15 太阳病，下之后，其气上冲者，可与桂枝汤。方用前法。若不上冲者，不得与之。In the case of Taiyang disease, after purgation, if the qi surges upward, Guizhi Decoction can be administered. The method of decocting is the same as before. If the qi does not surge upward, it should not be given.首先是“太阳病”，说明有表证，其证略去了。医生给治错了，用了泻药。为什么用泻药是错误的呢？这里要先说一个治病的大原则：病在表从表解；病在里从里解；病在半表半里和解。Firstly, "Taiyang disease" indicates the presence of an exterior syndrome, but the details of the syndrome are omitted here. The doctor made a wrong treatment and used purgatives. Why is using purgatives wrong? Here, a major principle of treating diseases needs to be mentioned first: for diseases in the exterior, they should be resolved from the exterior; for diseases in the interior, they should be resolved from the interior; for diseases in the semi-exterior and semi-interior, the harmonizing method should be used.从表解常用汗法；从里解常用下法，就是泻下，从肠道解。汗与下本来就是人体排除邪气的自然模式，药物只是顺势而为。这两个都好理解。To resolve diseases from the exterior, the sweating method is commonly used; to resolve diseases from the interior, the purgative method, that is, purging, resolving from the intestinal tract, is often used. Sweating and purging are originally the natural ways for the human body to expel pathogenic factors, and drugs just follow this trend. These two are quite easy to understand.那半表半里“和解”怎么理解呢？当邪气在半表半里，里外都不能解的时候，人体还有另外一种方式，就是通过三焦网膜系统的水液上下运行交换来代谢排邪。How to understand the "harmonizing" method for diseases in the semi-exterior and semi-interior? When pathogenic factors are in the semi-exterior and semi-interior and cannot be resolved either externally or internally, the human body has another way, which is to metabolize and expel pathogenic factors through the upward and downward movement and exchange of water fluids in the tri-jiao reticuloendothelial system.邪气陷入半表半里往往是因为人体脾胃虚弱了。脾胃虚弱则痞塞，上下便不能交通，于是常发生一种现象——上热下寒。人体正常应该是下面热上面寒才对，如此上面的阴往下降，下面的阳往上升，这样循环起来便是“泰”卦，阴阳交泰之意。Pathogenic factors often fall into the semi-exterior and semi-interior because the spleen and stomach of the human body are weakened. When the spleen and stomach are weak, there will be blockage, and the upper and lower parts cannot communicate. As a result, a common phenomenon occurs - heat in the upper part and cold in the lower part. Normally, it should be warm in the lower part and cool in the upper part of the human body. In this way, the yin in the upper part descends, and the yang in the lower part ascends. Such a circulation forms the "Tai" hexagram, which means the harmonious interaction of yin and yang.如果上面是阳，下面是阴，上面的阳更往上，下面的阴更往下，便阴阳离绝，成了“否”卦，若严重了人就要死了。半表半里证就是否卦。只有让上下阴阳和解归位，疾病才能自退。这就是半表半里证须用和解之法的阴阳之理。If there is yang in the upper part and yin in the lower part, and the yang in the upper part goes even higher and the yin in the lower part goes even lower, yin and yang will be separated, forming the "Pi" hexagram. If it gets severe, the person may die. The semi-exterior and semi-interior syndrome is like the "Pi" hexagram. Only when the yin and yang in the upper and lower parts are harmonized and return to their proper positions can the disease subside on its own. This is the yin-yang principle for using the harmonizing method in semi-exterior and semi-interior syndromes.
说回条文，医生用了下药，因为药物的作用，人体气血暂时会往下往里走。但是表证还在，药效过了，气血的自然模式还是要往上往表走的。若气血能正常顺畅上行，是感觉不到气上冲的。Returning to the text, the doctor used purgatives. Due to the effect of the drugs, the qi and blood of the human body will temporarily move downward and inward. However, the exterior syndrome still exists. After the drug effect wears off, the natural tendency of qi and blood is still to move upward and to the exterior. If qi and blood can ascend smoothly and normally, one will not feel the upward surging of qi.
因为腹泻损失了津液，气血往上走的时候能量不够走不上去，便会感觉到一次次往上冲，就像汽车爬坡发动机的反应一样，这是人体在努力。Because of the loss of body fluids due to diarrhea, when qi and blood try to move upward, there is not enough energy to do so, so one will feel repeated upward surges, just like the reaction of a car engine when climbing a slope. This is the body's effort.
后世有医家说气上冲是肾有积气积寒。类似于肾积气这样的臆断之语后世很多。肾又不是肺，怎么会积气呢？寒性沉潜，积寒和上冲似乎也没关系。后世医家的问题就是凭附会想象出一些貌似有道理的结论，再扣上一些玄学的帽子，使人不敢质疑。Some physicians in later generations said that the upward surging of qi was due to stagnant qi and cold accumulated in the kidneys. There were many such speculative statements like the so-called stagnant qi in the kidneys in later generations. After all, the kidney is not the lung. How could it accumulate qi? Coldness has the property of sinking, and it seems that the accumulated cold has nothing to do with the upward surging. The problem with the physicians in later generations was that they came up with seemingly reasonable conclusions through far-fetched associations, and then added some mysterious overtones, making people afraid to question. 那这种情况为什么要用桂枝汤呢？因为桂枝汤与其说是治汗出的太阳病，不如说是治津液虚的太阳病更究竟。此条既是太阳病，又有津液虚，桂枝达外以驱邪，芍、姜、草、枣建中而回津液，无药治冲，而其冲自平，所以桂枝汤适用。有经方家说桂枝是治冲的，这样的解释是知其然不知其所以然，终究难以应变于临证。Why should Guizhi Decoction be used in this situation? Because rather than saying that Guizhi Decoction treats Taiyang disease with sweating, it is more accurate to say that it treats Taiyang disease with deficiency of body fluids. In this case, it is both Taiyang disease and there is deficiency of body fluids. Guizhi reaches the exterior to expel pathogenic factors, while peony, ginger, licorice, and jujube strengthen the middle and restore body fluids. There is no medicine specifically for treating the surging, but the surging will subside on its own. Therefore, Guizhi Decoction is applicable. Some classic formula experts said that guizhi is for treating the surging. Such an explanation only knows the result but not the reason, and it is ultimately difficult to adapt to clinical situations.
