东垣曰∶古人以脉上辨内外伤于人迎气口，人迎脉大于气口为外伤，气口脉大于人迎为
内伤，此辨固是，但其说有所未尽耳。外感风寒皆有余之证，是从前客邪来也，其病必见于
左手，左手主表，乃行阳二十五度。内伤饮食及饮食不节，劳役所伤，皆不足之病也，必见
于右手，右手主里，乃行阴二十五度。故外感寒邪，则独左手人迎脉浮紧，按之洪大。紧者
，后甚于弦，是足太阳寒水之脉；按之洪大而有力，中见手少阴心火之脉；丁与壬合，内显
洪大，乃伤寒脉也。若外感风邪，则人迎脉缓，而大于气口一倍，或两倍、三倍。内伤饮食
，则右寸气口脉大于人迎一倍；伤之重者，过在少阴则两倍，太阴则三倍，此内伤饮食之脉
。
愚谓东垣发明内伤一证，其功诚为不小，凡其所论，有的确不易者，兹俱详述于后，或
稍有疑似者，姑已置之。至若辨脉一条，则有不容不辨者，乃以左为人迎主表，右为气口主
里；外感则左手人迎浮紧，内伤则右手气口脉大，此其长中之短也。夫人迎本阳明胃脉，在
结喉两旁，气口本太阴肺脉，两手所同称也。迨晋之王叔和不知何所取义，突谓左为人迎，
右为气口，左以候表，右以候里，而东垣宗之，故亦以为言，则大谬矣。且内伤外感之分，
乃一表一里，不容紊也。如肝肾在左，岂无里乎？肠胃在右，岂非表乎？即如仲景之论伤寒，
亦但以浮大为表，沉细为里。历溯仲景之前，以至仓、扁、轩、岐，初未闻有以左右言表里
者。迨自叔和之后，则悉宗其谬，而传始讹矣。
即无论六经之表里，而但以亲历所见者言之，如脉见紧数，此寒邪外感也，然未有左数
而右不数者。又如所云左大者为风邪，右大者为饮食，则尤其不然。夫人生禀赋之常，凡右
脉大者，十居八九，左脉大者，十居一二。若果阳邪在表，则大者更大，岂以右脉本大，而
可认为食乎？若饮食在脏，则强者愈强，岂以左脉本强，而可认为寒乎？不知此之大而紧，则
彼之小者亦必紧，彼之小而缓，则此之大者亦必缓，若因其偏强而即起偏见，则忘其本体者
多矣。故以大小言，则脉体有不同，可以左右分也；若以迟疾言，则息数本相应，不可以左
右分也。矧左表右里之说，既非经旨，亦非病征，乌足信哉！
或曰∶然则内伤外感何以辨之？曰∶六脉俱有表里，左右各有阴阳。外感者，两手俱紧
数，但当以有力无力分阴证阳证。内伤者，左右俱缓大，又必以有神无神辨虚邪实邪。然必
察左右之常体，以参久暂之病因，斯可得脉证之真。不然，则表里误认，攻补倒施。自叔和
至今，凡阴受其殃者，不知几多人矣，此不得不为辨正，以为东垣之一助也。此别有辨，在
《类经·藏象类》第十一篇，所当互证。
李东垣说：古人通过人迎脉和气口脉来辨别内伤和外感。人迎脉大于气口脉是外感，气口脉大于人迎脉是内伤，这种辨别固然正确，但他们的说法还有不详尽的地方。外感风寒都属于有余的实证，是由外来邪气引起的，病症必然表现在左手，左手主表，运行阳气二十五度。内伤饮食及饮食不节制、劳役过度所致的损伤，都属于不足的虚证，必然表现在右手，右手主里，运行阴气二十五度。所以外感寒邪，则独见左手人迎脉浮紧，按之洪大。紧脉，比弦脉更甚，这是足太阳寒水经的脉象；按之洪大且有力，中间显现出手少阴心火经的脉象；丁（阴火）与壬（阳水）相合，内部显现出洪大的脉象，这就是伤寒的脉象。如果外感风邪，则人迎脉缓，且比气口脉大一倍，或两倍、三倍。内伤饮食，则右寸气口脉比人迎脉大一倍；伤势重的，涉及少阴经则大二倍，涉及太阴经则大三倍，这就是内伤饮食的脉象。
我认为李东垣阐发内伤这一病证，功劳确实不小，凡是他论述中确切无疑的内容，这里都详细陈述在后面，如果有稍显疑似之处，暂且搁置不论。至于辨别脉象这一条，则有不容不辨明的地方，即把左脉当作人迎主表，右脉当作气口主里；外感则左手人迎脉浮紧，内伤则右手气口脉大，这是其理论中的短处。其实人迎本是阳明胃经的脉，位于结喉两旁，气口本是太阴肺经的脉，两手都称为气口。到了晋代的王叔和不知依据什么意义，突然说左脉为人迎，右脉为气口，左脉候表，右脉候里，而李东垣遵循了这一说法，所以也这样讲，这就大错特错了。况且内伤与外感的区别，在于一表一里，不容混淆。比如肝肾在左侧，难道没有里证吗？肠胃在右侧，难道不是表证吗？就像张仲景论述伤寒，也只是以浮大为表，沉细为里。追溯张仲景之前，直到仓公、扁鹊、轩辕、岐伯，从未听说过用左右来区分表里的。等到王叔和之后，大家都遵循他的谬误，传承才开始讹误。
即使不论六经的表里关系，仅从我亲历所见来说，如脉象见紧数，这是寒邪外感，但没有左脉数而右脉不数的情况。又如所谓左脉大为风邪，右脉大为饮食，这尤其不对。人的生理常态，凡是右脉大的，占十分之八九，左脉大的，只占十分之一二。如果确实是阳邪在表，那么大的脉会更大，怎么能因为右脉本来大，就认为是食积呢？如果饮食停滞在脏，那么强的脉会更强，怎么能因为左脉本来强，就认为是寒邪呢？不知道这里的脉大而紧，那里的脉小也必然紧；那里的脉小而缓，这里的脉大也必然缓，如果因为脉象偏强就产生偏见，就会忘记脉象的本体特征的人很多了。所以从大小来看，脉体有不同，可以分左右；但从迟疾来看，呼吸次数本应相应，不可以分左右。况且左表右里的说法，既不符合经典旨意，也不是病征表现，哪里值得相信呢！
