十六难曰∶脉有三部九候，有阴阳，有轻重，有六十首，一脉变为四时，离圣久远，各自是其法，何
以别之？
然∶是其病有内外证。
脉有三部九候，见后十八难。阴阳详第四难。轻重详第五难。六十首见《素问·方盛衰论》，王注谓
奇恒六十首，今世不存。或谓即各旺六十日之义。一脉变为四时，即十五难春弦、夏钩、秋毛、冬石也。
然脉法不一，离圣久远，各自是其法，何以别其是非长短也，是其病有内外证。言凡病但以内外之证验之，
自得其真，不必拘于诸法也。
其病为之奈何？
然∶假令得肝脉，其外证善洁，面青，善怒；其内证脐左有动气，按之牢若痛；其病
四肢满，闭淋，溲便难，转筋。有是者肝也，无是者非也。
得肝脉，诊得弦脉也，肝与胆合，为清净之腑，故善洁。青者木之色，肝属木，故面青。肝在志为怒，
故善怒。此外证之色脉情好也。脐左为肝木左升之部，动气、真气不能藏而发现于外也。牢者，气结而坚；
痛者，气郁而滞也；满，闭塞也。筋急则四肢满胀，《左氏传》云∶风淫末疾者是也。厥阴脉循阴器，肝
病故溲便难。转筋者，肝主筋，故病筋。此内证之部属及所
主病也。
假令得心脉，其外证面赤，口干，喜笑；其内证脐上有动气，按之牢若痛；其病烦心心痛，掌中热而 。
有是者心也、无是者非也。
得心脉，诊得钩脉也。心在色为赤，故面赤。心气通于舌，火上炎，故口干。心在声为笑，故喜笑。此
外证之色脉情好也。脐上心之部，动气，按之牢痛，心烦，乃心包络受邪，非真心病也。若心病，则旦占夕
死，夕占旦死矣。手厥阴心包络之脉，行于掌心，故掌中热。 、干呕也，心病火盛，故 。此内证之部属、
及所主病也。
假令得脾脉，其外证面黄，善噫，善思；善味。其内证当脐有动气，按之牢若痛；其病腹胀满，食不消，
体重节痛，怠惰嗜卧，四肢不收。有是者脾也，无是者非也。
得脾脉，诊得缓脉也。脾属土，在色为黄，故面黄。噫，嗳气也。《灵枢·口问篇》曰∶寒气客于胃，
厥气从下上散，复出于胃，故为噫。脾与胃合、故同病也。脾在志为思，故善思。
脾在窍为口，故善味。此外证之色脉情好也。脾位乎中，故动气当脐而牢痛也。脾主营运，运
行不健，故腹满食不消也。脾主肌肉，故体重。阳明主束骨而利机关，脾与胃合，故主节痛劳倦伤脾，
湿旺睥郁，皆主怠惰嗜卧也。脾主四肢，故四肢不收。此内证之部属及所主病也。
假令得肺脉，其外证面白，善嚏，悲愁不乐，欲哭；其内证脐右有动气，按之牢若痛；其病喘咳，
洒淅寒热。有是者肺也，无是者非也。
得肺脉，诊得毛脉也。肺在色为白，故面白。《灵枢·口问篇》曰∶阳气和利，满于心，出于鼻，
故嚏。肺气通于鼻，故善嚏。肺在志为忧，故悲愁不乐。在声为哭，故欲哭。此外证之色脉情好也。
脐右为肺金右降之部，动气按之牢痛者，肺气结也。肺主气，气逆故病喘咳。肺主皮毛。故洒淅寒热。
此内证之部属及所主病也。
假令得肾脉，其外证面黑，善恐欠；其内证脐下有动气，按之牢若痛；其病逆气，小腹急痛，泄
如下重，足胫寒而逆。有是者肾也，无是者非也。
得肾脉，诊得石脉也。肾在色为黑，故面黑，肾在志为恐，故善恐。《灵枢·口问篇》曰∶阴气
积于下，阳气未尽，阳引而上，阴引而下，故数欠。是肾主欠。此外证之色脉情好也。肾居最下，脐
下肾之位，肾气结，故动气按之牢痛。肾气不足，伤于冲脉，故病逆气。少阴之脉循少腹，故小腹急痛
也。肾者胃之关，今气虚，故为下重泄，谓食毕即思圊也。《灵枢·经脉篇》曰∶足少阴肾之脉，循
内踝之后，别入跟中，以上 内，故病足胫寒而逆。此内证之部
属及所主病也。泄如下重‘如’字，滑氏易作‘而’字，极是。
第十六难说：脉诊有三部九候，有阴阳之分，有轻重之别，还有六十首脉法。一脉随四季变化而不同，但距离圣人时代已久，各家各自坚持自己的方法，如何辨别其是非长短呢？
回答说：这要看疾病是否有外在和内在的证候。
关于脉的三部九候，详见第十八难；阴阳详细解释见第四难；轻重详细解释见第五难；六十首见于《素问·方盛衰论》，王冰注称为“奇恒六十首”，如今世间已失传。有人说是各脏气旺盛六十日的含义。“一脉变为四时”，即指第十五难中提到的春弦、夏钩、秋毛、冬石四种脉象。
