少阴君火。在正六气居卯辰之位。木方用事。火气方舒。而木出于阴。故君火之出为少阴。然君者帝也。出于显明
卯位。所谓帝出乎震者是也。本候为木。主春用事。所以君火不用。其在司天。则当子午。午本南离。故为热化。居气
为灼化。灼与热异。热则临之。灼则近之也。天之六元。火在上。少阴在下。火为本。少阴为标。亦本阳而标阴也。是
以少阴所至。本标之间。心火与气相乘。或至而不足。或至而有余。凡为惊惑恶寒谵妄。又或悲妄衄蔑。皆火不足。而
阴乘之。热收于内也。其为疡疹身热语笑。皆火有余。而自乘于心神。并及血脉也。若在戊癸火运。位戊午戊子。为天
符。为赫曦。则火太过动为炎灼妄扰。其病笑疟疮疡血流狂妄。此亦君火自乘。而伤神魄血脉也。鼓行刑金。则金肺受
邪。是以民病疟、少气喘咳、血溢、血泄、注下、嗌燥、耳聋、中热、肩背热。盖肺气不行。木火交煽。而寒热争。故
疟。壮火食气刑金。故少气喘咳。火逼血妄行。使阴阳两伤。故上嗌口鼻。下泄二阴。火急逼。故奔迫注下。火盛水涸
而伤肾。故嗌燥耳聋。火炎上焦。故肩背热。皆金木足而不能救。以致伤及诸脏也。甚则胸中痛。胁支满。胁痛。膺背
肩胛间痛。两臂内痛。身热骨痛。而为浸淫。皆心经及手心主所行之处。火盛为邪。而遍及本经也。又值二火司天。则
心将自焚而神乱。故谵妄狂乱。以至喘咳息鸣。下甚者金水俱敝。而下元不归也。血溢血泄不已。阴伤尽矣。此太过之
病也。若火不及。则火不能施化。少阴标病郁于经络。故于经所行之处皆病此。寒乃大行。阴邪入而营脉伤也。如郁冒
蒙昧者。寒湿之气冒明也。心主言。故暴喑也。心为太阳。而主诸阳之气。今寒淫病。火则并纳于寒水。之生阳亦虚。
故屈伸不能。髋髀如别也。然至寒淫所胜。则寒临于上。而内阳居中。所谓凡伤于寒。则为病热。寒热更胜。是以痈疡
呕血鼽衄腹痛。乃阳热中盛之症。心痛眩仆。面赤目黄。色 善噫。乃寒凌心火。逼热上炎之故。水火寒热交争。则神
门脉绝。而心气灭矣。所谓郁者。火不外发。必将内盛。病为少气。疮疡壅肿。胁腹胸背。面首四肢。 胪胀 。呕
逆螈 。骨节痛。乃有动皆火。实蕴隆而外不得宣。故每见愤盈之症。伤于经及筋。故所过所动如此也。又若火奔迫则
注下。与少阳搏则温疟。以至腹中暴痛。血溢流注。精液乃少。目赤心热。黄则瞀闷懊 。善暴死。则伤阴之尽。自焚
之患。并伤五内矣。此郁与火不足之异状也。病机曰。诸痛疮疡。皆属于心。诸热瞀闷。诸躁狂越。皆属于火。此即火
有余。火郁之症。诸痛 肿。疼酸惊骇。诸禁鼓栗。如丧神守。此即火不足。寒气内乘之病。要皆以火之有余。或郁与
不足。受乘之至。故皆谓之属火也。刘守真见属火属热诸条。皆以有余释之。岂知病情者哉。
少阴君火，在正六气中位于卯、辰之位。此时木气正在主事，火气刚刚舒展。因为木是从阴中生发出来的，所以君火的出现被称为“少阴”。然而，“君”即帝王之意，出自显赫光明的卯位，这就是所说的“帝出乎震”的道理。本候对应的是木，主管春季的主事，因此君火不单独主事。如果是在司天的位置上，则对应子年和午年。午年原本属于南方的离卦，所以表现为热化。居气（在泉之气）则表现为灼化。“灼”与“热”不同，热是施加于外，灼则是贴近于内。
天之六元中，火在上，少阴在下，火为本，少阴为标，这也是本属阳而标属阴的情况。因此，当少阴之气到来时，在本与标之间，心火与气相互乘袭。或者气至而不足，或者气至而有余。凡是出现惊骇、疑惑、恶寒、胡言乱语、谵妄，或者是悲伤妄动、鼻出血、蔑视他人等症状，都是因为火气不足，而阴气乘虚而入，导致热气被收束在体内。如果是出现疮疡、皮疹、身体发热、言语错乱、喜笑等症状，都是因为火气有余，而自乘于心神，并波及血脉。
如果在戊癸年的火运中，位置在戊午、戊子年，称为“天符”，称为“赫曦”（火势盛大），那么火气太过，动作表现为炎灼、妄扰。其病症包括笑疟、疮疡、血流不止、狂妄等。这也是君火自乘，而损伤神魄和血脉。鼓行刑罚金气，则金肺受到邪气侵袭。因此民众患病有疟疾、少气、气喘咳嗽、血溢、血泄、泄泻、咽喉干燥、耳聋、心中发热、肩背发热。这是因为肺气不行，木火交相煽动，而寒热相争，所以发生疟疾。壮火消耗元气并刑克金气，所以出现少气、气喘、咳嗽。火逼迫血液妄行，使阴阳两伤，所以上见咽喉、口鼻出血，下见二阴泄血。火势急迫，所以奔迫而下发生泄泻。火盛导致水干涸而损伤肾脏，所以出现咽喉干燥、耳聋。火炎上焦，所以出现肩背发热。这些都是因为金木之气充足却无法救助，以致损伤了各个脏腑。严重时会出现胸中痛、胁肋支撑胀满、胁痛、胸部背部肩胛间疼痛、两臂内侧疼痛、身体发热、骨痛，以及发展为浸淫疮。这些都是心经及手厥阴心包经所经过的地方，火盛成为邪气，而遍及本经。
又遇到二火（少阴君火、少阳相火）司天，则心将自焚而神志混乱，所以出现谵妄、狂乱，以至于气喘咳嗽、呼吸有声。下焦严重的，金和水都败坏，而下元不能归藏。血溢、血泄不止，阴气损伤殆尽。这是火气太过的病症。
如果火气不及，则火不能施化，少阴的标病郁结在经络，所以在经络所经过的地方都会发生此类疾病。寒气于是大行，阴邪进入而损伤营脉。如出现郁冒、蒙昧不清的症状，是寒湿之气遮蔽清明的缘故。心主言语，所以突然失音。心为太阳，而主宰诸阳之气。现在寒邪淫溢致病，火则并入寒水之中，生阳之气也虚弱，所以出现屈伸不利、髋部和 thighs 像分离一样的感觉。
