喻嘉言曰∶肺痈由五脏蕴祟之火，与胃中停蓄之热，上乘乎肺，肺受火热熏灼，即血为之凝，血凝即
痰为之裹，遂成小痈。所结之形日长，则肺日胀而胸骨日昂，乃至咳声频并，浊痰如胶，发热畏寒，日晡尤甚
，面红鼻燥，胸中甲错。如先即能辨其脉症，属表属里，极力开提、攻下，无不愈者。若至脓血吐出，
始识其症，嗟无及矣，间有痈小气壮，胃强善食，仍可得生。然不过十中一二。此症治法，用力全在成
痈之先。
盖肺痿者，其渐积已非一日，其寒热不止一端，总由胃中津液不输于肺，肺失所养。转枯转燥，然后
成之。但胃中津液暗伤之窦实多，医者不知爱护，或腠理素疏，无故而大发其汗；或中气素馁，频吐以倾倒
其囊；或瘅成消中，饮水而渴不解，泉竭自中；或肠枯便秘，强利以求其快，漏卮难继。于是肺火日炽，
肺热日深，肺中小管日窒，咳声以渐不扬，胸中脂膜日干，咳痰艰于上出，行动数武气即喘鸣。治法大要，
缓而图之，生胃津，润肺燥，下逆气，开积痰，止浊唾，补真气以通肺之小管，散火热以复肺之清肃。如半
身痿废，及手足痿软，治之得法，亦能复起。
然肺痈属在有形之血，血结宜骤攻；肺痿属在无形之气，气伤宜徐理。肺痈为实，误以肺痿治之，是谓
实实；肺痿为虚，误以肺痈治之，是为虚虚。此辨症用药之大略也。
《金匮》论肺痈、肺痿之脉云∶寸口脉数，其人咳，口中反有浊唾涎沫者，为肺痿之病。若口中辟辟燥，
咳即胸中隐隐痛，脉反滑数，此为肺痈，咳吐脓血。脉数虚者为肺痿，数实者为肺痈。
又云∶寸口脉微而数，微则为风，数则为热；微则汗出，数则畏寒。风中于卫，呼气不入；热过于荣，
吸而不出。风伤皮毛。热伤血脉，风舍于肺，其人则咳，口干喘满，燥而不渴，时唾浊沫，时时振寒。热之所
过，血为之凝滞，蓄结痈脓，吐如米粥，始萌可救，脓成则死。
咳嗽之初，即见上气喘急者，乃外受风寒所致，其脉必浮，宜从越婢加半夏之法，及小青龙加石膏之法，
亟为表散。不尔，即是肺痈、肺痿之始基。须亟散邪下气，以清其肺。然亦分表里虚实为治，不当误施，
转增其困矣。
程郊倩曰∶肺痿气虚不能化血，故血干不流，只随火热
沸上，火亢乘金，不生气血而生痰，可知无血无液，而枯金被火，肺叶安得不焦？盖肺处脏之最高，叶间
布有细窍，凡五脏之蒸溽，从肺脘吸入之便是气，从泉眼呼出之便成液，息息不穷，以之灌溉周身，此所
谓水出高源也。一受火炎，呼处成吸，有血即从此眼渗入，碍了窍道，便令人咳，咳则见血，愈咳愈渗，愈
渗愈咳，久则细窍俱闭。吸时从引火升喉间，或痒或疮；呼时并无液出，六叶逐尔枯焦，此肺痿之由也，补肺
散中，用杏仁、大力子者，宣窍道也；用阿胶者，消窍淤也；用马铃者，消窍热也。肺全无一补药，而反以
糯米补及脾者，但取母气到肺。立方之旨，全从肺家细窍着想，使此处呼吸无阻，则气入液出，肺不补而自
补矣。
喻嘉言说：肺痈是由于五脏蕴积的邪火，与胃中停蓄的热气，向上熏蒸于肺。肺受到火热熏灼，血液就会凝结；血液凝结后，痰液随之包裹血块，从而形成小的痈肿。这种结聚的形状日益长大，导致肺部日渐胀大，胸骨日渐高耸，以至于咳嗽声频繁发作，咳出如胶般的浊痰，伴有发热和畏寒，下午（日晡）症状尤为严重，面色发红，鼻窍干燥，胸部皮肤粗糙如鳞甲交错。如果在初期就能辨别其脉象和症状，判断病位在表还是在里，极力采用开提宣散或攻下泄热的方法治疗，没有不能治愈的。如果等到脓血吐出时，才认识到这是肺痈的症状，那就来不及救治了。偶尔有痈肿较小、正气壮实、胃口好能进食的患者，仍有可能存活，但不过十分之一二。此症的治疗关键，全在于痈肿形成之前。
至于肺痿，它是逐渐积累而成，并非一日之寒，其寒热表现不止一种原因，总归是因为胃中的津液不能输送到肺，肺失去滋养，逐渐干枯燥热，最终形成肺痿。然而，暗中损伤胃中津液的途径实在很多，医生不知爱护，或者患者腠理本来疏松，无故而大发汗；或者中气本来虚弱，频繁呕吐以倾倒胃中之物；或者患消渴病，饮水却解不了渴，体内津液枯竭；或者肠道干枯便秘，强行使用利尿药以求痛快，如同漏勺难以维持。于是肺火日益炽盛，肺热日益加深，肺内细小管道日益闭塞，咳嗽声音逐渐变得低沉不扬，胸部脂膜日渐干枯，咳痰艰难难以排出，行走几步气息就喘息鸣响。治疗的大要，在于缓慢调理，滋生胃中津液，滋润肺中燥热，降逆气，开通积痰，止住浊唾，补益真气以通畅肺的小管，疏散火热以恢复肺的清肃功能。即使是半身痿废，以及手足痿软，只要治疗方法得当，也能康复。
然而，肺痈属于有形之血，血结应当迅速攻逐；肺痿属于无形之气，气伤应当徐徐调理。肺痈是实证，误用治疗肺痿的方法，这叫“实实”（使实证更实）；肺痿是虚证，误用治疗肺痈的方法，这叫“虚虚”（使虚证更虚）。这是辨证用药的大致原则。
《金匮要略》论述肺痈、肺痿的脉象说：寸口脉数，其人咳嗽，口中反而有浊唾涎沫的，是肺痿的病。如果口中感觉辟辟干燥，咳嗽时胸中隐隐作痛，脉象反而滑数，这是肺痈，会咳吐脓血。脉数而虚的是肺痿，脉数而实的是肺痈。