有人问：那么内伤和外感如何辨别呢？我说：六脉都有表里，左右各有阴阳。外感病，两手脉都紧数，但应当以有力无力来区分阴证和阳证。内伤病，左右脉都缓大，又必须以有神无神来辨别虚邪和实邪。然而必须考察左右脉的常态，以参考病因的久暂，这样才能得到脉证的真相。否则，就会误认表里，攻补颠倒。自王叔和至今，凡受其害的人，不知有多少，这是不得不加以辨正，作为对李东垣理论的补充。这一点另有辨析，在《类经·藏象类》第十一篇，应当互相印证。
Li Dongyuan stated: The ancients distinguished between external injuries (exogenous diseases) and internal injuries by comparing the Renying pulse and the Qikou pulse. When the Renying pulse is larger than the Qikou pulse, it indicates an external injury; when the Qikou pulse is larger than the Renying pulse, it indicates an internal injury. While this distinction is correct, their explanation is not exhaustive. External contraction of wind-cold belongs to excess syndromes caused by invading pathogenic factors, and the pathology must manifest on the left hand. The left hand governs the exterior (Biao), corresponding to the circulation of Yang qi for twenty-five cycles. Internal injuries due to improper diet, dietary irregularities, or overwork belong to deficiency syndromes, and the pathology must manifest on the right hand. The right hand governs the interior (Li), corresponding to the circulation of Yin qi for twenty-five cycles. Therefore, in cases of external cold contraction, only the left-hand Renying pulse appears floating and tight, feeling surging and large upon pressure. A tight pulse is more severe than a string-like pulse, representing the pulse of the Foot-Taiyang Bladder channel (Cold Water); feeling surging and large with strength reveals the pulse of the Hand-Shaoyin Heart channel (Fire). The combination of Ding (Yin Fire) and Ren (Yang Water) internally manifests as a surging-large pulse, which is the pulse pattern of Cold Damage (Shanghan). If external wind contraction occurs, the Renying pulse is slow and larger than the Qikou pulse by one, two, or three times. In cases of internal dietary injury, the right Cun position of the Qikou pulse is larger than the Renying pulse by one time; if the injury is severe, involving the Shaoyin channel, it is larger by two times, and involving the Taiyin channel, by three times. This constitutes the pulse pattern of internal dietary injury.
