之相火。相火虽烈。实为万物
盛长之气。若无相火。是在天之六化废其长令也。于人亦然。心胞代君行事。在三焦之中。处两阳合明之地。以应天之
夏令。而主腐熟水谷。经曰。阳明者。午也。盖以阳明当相火夏令。不言心胞。而心胞在其中。今言心胞。而不言胃。
以胃归土也。而相火之义。亦从可识矣。盖人之相火。起少阳胆。游行三焦。督署于心胞。为阳明胃腐熟水谷之功。是
火之能相在少阳耳。先辈丹溪诸公。倡言厥阳五志之火为五火。而无其名。遂以龙雷之阴火为相火。而起其说。承讹至
今。至赵献可又为相火说。喻如鳌山之灯。人物跳掷。皆赖中心之火。而大七节之旁。中为小心。为火之主。而十二官
以听命焉。不知七节之旁。中有小心者。非当肾之命门。乃心俞之出背。不可针灸。故内经提出以戒学人。非谓相火也。
且鳌山之火。本以出风。故必取之于焰。以转其轮。若据此为论。非惟不知相火。并亦不知真火矣。昙氏曰。性火真空。
性空真火。阴符曰。火生于木。祸发必克。盖阳燧真形。即在阴阳奠宅之中。而此火又在君相有形之外。于人则隐胎坎
水。朕兆风木。是谓龙雷。无事则不现。而亦不用。故水濡木柔。虽激之而不起。唯水涸木枯。气逆血沸。则势遂焚巢
燎原而不可止。此火若起。是犹反君灭相。岂君相治平之火哉。缘此火不起于子半。不循行于少阳胆。猝犯之而猝起。
正所谓火生于木。祸发必克者也。相火云乎哉。
火在八卦中位居第一。在六气司天之中唯独位居第二。人体的脏腑也有两个（指心与命门/肾等，此处特指君相二火对应的脏腑功能核心）。大概上天之帝与人之心，都以光照普照为德行。其居于神明的物体，具有火的形象。这就是所说的“君火”。因此，在天之君火，本来不是以燃烧发热为用，只是用来彰显帝王之德。所以它主宰十二辰而首先出现。在人身的君火，也不是以燃烧发热为用，只是用来建立极致的广大光明。所以它主宰十二官（五脏六腑）而临照它们。起初并不是以灼烧焚烧为令。《内经》说：“君火以明。”明，意思是明白它是为了照明。天之君火，降临于卯位，位于午位。而在主管火气时并非没有让人热的感觉，是因为午时正值夏季，当令之气自然炎热。人身的君火，正位于广明之地，即膻中。膻中是神明喜乐之官，是清明广大的地方，是生命的根本，营气所居之处。只有如果没有精气来滋养，才可能有神志飞越而自焚的祸患。否则，清静安宁，哪里有爆炸之理？而君火不用的道理，由此就可以知道了。
相火，在天则生于巳、午之时，其职能属火，正是奉行天的职责以确立暑令。不能等同于君火，所以称为相火。相火虽然猛烈，实则是万物盛大生长的气机。如果没有相火，那么在天的六化就废除了生长的时令。对人来说也是如此。心包代君主行事，在三焦之中，处于两阳合明之地，以对应天上的夏令，而主管腐熟水谷。《内经》说：“阳明者，午也。”大概是因为阳明经当值如同相火的夏令，这里虽未直言心包，但心包包含在其中。现在只说心包，而不说胃，是因为胃归属于土。而相火的含义，也可以从此认识了。大概人身的相火，起于少阳胆，游行于三焦，统辖于心包，以完成阳明胃腐熟水谷的功能。这火的能够作为“相”的作用，关键在于少阳罢了。前辈丹溪诸公，倡导说厥阳和五志之火为五火，但没有给它们命名，于是将龙雷之阴火称为相火，从而兴起这种说法。沿袭错误至今，到了赵献可又提出相火说，比喻像鳌山上的灯，人物跳跃掷物，都依赖中心之火，而大七节之旁，中间的小心，是火的主宰，而十二官都听从它的命令。不知道“七节之旁，中有小心”，并不是指肾脏旁的命门，而是指心俞穴出于背部，不可针灸的地方。所以《内经》提出这一点是为了告诫学者，并不是指相火。况且鳌山之火，本来是从风中生出，所以必须从火焰中取象，来转动其轮盘。如果据此来论述，不仅不知道相火，甚至连真火也不知道。昙氏说：“性火真空，性空真火。”《阴符经》说：“火生于木，祸发必克。”盖阳燧的真形，就在阴阳奠宅之中，而这火又在君相有形之外。于人而言，则隐于胎坎之水，朕兆于风木，这叫做龙雷。无事的时候不显现，也不使用。所以水湿润、木头柔和，即使激怒它也不会起来。只有当水枯竭、木头干枯，气逆血沸时，火势才会像焚烧巢穴、燎原一样不可停止。这种火一旦起来，就像是反叛君主、消灭宰相，哪里还是君相治平之火呢？因为这火不起于子半（半夜），不循行于少阳胆，猝然侵犯它就猝然发作，正所谓“火生于木，祸发必克”啊。这能叫相火吗？
Fire occupies the first position in the Eight Trigrams (Bagua). In the Six Qi (Liuqi) governing Heaven, it uniquely occupies the second position. The human viscera and bowels also have two [core aspects related to fire]. Essentially, the Emperor of Heaven and the Human Heart both possess the virtue of illuminating and overseeing. The entity residing in the Spirit (Shen) bears the image of Fire. This is what is called the Ministerial Fire (Junhuo, Sovereign Fire). Therefore, the Sovereign Fire in Heaven does not originally function by burning or heating; rather, it serves to manifest the virtue of the Emperor. Thus, it governs the Twelve Earthly Branches (Shi'er Chen) and emerges first. The Sovereign Fire in the human body also does not function by burning or heating; rather, it establishes extreme vastness and brightness. Thus, it oversees the Twelve Officials (Shi'er Guan, referring to the Zang-Fu organs) with its illumination. Initially, it does not issue commands through scorching or burning. The Classic states: "Sovereign Fire manifests clarity." Clarity means understanding its role as illumination. The Sovereign Fire in Heaven descends to the Mao position and is located at the Wu position. Although there is no sensation of heat when it governs Fire, this is because the Wu position corresponds to Summer, where the commanding Qi naturally brings heat. The Sovereign Fire in the human body resides precisely in the place of Broad Brightness (Guangming), which is the Danzhong (Chest Center/Shanzhong). Danzhong is the Official of Spirit, Clarity, and Joy, a place of clarity and vastness, serving as the root of life and the dwelling of Ying (Nutritive) Qi. Only if there is no Essence (Jing) to nourish it might there be the danger of the Spirit flying away and self-immolation. Otherwise, being clear, quiet, and serene, how could there be explosion? The reason why Sovereign Fire does not actively burn can thus be understood.
