膜原者，夹缝之处也。人之一身，皮里肉外，皮与肉之交际有隙焉，即原也；膜托腹里
，膜
与腹之交际有隙焉，即原也；肠胃之体皆夹层，夹层之中，即原也；脏腑之系，形如脂膜，
夹层中空，即原也；膈盲之体，横隔中焦，夹层中空，莫非原也!原者，平野广大之谓也。
故能邪伏其中，不碍大气之往来，古书所谓∶皮中淫淫如虫行。及行痹、周痹，左右上下相
移者，皆在皮肉夹缝之中也。药力亦复不能直达其处，何者?药力不过鼓正气以攻邪。今气
道宽大，中虽有邪，而正气仍绰有可行之道，即不必与邪气相值矣。若夫吴又可所谓∶瘟疫
之邪，盈溢膜原，是邪气自行发动，与正气相触也。犹以外皮既坚，内膜亦固，中道宽大，
疏泄维艰，故有屡淤到胃、屡泄始尽之法，更有必俟复淤到胃，方能再下之议，此从里泄也
。叶天土治温热，有再从里托于表之说，是从外泄也。故养生者，只当闭密，使邪勿入膜原
。即入膜原，必待发病，邪气舒张，始能攻泄，当其未发，邪正相避，无从着力。故《难经
》谓∶温病之脉，行在诸经，不知何经之动也，各随其所在而取之。即俟其既动而后治之之
义也。既动则有所动之专经，而可施专攻矣。《内经》四时之伤，伏气为病，皆伏于膜原也
。吴又可既知有膜原之事，又力斥伏气之非，谓∶人身之中，何处可客邪伏，越时许久，而
后发耶?仍未彻膜原之情形者也。夫果百邪皆即伤即病，是人身只有邪伤肤表之病，何以有
邪在膜原之病?且如人之一病，累愈累发 ，或一年，或数年，不能除根者，当其暂愈，岂非
内伏之明验耶?其所伏，必不在呼吸之冲道，亦必不在血气之细络，而必在空阔无所拘束之
部，此即膜原是也。然而邪又何以遽入膜原也?曰∶其由皮毛入者，方始中于表也，必发寒
热；由呼吸入者，其始中于肺也，必发呛咳；中于胃也，必发呕满。或以其势微而忍之，或
攻之而未尽，适遇劳力汗出，及与房室，膜原之中大气暂虚，遂摄入之而不觉矣。亦有不发
寒热、咳、呕，而浸润渐渍以深入者。邪入膜原，身中即隐隐常不自在，或头痛晕眩，或身
常汗出，或常畏寒畏热，或骤苦气短，不能任劳，或四肢少力，或手心常热，或小便赤涩，
或大便常泄，或大便常秘，或饮食不消，或饮食倍增，或口常渴，或口淡少味，或舌苔倍浓
，或夜不成眠，或多梦纷纭。及其发也。随邪毒之微甚，正力之强弱，而变化焉。寒化为温
者，其阳盛也；风化为泄者，其阴盛也；暑化为疟者，发于表也；湿化为咳者，发于里也；
更有发为痹痛，身中累累如桃李核，久不愈者；有发为瘾疹，发于一肢一脔，逐年应期即发
，不得断根者。尝治此证，疏表清里，展转搜剔，久而乃效。以其邪在膜原，不在腠理，又
仅发于一脔，能与药力相避故也。当其既愈，中气必虚，《千金方》论治肿胀，必攻之使其
人虚弱，病乃可愈，即此义也。始表散之，继清泄之，乘其外发而散之，因其内留而泄之，
散而泄之，泄而散之，而邪可净矣，而其人有不虚弱者乎?是又在调理之得法也。常有调理
之后，余焰复炽，诸证微发，仍复间用攻泄，始得净尽者。甚矣!膜原之邪之不易治也。
膜原，是指人体内的夹缝之处。人的全身，在皮肤之内、肌肉之外，皮肤与肌肉交接的地方存在间隙，这就是“原”；腹膜托举着腹腔内部，腹膜与腹部脏器交接的地方存在间隙，这也是“原”；肠胃的形体都是夹层结构，夹层中间的部分，就是“原”；脏腑的系带，形状像脂膜一样，夹层中空，也是“原”；膈膜和盲膜的形体，横亘在中焦，夹层中空，没有不是“原”的地方！所谓“原”，是指平坦广阔的原野。所以邪气可以潜伏在其中，不阻碍大气的往来流通。古书中所说的：皮肤中瘙痒如虫爬行一般。以及行痹（疼痛游走不定）、周痹（疼痛周身上下移动），左右上下相互转移的症状，都是在皮肉夹缝之中产生的。药物的力量也不能直接到达那个部位，为什么呢？因为药力不过是鼓动正气来攻击邪气。现在气道宽大，虽然中间有邪气，但正气仍然有充足可行的道路，就不必一定要与邪气正面冲突了。至于吴又可所说的：瘟疫的邪气，充满溢满膜原，这是邪气自行发动，与正气相接触。就像外皮已经坚固，内膜也牢固，中间通道宽大，疏泄非常艰难，所以有屡次淤积到胃、多次泻下才能排尽的方法，更有必须等到再次淤积到胃，才能再次使用攻下法的议论，这是从体内向外排泄邪气。叶天士治疗温热病，有“再从里托于表”的说法，这是从体表向外排泄邪气。所以养生的人，只应当闭密腠理，使邪气不要进入膜原。即使邪气进入了膜原，也必须等到发病时，邪气舒张，才能进行攻伐排泄，当邪气尚未发作时，邪气与正气相互回避，无从着力。所以《难经》说：温病的脉象，运行在各条经脉中，不知道是哪条经脉发生变动，各自随着其所在部位而选取穴位治疗。这就是等待邪气已经发动后再进行治疗的意义。既然已经发动，就有特定发动的专属经脉，就可以实施专门的攻治了。《内经》所说四季受邪，伏气致病，都是潜伏在膜原中的。吴又可既然知道有膜原这回事，又极力排斥伏气理论的非议，说：人身之中，哪里可以让邪气潜伏，经过很长时间后才发作呢？他仍未透彻了解膜原的情形。如果果然所有邪气都是即时受伤即时发病，那么人身只有邪气伤害肤表的病，怎么会有邪气在膜原的病呢？况且比如一个人患病，屡次痊愈屡次复发，或一年，或数年，不能除根的时候，当其暂时痊愈，难道不是内伏邪气的明显验证吗？所潜伏的邪气，一定不在呼吸的冲要之道，也一定不在气血的细微络脉，而一定在空阔无所拘束的部位，这就是膜原。然而邪气又为什么能迅速进入膜原呢？回答说：由皮毛进入的，刚开始是伤及体表，必定会发寒热；由呼吸进入的，刚开始是伤及肺脏，必定会引发呛咳；伤及胃腑，必定会引发呕吐胀满。有的人因为其势头微弱而忍耐它，或者攻伐邪气却没有除尽，恰好遇到劳累用力出汗，以及房事过度，膜原中的大气暂时虚弱，于是邪气趁机摄入而人不觉察。也有不发寒热、咳嗽、呕吐，而是浸润渗透逐渐深入的情况。邪气进入膜原，身体内部就会隐隐常常感到不自在，有的头痛头晕，有的身体经常出汗，有的经常畏寒畏热，有的突然痛苦气短，不能从事体力劳动，有的四肢无力，有的手心经常发热，有的小便红赤涩痛，有的大便经常泄泻，有的大便经常秘结，有的饮食不消化，有的食欲倍增，有的口中常渴，有的口淡无味，有的舌苔加倍浓厚，有的夜里无法入睡，有的多梦纷纭。等到邪气发作时，会随着邪毒的轻重、正气的强弱而变化。寒邪转化为温病的，是因为阳气盛；风邪转化为泄泻的，是因为阴气盛；暑邪转化为疟疾的，是发于体表；湿邪转化为咳嗽的，是发于体内；更有发作成为痹痛，身体中累累出现像桃李核一样的肿块，久不愈合的；有发作成为瘾疹（荨麻疹），发作在一肢一节，每年按时即发，不得断根的。我曾经治疗这类病症，疏解表邪、清泄里热，辗转搜剔病邪，很久才见效。因为邪气在膜原，不在腠理，而且仅发作在一肢一节，能与药力相避开的原因。当它既已痊愈，中气必定虚弱，《千金方》论述治疗肿胀，必须攻伐使其人虚弱，病才能痊愈，就是这个道理。开始用表散法，接着用清泄法，趁着邪气外发而疏散它，因为邪气内留而排泄它，散而泄之，泄而散之，这样邪气就可以净尽了，那人能不虚弱吗？这又在于调理是否得法。常有调理之后，余焰重新炽盛，各种症状轻微发作，仍然需要间或使用攻泄法，才得以彻底清除。唉！膜原的邪气真是不容易治疗啊。