既然脉法不一，且距离圣人时代久远，各家各自坚持己法，如何辨别其是非长短呢？关键在于疾病有外在和内在的证候。意思是凡是疾病，只要通过内外证候来验证，自然能得其真谛，不必拘泥于各种脉法。
那么具体是怎样的呢？
回答说：假如诊得肝脉，其外在证候是爱干净、面色青、易怒；其内在证候是肚脐左侧有搏动感，按压时坚硬且疼痛；其病症表现为四肢胀满、小便不通或淋漓不尽、排尿困难、筋脉抽搐。具备这些症状的是肝病，不具备这些症状的就不是肝病。
诊得肝脉，即是诊得弦脉（Chord-like pulse）。肝与胆相表里，为清净之腑，所以患者爱干净。青色属木，肝也属木，所以面色发青。肝在情志上主怒，所以容易发怒。这是外在证候中的色、脉及情志表现。肚脐左侧是肝木之气左升的部位，动气是因为真气不能内藏而显露于外。所谓“牢”，是指气结而坚实；所谓“痛”，是指气郁而阻滞；所谓“满”，是指闭塞不通。筋脉拘急则导致四肢胀满，《左氏传》中说：“风邪淫溢导致四肢末端的疾病”就是这种情况。厥阴经脉循行经过阴器，肝病故而导致小便排泄困难。转筋是因为肝主筋，所以病及筋脉。这是内在证候的部位归属及其所主的病症。
假如诊得心脉，其外在证候是面色红赤、口干、喜欢笑；其内在证候是肚脐上方有搏动感，按压时坚硬且疼痛；其病症表现为心烦心痛、手掌心发热并伴有干呕。具备这些症状的是心病，不具备这些症状的就不是心病。
诊得心脉，即是诊得钩脉（Hook-like pulse）。心在五色中对应红色，所以面色红赤。心气通于舌，心火炎上，所以口干。心在五声中对应笑，所以喜欢笑。这是外在证候中的色、脉及情志表现。肚脐上方是心的部位，出现动气，按压时感到坚硬疼痛、心烦，这实际上是心包络受邪所致，并非真正的心脏病变。如果是真正的心脏病，早晨诊断晚上就会死亡，晚上诊断早晨就会死亡。手厥阴心包络的经脉行于掌心，所以手心发热。干呕（Gan Ou, dry heaving）也是由于心火过盛所致。这是内在证候的部位归属及其所主的病症。
假如诊得脾脉，其外在证候是面色黄、经常嗳气、多思虑、味觉敏感；其内在证候是肚脐正中有搏动感，按压时坚硬且疼痛；其病症表现为腹部胀满、食物不消化、身体沉重关节疼痛、倦怠嗜卧、四肢无力收持。具备这些症状的是脾病，不具备这些症状的就不是脾病。
诊得脾脉，即是诊得缓脉（Slow/Relaxed pulse）。脾属土，在五色中对应黄色，所以面色发黄。噫，即嗳气。《灵枢·口问篇》说：“寒气客居在胃，逆气从下向上散出，再出于胃，所以形成嗳气。”脾与胃相表里，所以同病。脾在情志上主思，所以多思虑。脾在窍开于口，所以味觉敏感。这是外在证候中的色、脉及情志表现。脾位于中焦，所以动气出现在肚脐正中且按压坚硬疼痛。脾主营运功能，运行不健，所以腹部胀满、食物不消化。脾主肌肉，所以身体沉重。阳明经主束骨而利关节，脾与胃相表里，所以主节痛。劳倦伤脾，湿气旺盛导致脾郁，都主倦怠嗜卧。脾主四肢，所以四肢无力收持。这是内在证候的部位归属及其所主的病症。
假如诊得肺脉，其外在证候是面色白、经常打喷嚏、悲伤忧愁不快乐、想哭；其内在证候是肚脐右侧有搏动感，按压时坚硬且疼痛；其病症表现为气喘咳嗽、恶寒发热如洒淅状。具备这些症状的是肺病，不具备这些症状的就不是肺病。
诊得肺脉，即是诊得毛脉（Feather-like pulse）。肺在五色中对应白色，所以面色白。《灵枢·口问篇》说：“阳气调和滑利，充满于心，出于鼻，所以打喷嚏。”肺气通于鼻，所以经常打喷嚏。肺在情志上主忧，所以悲伤忧愁不快乐。肺在五声中对应哭，所以想哭。这是外在证候中的色、脉及情志表现。肚脐右侧是肺金之气右降的部位，动气按压时坚硬疼痛，是肺气郁结的表现。肺主气，气逆所以生病表现为气喘咳嗽。肺主皮毛，所以出现恶寒发热如洒淅状。这是内在证候的部位归属及其所主的病症。
