十九难曰∶经言脉有逆顺，男女有恒，而反者，何谓也？
恒，常也。反，谓上下相反也。此男女之脉，有一定恒常之法，得其脉为顺，不得其脉为逆，
若强弱相反，则为何病。
然∶男子生于寅，寅为木，阳也。女子生于申，申为金，阴也。故男脉在关上，女脉在关下，是
以男子尺脉恒弱，女子尺脉恒盛，是其常也。
此推本生物之初，而言男女阴阳也。杨氏曰∶元气始于子，人之所生也。自子推之，男从左行三
十，而至于巳；女从右行二十，而至于巳，为夫妇怀妊也。古者男子三十，女子二十，然后行嫁娶，
法本于此。十月而生，男从巳左行十月至寅，故男行年起于丙寅，女从巳右行十月至申，故女行年起
于壬申。所以男子生于寅，女子生于申也。谢氏曰∶寅为阳木，木生火。火
生于寅，其性炎上，故男脉在关上，申为阴金，金生水，水生于申，其性流下，故女脉在关下。男子阳
气盛，故尺脉弱；女子阴气盛，故寸脉弱。此男女之常也。
反者，男得女脉，女得男脉也。其为病何如？
男得女脉，女得男脉，异乎恒常，谓之反。然反之为病如何？设此问以起下文之义。
然∶男得女脉为不足，病在内，左得之，病在左，右得之，病在右，随脉言之也。女得男脉为太过，
病在四肢，左得之，病在左，右得之，病在右，随脉言之，此之谓也。
男得女脉者，寸脉当盛反弱，尺脉当弱反盛，为阴气盛，阳陷于阴，故为不足。阴主内，故病在内。
阳气入阴，病见于阴位也。女得男脉者，寸脉当弱反盛，尺脉当盛反弱，为阳气盛，阴越于阳，故为有余。
四肢属乎阳，阴气从阳，则病见于阳位也。左右者，以脉之左右，以验病之左右耳。徐氏曰∶阳道全而
阴道半。故阳得阴脉为不足、阴得阳脉为有余也。
按∶丁锦曰∶人之有尺，犹树之有根，欲其盛而不可得也。若男得女脉指尺盛、岂可谓之不足乎？女得
男脉指尺弱，岂可谓之太过乎？盖男得女脉为不足者，寸脉弱，阳气不足于内，故病在内也。女得男脉为
太过者，寸脉盛，阳气有余于外，故病在四肢也。斯言也，似亦近理，而不可拘泥者也。夫尺为脉之根，宜
盛不宜弱是矣。然阴虚火动，两尺洪而有力者，岂非不足乎？火炎于上，两寸洪而有力者，岂非太过乎？
更有两寸豁大无力，宜大补者；两尺豁大无力，
宜升阳散火者；寸脉大于尺脉，而俱有力，为阴虚阳盛宜下者；尺脉大于寸脉，而俱有力，为阳虚阴
盛宜汗者。然脉之变，非一言能尽，岂可胶柱鼓瑟耶？越人示人以男女阴阳之体，内外不足太过之变，
要在一隅三反耳，学人审诸。
第十九难说：医经上讲，脉象有顺逆之分，男女的脉象有固定的常态，如果出现相反的情况，这是什么意思呢？
恒，就是常理。反，指的是上下（寸、尺）脉象相反。这是指男女的脉象，有着一定且固定的常规法则，符合这种脉象称为顺，不符合称为逆，如果强弱表现相反，那是什么疾病呢？
回答说：男子生于寅年（对应东方木），寅属木，为阳。女子生于申年（对应西方金），申属金，为阴。所以男子的脉象重点在关部以上（寸部），女子的脉象重点在关部以下（尺部）。因此，男子的尺脉通常较弱，女子的尺脉通常较强，这是正常的规律。
这是在追溯生命起源之初，来论述男女阴阳的道理。杨氏说：元气始于子时，这是人出生的根源。从子时推算，男子从左向右运行三十年，到达巳时；女子从右向左运行二十年，到达巳时，此时结为夫妇并怀孕。古时候男子三十岁、女子二十岁才进行婚嫁，法度基于此。怀胎十月分娩，男子从巳时向左运行十个月到达寅时，所以男子的行年（虚岁年龄计算起点）始于丙寅；女子从巳时向右运行十个月到达申时，所以女子的行年始于壬申。这就是为什么说明男子生于寅、女子生于申的原因。谢氏说：寅是阳木，木能生火。火生于寅，其性质炎上，所以男子的脉象显现在关部以上；申是阴金，金能生水，水生于申，其性质流下，所以女子的脉象显现在关部以下。男子阳气旺盛，所以尺脉弱；女子阴气旺盛，所以寸脉弱。这是男女的正常规律。
所谓“反”，是指男子出现了女子的脉象，女子出现了男子的脉象。这会导致什么疾病呢？
男子出现女子的脉象，女子出现男子的脉象，这与常规不同，称为“反”。那么，“反”所导致的疾病是怎样的呢？提出这个问题是为了引出下文的意义。
回答说：男子出现女子的脉象，属于不足之证，病位在体内。如果在左手诊得，病在身体左侧；如果在右手诊得，病在身体右侧，这是随着脉象的位置来说明的。女子出现男子的脉象，属于太过之证，病位在四肢。如果在左手诊得，病在身体左侧；如果在右手诊得，病在身体右侧，随着脉象位置而言，说的就是这个道理。
