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The root of *Stephaniae Tetrandrae Radix* (Fangji) is white on the outside and yellow on the inside, with black striations resembling the spokes of a wheel radiating outward. Its flavor is pungent and neutral; therefore, it treats wind-dampness pathogens that travel from the Kidney to involve the Spleen and Lungs. The Lung governs the skin and hair; does not the pathogen disperse through the skin and hair? However, just as a wheel rotates in circles but does not overflow outward, *Stephaniae Tetrandrae Radix* never induces sweating but rather drains directly through urination. This can be verified by referring to *Jingui Yaolue*'s *Ji Jiao Li Huang Wan* (meaning see *Rhei Radix et Rhizoma*) and *Qianjin Fang*'s *Sanwu Mufangji Tang*.

Tao Hongjing stated: "*Stephaniae Tetrandrae Radix*" is an essential herb for treating Wind-Water edema. Water retention and Phlegm-Fluid are both categories of Dampness; thus, *Atractylodis Macrocephalae Radix* and *Stephaniae Tetrandrae Radix* Decoction (*Fangji Huangqi Tang*) treats Wind-Dampness, *Stephaniae Tetrandrae Radix* and Poria Decoction (*Fangji Fuling Tang*) treats Water-Qi, and *Bitter Orange, Stepahaniae Tetrandrae Radix* and Ginseng Decoction (*Mufangji Tang*) treats Phlegm-Fluid. Although the names differ, the underlying principles are largely identical. However, the term "Wind-Water" is indeed difficult to dissect precisely. Wind is a Yang pathogen entering from the exterior, causing chills and tremors; when Wind-Cold is initially contracted, diaphoresis (sweating) should be employed to resolve the exterior, a task for which *Stephaniae Tetrandrae Radix* is not responsible. Internal latent Wind cannot persist alone without Yin pathogens as its foundation; thus, Water, Phlegm-Fluid, and Dampness rely on specific dependencies. Once Water, Phlegm-Fluid, and Dampness are eliminated, Wind departs with them. Only such Wind can be treated with *Stephaniae Tetrandrae Radix*. The reason why *Atractylodis Macrocephalae Radix* and Poria cannot achieve this while *Stephaniae Tetrandrae Radix* can lies in its black striations resembling radiating wheel spokes, embodying the subtle mechanism of Wind accompanying Water.

Some ask: *Stephaniae Tetrandrae Radix* and Rehmannia Decoction (*Fangji Dihuang Tang*) treats conditions presenting as mania-like states, aimless walking, continuous solitary speech, without chills or fever, and with a floating pulse. Does this also involve Water, Phlegm-Fluid, or Dampness, warranting the use of *Stephaniae Tetrandrae Radix*? I reply: This is a unique prescription by Zhang Zhongjing, not to be compared with others. Zhao believed that Blood deficiency allows pathogens to invade, merging into the Yang level. The text indeed cites the floating pulse as evidence of Blood deficiency; *Suwen* states that if Yin cannot overcome Yang, the pulses flow rapidly, leading to mania, which supports the diagnosis of mania-like symptoms. This annotation is sound but fails to specify the nature of the pathogen. Xu argued that Wind-pathogen merges into the Heart, causing blazing Heart-Fire, resulting in mania, aimless walking, and continuous speech, which is clearer than Zhao's note. However, neither explains the rationale behind the herbal composition. Upon careful study: Soaking the Four Substances (*Sìwù*) in wine to extract juice implies the presence of Yang or Exterior pathogens. The predominant use of Prepared Rehmannia Root (*Shu Dihuang*) or Raw Rehmannia Root (*Sheng Dihuang*) indicates the intent to nourish Blood and cool Blood. The inclusion of Cinnamon Twig (*Guizhi*) and Saposhnikovia Root (*Fangfeng*) alongside these confirms an external Wind-pathogen. Combining Rehmannia with Cinnamon Twig and Saposhnikovia indicates treatment is not aimed at inducing sweating. Since sweating is not the method, wine is used to circulate the medicinal power to search out pathogens, ensuring none are left behind. Extracting juice from raw herbs versus steamed Rehmannia allows for the distinct regulation of Yin and Yang, thereby subduing Yang and calming Yin. However, if Wind has no exit, it will not cease; if Yin does not return to its proper position, it will constrain Yang. To separate what has merged, Zhang Zhongjing utilized *Stephaniae Tetrandrae Radix*. *Stephaniae Tetrandrae Radix* travels to the exterior and descends internally. With its rotating capability, Wind in the exterior naturally subsides. With its ability to restore origin, disturbed Yin becomes tranquil. Some claim *Stephaniae Tetrandrae Radix* treats Wind-Dampness but not Wind-Dryness. They fail to realize that adding Rehmannia in multiples within Wind-dispersing herbs transforms Wind-Dryness into Moisture, perfectly complementing *Stephaniae Tetrandrae Radix*, achieving a skill that rivals nature itself.