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This refers to Trichosanthis Radix (Tianhuafen) and Trichosanthis Fructus (Gualou Shi).

Both the root and fruit of Gualou are recorded in the *Shennong Bencao Jing* as bitter and cold. Mr. Li stated that the root is sweet, slightly bitter and sour, and slightly cold, while the fruit is sweet and cold; his differentiation is very thorough.

The roots of herbs and trees generally have an ascending nature, whereas fruits tend to descend. Trichosanthis Radix can raise Yin Qi to moisten upwards, thus it primarily treats dryness-heat causing vexation and thirst. Trichanthis Fructus guides turbid phlegm downward, making it essential for treating Jie Xiong (Chest Binding) and Xiong Bi (Chest Obstruction). However, it can guide movement but cannot forcibly expel. Its nature is soft and moist; without the assistance of firm/drastic agents, its descending power is insufficient. Therefore, Xiao Xian Xiong Tang combines it with Huanglian (Coptidis Rhizoma) and Banxia (Pinelliae Rhizoma), while Gualou Xiebai Baijiu Tang combines it with Xiebai (Allii Macrostemonis Bulbus), Jiuniu (Alcohol), Guizhi (Cinnamomi Ramulus), and Houpo (Magnoliae Officinalis Cortex). These combinations utilize its strengths and compensate for its weaknesses by pairing it with bitter, acrid, and rapid-acting substances.

Trichosanthis Radix and Puerariae Radix (Ge Gen) both treat Xiao Ke (Wasting-Thirst) and body heat. However, when Zhang Zhongjing treated Jing Bing (Spasm Disease), he used Ge Gen in one case and Trichosanthis Radix in another. Why? Generally, if there is no sweating and urine output is unexpectedly low, with Qi rushing upward causing mouth lock, this indicates pathogenic wind-cold-dampness struggling at the intersection of the Taiyang and Yangming meridians without resolving. Using Ge Gen allows it to be dispersed outward along with Mahuang (Ephedrae Herba) and others. Trichosanthis Radix lacks the advantage of releasing the exterior. In cases where the body is stiff and rigid, pairing it with Guizhi (Cinnamomi Ramulus) and Shaoyao (Paeoniae Radix) to nourish the sinews is appropriate. This is the distinction between them.

Trichosanthis Radix fundamentally treats heat and thirst. Yet, in Muli Zexie San, thirst is not mentioned, despite its ingredients being water-draining agents. This is because after a major illness subsides, deficient heat remains inevitable. As water drains, Yin is further injured. Trichosanthis Radix moistens fluids and tonifies deficiency, thereby handling post-illness care alongside disease elimination. In Gualou Qumei Wan, although there is thirst above, there is cold below. Cold in the lower jiao causes Bladder Qi transformation dysfunction and water accumulation. Water accumulating below causes Yang to float above. Thus, thirst is the branch manifestation, while cold is the root cause. Shanyao (Dioscoreae Rhizoma) and Fuzi (Aconiti Lateralis Radix Praeparata) are used to warm the Lung and Kidney.

Regarding the strength of Trichosanthis Fructus, it lies in guiding turbid phlegm downward, making it indispensable for Jie Xiong and Xiong Bi. However, it guides movement but does not forcefully expel. Its nature is soft; without firm partners, its descending force is weak. Hence, Xiao Xian Xiong Tang pairs it with Lian (Huanglian) and Xia (Banxia), while formulas like Gualou Xiebai Tang pair it with Xie, wine, Gui (Guizhi), and Po (Houpo), utilizing bitter-acrid and swift agents to leverage its strengths and offset its shortcomings.

Both Ge Gen and Trichosanthis Radix are recorded in the *Bencao Jing* as treating Xiao Ke. Ge Gen raises Yin Qi, whereas Trichosanthis Radix is not described as raising Yin Qi. Zhang Yinan argued that Gualou vines spread widely, and when fruits set, the starch in the roots is consumed. Once fruits are formed, the roots regenerate starch. Combined with the general rule that herb roots ascend, he concluded Trichosanthis Radix raises Yin Qi to moisten upwards. Mr. Zou agreed. I disagree. Practitioners know Ge Gen as an agent that ascends Yangming Qi. Trichosanthis Radix is never used for ascending purposes. Although all roots contain ascending potential, not all root drugs are ascending. If "ascending" meant starch consumption, this occurs when ascending power has already faded. The reason Trichosanthis Radix treats Xiao Ke is its moistening nature and bitter-cold taste. With yellow skin and white flesh, it clears Heat from the Lung and Stomach and moistens their dryness. Its aliases "Tian Hua Fen" (Heavenly Flower Powder) and "Rui Xue" (Auspicious Snow) imply cold, moistening, and descending properties. Ge Gen is different: it is sweet and neutral, a primary drug for the Yangming channel. Internally white, it moves from Stomach to Lung; externally purple-black, it moves from Lung to Taiyang. Sweet and acrid, it excels at dispersing, ascending layer by layer and spreading horizontally. Ascending, it raises Stomach fluids to moisten the Lung; dispersing, it releases exterior pathogens to relieve the muscle layer. Thus, Trichosanthis Radix treats body heat by overcoming heat with cold; Ge Gen treats body heat by dissipating heat with acridity. Trichosanthis Radix stops thirst by replenishing what is lacking; Ge Gen stops thirst by drawing fluid from below to above. Overuse of Ge Gen can deplete fluids.

Ge Gen Tang adds Mahuang to Guizhi Tang. Is this insufficient to release Taiyang pathogens? Yet Ge Gen is heavily used. This is because neither Mahuang Tang nor Guizhi Tang indications feature stiff neck and back. When Taiyang disease progresses to stiffness in the neck and back, wind-cold has transformed into heat, consuming fluids, and is about to enter Yangming. Mahuang and Guizhi are drying agents, insufficient alone. Only Ge Gen can enter Yangming, raise Yin Qi, lubricate joints, and resolve exterior heat. Thus, Ge Gen is the chief ingredient.

When cold obstructs the meridians, intending to transform but not yet fully transformed, presenting with exterior heat, Ge Gen can reach the exterior and resolve it. If heat has already transformed and entered the interior, or if the heat should not be resolved via the exterior...