假如诊得肾脉，其外在证候是面色黑、容易恐惧、频繁打哈欠；其内在证候是肚脐下方有搏动感，按压时坚硬且疼痛；其病症表现为气逆、小腹急痛、腹泻伴有肛门重坠感、足胫寒冷且逆冷。具备这些症状的是肾病，不具备这些症状的就不是肾病。
诊得肾脉，即是诊得石脉（Stone-like pulse）。肾在五色中对应黑色，所以面色黑。肾在情志上主恐，所以容易恐惧。《灵枢·口问篇》说：“阴气积聚在下部，阳气未尽，阳气牵引向上，阴气牵引向下，所以频繁打哈欠。”这是肾主打哈欠的原因。这是外在证候中的色、脉及情志表现。肾居于最下部，肚脐下方是肾的位置，肾气郁结，所以动气按压时坚硬疼痛。肾气不足，损伤冲脉，所以病表现为气逆。少阴经脉循行经过小腹，所以小腹急痛。肾是胃的关口，现在气虚，所以出现肛门重坠感的腹泻，即吃完饭后就想上厕所。《灵枢·经脉篇》说：“足少阴肾经，循行经过内踝之后，分支进入脚跟中，向上进入腓肠肌内”，所以病表现为足胫寒冷且逆冷。这是内在证候的部位归属及其所主的病症。“泄如下重”中的“如”字，滑寿先生改为“而”字，非常正确。
Chapter 16 states: Pulse diagnosis involves three positions (Sanbu) and nine inspections (Jiuhou), distinctions of Yin and Yang, variations in pressure depth (Qingzhong), and sixty pulse categories. A single pulse type changes according to the four seasons. However, as time has passed since the Sage, each school adheres to its own methods. How can one distinguish between their correctness and errors?
The response is: This depends on whether the disease presents with external and internal signs (Zheng).
Regarding the three positions and nine inspections of the pulse, see Chapter 18. The details of Yin and Yang are explained in Chapter 4. The details of pressure depth are explained in Chapter 5. The sixty pulse categories are found in *Suwen: Fang Sheng Shuai Lun*. Wang Bing's commentary refers to them as "Qiheng Sixty Categories," which are no longer extant in the world today. Some believe this refers to the concept that each organ governs for sixty days. "A single pulse changing according to the four seasons" refers to the spring chord-like pulse (Xian), summer hook-like pulse (Gou), autumn feather-like pulse (Mao), and winter stone-like pulse (Shi) mentioned in Chapter 15.