Membrane source (Moyuan, the space between the skin/muscle and internal organs) refers to the crevice areas. In the human body, outside the skin but inside the flesh, there is a gap where the skin and muscle interface; this is the "Yuan" (original space); the peritoneum supports the abdominal interior, and there is a gap where the membrane interfaces with the abdomen; this is also the "Yuan"; the structure of the intestines and stomach consists of double layers, and the middle of these double layers is the "Yuan"; the ligaments of the zang-fu organs are shaped like fatty membranes, hollow in the middle of the double layers, which is also the "Yuan"; the diaphragm and blind membrane span the middle jiao, hollow in the middle of the double layers, all of which are "Yuan"! "Yuan" refers to flat, vast plains. Therefore, pathogenic factors can lie dormant within it without obstructing the flow of vital qi (Zhengqi). Ancient texts mention: itching in the skin as if insects were crawling. As well as Xing Bi (Bi syndrome with wandering pain) and Zhou Bi (Bi syndrome with pain moving up and down), symptoms that shift left, right, up, and down, all occur in the crevices between skin and muscle. The power of medicine cannot directly reach this place either. Why? Because medicinal power merely stimulates Zhengqi to attack pathogens. Now, the Qi pathways are wide; although pathogens exist in the middle, Zhengqi still has ample room to move, so it need not necessarily confront the pathogens directly. Regarding Wu Keyi's statement: the pathogenic factors of plague fill and overflow the Membrane Source; this is when pathogens activate themselves and touch Zhengqi. It is like the outer skin being hard and the inner membrane being solid, with a wide central channel making drainage difficult. Thus, there are methods requiring repeated stagnation reaching the Stomach and repeated purging to exhaust the pathogens, and discussions stating one must wait for re-stagnation reaching the Stomach before purging again; this is draining from the interior. Ye Tianshi's treatment of warm diseases includes the theory of "draining from the interior to support the exterior," which is draining from the exterior. Therefore, those who practice health preservation should only keep the pores closed and dense, preventing pathogens from entering the Membrane Source. Even if pathogens enter the Membrane Source, they must wait until disease manifests, when pathogens expand, to be attacked and drained. When not yet manifested, pathogens and Zhengqi avoid each other, leaving no point of leverage. Thus, *Nan Jing* states: The pulse of warm diseases travels through various meridians; one does not know which meridian is active, so one treats according to its location. This implies treating after the pathogens have moved. Once moved, there is a specific meridian of activation, allowing for specific attacks. *Nei Jing* states that injuries from the four seasons, causing illness via latent Qi, all lie dormant in the Membrane Source. Wu Keyi knew of the Membrane Source but vehemently denied the concept of latent Qi, asking: Where in the human body could pathogens hide for long periods before manifesting? He had not thoroughly understood the condition of the Membrane Source. If indeed all pathogens cause immediate illness upon injury, then humans would only