又说：寸口脉微而数，微则代表风邪，数则代表热邪；微则汗出，数则畏寒。风邪伤及卫分，呼气不能深入；热邪过于营分，吸气不能外出。风邪伤害皮毛，热邪伤害血脉。风邪舍居于肺，患者就会咳嗽，口干气喘胸闷，身体燥热但不口渴，时常唾吐浊沫，时时发冷战栗。热邪经过的地方，血液凝滞，蓄积结成痈脓，咳出的痰像米粥一样。在疾病初起阶段尚可救治，一旦脓成则预后不良甚至死亡。
咳嗽之初，就出现上气喘急的，乃是外受风寒所致，其脉象必然浮，适宜采用越婢加半夏汤法，或小青龙加石膏汤法，紧急进行解表发散。如果不这样，就是肺痈、肺痿的起始基础。必须紧急疏散邪气、降逆肺气，以清肃肺脏。但也需分辨表里虚实进行治疗，不可误施治法，否则会增加患者的困苦。
程郊倩说：肺痿因气虚不能化生血液，所以血液干枯不流动，只随着火热沸腾而上逆。火亢盛乘克肺金，不生气血而生痰，可知无血无液，枯槁的肺被火烤，肺叶怎能不焦？肺处于脏腑的最高位置，叶间布有细窍。凡五脏蒸腾湿润之气，从肺脘吸入的就是气，从泉眼呼出的就变成液，呼吸无穷无尽，以此灌溉周身，这就是所谓“水出高源”。一旦受到火炎熏灼，呼气处变成吸气处，有血就从这眼渗入，阻碍了窍道，便令人咳嗽，咳嗽则见血，愈咳愈渗，愈渗愈咳，久而久之细窍全部闭塞。吸气时引火升至喉间，或痒或疮；呼气时并无液体流出，六叶逐渐枯焦，这就是肺痿的成因。补肺散方中，用杏仁、牛大力子，是为了宣通窍道；用阿胶，是为了消除窍道的淤滞；用马铃（指马兜铃），是为了消除窍道的热邪。肺全无一味补药，反而用糯米来补脾，只是取母气（土生金）到达肺。立方的宗旨，完全从肺家细窍着想，使此处呼吸无阻，那么气入液出，肺不用补而自然补益了。
Yu Jiayan stated: Fei Yong (Lung Abscess) arises from the accumulated pathogenic fire of the five zang organs and the stagnant heat in the stomach, which ascend to smolder the lung. When the lung is scorched by this fire and heat, the blood coagulates; once the blood coagulates, phlegm wraps around it, thereby forming a small abscess. As this accumulation grows day by day, the lung swells progressively, and the chest bone elevates, leading to frequent coughing, expulsion of thick turbid sputum like glue, fever, aversion to cold, with symptoms worsening significantly at dusk (rib hour), facial redness, dry nasal passages, and rough, scaly skin on the chest. If one can identify the pulse and symptoms at the onset, determining whether the pathology is in the exterior or interior, and vigorously employs methods to raise and disperse or purge and descend, there will be no case that cannot be cured. However, if one only recognizes the condition after pus and blood are expectorated, it is too late to save the patient. Occasionally, patients with small abscesses, strong vital energy, and good appetite may survive, but such cases account for only one or two out of ten. The key to treating this condition lies entirely before the abscess forms.
