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Rainwater, being light and clear in nature, has a sweet and bland taste, ranking supreme among all waters. It can be used in all four seasons, but is particularly excellent in summer. Rainfall obtained after a severe drought must be collected and stored; drinking it can dispel diseases.

Someone asked: "The *Bencao* records that rainwater is cold in nature, yet you say it is light and clear. Why?" I replied: "All waters are inherently cold, with the sole exception of hot springs which are hot. However, once flowing out externally, even their warmth turns cold. Why should only rainwater be considered uniquely cold? Since all waters are cold, I do not specifically emphasize its coldness. The Qi of Heaven is the clearest, thus Heavenly Qi belongs to Yang. Yin Qi is heavy and turbid, while Yang Qi is clear; this is the principle. Although rainwater is transformed from Earthly Qi, if Heavenly Qi does not interact with Earthly Qi, Earthly Qi cannot ultimately transform into rain. Therefore, rainwater is still generated by Heavenly Qi, not Earthly Qi. Having acquired much of Heavenly Qi, how could it not be light and clear?"

Someone asked: "Regarding rainwater at the Beginning of Spring, if a couple drinks it, is it true that they are more likely to conceive?" I said: "Spring is the beginning of Yang Qi. Rainwater at the Beginning of Spring seems to embody the meaning of development and growth. However, only through the union of male and female essence can children be born; it has never been heard that drinking water can produce a son. This claim remains between credible and incredible. One cannot fully rely on drinking water from the Beginning of Spring as a miraculous prescription for conception."

Someone asked: "Why is plum rain (Meiyu) toxic?" I said: "Plum rain has a sweet taste and neutral nature; how could it be toxic? Due to the stifling heat and humidity of the weather, water easily causes substances to change. Things that do not normally change will undergo transformation when exposed to it; thus, water and gruel easily become hot, items touched by water easily develop spots, brewing wine or vinegar alters their flavor, and washing clothes removes dirt. In reality, where is the toxicity? If stored for a long time, it not only loses its toxicity but can also resolve toxins."

Someone asked: "Is it true that entering the Plum Rain season occurs on the Ren day after Mangzhong (Grain in Ear), exiting on the Ren day after Xiaoshu (Minor Heat), entering 'Ye' (fluids) ten days after Lidong (Start of Winter), and exiting at Xiaoxue (Minor Snow)?"
I said: "This is recorded in the *Yueling* (Monthly Ordinances). How dare I refute its errors? But to say that the water drunk by hundred insects during 'Ye' causes them to hibernate, and thus one should prepare insecticidal medicines, is something I, Chen Shiduo, do not believe. If there is no rain during 'Ye', and insects do not drink water, do they not hibernate? If insects do not hibernate, would the prepared medicines be ineffective? Generally, hundred insects bow down in winter; bowing down is hibernation. Why must they necessarily drink rainwater from the 'Ye' period?"

Someone asked: "When storing objects in snow water from the twelfth lunar month, they do not rot or get infested with worms. Is there a rationale for this?" I said: "How could there not be? Winter is a time of storage and concealment, when Heaven and Earth do not interact. Winter rain represents an interaction within non-interaction. It seems like the storage energy of winter dissipates. However, when it rains, Heavenly Qi interacts with Earthly Qi; when rain turns to snow, Earthly Qi interacts with Heavenly Qi, while Heavenly Qi still does not interact with Earthly Qi. Since Heavenly Qi does not interact with Earthly Qi, the Qi of snow is purely isolated Yin without Yang. Isolated Yin cannot grow; if it cannot grow, it cannot transform. Thus, when storing objects, worms do not arise, and flavors do not change. Not only does it not breed worms, but it can also kill them, for Yin governs killing. Therefore, water after the Winter Solstice, called La Shui (Winter Water), sealed and stored in yin places, can also preserve objects, precisely because it is pure Yin without Yang and resides in the most Yin location. Once winter passes and spring arrives, rain—even if it becomes snow—will inevitably cause stored objects to breed worms and spoil, precisely because it contains Yang within Yin."

Someone asked: "Do snow and ice have the same nature and taste?" I said: "No. Snow is bland and cold; ice is sweet and cold. Bland and cold snow can wash away winter heat pathogens; sweet and cold ice can resolve summer heat pathogens. However, although these two can resolve winter and summer pathogens, excessive consumption反而 (instead) aids the pathogen. Because cold and heat clash, over time one succumbs to the pathogen; the pathogen remains in the abdomen and is difficult to cure quickly. Thus, one can only temporarily relieve heat, but cannot long rely on its coldness."

