如得病脉便沉，而里病表和者，内伤也；脉浮而表病里和者，外伤也。
病在身体四肢为表病，病在胸腹之内为里病。
身热为热在表。
言皮肤壮热而反憎寒，非谓自发热燥也。
引饮（烦渴）或小便黄赤为热在里。身热、饮水或小便黄赤，为表里皆有热。身
凉不渴，小便清白，则表里皆无热。
不言为寒者，盖表里热微，则亦有身表不热而里亦不渴故也。
浑身疼痛拘急，表热恶寒而脉浮者，皆为热在表也。引饮、谵妄、腹满实痛，发热而脉沉者，皆为
热在里也。胸胁痞痛或呕，而寒热往来，脉在肌肉，不浮不沉，则邪热半在表、半在里也。
夫邪热在表而浅，邪微而畏正，故病热而反憎寒也。寒则腠理益闭而怫
热益加故也。邪热在里而深，邪甚则不畏于正，物盛其极，故不恶寒而反自
恶热也。半在表、半在里，进退无常，则寒热往来也。寒多，为表多，脉稍浮，热多，为里多，脉
稍沉也。诸病寒热并同，惟疟疾反此。由表之正气与邪热并之于里，表气虚而里热实，亢则害，承
乃制，故里之火热极甚，而反兼寒水之化制之，故病热极而反寒战也。临汗而战及诸战皆然，寒战为
里热表虚故也，饮水而脉微不见也。里之正气与邪气并出于表，则表热里虚，是以烦热汗出而脉浮也。
经以热并于里之阴分，则为阴胜而发寒；热并于表之阳分，则为阳胜而发热也。俗未知其为表里之阴阳，
而妄为寒热之阴阳，故皆失《内经》之本旨也。夫伤寒之寒热者，恶寒为表热里和，故脉浮；发热为
里，表气不虚，故发热而脉沉实也。气并、不并，故寒热相反而有微甚也，热并则甚，不并则微也。
If the pulse is sunken immediately upon the onset of illness, and there are interior symptoms with a harmonious exterior, it is an internal injury; if the pulse is floating and there are exterior symptoms with a harmonious interior, it is an external injury.
Diseases manifesting in the body and four limbs are termed *Biao Bing* (Exterior Disease); diseases manifesting within the chest and abdomen are termed *Li Bing* (Interior Disease).
Body heat indicates heat in the *Biao* (Exterior).
The statement "skin is intensely hot yet there is aversion to cold" does not refer to the patient feeling internally dry or hot.
Thirst for drinking water (*Fan Ke*, irritability and thirst) or yellow-red urine indicates heat in the *Li* (Interior). If there is body heat, desire for water, or yellow-red urine, it indicates heat in both the *Biao* and *Li*. If the body is cool, there is no thirst, and urine is clear and white, then there is no heat in either the *Biao* or *Li*.
Cold syndromes are not explicitly discussed here because when heat in the *Biao* and *Li* is slight, there may also be no heat on the body surface and no thirst inside.
Generalized body pain and stiffness, with heat on the body surface, aversion to cold, and a floating pulse, all indicate heat in the *Biao*. Thirst for drinking, delirium, abdominal fullness and solid painfulness, fever, and a sunken pulse all indicate heat in the *Li*. Chest and hypochondriac stuffiness and pain or vomiting, with alternating chills and fever, and a pulse located at the muscle level that is neither floating nor sunken, indicate that pathogenic heat is half in the *Biao* and half in the *Li*.
When pathogenic heat is in the *Biao* and shallow, the pathogen is weak and fears the healthy Qi, so although there is fever from illness, there is aversion to cold. This is because cold causes the *Cou Li* (pores/skin texture) to close further, thereby intensifying the trapped heat. When pathogenic heat is deep in the *Li*, the pathogen is strong and does not fear the healthy Qi; when things reach their extreme, they reverse, so there is no aversion to cold but rather aversion to heat. Pathogenic heat being half in the *Biao* and half in the *Li*, moving forward and backward without constancy, results in alternating chills and fever. More chills indicate more *Biao* involvement, with a slightly floating pulse; more heat indicates more *Li* involvement, with a slightly sunken pulse. In most diseases, chills and fever present similarly, except for *Nue Ji* (Malaria), which is the opposite. This occurs because the healthy Qi of the *Biao* combines with pathogenic heat and enters the *Li*, resulting in deficiency of *Biao* Qi and excess of *Li* heat. When one aspect becomes hyperactive, it causes harm, requiring a counteracting force to regulate it; thus, when internal fire-heat reaches its extreme, it assumes the transformation of cold-water to restrain itself, causing extreme heat to manifest as chills. Chills occurring just before sweating, and all types of chills, are due to excess heat in the *Li* and deficiency of *Biao* Qi, often accompanied by thirst and a faint or imperceptible pulse. When the healthy Qi of the *Li* and the pathogen emerge together to the *Biao*, it results in heat in the *Biao* and deficiency in the *Li*, leading to irritability, heat, sweating, and a floating pulse. The Classics state that when heat merges into the Yin portion of the *Li*, it leads to Yin excess and the manifestation of chills; when heat merges into the Yang portion of the *Biao*, it leads to Yang excess and the manifestation of fever. Laypeople do not understand this distinction between *Biao/Li* Yin-Yang and mistakenly attribute it to simple cold-heat Yin-Yang, thereby missing the original intent of the *Huangdi Neijing* (Yellow Emperor's Inner Canon). Regarding the chills and fever of *Shanghan* (Cold Damage), aversion to cold indicates heat in the *Biao* with a harmonious *Li*, hence the floating pulse; fever indicates pathology in the *Li* with non-deficient *Biao* Qi, hence fever and a sunken, solid pulse. Whether Qi merges or not determines whether chills and fever are opposite and vary in severity; when heat merges, symptoms are severe; when they do not merge, symptoms are mild.