东垣云∶三焦，有名无形，主持诸气，以象三才之用，故呼吸升降，水谷往来，皆恃此以通达。是以
上焦在心下，主内而不出；中焦在胃中脘，主腐熟水谷；下焦在脐下，主分别清浊，出而不内。统而论之
，三才之用，本于中焦。中焦者，胃脘也，禀天五之冲气, 阴阳清浊自此而分，十二经络自此而始。或不
得其平，则寒热偏胜，虚实不同，荣卫涩滞，清浊不分，而生诸病。故曰∶气会三焦，手少阳脉通于膻中
。膻中者，臣使之官，为气之海。审
此，则知三焦者，冲和之本也。三焦，相火及包络之脉，人之元气也，周身何处无之，是名相火用事，
主持阴阳之气，神明之府也。（出《医学发明》）
或有难于生生子曰∶心主、包络、三焦之说，已得闻命矣，但诊法尚未详明，如子所言，动脉下行
于足经者，法当诊于下部欤？诚如是，令人之惑滋甚也。且足经肾肝之动脉，皆不上行于手，又何故取
法于手之尺部而诊肾肝耶？请再悉之。余曰∶嘻！如上所疑，是殆未知寸关尺上下阴阳之义也。夫脉之
一字，有二义焉，十二经之动脉，乃路陌之脉，非寸关尺之谓也；寸失尺之脉，乃气血之先，人之神
也，故可以候周身百骸之疾。余之所指，非即动脉为诊，乃宗《内经》、《脉经》，形于上者上诊之；形
于下者下诊之，乃法象也，非为动脉之出入而言也。昔秦越人述《内经》之微旨，而取诊法于寸关尺者，
又岂无所本哉？寸关尺之部位，乃手太阴经经渠、太渊穴也，实手太阴经之动脉出入之地。古人取此以验
五脏之脉者，以肺受百脉之朝，又五脏六腑之气味皆出于胃，变见于气口，以气口为五
脏主，而脉之大要会也。按《脉要精微论》曰∶“尺内两傍，则季胁也。尺外以候肾，尺里以候腹中。附
上，左外以候肝，内以候膈；右外以候胃，内以候脾。上附上，右外以候肺，内以候胸中；左外以候心，内
以候膻中。前以候前，后以候后。上竟上者，胸喉中事也；下竟下者，少腹腰股膝胫足中事也。”按此，附
上，谓关也；上附上，谓寸也。寸关皆有左右手分诊，而尺独不分左右者，则两尺皆以肾为诊也明矣。《
内经》论诊法部位，前后上下如此，皆法象天地，配合阴阳，诚万古不可少易者。越人阐明《内经》之旨，
取寸关尺以诊一身脏腑上下之候，而王叔和宗之，皆本于此。心包络附近于君，当宗《脉经》心部诊之，乃
上以候上之意也。三焦亦当如《脉经》，上中下分诊之。其肾肝之动脉，虽不上行于手，而肾肝之元神，气
血之先，岂有不随胃之元气上行耶？！《玉机真脏论》曰∶“脏气者，不能自致于手太阴，必因于胃气，乃
至于手太阴也。”故一难独取寸口，以决五脏六腑死生吉凶之法，其义可见。是以医者，要明天地阴阳上
下之理，以譬周身，则自然贯通，不为异论束缚。为医而不本《素》、《难》、《脉经》，而一听庸俗口耳之学，
与为儒而不讲明四书五经，惟徒剽窃时义者何异。孙思邈曰∶不知《易》者。不足以言太医。斯言诚有味
哉。
Li Dongyuan stated: The Sanjiao (Triple Burner) has a name but no substantial form; it governs all Qi in the body, symbolizing the functions of Heaven, Earth, and Humanity ("Sancai"). Therefore, the ascending and descending of respiration, and the movement of water and food, all rely on it for communication. Thus, the Upper Jiao is located below the heart, governing intake without excretion; the Middle Jiao is located at the epigastrium (Stomach region), governing the rotting and ripening of food and drink; the Lower Jiao is located below the umbilicus, governing the separation of clear and turbid substances, excreting without reabsorbing. Generally speaking, the functions of Sancai originate from the Middle Jiao. The Middle Jiao is the epigastrium, inheriting the neutral Qi of Heaven and Earth; Yin and Yang, clear and turbid are divided here, and the Twelve Meridians begin here. If balance is not maintained, it leads to excess cold or heat, deficiency or excess, stagnation of Ying (Nutrient) and Wei (Defensive) Qi, and confusion of clear and turbid, resulting in various diseases. It is said: Qi converges at the Sanjiao, and the Hand-Shaoyang meridian connects with the Danzhong (Conception Vessel point CV17). Danzhong is the official of the ministerial envoy and serves as the Sea of Qi. Understanding this reveals that the Sanjiao is the root of neutral harmony. The meridians of the Sanjiao and Pericardium belong to the Yuan Qi (Original Qi) of humans, present throughout the body; this is where Xianghuo (Ministerial Fire) exerts its function, governing Yin and Yang Qi, serving as the residence of Shen (Spirit/Mind). (From *Yixue Faming*)
Someone found it difficult to understand and asked Shengshengzi (Sun Yikui's courtesy name): I have heard your explanation regarding the Heart Master, Pericardium, and Sanjiao, but the diagnostic methods remain unclear. You mentioned that the arterial pulse descends into the Foot meridians; according to the method, should one diagnose the lower part? If so, this deepens my confusion. Moreover, the arterial pulses of the Kidney and Liver in the Foot meridians do not ascend to the Hand; why then use the Chi (Cunian) position on the Hand to diagnose the Kidney and Liver? Please explain further. I replied: Alas! The doubts raised above stem from a lack of understanding of the meanings of Yin and Yang in the upper and lower positions of Cun, Guan, and Chi. The term "Mai" (Pulse) has two meanings: the arterial pulses of the Twelve Meridians refer to the pathways of vessels, not the specific positions of Cun, Guan, and Chi; the pulses at Cun, Guan, and Chi represent the precursor of Qi and Blood, the manifestation of Shen (Spirit), and thus can be used to diagnose diseases throughout the entire body. What I referred to was not diagnosing directly via the arterial pulses themselves, but following the *Neijing* and *Maiching*: if the manifestation is superior, diagnose the superior part; if inferior, diagnose the inferior part. This is based on the principle of Xiangshu (Image and Number), not discussing the entry and exit of arterial pulses. In ancient times, Qin Yue Ren (Bian Que) expounded the subtle principles of the *Neijing* and adopted the diagnostic method of Cun, Guan, and Chi; did he have no basis for this? The positions of Cun, Guan, and Chi correspond to the Jingqu (LU9) and Taiyuan (LU9) acupoints of the Hand-Taiyin Lung Meridian, which are indeed the places where the arterial pulse of the Hand-Taiyin Lung Meridian enters and exits. The ancients selected this location to verify the pulses of the Five Zang organs because the Lung receives the convergence of all meridians, and the qi and flavor of the Five Zang and Six Fu organs all originate from the Stomach and manifest at the Qikou (Radial Artery pulse position). Since Qikou is the master of the Five Zang and the convergence of major pulse principles, according to the *Luyao Jingwei Lun* (Treatise on the Essential Subtleties of Pulse Diagnosis): "The inner sides of the Chi area correspond to the hypochondrium. The outer side of Chi diagnoses the Kidney; the inner side of Chi diagnoses the abdominal cavity. Adjacent to the Guan, the left outer side diagnoses the Liver; the inner side diagnoses the Diaphragm. On the right, the outer side diagnoses the Stomach; the inner side diagnoses the Spleen. Further up, the right outer side diagnoses the Lung; the inner side diagnoses the Chest Center. The left outer side diagnoses the Heart; the inner side diagnoses the Danzhong. The anterior aspect diagnoses the anterior body; the posterior aspect diagnoses the posterior body. The end of the Cun area corresponds to matters of the chest and throat; the end of the Chi area corresponds to matters of the lower abdomen, waist, thighs, knees, shins, and feet." According to this, "adjacent to Guan" refers to the Guan position; "further up" refers to the Cun position. Both Cun and Guan have left-right differentiation, while Chi does not differentiate left and right, indicating clearly that both Chi positions diagnose the Kidney. The *Neijing* discusses diagnostic positions as described above, modeling Heaven and Earth, coordinating Yin and Yang, which is indeed unchangeable through the ages. Qin Yue Ren elucidated the principles of the *Neijing*, adopting Cun, Guan, and Chi to diagnose the upper and lower states of the body's Zang-Fu organs; Wang Shuhe followed this, both based on these principles. The Pericardium is close to the Monarch (Heart); one should follow the *Maiching* to diagnose it at the Heart position, adhering to the principle of diagnosing the upper with the upper. The Sanjiao should also be diagnosed in upper, middle, and lower sections as per the *Maiching*. Although the arterial pulses of the Kidney and Liver do not ascend to the Hand, do not the Yuan Shen (Original Spirit) and the precursors of Qi and Blood of the Kidney and Liver ascend along with the Yuan Qi of the Stomach?! The *Yuji Zhenzang Lun* states: "Zang Qi cannot reach the Hand-Taiyin by itself; it must rely on Stomach Qi to arrive at the Hand-Taiyin." Thus, the unique selection of the Cun Kou (Radial Pulse) in the *Nanjing* to determine the life, death, auspiciousness, and misfortune of the Five Zang and Six Fu organs reveals its underlying logic. Therefore, physicians must understand the principles of Heaven, Earth, Yin, Yang, and Up/Down, using them to analogize the human body, thereby achieving natural integration and avoiding being bound by heterodox theories. Practicing medicine without basing it on the *Suwen*, *Nanjing*, and *Maiching*, but instead listening only to vulgar oral teachings, is no different from scholars who do not study the Four Books and Five Classics and merely plagiarize contemporary essays. Sun Simiao said: One who does not know the *I Ching* (Book of Changes) is insufficient to speak of being a Grand Physician. These words are truly profound.