Someone asked: "Dew is also water from Tian Yi (Heaven One). Does consuming it necessarily benefit humans?" I said: "Dew can be used internally and externally. For external use, dew collected on the seventh day of the seventh lunar month is best for washing the eyes. However, one must not collect dew from *Campsis grandiflora* (Lingxiao flower), as it damages the eyes. For internal use, it is best at resolving dryness of Lung Metal, but must be collected at dawn from the heads of hundred herbs. Ancients collected autumn dew to brew wine, named 'Autumn Dew White,' taking advantage of its ability to resolve dryness of Lung Qi. Autumn dew greatly enters the Yin of the five Zang organs. When using herbs intended to enter the Yin aspect, one must use it as a guiding substance; it is not that autumn dew alone benefits the five Zang organs. Used together with Yin-nourishing herbs, it truly achieves miraculous results."

Someone asked: "Does Ban Tian He Shui (Half-Sky River Water) contain toxicity?" I said: "Water taken from dead bamboo tips is non-toxic. If taken from hollow trees, one must guard against snake and scorpion toxicity. Ban Tian He Shui refers to water that has not yet entered the ground. My opinion is that using Ban Tian He Shui is inferior to collecting rainwater before it hits the ground. If one must collect water when it is not raining, then collecting Ban Tian He Shui is acceptable out of necessity."

Someone asked: "What is the difference between rainwater under eaves and roof leakage water? Yet some people who drink it get sick, while others do not. Why?" I said: "Roof leakage water falls mixed with dust and is extremely unclean. It inevitably carries filth from hundred insects. Not only is it bitter and cold, but it also has great toxicity, so consuming it kills. Water under eaves, washed by prolonged rain through tiles, dissolves any insect filth upon contact with rain, so drinking it leaves one unharmed. However, during initial rainfall, insect filth remains, and toxins are not fully resolved. Drinking it may not kill, but how can one avoid disease?"

Someone asked: "Winter frost is similar to snow. If snow can resolve winter heat pathogens, can winter frost do so too?" I said: "Winter frost is sweet and cold, similar to snow, but its function differs. Frost can be used externally but not internally. It is most effective for treating external heat toxins; symptoms subside as it dries. If used internally for heat syndromes, one feels slightly relieved upon swallowing, but abdominal pain ensues upon entering the stomach. This is because winter frost is austere and killing, its Qi too rigid. Heat in the five Zang organs is mostly false heat; encountering true cold breaks the false heat instantly. The false heat dares not struggle and flees, invading paths it normally would not, hence it should not be used lightly."

Someone asked: "Hailwater is also like frost and snow; can it be used in medicine?" I said: "Hail is the Qi of heaven and earth in discord, sent to plague humanity. How can such discordant Qi enter medicine? If swallowed by mistake, it brings disaster. Its taste is salty and odor fishy, believed to be transformed by venomous dragons from seawater. Medication is strictly contraindicated."

Someone asked: "Are there distinctions among flowing waters?" I said: "Flowing waters differ: there are river waters, stream waters, creek waters, and ravine waters. Among these, there are逆流 (counter-flowing) and 顺流 (downstream) waters. Generally, those with long sources and smooth downstream flow are best. Among downstream flows, eastward-flowing ones are superior, as they flow into the East (Wood direction, representing life). However, diseases have favorable and unfavorable courses. Sometimes counter-flowing water is taken to reverse the disease's course by utilizing its counter-flow, achieving harmony through opposition. Lao Shui (Labor Water) is made by taking flowing water and tossing it thousands of times before adding to medicine, a method of refining raw to cooked."

Someone asked: "Are well water and flowing waters different?" I said: "Their cold nature is the same, but their tastes (sweet, salty, bland) differ. Using flowing water is generally better than well water. However, sometimes medicine requires well water and cannot use flowing water, due to its stillness. Well water absorbs much Earthly Qi. Jing Hua Shui (Well Flower Water) collected at dawn is Tian Yi water, obtaining Heavenly Qi from within the earth. Thus, well water indoors has slight toxicity because it is pure Yin without Yang. Ancients added cinnabar to dissolve its Yin Qi. Boiling well water is undrinkable, indicating pure Yin attempting to transform. Untransformed, it causes abdominal distension. Adding two pieces of *Gastrodia elata* (Guan Zhong) is good. Twice a year is sufficient to eliminate toxicity."