然而，到了寒气淫胜的时候，寒气临于上部，而内阳居中。所谓凡是受寒邪伤害，就会变成热病。寒热交替胜负，所以出现痈疡、呕血、鼻衄、腹痛。这是阳热在中部旺盛的症状。心痛、眩晕仆倒、面色红赤、目黄、容易嗳气，这是寒气凌犯心火，逼迫热邪上炎的缘故。水火寒热交争，则神门脉绝，而心气灭矣。
所谓“郁”，是指火不外发，必将内盛。病症表现为少气、疮疡壅肿、胁腹胸背、面首四肢肿胀、呕吐逆气、抽搐、骨节疼痛。这是因为有动皆因火，实蕴隆盛而外不得宣散，所以每见愤懑充盈的症状。伤及经脉及筋脉，所以所经过、所动的地方如此。另外，如果火气奔迫则发生泄泻，与少阳搏结则发生温疟，以至于腹部突然疼痛、血溢流注、精液减少、眼睛红赤、心中发热。如果出现黄疸、昏闷懊恼、容易突然死亡，则是损伤阴气殆尽，自焚之患，并损伤五脏。这是火郁与火气不足的异状。
《病机十九条》说：“诸痛疮疡，皆属于心。”“诸热瞀闷，诸躁狂越，皆属于火。”这就是火有余、火郁的病症。“诸痛肿，疼酸惊骇，诸禁鼓栗，如丧神守”，这就是火不足、寒气内乘的病症。总之，都是因为火的有余，或郁结，或不足，受乘袭而至，所以都称之为属于火。刘完素（守真）见到属于火、属于热的各条，都以有余来解释，哪里懂得病情的变化呢？
Shaoyin Junhuo (Ministerial Fire) occupies the positions of Mao and Chen in the standard Six Qi. At this time, Wood Qi is in command, and Fire Qi is just beginning to expand. Since Wood emerges from Yin, the emergence of Ministerial Fire is referred to as "Shaoyin." However, "Jun" (Minister/Emperor) implies sovereignty, emerging from the bright and prominent position of Mao, which corresponds to the saying "The Emperor comes forth from Zhen (Thunder)." The primary influence here corresponds to Wood, governing the spring season; therefore, Ministerial Fire does not govern independently. If it is in the position of Si Tian (Heavenly Ruler), it corresponds to the Zi and Wu years. The Wu year originally belongs to the Li Trigram in the South, thus manifesting as Heat transformation. The Ju Qi (Earthly Ruler) manifests as Scorching transformation. "Scorching" differs from "Heat"; Heat applies externally, while Scorching is intimate and internal.
Among the Six Primal Energies of Heaven, Fire is above, and Shaoyin is below. Fire is the Root (Ben), and Shaoyin is the Mark (Biao). This also represents a Root that is Yang and a Mark that is Yin. Therefore, when Shaoyin energy arrives, between the Root and the Mark, Heart Fire and Qi mutually invade each other. The arrival may be insufficient or excessive. Symptoms such as fright, confusion, aversion to cold, delirium, and妄语 (wild speech) arise because Fire is insufficient, allowing Yin to invade, causing Heat to be confined internally. Conversely, symptoms such as sores, rashes, fever, incoherent speech, and excessive laughter arise because Fire is excessive, invading the Heart Spirit and affecting the blood vessels.