男子出现女子脉象的人，寸脉应当强盛反而虚弱，尺脉应当虚弱反而强盛，这是因为阴气盛，阳气陷入阴分，所以称为不足。阴主内，所以病在体内。阳气入于阴分，病症表现在阴位（下部/内部）。女子出现男子脉象的人，寸脉应当虚弱反而强盛，尺脉应当强盛反而虚弱，这是因为阳气盛，阴气越出于阳分，所以称为有余（太过）。四肢属于阳，阴气跟随阳气，则病症表现在阳位（四肢/外部）。左右两侧，是通过脉象的左右来验证病变部位的左右罢了。徐氏说：阳道全备而阴道半缺。所以阳得到阴脉表现为不足，阴得到阳脉表现为有余。
按语：丁锦说：人有尺脉，就像树有根一样，希望它强盛而不应该虚弱。如果男子出现女子脉象指尺脉强盛，怎么能说是不足呢？女子出现男子脉象指尺脉虚弱，怎么能说是太过呢？大概男子出现女子脉象称为不足，是因为寸脉弱，阳气在内不足，所以病在体内。女子出现男子脉象称为太过，是因为寸脉盛，阳气在外有余，所以病在四肢。这番话，似乎也有道理，但不能拘泥固执。尺脉作为脉之根本，宜盛不宜弱，这是对的。然而阴虚火动，导致两尺脉洪大有力，难道不是不足吗？火炎于上，导致两寸脉洪大有力，难道不是太过吗？更有两寸脉豁大无力的，应当大补；两尺脉豁大无力的，应当升阳散火；寸脉大于尺脉，且都有力，是阴虚阳盛，适宜用下法；尺脉大于寸脉，且都有力，是阳虚阴盛，适宜用汗法。然而脉象的变化，不是一句话能说完的，怎么能像胶住瑟柱那样死板地对待呢？越人（扁鹊）向人们展示男女阴阳的体质，以及内外不足太过的变化，关键在于举一反三。学习者请仔细审察。
Chapter 19 states: The classic texts mention that pulses have distinctions of compliance (Shun) and non-compliance (Ni), and there are constant norms for men and women. What is meant by a reversal?
"Heng" refers to constancy or normality. "Fan" refers to the reversal between upper (Cun) and lower (Chi) positions. This refers to the pulse patterns of men and women, which follow certain fixed and constant laws. Adhering to these pulse patterns is considered compliant (Shun), while deviating from them is considered non-compliant (Ni). If the strength and weakness are reversed, what disease does this indicate?
The response is: Men are associated with Yin (the third earthly branch), which corresponds to Wood and Yang. Women are associated with Shen (the ninth earthly branch), which corresponds to Metal and Yin. Therefore, in men, the pulse manifestation is primarily above the Guan (barrier) position (i.e., Cun), while in women, it is primarily below the Guan position (i.e., Chi). Consequently, the Chi pulse in men is typically weak, whereas the Chi pulse in women is typically strong; this is the norm.
