脉为人之神。气血之本。而见于营之行。营之行也。其根原有二。一出于中焦之谷神。化精液以输肺。以治节施之
隧道。故营血之能通流。实胃气为之充澈。此脉之本于胃气也。一起于太冲。而出少阴肾。下汇血海于厥阴。上发真阳
于太阳。此太冲之精气。能灌溉十二经。得与阳明胃之盛气。同驻中焦。共为宗气。故亦得与营。俱行十二经。而备五
十营。脉至五十营。则先后天之气合。而五脏之真备矣。以是上朝于肺。肺统行之。故曰气口成寸。以决死生。决死生
者。以气口能显胃气形藏真。占四时度六部。有诸中者。必形诸外。而无差忒。此脉之所以为人之神也。内经论脉必自
下而上推。始于季胁。以次附上。定其部位。自肘中曲池。量至神门。得一尺为尺。自尺至寸。得一寸为寸。其诊先尺
后寸。先阴后阳者。以人身阴阳。皆起于足下。五脏之气。会于章门。章门在季胁之次。脉从三阴起足三阳而上之。先
会于此。故内经诏人以脉必自下而上也。至于诊之精微。其占亦有二。一呼脉行三寸。一吸脉行三寸。呼吸脉行六寸常
流无间。昼夜六时。而为五十营。此以流行者占之也。五十动不一代。乃为生人之太和。不及是者。为脏无气。命曰狂
生。狂生者。反太和也。左以候左。右以候右。上以候上。下以候下。前以候前。后以候后。六部一定。候之不移。而
以五脏为占。此以部位占之也。原其然者。肺统元气。为心血脉之相。非惟能朝百脉。亦能显百脉。脉虽藉营气之行而
充满之。而其所以能充满者。皆肺神藏真之所 泓。此其中之胎涵映澈。行者居者。各为充满。非以一流行而尽之也。
盖其元神能常照百脉。为五脏镜。以显其纯疵。故太渊一脉。五脏之全体俱现。是以上下左右可占。六部可诊也。然人
之阴阳必奉天而应四 。故春弦夏钩秋毛冬石。虽六脉各为脏主。而有不得不听令于时者。此由天人葆合。故人气有不
离如此也。乃人又有平生之诊者。阴阳之禀。气态各不同。则其脉亦异。如六阴六阳。以至老少肥瘦。脉必不一。善脉
者。必先察其本元之候。其胃气藏真。与四时之正反。老少之攸分。而后及其病脉。以兹四诊。兼之望闻问谓之七诊。
而脉之道得矣。今世以左手为人迎。此出自难经。叔和祖之。不知人迎者。阳明胃之本。输在结喉两旁动脉者。是此六
阳之所迎。古人以候六腑之阳。而察其盛衰。若以左之寸口当之。岂人迎之所候哉。趺阳者。乃穴之动脉。在足趺三寸
之间。是胃脉之下行。复上与太冲之脉合。故得先后天并符之气会合于此。为人之根蒂。死生之诊。于是最切。故仲景
法趺阳与少阴同诊。一诊先天。一诊后天。每并取以决百病。今人废之。此仲景所斥。为按手不及足之庸工也。
脉是人体的精神所在，也是气血的根本，它显现于营气的运行之中。营气的运行，其根源有两个方面：一是源于中焦的水谷精微（谷神），转化为精液输送至肺，由肺的治节功能施布于经络隧道。因此，营血能够通畅流动，实际上是依靠胃气的充养和贯通，这是脉气根源于胃气的表现。二是起于太冲穴，出于少阴肾经，向下汇聚于厥阴肝经的血海，向上激发真阳于太阳经。太冲的精气能够灌溉十二经脉，并与阳明胃的盛气共同驻留于中焦，合为宗气。所以，它也能随着营气一起运行于十二经脉，完成五十次循环（五十营）。当脉气运行达到五十营时，先天之气与后天之气相合，五脏的真气也就完备了。由此上朝于肺，由肺统率运行，所以说“气口成寸”，通过诊察寸口脉可以决断生死。决断生死的依据是，气口能显露胃气和脏腑的真气，占测四时变化及六部脉象，体内有病变必然反映在体表，且没有差错，这就是脉之所以成为人体精神外在表现的原因。
《内经》论述脉法，一定是从下往上推导，始于季胁部位，依次向上推演，确定脉的部位。从肘部的曲池穴量到腕部的神门穴，得一尺的长度定为“尺”；从尺部到寸部，得一寸的长度定为“寸”。诊脉先诊尺部后诊寸部，先诊阴脉后诊阳脉，是因为人身体的阴阳之气都起始于足下，五脏之气会聚于章门穴。章门穴位于季胁旁边，脉气从三阴经起于足部，沿足三阳经上行，首先会聚于此。所以《内经》教导人们诊脉必须从下往上进行。至于诊脉的精微之处，其占测方法也有两种：一呼之间脉行三寸，一吸之间脉行三寸，呼吸一次脉行六寸，常流无间断，昼夜六个时辰，共完成五十营。这是以脉气的流行来占测。脉搏跳动五十次而不出现代脉（间歇脉），是生命和谐的状态；达不到这个次数，说明脏腑无气，称为“狂生”。“狂生”是指违背了太和之气。左手脉候左侧身体，右手脉候右侧身体，上部脉候上部身体，下部脉候下部身体，前部脉候前部身体，后部脉候后部身体。六部脉位固定，候诊时不移易，并以五脏作为占测依据。这是以部位来占测。
探究其原理，肺统帅元气，是心血脉的宰相，不仅能朝会百脉，也能显映百脉。脉虽然借助营气的运行而充满，但其之所以能充满，都是肺神藏真的深润所致。其中蕴含的清澈映照，行者居者，各自充满，并非仅仅靠一种流行就能完全解释。大概因为元神能常照百脉，如同五脏的镜子，以显示其纯正或瑕疵。所以太渊一脉，五脏的全体都会显现出来，因此上下左右可以占测，六部可以诊察。然而人的阴阳必须顺应天道并回应四时变化，所以春季脉弦、夏季脉钩、秋季脉毛、冬季脉石。虽然六部脉各自主管不同的脏腑，但有不得不听从时令命令的情况。这是由于天人合一的缘故，所以人气不能不如此。