In the Fire Movement of Wu-Gui years, specifically at Wu-Wu and Wu-Zi positions, known as "Tian Fu" (Heavenly符/Match) and "He Xi" (Blazing Intensity), Fire becomes excessive, leading to inflammatory scorching and chaotic disturbance. Diseases include laughing malaria, sores, hemorrhage, and madness. This is Ministerial Fire self-invading, damaging the Spirit (Shen) and Blood Vessels. It acts like punishment against Metal, causing the Lung-Metal to suffer from pathogenic factors. Consequently, the people suffer from malaria, shortness of breath, asthma, cough, hematemesis, hematochezia, diarrhea, dry throat, deafness, internal heat, and heat in the shoulder and back. This is because Lung Qi fails to circulate, Wood and Fire fan each other, and Cold and Heat contend, resulting in malaria. Vigorous Fire consumes Qi and penalizes Metal, causing shortness of breath, asthma, and cough. Fire forces blood to move recklessly, injuring both Yin and Yang, leading to bleeding from the upper orifices (throat, mouth, nose) and lower orifices. Due to the urgency of Fire, there is urgent diarrhea. Excessive Fire dries up Water and injures the Kidney, causing dry throat and deafness. Fire flares upward to the Upper Jiao, causing shoulder and back heat. These occur because Metal and Wood are sufficient but unable to rescue, leading to injury of all Zang organs. Severe cases involve chest pain, fullness and pain in the hypochondrium, pain between the chest, back, and scapula, pain in the inner arms, fever, bone pain, and spreading sores. These are areas traversed by the Heart Meridian and the Pericardium Meridian of Hand-Jueyin. Excessive Fire becomes pathogenic and spreads throughout these meridians.
Furthermore, if two Fires (Shaoyin Ministerial Fire and Shaoyang Ministerial Fire) govern Si Tian, the Heart will essentially burn itself, leading to mental confusion. Thus, delirium, mania, asthma, cough, and wheezing occur. In severe lower-jiao cases, Metal and Water are both exhausted, and the Lower Yuan fails to return. Continuous hemorrhage indicates complete Yin depletion. This characterizes diseases of Fire excess.
If Fire is deficient, it cannot transform properly. The Biao disease of Shaoyin stagnates in the meridians, causing illness wherever the meridians traverse. Cold then prevails largely, with Yin pathogens entering and injuring the Ying (Nutritive) vessels. Symptoms include depression, dizziness, and mental cloudiness, caused by Cold-Dampness obscuring clarity. Since the Heart governs speech, sudden aphonia occurs. The Heart is Taiyang and governs all Yang Qi. Now, due to Cold invasion, Fire merges into Cold-Water, and Sheng Yang (Generating Yang) becomes deficient, causing inability to flex and extend, and a sensation of separation in the hips and thighs.
However, when Cold dominates, Cold descends upon the upper part while Internal Yang remains central. As stated, "All injuries from Cold transform into Heat diseases." Alternating Cold and Heat lead to sores, vomiting blood, epistaxis, and abdominal pain, which are signs of intense internal Heat. Heart pain, vertigo, fainting, red face, yellow eyes, and frequent belching result from Cold insulting Heart Fire and forcing Heat upward. The struggle between Water, Fire, Cold, and Heat leads to the cessation of Shenmen pulse and the extinction of Heart Qi.
"Duplication" (Yu) refers to Fire failing to emit outward, thus accumulating internally. Diseases include shortness of breath, sores, swelling in the hypochondrium, abdomen, chest, back, face, head, and limbs, vomiting, convulsions, and joint pain. This is because movement is driven by Fire, which is solid and abundant but cannot vent externally, leading to feelings of frustration and fullness. Injury to meridians and sinews causes pathology in affected areas. If Fire rushes urgently, it causes diarrhea. If it contends with Shaoyang, it causes warm malaria. Symptoms include sudden abdominal pain, hemorrhage, decreased essence/fluids, red eyes, and heart heat. Jaundice, mental fog, restlessness, and sudden death indicate complete Yin injury, self-burning hazards, and damage to the Five Zang. These are distinct manifestations of Fire stagnation and Fire deficiency.
The *Jingui Yaolue* (Essential Meaning of the Canon) states: "All painful sores and ulcers belong to the Heart." "All fevers, mental cloudiness, oppression, restlessness, and mania belong to Fire." These are symptoms of Fire excess and Fire stagnation. "All painful swellings, soreness, acid sensations, fright, and terror, all inhibitions, shivering, and feeling as if losing one's spirit," are symptoms of Fire deficiency and internal invasion by Cold. Ultimately, all are attributed to Fire being excessive, stagnant, or deficient, and suffering invasion. Liu Wansu (Zhenzhen) interpreted all clauses belonging to Fire and Heat as excess. How could he understand the nuances of disease?