以火言之，有阳火，有阴火。有水火之火，有土中之火，有金中之火，有木中之
火。阳火者，天上日月之火，生于寅，而死于酉∶阴火者，灯烛之火，生于酉而死于
寅，此对待之火也。水中火者，霹雳火也，即龙雷之火，无形而有声，得雨而益炽，见
于季春，而伏于季秋，以五月一阴生，水底冷而天上热，龙为阳物，故随阳而上升，至
冬一阳来复，故龙亦随阳下伏，雷亦收声，人身肾中相火，亦犹是也。平日不能节欲，
以致命门火衰，肾中阴盛，龙火无藏身之位，故游上而不归，是以上焦烦热、咳嗽等
症。善治者，以温肾之药，从其性而引之归原，使之秋冬阳伏之令，而龙归大海，此至
理也。奈何今之治阴虚火衰者，以黄柏、知母为君，而逾寒其肾，益速其毙，良可悲
哉！若有阴虚火旺者，此肾水干枯，而火偏盛，宜补水以配火，亦不宜苦寒之品以灭
火，故云壮水之主，以镇阳光，正谓此也。如灯烛火，亦阴火也，须以膏油养之，不得
杂一滴寒水，得水即灭矣。独有天上火入于人身，如河间所论六气暑热之病，及伤暑中
暑之疾，可以凉木沃之，可以苦寒解之。其余炉中火者，乃灰土中无温之火，得木则
烟，见湿则灭，须以炭培，实以温烬，如人身脾土中之火，宜以甘温养其火，而火自
退。《经》曰∶劳者温之，损者温之，甘能除大热，温能除大热者此也。
空中之火附于木中，以当有坎水滋养，故火不外见，惟干柴生火，燎原不可止遏，
力穷方止。人身肝火内炽，郁闷烦躁，须以辛凉之品发达之。《经》曰∶木郁则达之，
火郁则发之。使之得遂其炎上之性。若以寒药下之，则愈郁矣；热药投之，则愈炽矣。
金中火者，凡山中有金银之矿，或五金埋瘗之处，夜必有火光，此金郁土中而不得
越，故有光辉发见于外。人身皮毛空窍中，自觉针刺蚊咬，及巅顶如火炎者，此肺金气
虚也，补北方之水，即所以泻南方之火。
以水言之，有阳水，有阴水，有火中之水，有土中之水，有金中之水，有木中之
水。阳水者，坎水也，气也。《阴阳消息论》曰∶坎，以一阳陷于二阴，水气潜行地中，
为万物受命根本。盖润液也，气之液也，月令于仲秋云，煞气浸盛，阳气日衰，水始涸
是水之涸，地之死也。于仲冬云∶水泉动是月一阳生。是水之动，地之生也，谓之火中
之水可也，谓之土中之水亦可也。阴水者，兑，泽也，形也。一阴上彻于二阳之上，以
有形之水普施万物，下降为资生之利泽，在上即可谓雨露之水，在下即为木溪之水。人
之饮食入胃，命门之火，蒸腐水谷，水谷之气，上熏于肺，肺通百脉，水精四布，五经
并行，上达皮毛，为汗为涕，为津为唾，下濡膀胱，为便为液。至于血，亦水也，以其
随相火而行，故其色独红，周而复始，滚滚不竭，在上即可为天河水，在下即为长流
水，始于西北天门，终于东南地户，正所谓“黄河之水天上来，奔流到海不复回”。故黄
河水，皆同色也。
金中之水，矿中之水银是也。在人身为骨中之髓，至精至贵，人之宝也。木中水
者，巽木入于坎水，而上出其水，即木之胀膏，人身足下有涌泉穴，肩上有肩井穴，此
暗水潜行之道。凡津液润布于皮肤之内者，皆井泉水也。夫水有如许之不同，总之归于
大海。天地之水。以海为宗；人身之水，以肾为源。而其所以昼夜不息者，以其有一元
之干气为太极耳。此水中之五行也，明此水火之五行，此土木金可例推矣。《经》曰∶
纪于水火，余气可知。
从火的角度来说，有阳火，有阴火。有水中之火，有土中之火，有金中之火，有木中之火。所谓阳火，是指天上日月的火光，它生于寅时（凌晨3-5点），死于酉时（下午5-7点）；所谓阴火，是指灯烛之火，它生于酉时，死于寅时，这是相对立的两种火。水中之火，就是霹雳火，也就是龙雷之火，它无形但有声，遇到雨水反而更加猛烈，出现在春季末尾，潜伏在秋季末尾。因为五月一阴初生，水底寒冷而天上炎热，龙是阳物，所以随着阳气上升；到了冬天一阳来复，龙也随着阳气下沉潜伏，雷也收敛声音。人身肾中的相火（命门之火），也是同样的道理。如果平日不能节制欲望，导致命门火衰，肾中阴气过盛，龙火就没有藏身之处，所以游散于上而不能回归，从而出现上焦烦热、咳嗽等症状。善于治疗的人，用温补肾阳的药物，顺从其本性引导它回归本源，使其像秋冬季节阳气潜藏一样，让龙回归大海，这才是至理。可惜现在治疗阴虚火衰的人，把黄柏、知母作为主药，使肾脏更加寒冷，加速死亡，实在可悲啊！如果有阴虚火旺的情况，这是肾水干枯，而火偏盛，应该补水以配合火，也不宜用苦寒的药物来灭火，所以说“壮水之主，以镇阳光”，正是这个意思。至于灯烛之火，也是阴火，需要用膏油来滋养它，不能混杂一滴寒水，遇到水就会熄灭。只有天上的火进入人体，比如刘河间所论述的六气中暑热病，以及伤暑、中暑的疾病，可以用清凉的方法治理，也可以用苦寒的药物解除。其余如炉中之火，是灰土中无温度的火，遇到木头就冒烟，见到湿气就熄灭，需要用炭来培补，充实以温暖灰烬，就像人身脾土中的火，应该用甘温的药物来养火，火自然消退。《内经》说：“劳者温之，损者温之”，甘味能除大热，温性能除大热，说的就是这个道理。
空中的火依附于木中，因为有坎水滋养，所以火不外现，只有干柴生火，燎原之势不可遏制，力量耗尽才停止。人身肝火内炽，郁闷烦躁，需要用辛凉的药物发散它。《内经》说：“木郁则达之，火郁则发之”，使其得以顺应其炎上的本性。如果用寒药攻下，则会更加郁结；投用热药，则会更加炽盛。
金中之火，凡是山中有金银矿藏，或五金埋藏的地方，夜晚必定有火光，这是金郁结在土中而不能超越，所以有光辉显露在外。人身皮毛孔窍中，自觉像针刺蚊咬，以及头顶如火烧灼的感觉，这是肺金气虚的表现，补益北方之水，就是泻除南方之火的方法。
从水的角度来说，有阳水，有阴水，有火中之水，有土中之水，有金中之水，有木中之水。所谓阳水，就是坎水，属于气。《阴阳消息论》说：坎卦，是一阳陷于二阴之中，水气潜行在地中，是万物受命的根本。它是润泽的液体，是气的液体。《月令》在仲秋时说：肃杀之气浸盛，阳气日渐衰弱，水开始枯竭，这是水的枯竭，地的死亡。在仲冬时说：泉水涌动，这个月一阳初生，这是水的涌动，地的生机，这可以称为火中之水，也可以称为土中之水。所谓阴水，就是兑卦，代表泽，属于形。一阴上彻于二阳之上，以有形的水普遍施予万物，下降为资生的利益和恩泽，在上面就可以称为雨露之水，在下面就是溪涧之水。人的饮食进入胃中，命门之火蒸腐水谷，水谷的精气，向上熏蒸于肺，肺通调百脉，水精四布，五脏经脉并行，上达皮毛，化为汗、涕，化为津、唾，下濡膀胱，化为便、液。至于血，也是水，因为它随着相火而行，所以它的颜色特别红，周而复始，滚滚不竭，在上面就可以称为天河水，在下面就是长流水，始于西北天门，终于东南地户，正所谓“黄河之水天上来，奔流到海不复回”。所以黄河水，颜色都是一样的。
金中之水，就是矿中的水银。在人身中是骨中的髓，是最精最贵的，是人的宝贝。木中之水，是巽木进入坎水，而上出其水，即树木的汁液，人身足下有涌泉穴，肩上有肩井穴，这是暗水潜行的通道。凡是津液滋润分布在皮肤之内的，都是井泉水。水有如此多的不同，总之归于大海。天地之水，以海为宗主；人身之水，以肾为源头。而其所以昼夜不息的原因，是因为有一元之乾气作为太极罢了。这就是水中之五行，明白了水火之五行，土木金就可以类推了。《内经》说：“纪于水火，余气可知。”