此外，人还有平素的脉象，由于禀赋的阴阳不同，气态各异，其脉象也不同。如六阴六阳，以及老少肥瘦，脉象必然不一样。善于诊脉的人，必须先察探其本元的状态，分辨胃气藏真与四时的顺逆，区分老少的不同，然后才去诊察病脉。将这种四诊方法与望、闻、问、切结合，脉学的道理就完备了。
当今世人将左手寸口脉当作人迎脉，这出自《难经》，王叔和沿袭了这种做法。他们不知道人迎脉是阳明胃经的本脉，输注在结喉两旁的动脉处，是六阳经所迎受的地方。古人用它来候察六腑之阳气，以观察其盛衰。如果将左手的寸口脉当作人迎脉，哪里还是人迎脉所应该候察的内容呢？趺阳脉，是足背上的动脉，位于足背三寸之间，是胃脉下行，再向上与太冲脉相合的地方。所以这里汇聚了先后天并符的气机，是人体的根本，死生诊察的关键所在。所以张仲景的法度中，趺阳脉与少阴脉同诊，一诊先天，一诊后天，常常同时取用以决断各种疾病。现在的人废弃了这种方法，这正是张仲景所斥责的，认为是手诊不及足诊的平庸医生。
The pulse is the spirit of the human body, the root of Qi and Blood, manifesting in the circulation of Ying (Nutritive) Qi. The circulation of Ying Qi has two origins: one originates from the grain spirit (Gu Shen) of the Middle Jiao, transforming into essence and fluid to be transported to the Lung, which distributes it via its governance and regulation function into the meridians and collaterals. Thus, the free flow of Ying Blood is actually filled and cleared by Stomach Qi; this is how the pulse is rooted in Stomach Qi. The other origin begins at Taichong (LR3), emerges from the Shaoyin Kidney channel, gathers downward into the Blood Sea of the Jueyin Liver channel, and ascends to stimulate True Yang in the Taiyang channel. The essence and Qi of Taichong can irrigate the Twelve Meridians, residing together with the abundant Qi of the Yangming Stomach in the Middle Jiao, forming Zong (Gathering) Qi. Therefore, it also travels with Ying Qi through the Twelve Meridians, completing fifty cycles (Wu Shi Ying). When the pulse completes fifty cycles, the Postnatal and Prenatal Qi combine, and the true Qi of the Five Zang organs becomes complete. From there, it ascends to the Lung, which governs its distribution. Hence, it is said that "the Qi Kou (Radial Artery) forms the Cun inch," allowing one to determine life and death. Determining life and death relies on the fact that the Qi Kou reveals the form of Stomach Qi and the true Qi of the Zang organs, assessing the four seasons and the six positions. What exists internally must manifest externally without error; this is why the pulse serves as the spirit of the human body.
