古之至人，穷于阴阳之化，究乎生死之际，所着《内外经》，悉言人以胃气为本。盖
人受水谷之气以生，所谓清气、营气、运气、卫气，春升之气，皆胃气之别称也。夫胃为水
谷之海，饮食入胃，游溢精气，上输于脾；脾气散精，上归于肺；通调水道，下输膀胱；
水精四布，五经并行，合于四时五脏阴阳，揆度以为常也。
若饮食失节，寒温不适，则脾胃乃伤。喜、怒、忧、恐，损耗元气。既脾胃气衰，元气
不足，而心火独盛。心火者，阴火也。起于下焦，其系系于心。心不主令，相火代之。相火
，下焦胞络之火，元气之贼也。火与元气不两立，一胜则一负。脾胃气虚，则下流于肾，阴
火得以乘其土位，故脾证始得，则气高而喘，身热而烦，其脉洪大而头痛，或渴不止，其皮
肤不任风寒，而生寒热。盖阴火上冲，则气高喘而烦热，为头痛，为渴，而脉洪。脾胃之气
下流，使谷气不得升浮，是春生之令不行，则无阳以护其营卫，则不任风寒，乃生寒热，此
皆脾胃之气不足所致也。
然而与外感风寒所得之证，颇同而实异，内伤脾胃，乃伤其气，外感风寒，乃伤其形；
伤其外为有余，有余者泻之，伤其内为不足，不足者补之。内伤不足之病，苟误认作外感有
余之病，而反泻之，则虚其虚也。实实虚虚，如此死者，医杀之耳！然则奈何？惟当以辛甘温
之剂，补其中而升其阳，甘寒以泻其火则愈矣。经曰∶劳者温之，损者温之。又云∶温能除大热
，大忌苦寒之药，损其脾胃。脾胃之证，始得则热中，今立治始得之证。
古代的至人，深入探究阴阳变化的规律，究察生死的界限，所著《内外经》中，完全强调人以胃气为根本。大概人依靠摄入的水谷之气而生存，所说的清气、营气、运气、卫气、春升之气，都是胃气的不同称呼。胃是容纳水谷的海洋，饮食进入胃中，游溢精气，向上输送给脾；脾气散布精微物质，向上归于肺；肺通调水道，向下输送到膀胱；水液和精微四布全身，五脏经脉并行运行，符合四季和五脏阴阳的规律，以此作为常态。
如果饮食没有节制，寒热不适，那么脾胃就会受伤。喜悦、愤怒、忧愁、恐惧，会损耗元气。既然脾胃之气衰弱，元气不足，而心火独自旺盛。心火，就是阴火。它起源于下焦，其联系系于心。心不主导命令，由相火代替。相火，是下焦胞络之火，是元气的贼害者。火与元气不能两立，一方胜则另一方负。脾胃气虚，则气下流于肾，阴火得以乘袭土位（脾），所以脾证刚开始出现时，就表现为气逆而喘，身体发热而烦躁，脉象洪大且头痛，或者口渴不止，皮肤不能耐受风寒，从而产生寒热症状。大概阴火上冲，就会导致气逆喘息而烦热，引起头痛、口渴，以及脉象洪大。脾胃之气下流，使得谷气不能上升浮越，这是春生之令不能施行，就没有阳气来护卫营卫，因而不能耐受风寒，于是产生寒热，这都是因为脾胃之气不足所导致的。
然而这与外感风寒所得到的病证，颇为相似但实际上不同，内伤脾胃，是损伤了气，外感风寒，是损伤了形；损伤外在形体属于有余（实证），有余应当用泻法，损伤内在正气属于不足（虚证），不足应当用补法。内伤不足的病，如果错误地认作外感有余的病，反而使用泻法，那就是使虚者更虚。实其实、虚其虚，像这样导致死亡的，是医生杀死了病人！那么该怎么办呢？只应当用辛甘温的药剂，补益其中气并升发阳气，用甘寒的药来清泻火邪，病就好了。经文说：劳损的用温法，亏损的用温法。又说：温能除大热，非常忌讳苦寒的药物，以免损伤脾胃。脾胃的病证，刚开始则是热中，现在确立治疗刚开始出现的病证的方法。
The ancient sages thoroughly investigated the transformation of Yin and Yang, and explored the boundaries of life and death. In their work *Nei Wai Jing* (Classic of Internal and External), they emphasized that human beings rely on Stomach Qi (Stomach Energy) as the foundation. Essentially, humans derive life from the Qi of water and grain. The so-called Clear Qi (Clear Energy), Ying Qi (Nutritive Energy), Yun Qi (Transporting Energy), Wei Qi (Defensive Energy), and Spring-rising Qi are all alternative names for Stomach Qi. The Stomach is the sea of water and grain. When food and drink enter the Stomach, their essence and qi overflow and are transported upward to the Spleen; the Spleen disperses these essences upward to the Lung; the Lung regulates the water passages, transporting them downward to the Bladder; water and essence are distributed throughout the body, and the five meridians function in parallel, conforming to the patterns of the four seasons and the Yin-Yang of the five zang organs, establishing this as the normal state.
