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[General Information]
[Flavor and Properties] Sweet in flavor, neutral in nature, non-toxic.
[Indications] It is the supreme medicine for regulating the Spleen and Stomach and eliminating damp-heat.
[Analysis] It is said: Rainwater is called "Liao" (rainwater collected on the ground), sudden rain is called "Zhou", slow rain is called "Ling", prolonged rain is called "Ku Yu" (bitter rain) or "Chou Lin" (melancholy drizzle), rain clearing after falling is called "Ji", timely rain is called "Shu", and rain that clears during the day is called "Qi". Generally, rain descends from clouds; when the Qi of Heaven and Earth harmonizes, rain forms; when it agitates, wind forms. Therefore, whenever rain is mentioned in the *I Ching* (Book of Changes), it represents an image of harmony. The *Classic of Poetry* says: "The lush vegetation thrives, the gentle rain falls slowly." " " refers to overcast rain, sometimes written as " ". " " refers to clouds formed by water vapor. Commentaries state: Rain is water vapor within clouds. "Qiqi" describes a lush appearance; "Qiqi" describes a slow manner. Generally, if clouds wish to be lush, lushness ensures sufficient rain; if rain wishes to fall slowly, slowness allows it to penetrate the soil. Moreover, if rain falls before cloud masses gather, it is not a sign of Yin harmony. Thus, the *Classic of Poetry* considers lush vegetation and slow rain as auspicious. The *Classic of Poetry* also states: "The spiritual rain has fallen, commanding the servants to drive their carts early under the stars, resting at the fields." The *Ruiying Tu* (Chart of Auspicious Responses) states: Spiritual rain is auspicious rain. Descending to respond to all things, it is called spiritual rain. "Star" indicates clear weather. This means it rained at night, and by morning the stars were visible, prompting supervision and encouragement of farming, which corresponds to the commentary's description of managing resources and instructing farmers. The *Yantie Lun* (Discourses on Salt and Iron) states: In the time of the Duke of Zhou, rain did not break clods, and wind did not make branches sing; rain always occurred at night. Night is the proper time for rain. The *Classic of Poetry* says: "I came from the east, the fine rain drizzled," " " is good at moistening and nourishing, yet fond of cold condensation, failing to dispel the sorrow of travel, thus becoming particularly severe; the poem expresses this emotion. *Xiao Ya · Yu Wu Zheng* states: Rain falls from above. Numerous like rain, but this is not suitable for governance. Governance means correctness. In character formation, one 'stop' constitutes 'correct'; numerous like rain implies a lack of 'correctness'. The *Classic of Poetry* says: "When the moon approaches the Bi constellation, heavy rains follow." It also says: "Adding torrential downpours, these are heavy rains; light rain is called ." The *Shiming* (Explaining Names) states: Speaking of dripping and soaking, like a person bathing, only the upper limbs are wetted, while the roots remain dry. Generally, [the substance] moistens the soil like human blood vessels, hence it is called . The *Shuowen Jiezi* states: Autumn [wheat] is dense, hence it is called wheat. Thus, [term A] refers to the upper part, and [term B] refers to the lower part. The *Classic of Poetry* says: "Tall millet shoots, moistened by overcast rain, are seedlings in the heat." If summer rain stops suddenly without cloud cover, the sun evaporates moisture, and the seedlings wither. To moisten them would be harmful. Thus, the *Classic of Poetry* regards overcast rain as beneficial. Folk proverbs call May rain "Dragon-Separating Rain," known as "Wheel-Separating." It is said that summer rains often arrive violently; each dragon has its own domain, so rain often differs across a single wheel track. The *I Ching* states: "Thick clouds but no rain, from my western suburb," referring to the Hexagram Xiao Chu (Small Taming). Chu means accumulation. Rising Qi comes from the west, so it can only form thick clouds. Generally, Liao water used in medicine should be taken from rain under overcast clouds. This originally aligns with the harmony of Heaven and Earth. Taking continuous rain as Liao in Materia Medica does not conform to the orthodoxy of Yin and Yang. These classics and elegant terms are recorded in detail for the reference of scholars.
[Commentary] It is said: Earthly Qi rises to become clouds, Heavenly Qi descends to become rain. Rain originates from Earthly Qi, clouds from Heavenly Qi; they interact through rising and sinking, descending vigorously. Regarding the property of water being cold and sinking alone, let it rise promptly, steaming the skin, filling the body, and moisturizing hair like mist and dew irrigation. *Bencao Jing Jiuyi* (Supplement to the Divine Farmer's Materia Medica) calls it the supreme medicine for regulating and decocting the Spleen and Stomach. The Classics state that human Spleen and Stomach are named after earth and soil, and human sweat/Qi is described using wind and rain metaphors. The realm of utensils nourishes the root body; Shu (dispersing) and Xiang (mutual) cultivate Qin (closeness) and Xiang (relation); the lifeless reciprocally感召 (induces/resonates) with the sentient.