人身十二脏腑经络，《灵枢》《素问》详辨，各有定名部分，独三焦之名，在经文亦多臆说；后贤之
详其义者，更多旁杂，而无一定之论，是不能无疑，而为之考究，以正其指归。即如王海藏，为东垣高
弟，亦致疑于三焦之名，而问之曰三焦有几，启其端而究未能定其说。是以总会经文与诸贤之论而详之，
以知三焦有三三焦，而后之人不能明其义，故多歧而未有以正其名也。所谓三焦之有三三焦也，即以经文
正之。《灵》《素》之论三焦，与《难经》之论三焦，已自不同矣。《灵枢》曰∶三焦者，上合手少阳，出
关冲，小指次指之端。三焦下 ，在足大趾之前，少阳之后，出 中外 ，足太阳以络于手少阳。此论手
少阳三焦经脉之所行也。又曰∶脐下膀胱至足，为足三焦。下焦别回肠，注膀胱以渗入。此论足太阳膀
胱，为三焦一腑之所属也。手三焦之经为少阳，主于上；足三焦之腑为膀胱，主于下∶是二三焦也。
故《本脏篇》曰∶密理浓皮者，三焦、膀胱浓；粗理薄皮者，三焦、膀胱薄。《论勇》曰∶勇士，三焦理
横；怯士，三焦理纵。而《素问·五脏别论》又曰∶胆、胃、大小肠、三焦、膀胱五者，为天气之所主。
夫三焦、膀胱，与胆、胃、大小肠四腑并言，而又有浓、薄、结、直、纵、横之意，此所谓三焦者，属之于腑，
正有形有状之三焦也。若《灵枢》又曰∶上焦如雾，中焦如沤，下焦如渎。此三焦为一气之所主，故《三
十一难》因之曰∶上焦在胃上口，主内而不出，其治在膻中；中焦在胃中脘，主腐熟水谷，其治在脐傍，下焦在脐下，
主分别清浊，出而不内。此三焦者，即《灵枢》所谓如雾、如沤、如渎之三焦也。故《难经》又继言之，三焦为水谷之
道路，气之所以终始。三焦者，原气之别使。原气在两肾中间之动气，为人之生命，十二经之根本，主通行三气，经历
于五脏六腑。此所谓三焦者，属之于气，正王叔和所谓有名无状之三焦也。是又一三焦也。论其经则手少阳三
焦主之于上，论其腑则足太阳三焦主之于下，论其气则两肾原气之三焦以行于中。故曰《灵》《素》之论
三焦，与《难经》之论三焦，名各不同也。《灵》《素》之论手少阳三焦与足太阳三焦，是有形之腑
也。《难经》之论上中下之三焦，是无形之原气也。有形之腑，与胆、胃、大小肠为配；无形之气，游行
于五脏六腑之中，温分肉而充皮肤，是即肾间之原气，自下而中，自中而上，东垣所谓有名无形，主持诸气，
统领周身之气，熏肤充身泽毛者也。三焦之有三者，此也。王海藏问三焦有几，独能辨手少阳三焦主上，
足太阳三焦主下，而不及《难经》所云原气之三焦为命门之别使，是以使后人疑而莫辨耳。故王叔和所云三
焦无状空有名者，即是肾间原气之三焦也，不可谓尽非也。独是陈无择以脐下之脂膜为三焦∶袁淳甫以人
身着内一层，形色最赤者为三焦；虞天民以包涵肠胃之总司，指腔子为三焦∶是皆说之不可稽者也。至金
一龙舍手足之三焦不言，而易以前三焦、后三焦，尤诞妄而支离矣。予初注三焦论，漫引《灵枢》肺 在三焦，心 在
五焦，膈 在七焦，肝 在九焦，脾 在十一焦，肾 在十四焦之间，以躯体之外称焦，而从虞天民包罗六腑五脏之脂
膜，以证三焦之说。自马仲化以肺 、心 之“焦”为椎，则予之说要，亦可议而未有当焉也。
The human body possesses twelve zang-fu organs and meridians, which are detailed in the *Ling Shu* (Spiritual Pivot) and *Su Wen* (Basic Questions), each having fixed names and locations. Only the term "San Jiao" (Triple Burner) is subject to much speculation even in the canonical texts; later scholars who elaborated on its meaning introduced further confusion without reaching a definitive conclusion. This naturally raises doubts, necessitating investigation to clarify its true significance.
For instance, Wang Haicang, a senior disciple of Li Dongyuan, also questioned the name of San Jiao, asking, "How many San Jiaos are there?" He initiated this inquiry but failed to settle the theory. Therefore, I have synthesized the canonical texts and the discussions of various scholars to analyze this matter, revealing that San Jiao actually comprises three distinct concepts. Later generations failed to understand these distinctions, leading to divergent views and an inability to standardize the terminology. The assertion that there are three San Jiaos is verified by the canonical texts.