If dietary habits are irregular or exposure to cold and heat is inappropriate, the Spleen and Stomach will be injured. Joy, anger, worry, and fear deplete Yuan Qi (Original Energy). Once the Qi of the Spleen and Stomach declines and Yuan Qi becomes insufficient, Heart Fire (Heart Heat) becomes excessively prominent alone. Heart Fire is also known as Yin Fire. It originates in the Lower Jiao (Lower Burner) and its connections are linked to the Heart. Since the Heart does not issue commands, Xiang Fire (Ministerial Fire) takes over. Xiang Fire is the fire of the Bao Luo (Pericardium Collaterals) in the Lower Jiao and is a thief harming Yuan Qi. Fire and Yuan Qi cannot coexist; when one prevails, the other declines. When Spleen and Stomach Qi is deficient, it flows downward into the Kidney, allowing Yin Fire to invade the Earth position (Spleen). Therefore, at the onset of Spleen syndromes, symptoms include rapid breathing and wheezing due to rebellious Qi, feverish sensation and irritability, a flooding and large pulse accompanied by headache, or unquenchable thirst. The skin becomes unable to withstand wind and cold, leading to alternating chills and fever. Generally, when Yin Fire rushes upward, it causes rebellious breathing, wheezing, irritability, heat, headache, thirst, and a flooding pulse. Because Spleen and Stomach Qi flows downward, Grain Qi cannot ascend and float, meaning the command of Spring generation fails. Without Yang to protect Ying and Wei, the body cannot withstand wind and cold, thus generating chills and fever. All these conditions result from the insufficiency of Spleen and Stomach Qi.
However, these symptoms are similar yet fundamentally different from those caused by external contraction of wind and cold. Internal injury to the Spleen and Stomach damages Qi, whereas external contraction of wind and cold damages the Form (body structure). Injury to the exterior constitutes an Excess pattern (Shi), which should be treated with draining methods; injury to the interior constitutes a Deficiency pattern (Xu), which should be treated with tonifying methods. For internal deficiency diseases, if mistakenly diagnosed as external excess diseases and treated with draining methods, it results in further depletion of the already deficient state. This error of "tonifying excess and draining deficiency" leads to death, effectively constituting medical homicide. So, what should be done? One must use acrid, sweet, and warm formulas to tonify the Middle Jiao and raise Yang, and use sweet-cold herbs to clear the fire, thereby achieving recovery. The Classics state: "For exhaustion, use warmth; for loss, use warmth." It is also said: "Warmth can eliminate great heat." Bitter-cold medicines must be strictly avoided as they damage the Spleen and Stomach. Spleen and Stomach disorders initially present as Heat in the Middle (Re Zhong); here, we establish the treatment for these initial manifestations.