As for Fei Wei (Lung Withering), it develops gradually over time, not in a single day, and its manifestations of cold and heat vary. Ultimately, it results from the failure of stomach fluids to transmit to the lung, causing the lung to lose nourishment, becoming increasingly dry and arid until Fei Wei is formed. In reality, there are many ways in which stomach fluids are secretly damaged. Physicians often fail to protect them. For instance, if the couli (pores) are naturally loose, excessive sweating may occur without cause; if the middle qi is inherently deficient, frequent vomiting may deplete the stomach's contents; if damp-heat transforms into Xiao Zhong (wasting-thirst), drinking water fails to quench thirst, leading to internal exhaustion of fluids; or if the intestines are dry with constipation, forcing diuresis to achieve relief creates a leaky vessel that cannot sustain itself. Consequently, lung fire intensifies daily, lung heat deepens, and the small tubes within the lung become obstructed. Cough sounds gradually become weak and indistinct, the fatty membranes in the chest dry up, expectoration becomes difficult, and panting occurs after walking just a few steps. The general principle of treatment is to proceed slowly, generate stomach fluids, moisten lung dryness, direct rebellious qi downward, resolve accumulated phlegm, stop turbid saliva, tonify true qi to unblock the lung's small tubes, and dissipate fire-heat to restore the lung's clear and descending function. Even in cases of hemiplegic withering or flaccidity of the limbs and hands, proper treatment can lead to recovery.
However, Fei Yong involves tangible blood, so blood stasis should be attacked rapidly; Fei Wei involves intangible qi, so qi injury should be managed gradually. Fei Yong is an excess syndrome; treating it with methods for Fei Wei constitutes "treating excess as excess" (exacerbating an excess condition). Fei Wei is a deficiency syndrome; treating it with methods for Fei Yong constitutes "treating deficiency as deficiency" (exacerbating a deficiency condition). This is the general principle of syndrome differentiation and medication.