In the *Nei Jing* (Inner Canon), pulse discussion always deduces from bottom to top, starting from the costal margin, progressively moving upward to define locations. Measuring from Quchi (LI11) in the elbow to Shenmen (HT7) at the wrist yields one chi (foot); measuring from Chi to Cun yields one cun (inch). Pulse diagnosis first examines the Chi position then the Cun position, Yin channels before Yang channels, because the Yin and Yang of the human body both originate from the soles of the feet. The Qi of the Five Zang organs converges at Zhangmen (LR13). Zhangmen is located next to the costal margin. Pulse Qi starts from the Three Yin channels at the feet and ascends via the Three Yang channels of the foot, converging here first. Thus, the *Nei Jing* instructs that pulse diagnosis must proceed from bottom to top.
Regarding the subtlety of pulse diagnosis, there are two aspects of assessment. In one exhalation, the pulse moves three cun; in one inhalation, it moves three cun. With each breath cycle, the pulse moves six cun continuously without interruption. Over six hours of day and night, it completes fifty Ying cycles. This assesses based on continuous flow. Fifty beats without a intermittent pulse (Dai Mai) represents the supreme harmony (Tai He) of life; falling short indicates organ deficiency of Qi, termed "Kuang Sheng" (Mad Life). Kuang Sheng contradicts Tai He. The left side diagnoses the left, the right side diagnoses the right; the upper part diagnoses the upper, the lower part diagnoses the lower; the anterior diagnoses the anterior, the posterior diagnoses the posterior. Once the six positions are fixed, the diagnosis remains steady, using the Five Zang organs as the basis for assessment. This is assessment by position.
Investigating the principle, the Lung commands Yuan (Original) Qi and acts as the minister of the Heart and blood vessels. It not only receives all pulses but also manifests them. Although the pulse is filled by the circulation of Ying Qi, the reason it can be filled lies in the profound nourishment of the Lung's Shen and Zang True Qi. The clarity contained within ensures that both circulating and stationary elements are fully manifested, not merely explained by a single flow. Essentially, the Original Shen constantly illuminates all pulses, acting as a mirror for the Five Zang organs to reveal purity or defect. Thus, at the Taiyuan (LU9) pulse point, the entirety of the Five Zang organs is reflected, allowing assessment of up/down and left/right, and diagnosis of the six positions.
However, human Yin and Yang must follow Heaven and respond to the Four Seasons. Therefore, Spring pulses are wiry (Xian), Summer pulses are hook-like (Gou), Autumn pulses are floating/hairy (Mao), and Winter pulses are stone-like (Shi). Although the six pulses are each governed by specific Zang organs, they must obey seasonal commands due to the unity of Heaven and Humanity. Thus, human Qi cannot be otherwise.
Furthermore, individuals have baseline pulses. Due to different constitutions of Yin and Yang and varying Qi states, their pulses differ. Whether Six Yin/Six Yang, old/young, fat/thin, the pulse will vary. A skilled pulse diagnostician must first examine the state of the original constitution, distinguishing Stomach Qi and Zang True Qi against seasonal compliance, and differentiating between young and old, before diagnosing pathological pulses. Combining these four diagnostic methods with Observation, Auscultation/Olfaction, Inquiry, and Palpation completes the art of pulse diagnosis.
Currently, people treat the left hand's Cun Kou as Ren Ying (Human Welcome), originating from the *Nan Jing*, adopted by Wang Shuhe. They do not realize that Ren Ying is the root of the Yangming Stomach channel, located at the arterial pulse beside the larynx, where the Six Yang channels converge. Ancients used it to monitor the Yang of the Six Fu organs to observe excess or deficiency. If the left Cun Kou is substituted, it is no longer what Ren Ying should monitor. Fuyang (Foot Yang) is an arterial point on the dorsum of the foot, between three cun, representing the descending Stomach pulse merging upward with the Taichong pulse. Here, Prenatal and Postnatal Qi meet, serving as the root of life and the critical site for determining life and death. Therefore, Zhang Zhongjing's method diagnoses Fuyang alongside Shaoyin: one monitors Prenatal Qi, the other Postnatal Qi, often using both to decide upon myriad diseases. Modern practitioners discard this, which Zhang Zhongjing criticized as the work of mediocre physicians who palpate the hands but neglect the feet.