The discussion of San Jiao in the *Ling Shu* and *Su Wen* differs from that in the *Nan Jing* (Classic of Difficult Issues). The *Ling Shu* states: "San Jiao connects with the Hand-Shaoyang [Meridian], emerging at Guanchong (SI 1), at the tip of the fourth finger." It further describes the pathway descending to the foot, anterior to the big toe and posterior to the Shaoyang meridian, emerging at the lateral aspect of the ankle, connecting with the Foot-Taiyang meridian to link with the Hand-Shaoyang. This describes the course of the Hand-Shaoyang San Jiao Meridian. It also states: "From the bladder below the navel to the feet is called Foot-Sanjiao. The Lower Jiao separates into the ileum and pours into the bladder to permeate fluids." This refers to the Foot-Taiyang Bladder as belonging to one of the Fu organs associated with San Jiao. Thus, the Hand-Sanjiao Meridian (Shaoyang) governs the upper part, and the Foot-Sanjiao Organ (Bladder) governs the lower part; these constitute the first two San Jiaos.
Therefore, the *Ben Zang Pian* (Chapter on the Internal Organs) states: "Those with dense skin and thick texture have thick San Jiao and Bladder; those with coarse skin and thin texture have thin San Jiao and Bladder." The *Lun Yong* (Chapter on Courage) states: "In brave individuals, the San Jiao texture is transverse; in timid individuals, it is longitudinal." Furthermore, the *Su Wen · Wu Zang Bie Lun* (Differentiation of the Five Zang Organs) states: "The Gallbladder, Stomach, Large Intestine, Small Intestine, San Jiao, and Bladder are the five organs governed by Heaven Qi." Here, San Jiao and Bladder are mentioned alongside the other four Fu organs, implying physical characteristics such as thickness, density, and orientation. This San Jiao belongs to the category of Fu organs and is indeed a tangible entity with form and shape.
Conversely, the *Ling Shu* also states: "Upper Jiao is like mist, Middle Jiao is like fermentation, Lower Jiao is like a ditch." These three divisions are governed by a single Qi. Consequently, the *Nan Jing · Difficulty 31* adopts this view: "Upper Jiao is located at the upper orifice of the stomach, receiving but not expelling, with its treatment point at Danzhong (CV 17); Middle Jiao is at the middle of the stomach, responsible for ripening food and drink, with its treatment point near the umbilicus; Lower Jiao is below the umbilicus, separating clear from turbid, expelling but not receiving." This San Jiao corresponds to the mist, fermentation, and ditch descriptions in the *Ling Shu*. The *Nan Jing* continues: "San Jiao is the pathway for water and grain, the beginning and end of Qi. San Jiao is the special envoy of Yuan Qi (Source Qi)." Yuan Qi resides in the moving Qi between the two Kidneys, serving as the root of life and the foundation of the twelve meridians, facilitating the circulation of Qi through the Zang-Fu organs. This San Jiao belongs to the category of Qi and corresponds to what Wang Shuhe described as "having a name but no form." This constitutes the third San Jiao.
Thus, regarding its meridian, Hand-Shaoyang San Jiao governs the upper; regarding its organ, Foot-Taiyang San Jiao (Bladder) governs the lower; regarding its Qi, the San Jiao of Yuan Qi from the two Kidneys circulates in the middle. Hence, the San Jiao discussed in the *Ling Shu* and *Su Wen* differs in name and concept from that in the *Nan Jing*. The Hand-Shaoyang and Foot-Taiyang San Jiao in the former are tangible Fu organs, while the Upper, Middle, and Lower San Jiao in the latter refer to intangible Source Qi. The tangible Fu organs pair with the Gallbladder, Stomach, and Intestines; the intangible Qi circulates among the Zang-Fu organs, warming the muscles and nourishing the skin. This is the Yuan Qi between the Kidneys, ascending from below to the middle and above, as described by Li Dongyuan: having a name but no form, governing all Qi, commanding the body's Qi, and steaming the skin, filling the body, and moistening the hair. These are the three San Jiaos.
Wang Haicang asked how many San Jiaos exist. He correctly identified that Hand-Shaoyang San Jiao governs the upper and Foot-Taiyang San Jiao governs the lower, but he overlooked the *Nan Jing*'s description of Yuan Qi San Jiao as the special envoy of the Mingmen (Gate of Life). This omission caused later confusion. Therefore, Wang Shuhe's statement that San Jiao has no form and exists only in name refers specifically to the Yuan Qi San Jiao between the Kidneys and cannot be entirely dismissed. However, Chen Wuyue identified the fatty membrane below the navel as San Jiao; Yuan Chunfu identified the innermost red tissue layer as San Jiao; and Yu Tianmin identified the cavity containing the intestines and stomach as San Jiao. All these theories are unverified and speculative. Jin Yilong, discarding the Hand and Foot San Jiao entirely and proposing anterior and posterior San Jiaos, was particularly absurd and fragmented.
When I initially annotated the treatise on San Jiao, I arbitrarily cited passages from the *Ling Shu* mentioning the Lung in the "third Jiao," Heart in the "fifth Jiao," Diaphragm in the "seventh Jiao," Liver in the "ninth Jiao," Spleen in the "eleventh Jiao," and Kidney in the "fourteenth Jiao," interpreting "Jiao" as external segments of the body. I also adopted Yu Tianmin’s theory of the fatty membrane encompassing the Zang-Fu organs to support my view. However, since Ma Zhonghua pointed out that the "Jiao" in Lung and Heart refers to the vertebrae, my previous interpretation is open to criticism and lacks precision.