Speaking of Fire, there is Yang Fire and Yin Fire. There is Fire in Water, Fire in Earth, Fire in Metal, and Fire in Wood. Yang Fire refers to the fire of the sun and moon in the sky; it arises at Yin hour (03:00-05:00) and perishes at You hour (17:00-19:00). Yin Fire refers to the fire of lamps and candles; it arises at You hour and perishes at Yin hour. These are opposing forms of fire. The Fire in Water is thunderbolt fire, also known as Dragon-Thunder Fire. It is formless but audible, becomes more intense with rain, appears at the end of spring, and hides at the end of autumn. Because one Yin arises in the fifth month, the water bottom is cold while the sky is hot. Since the dragon is a Yang entity, it rises with Yang. When one Yang returns in winter, the dragon also descends and hides with Yang, and thunder ceases its sound. The Ministerial Fire (Mingmen Fire) in the human kidney operates similarly. If one fails to restrain desires daily, leading to Mingmen Fire decline and excessive Yin in the kidney, the Dragon Fire has no place to reside. Thus, it wanders upward without returning, causing symptoms such as upper Jiao irritability and heat, and coughing. A skilled practitioner uses herbs that warm the kidney to guide this fire back to its origin according to its nature, allowing it to follow the command of Yang hiding in autumn and winter, so the dragon returns to the sea. This is the supreme principle. Alas, nowadays, those treating Yin deficiency with Fire decline use Huangbai (Phellodendri Cortex) and Zhimu (Anemarrhenae Rhizoma) as principal agents, making the kidney colder and hastening death, which is truly pitiable! In cases of Yin deficiency with Fire hyperactivity, where Kidney Water is dry and Fire is predominant, one should nourish Water to harmonize with Fire. One should not use bitter-cold substances to extinguish Fire. Hence, "Strengthen the master of Water to suppress the sunlight" precisely refers to this. As for lamp-fire, it is also Yin Fire; it must be nourished with oil/grease and cannot tolerate even a drop of cold water, or it will be extinguished. Only when Heavenly Fire enters the human body, such as in the diseases of Summer-Heat Heat caused by the Six Qi discussed by Liu Hejian, or in injuries from Summer-Heat and Stroke from Summer-Heat, can one cool with Wood-like methods or resolve with bitter-cold herbs. As for Fire in the furnace, it is a fire without warmth in ash and earth; it smokes when meeting wood and extinguishes when seeing dampness. It requires charcoal to cultivate and fill to warm the embers. Similarly, the Fire in Spleen Earth in the human body should be nourished with sweet-warm herbs, and the Fire will naturally recede. The Classic states: "For exhaustion, warm it; for damage, warm it." Sweet flavor can remove great heat, and warm property can remove great heat; this is what is meant.