The *Jin Gui Yao Lue* discusses the pulses of Fei Yong and Fei Wei: A rapid pulse at the cunkou position, accompanied by cough and the presence of turbid saliva and froth in the mouth, indicates Fei Wei. If the mouth feels parched and dry, coughing causes hidden pain in the chest, and the pulse is slippery and rapid, this indicates Fei Yong, characterized by expectoration of pus and blood. A rapid and deficient pulse indicates Fei Wei, while a rapid and full pulse indicates Fei Yong.
It further states: A faint and rapid pulse at the cunkou position; faintness indicates wind, rapidity indicates heat; faintness leads to sweating, rapidity leads to aversion to cold. Wind invades the Wei (defensive) level, affecting exhalation so it does not penetrate deeply; heat overwhelms the Ying (nutritive) level, affecting inhalation so it does not exit smoothly. Wind damages the skin and hair; heat damages the blood vessels. When wind lodges in the lung, the patient coughs, experiences dry mouth, wheezing, and chest fullness, feels dry but not thirsty, spits turbid froth intermittently, and suffers from intermittent chills. Wherever heat passes, blood stagnates, accumulating to form pus and abscesses, with expectorated material resembling rice porridge. If treated at the initial stage, rescue is possible; once pus forms, death ensues.
When cough begins with immediate upper jiao wheezing and urgency, it is caused by external invasion of wind-cold. The pulse must be floating. It is appropriate to use the method of Yue Bi Jia Ban Xia Tang (Ephedra, Magnolia Flower, and Pinellia Decoction) or Xiao Qing Long Jia Shi Gao Tang (Minor Blue Green Dragon Decoction with Gypsum) to urgently disperse the exterior. Otherwise, this marks the beginning of Fei Yong or Fei Wei. One must urgently scatter pathogens and direct qi downward to clear the lung. However, treatment must distinguish between exterior/interior and excess/deficiency to avoid erroneous application, which would only increase the patient's distress.
Cheng Jiaoqian stated: In Fei Wei, qi deficiency prevents the transformation of blood, causing blood to dry and cease flowing, rising only with boiling fire. Excessive fire attacks Metal (lung), failing to generate qi and blood but instead generating phlegm. Thus, lacking blood and fluids, the withered Metal is scorched by fire; how can the lung lobes not become charred? The lung resides at the highest position among the zang organs, with fine orifices distributed between its lobes. The steaming moisture from the five zang organs enters through the lung root as qi, and exits through the spring-like openings as fluid during exhalation. This breathing is endless, irrigating the whole body, known as "water issuing from the high source." Once subjected to fire, the exhalation pathway becomes obstructed like inhalation; blood seeps through these openings, blocking the orifices, causing cough. Coughing leads to bleeding; more coughing leads to more seepage, and more seepage leads to more coughing. Over time, all fine orifices close. During inhalation, fire is drawn up to the throat, causing itching or sores; during exhalation, no fluid emerges, and the six lobes gradually wither and char. This is the origin of Fei Wei. In the Bu Fei San formula, Xing Ren (Almond Seed) and Da Li Zi (Arctii Fructus/Niu Bang Zi) are used to ventilate the orifices; E Jiao (Donkey-hide Gelatin) is used to resolve orifice stasis; Ma Ling (Aristolochiae Manshuriensis Fructus/Mar Luo Ling) is used to clear orifice heat. Although the formula contains no direct lung-tonifying herbs, Nuomi (Glutinous Rice) is used to tonify the spleen, taking advantage of the mother element (Earth generating Metal) reaching the lung. The intent of this prescription focuses entirely on the fine orifices of the lung, ensuring unobstructed respiration there, allowing qi to enter and fluid to exit, thereby tonifying the lung naturally without direct supplementation.