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Since ancient times, the exterior-interior pairing of the six Fu organs (hollow viscera) and five Zang organs (solid viscera) has been as follows: the Kidney pairs with the Bladder, corresponding to Ren-Gui Water; the Heart pairs with the Small Intestine, corresponding to Bing-Ding Fire; the Liver pairs with the Gallbladder, corresponding to Jia-Yi Wood; the Lung pairs with the Large Intestine, corresponding to Geng-Xin Metal; the Spleen pairs with the Stomach, corresponding to Wu-Ji Earth. This reflects the natural order of Yin-Yang, the Five Elements, heaven and earth positioning, and complete numerical harmony.

Why are there only five Zang organs mentioned, yet six Fu organs? The reason lies in the Sanjiao (Triple Burner). Although the Classic of Channels and Collaterals describes the Sanjiao as the "Official of Dredging" (responsible for unblocking water passages), in reality, it lacks both Qi and form. If it possesses neither form nor Qi, it is essentially non-existent. Yet, it is listed alongside the other six Fu organs, which contradicts fundamental medical principles. Consequently, later generations have debated endlessly without a solid basis: some divided the Sanjiao into Upper, Middle, and Lower sections; some distinguished between Hand and Foot Sanjiao; some identified it as the fat beside the Kidney; others described it as the fire protecting the Yang meridians. These views not only add unnecessary details but also confuse right and wrong.

The *Xuetan Yi Yue* (Snow Pool Medical Abridgement) asserts that the Sanjiao is indeed a Fu organ, named the "Solitary Fu." It states: "The Sanjiao connects from the highest point to the lowest, resembling the Six Directions (heaven, earth, and four cardinal directions), encompassing everything. It is essentially the large Fu organ located outside the Zang-Fu organs but within the body, containing all phenomena." Thus, "Zhongdu" is its name, and it supposedly has the shape of a large Fu organ. The statement in the *Nan Jing* (Classic of Difficult Issues) that it has a name but no form is indeed an error, akin to counting items in a bag while forgetting that the bag itself is an object. This argument is even more absurd than the previous ones. Let me clarify and refute this view:

If you acknowledge that the Sanjiao is a Fu organ, it should be equivalent to the Gallbladder, Stomach, Bladder, and Large/Small Intestines. Why do other Fu organs have their paired counterparts (e.g., Kidney-Bladder), while this one is solitary? Outside the Zang-Fu organs but inside the body, there are only diaphragms and fatty tissues; how can there be a large Fu organ capable of encompassing all viscera? You claim it spans from top to bottom, encompasses everything, has form and name, and resembles a sack or bellows. Apart from the abdominal skin, what else could this "Solitary Fu" be? Moreover, you yourself state that organs like the intestines and stomach are called Fu because they hold and store contents. What does the Sanjiao store? How can it be considered a Solitary Fu based on this? Such statements are frivolous, baseless, and misleading.

Alas! Principles are fixed; events do not occur by chance. When errors are transmitted for a long time, it is acceptable to leave doubts unresolved. However, if one holds preconceived notions, analyzing and correcting them causes no harm. The meanings of the Sanjiao and the six Fu organs in the *Nei Jing* (Inner Canon) appear clear but are actually obscure. Everyone should express their own views. Unfortunately, none of these views align with the Great Dao, causing people to become more confused the more they study. I feel compelled to rashly refute these fallacies, not out of intent to criticize predecessors and incur blame from contemporaries, but to clarify truth. Readers are urged to examine this carefully and show understanding.