灵枢经·五味论 Discourse on the Five Flavors
黄帝问于少俞曰：五味入于口也，各有所走，各有所病，酸走筋，多食之，令人癃；咸走血，多食之，令人渴；辛走气，多食之，令人洞心；苦走骨，多食之，令人变呕；甘走肉，多食之，令人挽心。余知其然也，不知其何由？愿闻其故。少俞答曰：酸入于胃，其气涩以收，上之两焦，弗能出入也，不出即留于胃中，胃中和温，则下注膀胱，膀胱之胞薄以懦，得酸则缩绻，约而不通，水道不行，故癃。阴者，积筋之所终也，故酸入而走筋矣。
黄帝曰：咸走血，多食之，令人渴，何也？少俞曰：咸入于胃；其气上走中焦，注于脉，则血气走之，血与咸相得，则凝，凝则胃中汁注之，注之则胃中竭，竭则咽路焦，故舌本干而善渴。血脉者，中焦之道也，故咸入而走血矣。
黄帝曰：辛走气，多食之，令人洞心，何也？少俞曰：辛入于胃，其气走于上焦，上焦者，受气而营诸阳者也，姜韭之气熏之，营卫之气，不时受之，久留心下，故洞心。辛与气俱行，故辛入而与汗俱出。
黄帝曰：苦走骨，多食之，令人变呕，何也？少俞曰：苦入于胃，五谷之气，皆不能胜苦，苦入下脘，三焦之道，皆闭而不通，故变呕。齿者，骨之所终也，故苦入而走骨，故入而复出，知其走骨也。
黄帝曰：甘走肉，多食之。令人悗心，何也？少俞曰：甘入于胃，其气弱小，不能上至于上焦，而与谷留于胃中者，令人柔润者也，胃柔则缓，缓则虫动，虫动则令人悗心。其气外通于肉，故甘走肉。
Huangdi asked Shaoyu: "When the five flavors enter the mouth, each travels to its own destination and each gives rise to its own disorder. Sour travels to the sinews, and eaten to excess it causes urinary blockage (long). Salty travels to the blood, and eaten to excess it causes thirst. Pungent travels to the qi, and eaten to excess it causes a hollow, gnawing sensation in the heart. Bitter travels to the bones, and eaten to excess it causes retching. Sweet travels to the flesh, and eaten to excess it causes oppression in the heart. I know that this is so, but I do not know the reason why — I wish to hear the explanation." Shaoyu replied: "Sour enters the stomach; its qi is astringent and constricting. Rising to the two upper burners, it cannot pass freely in or out; failing to be dispersed, it lingers within the stomach. When the stomach is warm and harmonious, it pours downward into the bladder, but the bladder's thin covering is delicate and yielding, and upon receiving the sour qi it contracts and shrivels, becoming constricted and impassable, so that the waterways fail to function — hence urinary blockage results. The genital region is where the accumulated sinews converge and terminate; hence sour, upon entering, travels to the sinews."
Huangdi said: "Salty travels to the blood, and eaten to excess it causes thirst — why is this?" Shaoyu said: "Salty enters the stomach; its qi travels upward to the middle burner and pours into the vessels, whereupon the blood and qi travel with it. When blood and salt combine, coagulation occurs; once coagulation occurs, the fluids of the stomach pour in to compensate, and once they pour in, the stomach's fluids become exhausted; once exhausted, the pathway of the throat becomes parched, so that the root of the tongue dries and the person is prone to thirst. The blood vessels are the pathway of the middle burner; hence salty, upon entering, travels to the blood."
Huangdi said: "Pungent travels to the qi, and eaten to excess it causes a hollow, gnawing sensation in the heart — why is this?" Shaoyu said: "Pungent enters the stomach, and its qi travels to the upper burner. The upper burner is that which receives qi and nourishes the various yang regions. When the fumes of ginger and chives suffuse it, the nutritive and defensive qi cannot receive this in due measure, and it lingers long beneath the heart — hence the hollow, gnawing sensation. Pungent travels together with the qi; hence pungent, upon entering, is expelled together with the sweat."
Huangdi said: "Bitter travels to the bones, and eaten to excess it causes retching — why is this?" Shaoyu said: "Bitter enters the stomach, and the qi of the five grains cannot overcome it. As the bitter enters the lower stomach duct, the pathways of the three burners all close and become impassable — hence retching occurs. The teeth are where the bones converge and terminate; hence bitter, upon entering, travels to the bones, and, having entered, comes back out again — this is how one knows that it travels to the bones."
Huangdi said: "Sweet travels to the flesh, and eaten to excess it causes oppression in the heart — why is this?" Shaoyu said: "Sweet enters the stomach; its qi is weak and slight, and cannot rise all the way to the upper burner. Remaining together with the grain within the stomach, it makes the stomach soft and moist; when the stomach is soft, it becomes slack, and when slack, the parasitic worms are stirred to movement, and when the worms stir, this causes oppression in the heart. Its qi communicates outwardly with the flesh; hence sweet travels to the flesh."