This explanation traces back to the origin of life to discuss the Yin-Yang of men and women. Yang Shi stated: Yuan Qi (Original Qi) begins at Zi. From Zi, counting forward, men move leftward for thirty years to reach Si; women move rightward for twenty years to reach Si, at which point they marry and conceive. In ancient times, men married at thirty and women at twenty, based on this principle. After ten months of gestation, a male fetus moves leftward from Si for ten months to reach Yin; thus, the male age cycle begins at Bing Yin. A female fetus moves rightward from Si for ten months to reach Shen; thus, the female age cycle begins at Ren Shen. This explains why it is said that men are born at Yin and women at Shen. Xie Shi stated: Yin represents Yang Wood, and Wood generates Fire. Fire originates at Yin, possessing an upward-flaring nature; hence, the male pulse manifests above the Guan. Shen represents Yin Metal, and Metal generates Water. Water originates at Shen, possessing a downward-flowing nature; hence, the female pulse manifests below the Guan. Men possess abundant Yang Qi, so their Chi pulse is weak; women possess abundant Yin Qi, so their Cun pulse is weak. This constitutes the normal state for men and women.
A "reversal" occurs when a man exhibits a woman's pulse pattern, or a woman exhibits a man's pulse pattern. What diseases result from this?
When a man exhibits a woman's pulse or a woman exhibits a man's pulse, it deviates from the norm and is termed a "reversal." But what kind of pathology does this reversal entail? This question is posed to introduce the subsequent discussion.
The response is: When a man exhibits a woman's pulse, it indicates Deficiency (Bu Zu), with the pathology located internally. If found on the left side, the disease is on the left side of the body; if found on the right, the disease is on the right. This interpretation follows the positional indication of the pulse. When a woman exhibits a man's pulse, it indicates Excess (Tai Guo), with the pathology located in the four limbs. If found on the left, the disease is on the left; if found on the right, the disease is on the right. This is what is meant by interpreting based on pulse position.
In a man exhibiting a woman's pulse, the Cun pulse should be strong but is instead weak, and the Chi pulse should be weak but is instead strong. This signifies an abundance of Yin Qi and the sinking of Yang Qi into Yin, hence termed Deficiency. Since Yin governs the interior, the disease is internal. Yang Qi entering Yin results in symptoms manifesting in Yin positions (interior/lower). In a woman exhibiting a man's pulse, the Cun pulse should be weak but is instead strong, and the Chi pulse should be strong but is instead weak. This signifies an abundance of Yang Qi and the transgression of Yin Qi into Yang, hence termed Excess. The four limbs belong to Yang; when Yin Qi follows Yang, symptoms manifest in Yang positions (limbs/exterior). The left and right sides refer to using the left and right pulse positions to verify the location of the disease on the corresponding sides of the body. Xu Shi stated: The Path of Yang is complete, while the Path of Yin is half. Thus, Yang receiving a Yin pulse indicates Deficiency, and Yin receiving a Yang pulse indicates Excess.
Commentary: Ding Jin stated: The Chi pulse in humans is like the roots of a tree; it should be robust, not weak. If a man exhibits a woman's pulse characterized by a strong Chi pulse, how can this be called Deficiency? If a woman exhibits a man's pulse characterized by a weak Chi pulse, how can this be called Excess? Presumably, when a man exhibits a woman's pulse and is termed Deficient, it is because the Cun pulse is weak, indicating insufficient Yang Qi internally, hence the disease is internal. When a woman exhibits a man's pulse and is termed Excessive, it is because the Cun pulse is strong, indicating excessive Yang Qi externally, hence the disease is in the limbs. This argument seems reasonable but should not be applied rigidly. It is true that the Chi pulse, as the root of the pulse, should be strong rather than weak. However, in cases of Yin Deficiency with Fire Hyperactivity, both Chi pulses may be洪大 (Hongda, flooding and forceful); is this not Deficiency? When Fire flares upward, both Cun pulses may be洪大 and forceful; is this not Excess? Furthermore, there are cases where both Cun pulses are vast and empty without force, requiring major tonification; or both Chi pulses are vast and empty without force, requiring raising Yang and dispersing fire. If the Cun pulse is larger than the Chi pulse and both are forceful, it indicates Yin Deficiency with Yang Excess, suitable for purgation. If the Chi pulse is larger than the Cun pulse and both are forceful, it indicates Yang Deficiency with Yin Excess, suitable for diaphoresis. However, the variations in pulse cannot be exhausted in a single statement. How can one treat it rigidly like a fixed bridge on a se (zither)? Yue Ren (Bian Que) demonstrated the Yin-Yang constitutions of men and women, and the variations of internal/external deficiency and excess, intending for students to infer other cases from one example. Learners should examine this carefully.