Since pulse methods vary and have been distant from the Sage for a long time, with each school adhering to its own methods, how can one distinguish their merits and flaws? It lies in the fact that diseases present with external and internal signs. This means that for any disease, by verifying through external and internal signs, one will naturally grasp the truth, without being constrained by various pulse methods.
How exactly does this manifest?
The response is: Suppose one obtains the Liver pulse (Gan Mai). Its external signs include a preference for cleanliness, a bluish complexion, and irritability. Its internal signs include pulsation at the left side of the umbilicus, which feels firm and painful upon palpation. The symptoms include fullness in the four limbs, urinary obstruction or dribbling, difficulty in urination, and tendon spasms. If these signs are present, it is a Liver disease; if not, it is not.
Obtaining the Liver pulse means diagnosing a Chord-like pulse (Xian Mai). The Liver and Gallbladder are interior-exteriorly related, and the Gallbladder is considered a clear and pure organ, hence the patient's preference for cleanliness. Blue/Green corresponds to Wood, and the Liver belongs to Wood, hence the bluish complexion. The Liver governs anger in the emotions, hence the irritability. These are the external signs regarding color, pulse, and emotional disposition. The left side of the umbilicus is the region where Liver Wood Qi ascends. Pulsation occurs because the True Qi cannot be stored internally and manifests externally. "Firm" (Lao) indicates Qi stagnation and solidity; "pain" indicates Qi depression and obstruction; "fullness" indicates blockage. Tendon tension leads to fullness in the four limbs; as stated in *Zuo Zhuan*, "wind pathogen causing disorders in the extremities." The Jueyin meridian circulates around the genitalia, so Liver disease causes difficulty in urination. Tendon spasms occur because the Liver governs tendons, so the pathology affects the tendons. These are the internal signs regarding location and associated diseases.
Suppose one obtains the Heart pulse (Xin Mai). Its external signs include a red complexion, dry mouth, and a tendency to laugh. Its internal signs include pulsation above the umbilicus, which feels firm and painful upon palpation. The symptoms include vexation, heart pain, heat in the palms, and dry heaving (Gan Ou). If these signs are present, it is a Heart disease; if not, it is not.
Obtaining the Heart pulse means diagnosing a Hook-like pulse (Gou Mai). The Heart corresponds to Red in colors, hence the red complexion. Heart Qi connects to the tongue, and Heart Fire flares upward, hence the dry mouth. The Heart corresponds to laughter in sounds, hence the tendency to laugh. These are the external signs regarding color, pulse, and emotional disposition. The area above the umbilicus is the region of the Heart. Pulsation with firmness and pain upon palpation, along with vexation, actually indicates pathogen affecting the Pericardium (Xin Bao Luo), rather than true Heart disease. If it were true Heart disease, death would occur within half a day (morning diagnosed, evening dies; evening diagnosed, morning dies). The Hand Jueyin Pericardium meridian runs through the palm, hence heat in the palms. Dry heaving is due to excessive Heart Fire. These are the internal signs regarding location and associated diseases.
Suppose one obtains the Spleen pulse (Pi Mai). Its external signs include a yellow complexion, frequent belching (Yi), excessive thinking, and heightened taste sensitivity. Its internal signs include pulsation at the center of the umbilicus, which feels firm and painful upon palpation. The symptoms include abdominal fullness, indigestion, heavy body with joint pain, lethargy and desire to lie down, and weakness in the four limbs. If these signs are present, it is a Spleen disease; if not, it is not.
