《素问·阴阳别论》帝曰∶人有四经十二从，何谓？岐伯曰∶四经应四时，十二从应十二月，十二月应
十二脉。脉有阴阳，知阳者知阴，知阴者知阳。凡阳有五，五五二十五阳。所谓阴者，真脏也，见则为败，败
必死矣。所谓阳者，胃脘之阳也。别于阳者，知病处也；别于阴者，知死生之期。三阳在头，三阴在手，所
谓一也。别于阳者，知病忌时；别于阴者，知死生之期。谨熟阴阳，无与众谋。
四经应四时者，肝经应春，心经应夏，肺经应秋，肾经应冬，脾土应四季，在其中矣。十二从者，手足三
阴三阳，共十二经，相从周流于一身，如十二月之周行成一岁，终而复始也。脉理之要，别其阴阳，能知其阴，
即知其阳，能知其阳，即知其阴。何也？盖阴阳之气相合，外行经络，内行脏腑，循环不已，而五脏皆禀胃
脘阳和之气，其一脏遍含五脏之胃阳，故五五有二十五阳。脏为阴，腑为阳，所以谓阴者，真脏孤阴之气也。
真脏脉现，则本元败，败必死矣。所以谓阳者，胃脘之阳也，胃为阳土，其能纳水谷，化精微，生气血者，实
由先天元阳蒸腾之力，故得阳生阴长，气血和平，而脉象柔缓调匀，是为胃气，故脉有胃气则生；若胃阳败，
则孤阴真脏之脉现，如弦钩毛石而但急强散乱，绝无和缓之气，则死矣。是故能别其胃肠之和否，可知其病处，
如弦多胃气少，病在肝之类也；能别其孤阴真脏脉，可知死生之期，如肝至悬绝急，十八日死之类也。三阳经
脉上头，三阴经脉止于手，而阴阳通贯周流则一也。故能知阳可以知阴，知阴可以知阳。辨其阳脉之太过不及，
可知病有宜忌之时，如春夏人迎微大为宜，反小为忌，秋冬微小为宜，反大为忌；辨其阴脉之逆顺，可知死生
之期，如肝病遇木旺时可生，遇金旺时则死之类。如是谨记熟悉阴阳生化、五行生克之理，则辨别自明，无须
与庸众谋议，徒滋惑乱也。
The Yellow Emperor asked: "Humans have 'Four Meridians' and 'Twelve Conformities'. What does this mean?"
Qibo replied: "The Four Meridians correspond to the Four Seasons, the Twelve Conformities correspond to the Twelve Months, and the Twelve Months correspond to the Twelve Meridians. Pulse qualities have Yin and Yang; knowing Yang means knowing Yin, and knowing Yin means knowing Yang. There are five types of Yang pulses, and five times five make twenty-five Yangs. The so-called 'Yin' refers to the Zang-Organ Pulse (True Visceral Pulse); when it appears, it indicates failure, and failure inevitably leads to death. The so-called 'Yang' refers to the Yang Qi of the Stomach Chamber. One who can distinguish Yang knows the location of the disease; one who can distinguish Yin knows the period of life or death. The Three Yang Meridians ascend to the head, and the Three Yin Meridians terminate at the hands; this is what is meant by 'One' (unity). One who distinguishes Yang knows the time contraindications for the disease; one who distinguishes Yin knows the period of life or death. Be diligent in mastering Yin and Yang, and do not consult with the masses."
Regarding "The Four Meridians corresponding to the Four Seasons," the Liver Meridian corresponds to Spring, the Heart Meridian to Summer, the Lung Meridian to Autumn, the Kidney Meridian to Winter, and the Spleen Earth corresponds to the middle of the four seasons, permeating them all. Regarding "The Twelve Conformities," these are the Hand Three Yin, Hand Three Yang, Foot Three Yin, and Foot Three Yang, totaling twelve meridians. They follow each other in circulation throughout the body, just as the twelve months cycle through to form a year, ending and beginning again. The essence of pulse theory lies in distinguishing Yin and Yang; understanding Yin allows one to understand Yang, and understanding Yang allows one to understand Yin. Why? Because the Qi of Yin and Yang combines, circulating externally in the meridians and internally in the zang-fu organs without cease. All five zang organs receive the harmonious Yang Qi of the stomach chamber. Each organ contains the stomach Yang common to all five, hence five times five equals twenty-five Yangs. Zang organs are Yin, and fu organs are Yang. Therefore, the "Yin" mentioned refers to the isolated Yin Qi of the true visceral state. When the True Visceral Pulse appears, the root vitality fails, and failure inevitably leads to death. Thus, the "Yang" mentioned refers to the Yang Qi of the stomach chamber. The Stomach is Yang Earth; its ability to receive food and water, transform essences, and generate Qi and Blood is actually due to the steaming power of congenital Primordial Yang. This allows Yang to generate and Yin to grow, resulting in harmonious Qi and Blood, and a pulse that is soft, slow, regular, and even—this is called Stomach Qi. Therefore, if the pulse has Stomach Qi, there is life; if Stomach Yang fails, the isolated Yin True Visceral Pulse appears. For example, pulses such as String-like (Xian), Hook-like (Gou), Feather-like (Mao), or Stone-like (Shi) may appear but manifest as rapid, strong, scattered, and chaotic, completely lacking any harmonious quality, leading to death. Thus, by distinguishing whether the harmony of the stomach and intestines is intact, one can know the location of the disease; for instance, if the String-like quality is excessive and Stomach Qi is scant, the disease is in the Liver. By distinguishing the isolated Yin True Visceral Pulse, one can know the period of life or death; for instance, if the Liver pulse becomes suspended, extreme, and rapid, death occurs in eighteen days. The Three Yang meridian channels ascend to the head, and the Three Yin meridian channels terminate at the hands, yet the principle of Yin and Yang penetrating and circulating uniformly remains the same. Therefore, knowing Yang allows one to know Yin, and knowing Yin allows one to know Yang. By distinguishing the excess or deficiency of Yang pulses, one can know the favorable and unfavorable times for the disease; for example, in spring and summer, a slightly larger Renying (Carotid) pulse is favorable, while a smaller one is unfavorable; in autumn and winter, a small and fine pulse is favorable, while a large one is unfavorable. By distinguishing the reversal or smoothness of Yin pulses, one can know the period of life or death; for instance, in Liver diseases, life is possible when Wood Qi is prosperous, but death occurs when Metal Qi is prosperous. By diligently remembering and familiarizing oneself with the principles of Yin-Yang generation/transformation and Five Elements mutual generation/restriction, discrimination will naturally become clear, eliminating the need to consult with mediocre crowds, which would only add confusion.