夫外疡之发也，不外乎阴阳、寒热、表里、虚实、气血、标本，与内证异流而同源者
也。其始或外由六淫之气所感，或内被七情受伤。经云∶邪之所凑，其气必虚。阴虚者，邪
必凑之。又云∶营气不从，逆于肉里，乃生痈肿。明乎此义，则治证了然矣。如夏令暑蒸炎
热，肌体易疏，遇凉饮冷，逼热最易内入，客于脏者，则为痧、为胀；客于腑者，则为吐、
为泻；客于肌表者，则为 、为瘰、为暑热疮、为串毒、为丹毒游火；客于肉里者，则为痈
、为疡；客于络脉者，为流注、为腿痈。斯时正气壮强，逼邪出外，根据法治之。在内证尤为
易愈，或三日，或五日，或一候即霍然矣；若外疡则稍多日期。亦有暑邪内伏，遇秋而发者
，在经则为疟，在腑则为痢，其在肌络则为流注、腿痈等证，是名阳挟阴，用药则以解散和
营通络；即不散而成脓，亦不至有大患。又有正亏邪伏深入，交寒露霜降而发者，在内则为
伏邪瘅疟，朝凉暮热，或昼夜热而不退，缠延不已，致阴虚化燥，痉厥神迷，内闭外脱，不
可为治；在外发痈疡，则为正虚邪实，阴中挟阳；成脓溃后，虽与性命无妨，然收功延日，
不能速愈。此阴阳、寒热、表里、虚实、气血、标本之大凡也，为疡科中之第一义，故首揭
之。
外疡的发生，不外乎阴阳、寒热、表里、虚实、气血、标本这些范畴，它与内证虽然表现不同，但根源是一致的。其起因或是外受六淫之气（风、寒、暑、湿、燥、火六种外感病邪）的侵袭，或是内因七情（喜、怒、忧、思、悲、恐、惊七种情志变化）的伤害。《内经》说：邪气聚集的地方，正气必然虚弱。阴虚的人，邪气必定会凑近。又说：营气运行不畅，逆乱于肌肉纹理之间，就会发生痈肿。明白了这个道理，治疗病症就清晰明了了。例如夏季暑气蒸腾炎热，肌腠容易疏松，此时若喝冷饮吃凉食，最容易将热邪逼入体内。热邪客留于脏，就会形成痧症、胀满；客留于腑，就会形成呕吐、腹泻；客留于肌表，就会形成疔疮、瘰疬、暑热疮、串毒、丹毒游火；客留于肌肉纹理之间，就会形成痈、疡；客留于络脉，就会形成流注、腿痈。这个时候如果正气强盛，逼迫邪气向外排出，按照正确的方法治疗，对于内证尤其容易痊愈，或者三天，或者五天，或者一个候（十五天）就能霍然病愈；如果是外疡，则所需日期稍多一些。也有暑邪潜伏在体内，到了秋季才发作的，在经脉则为疟疾，在腑则为痢疾，在肌络则为流注、腿痈等证，这叫做阳挟阴，用药则以解散邪气、调和营血、疏通经络为主；即使不散去而化脓，也不至于有大危害。又有正气亏损、邪气潜伏深入，遇到寒露霜降时节才发作的，在内表现为伏邪瘅疟，早晨凉爽傍晚发热，或者昼夜发热不退，缠绵不已，导致阴虚化燥，出现痉挛厥逆、神志昏迷，内闭外脱，无法救治；在外表现为痈疡，则是正虚邪实，阴中挟阳；成脓溃破后，虽然对性命没有妨碍，但是收口愈合拖延时日，不能快速痊愈。这就是阴阳、寒热、表里、虚实、气血、标本的大致规律，是疡科中的首要义理，所以首先揭示出来。
The occurrence of external sores (external ulcers) is governed by Yin and Yang, Cold and Heat, Exterior and Interior, Deficiency and Excess, Qi and Blood, and Root and Branch. Although its manifestations differ from internal diseases, they share a common origin. The initial cause may be an invasion by the Six Evils (Wind, Cold, Summer-heat, Dampness, Dryness, Fire) or injury caused by the Seven Emotions (Joy, Anger, Worry, Thought, Sorrow, Fear, Fright). The *Classic of Internal Medicine* states: "Where pathogenic factors gather, the body's righteous Qi must be deficient." In cases of Yin deficiency, pathogenic factors inevitably converge. It also states: "When Ying (Nutritive) Qi does not flow smoothly and reverses within the muscle tissue, abscesses and swellings arise." Understanding this principle makes the treatment of conditions clear. For instance, in summer when heat steams and scorching temperatures prevail, the skin pores are easily open. If one consumes cold drinks or food, heat is easily forced inward. If it lodges in the Zang organs, it results in Sha syndrome (heat stroke with sudden collapse) or distension; if it lodges in the Fu organs, it results in vomiting or diarrhea; if it lodges on the exterior of the muscles and skin, it results in Ding sores (hard, deep-rooted boils), Luoli (scrofula), summer-heat sores, Chuan Du (spreading toxins), Dan Du (erysipelas), or You Huo (wandering fire); if it lodges within the muscle tissue, it results in Yong (abscess) or Yang (ulcer); if it lodges in the collaterals, it results in Liuzhu (metastatic abscesses) or Tui Yong (leg abscesses). At this time, if the Righteous Qi is strong and forces the pathogen outward, treating according to proper methods will lead to easy recovery for internal conditions, resolving in three days, five days, or one pentad (15 days); for external sores, however, the duration may be slightly longer. There are also cases where Summer-heat pathogen lies latent internally and manifests in autumn. When in the meridians, it presents as Malaria; when in the Fu organs, as Dysentery; when in the muscle-collaterals, as Liuzhu or Tui Yong. This is termed "Yang carrying Yin," and medication should focus on dispersing pathogens, harmonizing Ying Qi, and unblocking collaterals. Even if it does not disperse but forms pus, it will not cause major harm. Furthermore, there are cases where Righteous Qi is deficient and pathogens lie latent deeply, manifesting during the Cold Dew or Frost Descent solar terms. Internally, this presents as Fu Xie Dan Nue (latent pathogen causing severe malaria), with cool mornings and hot evenings, or continuous fever day and night, lingering endlessly, leading to Yin deficiency transforming into dryness, spasms, convulsions, coma, internal closure and external collapse, which becomes incurable. Externally, it manifests as sores and ulcers, representing a condition of Righteous Deficiency and Pathogenic Excess, with Yang embedded in Yin. After pus formation and ulceration, although life is not threatened, healing is prolonged and cannot be rapid. These are the general principles of Yin and Yang, Cold and Heat, Exterior and Interior, Deficiency and Excess, Qi and Blood, and Root and Branch, constituting the primary doctrine of the Surgery Department, hence it is presented first.