I believe that Li Dongyuan’s elucidation of the syndrome of internal injury has been of considerable merit. All his discussions that are precise and unchangeable are detailed below, while those that are slightly ambiguous are temporarily set aside. Regarding the differentiation of pulses, however, there is no room for failure to clarify the error of treating the left pulse as Renying governing the exterior and the right pulse as Qikou governing the interior; i.e., external contraction presents with a floating-tight left Renying pulse, while internal injury presents with a large right Qikou pulse. This is a shortcoming within his otherwise strong theory. Actually, the Renying pulse originally refers to the Stomach channel of Yangming, located on both sides of the laryngeal prominence, while the Qikou pulse refers to the Lung channel of Taiyin; both hands are commonly referred to as Qikou. It was Wang Shuhe of the Jin Dynasty who, for unknown reasons, abruptly claimed that the left pulse is Renying and the right is Qikou, with the left observing the exterior and the right observing the interior. Li Dongyuan followed this view and thus repeated it, which is a major error. Furthermore, the distinction between internal and external injuries lies in the difference between interior and exterior, which must not be confused. For instance, the Liver and Kidney are on the left; do they not have interior aspects? The Intestines and Stomach are on the right; are they not exterior aspects? Even Zhang Zhongjing’s discussion of Cold Damage distinguishes the exterior as floating-large and the interior as deep-thin. Tracing back before Zhang Zhongjing to Cang Gong, Bian Que, Xuanyuan, and Qibo, there was never mention of distinguishing interior/exterior by left/right. Only after Wang Shuhe did everyone follow his fallacy, leading to erroneous transmission.
Regardless of the exterior/interior relationships of the Six Channels, speaking from personal experience: if the pulse is tight and rapid, this indicates external cold contraction; however, there is no case where the left pulse is rapid while the right is not. Similarly, the claim that a large left pulse indicates wind evil and a large right pulse indicates dietary retention is particularly incorrect. In normal human constitution, nine or ten out of ten people have larger right pulses, while only one or two out of ten have larger left pulses. If yang pathogens are truly in the exterior, the large pulse would become even larger; how can one attribute it to food retention simply because the right pulse is naturally large? If food stagnates in the Zang organs, the strong pulse would become stronger; how can one attribute it to cold simply because the left pulse is naturally strong? One should not fail to realize that where the pulse is large and tight elsewhere, the smaller pulse there must also be tight; where the pulse is small and slow elsewhere, the large pulse here must also be slow. If one forms biased judgments based on partial strength, many will forget the fundamental nature of the pulse. Therefore, regarding size, pulse bodies differ and can be distinguished by left/right; but regarding speed, respiratory rates correspond and cannot be distinguished by left/right. Moreover, the theory of left-exterior/right-interior contradicts classic principles and does not reflect pathological signs; how can it be trusted?
Someone might ask: Then how should internal and external injuries be differentiated? I reply: All six pulses contain aspects of interior and exterior, and both left and right possess Yin and Yang. In external injuries, both hands present with tight and rapid pulses, but one must distinguish Yin and Yang syndromes based on strength or weakness. In internal injuries, both left and right pulses are slow and large, and one must differentiate deficiency from excess based on the presence or absence of "Shen" (Spirit/Vitality). However, one must examine the normal state of the left and right pulses to reference the duration of the etiology, thereby obtaining the true nature of the pulse and symptoms. Otherwise, interior/exterior may be misidentified, and attacking/supplementing methods may be reversed. Since Wang Shuhe to the present day, countless individuals have suffered harm from this; hence, it is necessary to correct these errors to assist Li Dongyuan’s work. This topic is discussed separately in *Lei Jing* (Classified Classic), Volume 10, Chapter 11, under Zang-Fu Manifestations, and should be cross-referenced.