The Fire in the void attaches to Wood. Because Kan Water nourishes it, the Fire does not manifest externally. Only dry wood generates fire, spreading uncontrollably until its strength is exhausted. In the human body, when Liver Fire blazes internally, causing depression and irritability, one must use acrid-cool substances to disperse it. The Classic states: "When Wood is stagnant, vent it; when Fire is stagnant, diffuse it," allowing it to follow its nature of flaming upward. If cold herbs are used to purge downward, stagnation increases; if hot herbs are administered, intensity increases.
Fire in Metal refers to phenomena where mountains containing gold or silver ores, or places where five metals are buried, emit light at night. This is Metal stagnant in Earth unable to transcend, thus emitting brilliance externally. In the human body, sensations like needle pricks or mosquito bites in the skin and pores, or a burning sensation on the vertex, indicate Lung Metal Qi deficiency. Tonifying Northern Water is equivalent to draining Southern Fire.
Speaking of Water, there is Yang Water and Yin Water. There is Water in Fire, Water in Earth, Water in Metal, and Water in Wood. Yang Water is Kan Water, belonging to Qi. The *Yin-Yang Xiao Xi Lun* states: Kan consists of one Yang trapped between two Yins. Water Qi travels secretly underground, serving as the root foundation for all things receiving life. It is a moist fluid, the liquid of Qi. The *Monthly Ordinances* state in Mid-Autumn: "Killing Qi prevails, Yang Qi declines daily, water begins to dry up." This drying of water signifies the death of the earth. In Mid-Winter: "Spring waters move." This movement of water in the month of one Yang arising signifies the life of the earth. This can be called Water in Fire or Water in Earth. Yin Water is Dui, representing Marsh, belonging to Form. One Yin extends above two Yangs. With tangible water universally bestowing upon all things, descending as benefits and favors for generation, above it is Rain/Dew Water, and below it is Stream Water. When food and drink enter the Stomach, Mingmen Fire steams and rots them. The Qi of food and drink ascends to熏 (smoke/steam) the Lungs. The Lungs regulate the hundred vessels; Water Essence distributes in four directions, running through the five meridians. It reaches the skin and hair, transforming into sweat and nasal discharge, into Jin (thin fluids) and Tuo (saliva). It moistens the Bladder downward, transforming into urine and body fluids. Blood is also Water; because it flows with Ministerial Fire, its color is uniquely red. It cycles endlessly, rolling without depletion. Above, it is Heavenly River Water; below, it is Long-flowing Water. Starting from the Northwest Heavenly Gate and ending at the Southeast Earthly Door, it is precisely as the poem says: "Yellow River's water comes from heaven, rushing to the sea never to return." Thus, Yellow River water shares the same color.
Water in Metal is Mercury in ores. In the human body, it is Marrow in bones, the most refined and precious treasure of humans. Water in Wood is Xun Wood entering Kan Water and excreting water upwards, i.e., tree sap. In the human body, Yongquan (KI 1) on the feet and Jianjing (GB 21) on the shoulders are pathways for hidden water flow. All Jin and Ye moistening within the skin are Well Spring Waters. Although Water manifests in many differences, it ultimately returns to the Sea. For Heaven and Earth's Water, the Sea is the patriarch; for Human Body's Water, the Kidney is the source. The reason it flows day and night without cessation is due to the Primordial Qi of Qian acting as the Taiji. This is the Five Elements within Water. Understanding the Five Elements of Water and Fire allows one to deduce Earth, Wood, and Metal by analogy. The Classic states: "Recorded in Water and Fire, the rest of the Qi can be known."