Someone asked: "Are mountain spring waters all different?" I said: "Yes. Water falling from rock walls is drinkable; others should not be used lightly. Fear of black soil, toxic woods, and evil grasses harboring snakes and insects causing toxicity that kills. Among mountain springs, the best is Ru Quan (Milk Spring). Milk springs vary: those emerging from sand are secondary; those from stone bones are superior. They taste sweet and warm, unlike other cold waters. Freshly drawn milk spring water smells slightly fishy and is slightly turbid; after overnight settling, it becomes clear, fragrant, and crisp. Drinking it dispels disease and prolongs life, as it is the fluid of stones. If still fishy and turbid overnight, do not use it, indicating poor mountain quality."

Someone asked: "Water is cold; why is hot spring water hot and undrinkable?" I said: "Hot springs are not undrinkable, nor are baths forbidden. They are waters of hyperactive Yang, pure Yang without Yin, hence changing from cold to hot. People with strong Yang and weak Yin drink water to nourish Yang. Drinking hot springs further aids Yang, which is unbeneficial. Moreover, what is aided is pathogenic Yang, not true Yang, so it is undrinkable."

Someone asked: "Human essence corresponds to sea water; shouldn't the sea be a Yin-nourishing substance? Why is salt beneficial, but seawater useless, and brine fatal?" I said: "Kidney water corresponds to sea water in terms of flavor and nature, but sea water is not Kidney water. Kidney water is congenital, formless. Sea water is acquired, formed. Formed cannot nourish formless. Salt benefits Kidney water because water is transformed by fire. Fire is formless, entering the formless. However, excess salt over-aids Fire, yielding no benefit, just as drinking seawater □□□□□ is purely fire-transformed. Now lacking Yin Qi, and tasting very bitter, bitterness first enters □□□□□ membrane, blocking entry. Heart Qi does not circulate; brine finds Heart rejection, descends to invade □□□. Due to extreme bitterness and closure, Kidney Qi also stagnates. Flowing into □□□, it contracts Qi, leading to intestinal constipation and death. How can it aid the Kidneys?"

Someone asked: "If Yin water is unbeneficial, why do physicians use Di Jiang Shui (Earth Slurry)?" I said: "For patients suffering from □□□ Yang deficiency without Yin, Di Jiang Shui is necessary. Dig a pit, pour fresh well water, stir until turbid, let settle, and drink. It is pure Yin yet obtains Earth Qi, differing from well water. Waters with Earth Qi do not damage Spleen and Stomach Qi; toxins are resolved, and pathogenic heat is removed."

Someone asked: "Northwesterners like sour Jiang Shui (fermented rice water); is it beneficial?" I said: "Jiang Shui quenches thirst and helps fatigue, beneficial initially, but harmful long-term. Sour Jiang Shui, □ cooked rice/tea thrown into chives, spoils over time. Acceptable for three days in the South, seven in the North. Beyond these limits, it is unusable. Excessive acid injures Liver Qi; foul odor damages Spleen. Women consuming it may cease menstruation; pregnant women risk fetal emaciation. Caution is advised."

Someone asked: "Boiled water (Bai Fei Tang) was esteemed by ancients, but I think it lacks vital Qi due to excessive heat." I said: "□□□□ Tea and broth should not be boiled excessively. Over-boiling makes nature too urgent, affecting Five Zang □□□□□□ Qi. Yet, drinking immediately after boiling causes abdominal distension due to □□□□□□□"

Someone asked: "If half-boiled water is unusable, why do physicians use Yin-Yang Water □□□□□□□ Yang water is not commonly used. For alternating Yin-Yang conditions, □□□□□□□ is mixed and administered to induce vomiting, seeking neither Yin nor Yang. Using chaos to create chaos, stimulating vomit □□□□ Yin and Yang return to their respective poles. Vomiting without illness disrupts Yin-Yang. Wu □□□□."

Someone asked: "Can pond water in marshes be drunk?" I said: "Stagnant water is □□□ especially dangerous in May-June. Fear of sperm release from snakes, insects, fish, and turtles contaminating the water. Accidental ingestion □□□ Harmless in autumn/winter, but well water is still preferable."

Someone asked: "Are these all the waters one should avoid drinking?" I said: "I spoke of daily necessities. Considering variations, many are avoided: water soaking flowers, water stored in copper vessels, overnight water with five-colored luster, ancient well water, and turbid water are all undrinkable."