have diseases of pathogenic invasion of the skin surface; how could there be diseases of pathogens in the Membrane Source? Moreover, consider a person whose illness recurs repeatedly despite temporary remissions, lasting a year or years without root cure; during temporary remission, is this not clear evidence of internal dormancy? The dormant pathogens must not be in the main respiratory passages, nor in the fine collaterals of blood and Qi, but must be in empty, unconstrained spaces; this is the Membrane Source. However, why do pathogens quickly enter the Membrane Source? I say: Those entering via hair follicles initially invade the exterior, inevitably causing chills and fever; those entering via respiration initially invade the Lungs, inevitably causing coughing fits; those invading the Stomach inevitably cause vomiting and fullness. Some endure them due to weak intensity, or treatments fail to fully eliminate them. Coinciding with fatigue, sweating from exertion, or sexual activity, the vital Qi in the Membrane Source temporarily weakens, allowing pathogens to infiltrate unnoticed. There are also cases without chills, fever, cough, or vomiting, where pathogens infiltrate gradually and deeply. Upon entering the Membrane Source, the body feels constantly uneasy internally. Symptoms may include headache and dizziness, frequent sweating, aversion to cold and heat, sudden shortness of breath preventing labor, weakness in limbs, hot palms, red and scanty urine, frequent diarrhea, frequent constipation, indigestion, increased appetite, constant thirst, bland taste, thick tongue coating, insomnia, or vivid dreaming. When manifestation occurs, changes depend on the severity of pathogenic toxins and the strength of Zhengqi. Cold transforming into Warmth indicates Yang excess; Wind transforming into Diarrhea indicates Yin excess; Summerheat transforming into Malaria indicates exterior manifestation; Dampness transforming into Cough indicates interior manifestation. Others manifest as Bi pain with nodules like peach or plum stones persisting for a long time; or Urticaria recurring annually in specific limbs without root cure. I once treated such cases by releasing the exterior and clearing the interior, searching and eliminating pathogens repeatedly, achieving efficacy only after a long time. This is because pathogens are in the Membrane Source, not in the Couli (pores/skin texture), and manifest only in one limb, allowing them to evade medicinal force. After recovery, Middle Qi must be deficient. *Qianjin Fang* discusses treating swelling by purging until the patient becomes weak for cure; this illustrates the same principle. Initially dispersing via the exterior, then clearing via the interior; dispersing while pathogens emerge outward, purging while pathogens remain inward; alternating dispersion and purging cleanses the pathogens. Will the patient not become weak? This depends on proper regulation. Often, after regulation, residual fire reignites, symptoms recur mildly, requiring intermittent purging to completely eradicate. Indeed! Pathogens in the Membrane Source are extremely difficult to treat.