Obtaining the Spleen pulse means diagnosing a Slow/Relaxed pulse (Huan Mai). The Spleen belongs to Earth and corresponds to Yellow in colors, hence the yellow complexion. Belching (Yi) is eructation. *Ling Shu: Kou Wen* states: "Cold pathogen lodging in the Stomach causes rebellious Qi to rise from below, disperse, and exit the Stomach again, resulting in belching." The Spleen and Stomach are interior-exteriorly related, so they often suffer together. The Spleen governs thought in the emotions, hence excessive thinking. The Spleen opens into the mouth, hence heightened taste sensitivity. These are the external signs regarding color, pulse, and emotional disposition. The Spleen resides in the Middle Jiao, hence pulsation at the umbilicus with firmness and pain upon palpation. The Spleen governs transport and transformation; if this function is impaired, abdominal fullness and indigestion occur. The Spleen governs muscles, hence heaviness of the body. The Yangming meridian binds bones and facilitates joints; since the Spleen and Stomach are related, joint pain is relevant. Fatigue damaging the Spleen, or dampness overwhelming and depressing the Spleen, both lead to lethargy and desire to lie down. The Spleen governs the four limbs, hence weakness and inability to hold the limbs. These are the internal signs regarding location and associated diseases.
Suppose one obtains the Lung pulse (Fei Mai). Its external signs include a white complexion, frequent sneezing, sadness and sorrow, unhappiness, and a desire to cry. Its internal signs include pulsation at the right side of the umbilicus, which feels firm and painful upon palpation. The symptoms include wheezing and coughing, and chills and fever resembling a sprinkling sensation (Sa Xi). If these signs are present, it is a Lung disease; if not, it is not.
Obtaining the Lung pulse means diagnosing a Feather-like pulse (Mao Mai). The Lung corresponds to White in colors, hence the white complexion. *Ling Shu: Kou Wen* states: "When Yang Qi is harmonious and smooth, filling the Heart and exiting through the nose, sneezing occurs." Lung Qi connects to the nose, hence frequent sneezing. The Lung governs sorrow/worry in the emotions, hence sadness and unhappiness. The Lung corresponds to crying in sounds, hence the desire to cry. These are the external signs regarding color, pulse, and emotional disposition. The right side of the umbilicus is the region where Lung Metal Qi descends. Pulsation with firmness and pain upon palpation indicates Lung Qi stagnation. The Lung governs Qi; when Qi rebels, wheezing and coughing result. The Lung governs the skin and hair, hence chills and fever resembling a sprinkling sensation. These are the internal signs regarding location and associated diseases.
Suppose one obtains the Kidney pulse (Shen Mai). Its external signs include a black complexion, fearfulness, and frequent yawning. Its internal signs include pulsation below the umbilicus, which feels firm and painful upon palpation. The symptoms include rebellious Qi, acute pain in the lower abdomen, diarrhea with a sensation of rectal tenesmus (heavy feeling), and coldness with inversion in the feet and calves. If these signs are present, it is a Kidney disease; if not, it is not.
Obtaining the Kidney pulse means diagnosing a Stone-like pulse (Shi Mai). The Kidney corresponds to Black in colors, hence the black complexion. The Kidney governs fear in the emotions, hence fearfulness. *Ling Shu: Kou Wen* states: "When Yin Qi accumulates below and Yang Qi is not yet exhausted, Yang pulls upward and Yin pulls downward, resulting in frequent yawning." This explains why the Kidney governs yawning. These are the external signs regarding color, pulse, and emotional disposition. The Kidney resides at the lowest position; below the umbilicus is the location of the Kidney. Kidney Qi stagnation causes pulsation with firmness and pain upon palpation. Insufficient Kidney Qi damages the Chong Mai, resulting in rebellious Qi. The Shaoyin meridian circulates around the lower abdomen, hence acute pain in the lower abdomen. The Kidney is the gate of the Stomach; now, due to Qi deficiency, there is diarrhea with rectal tenesmus, meaning the urge to defecate immediately after eating. *Ling Shu: Jing Mai* states: "The Foot Shaoyin Kidney meridian circulates behind the medial malleolus, branches into the heel, and ascends into the gastrocnemius muscle," hence coldness and inversion in the feet and calves. These are the internal signs regarding location and associated diseases. Regarding the phrase "diarrhea with a sensation like heaviness" (Xie ru xia zhong), Mr. Hua Shou changed the character "ru" (like) to "er" (and), which is very correct.