Ministerial Fire (Xianghuo), in Heaven, arises during the Si and Wu hours. Its function belongs to Fire, strictly executing Heaven's duties to establish the Summer command. It cannot be equated with Sovereign Fire, hence it is called Ministerial Fire. Although fierce, Ministerial Fire is actually the Qi of vigorous growth for all things. Without Ministerial Fire, the Six Transformations (Liu Hua) in Heaven would fail to execute their growing command. The same applies to humans. the Pericardium (Xinbao) acts on behalf of the Sovereign. Located within the Sanjiao (Triple Burner), it resides in the place where the two Yangs combine and brighten, corresponding to the Summer command in Heaven, and governs the rotting and ripening of food and water. The Classic states: "Yangming corresponds to Wu." This is likely because the Yangming channel takes precedence during the Ministerial Fire's Summer command; although the Pericardium is not explicitly named here, it is included within this context. Now, speaking of the Pericardium without mentioning the Stomach is because the Stomach is attributed to Earth. From this, the meaning of Ministerial Fire can also be recognized. Generally, the human Ministerial Fire originates from the Shaoyang Gallbladder, circulates through the Sanjiao, and directs the Pericardium, facilitating the Stomach's Yangming function of rotting and ripening food. The ability of this Fire to act as a "Minister" lies essentially in the Shaoyang. Predecessors such as Danxi advocated that Jue-Yang and the Five Desires constitute five types of Fire but gave them no specific names. Consequently, they labeled the Yin Fire of Dragon and Thunder as Ministerial Fire, thereby initiating this theory. Errors have been passed down to the present. Zhao Xianke later proposed another theory of Ministerial Fire, comparing it to lamps on an Ao Mountain (a type of lantern structure); just as figures jumping and throwing rely on the central fire, he claimed that beside the seventh vertebra, the "Small Heart" in the middle is the master of Fire, and the Twelve Officials obey its commands. However, they did not know that "beside the seventh vertebra, there is the Small Heart" refers not to the Mingmen (Gate of Life) beside the Kidney, but to the Xinshu (Heart Shu) acupoint emerging from the back, which should not be needled or cauterized. Thus, the Neijing raises this point to warn students; it does not refer to Ministerial Fire. Moreover, the fire on Ao Mountain originally arises from wind, so one must take imagery from the flame to turn its wheel. If arguments are based on this, one knows neither Ministerial Fire nor True Fire. Tan Shi said: "Nature's Fire is True Emptiness; Nature's Emptiness is True Fire." The Yin Fu Jing states: "Fire arises from Wood; when disaster strikes, it overcomes." The true form of the Yang Sui (fire lens) lies within the foundation of Yin and Yang, yet this Fire exists beyond the tangible forms of Sovereign and Ministerial Fire. In humans, it hides in the Kan Water of the fetus and manifests in Wind-Wood. This is called Dragon and Thunder. When inactive, it does not appear and is not used. Thus, when Water moistens and Wood softens, even if provoked, it does not rise. Only when Water dries up and Wood withers, causing Qi rebellion and Blood boiling, does the momentum become uncontrollable like burning nests and raging prairie fires. If this Fire arises, it is akin to rebelling against the Sovereign and destroying the Minister; how can it be considered the harmonizing Fire of Sovereign and Minister rule? Since this Fire does not arise at Zi Ban (midnight), does not circulate through the Shaoyang Gallbladder, and erupts suddenly upon sudden invasion, it truly exemplifies "Fire arises from Wood; when disaster strikes, it overcomes." Can this be called Ministerial Fire?