水谷入胃。其浊者为渣滓。下出幽门。达大小肠。而为粪。以出于谷道。其清者。倏然而化。根据脾气而上升于
肺。其至清而至精者。由肺而灌溉乎四体。为汗液津唾。助血脉。益气力。为生生不息之运用也。其清中之
浊者。下入膀胱而为溺。此虞天民医学正传所论。其言水谷消化之道甚明。故全录之。凡食不化者。责之
于脾。六君子汤主之。水不化者。责之于肺。二陈汤。加防己桑皮桔梗木通治之。消渴者肺火也。甘露饮加
花粉治之。消谷者胃火也。白虎汤。加黄连人参枳壳浓朴生地黄治之。饮一溲二。为下消。肾虚也。肾气丸
主之。食入即吐。为火逆。泻心汤加生姜竹沥治之。但用水漱口。而不欲饮者。多是经脉中有瘀血。宜四物
汤。加红花血通干漆冰片葱白桃仁治之。食入良久。翻胃吐出。或不化而飧泄者。为脾不磨食。六君子汤。
加肉豆蔻破故纸吴茱萸五味子治之。
夫人之所以能化食思食者。全赖胃中之津液。吾于总论已详言之。有津液则能化食。能纳食。无津液则
食停不化。观停食病。食入反吐。粪如羊屎。可知无津液则食不能化之故矣。观噤口痢。咽干津竭。食不得
下。可知无津液则食不能纳之故矣。痢证噤口者。另详便血门。膈食不化。以及血虚津枯。不思饮食者。宜
用左归饮。加天花粉人参玉竹党参莲米白芍芝麻治之。
一凡平人内伤饮食。多是中寒洞泄。治宜理中汤。平胃散。以温燥之。若失血之人。内伤饮食。则反多壅实
生热之证。往往手足潮热。口干气逆。冲脉作咳。若用温燥之药。不惟饮食不化。且更加壅热矣。用小柴胡
汤。加枳壳浓朴大黄。轻则加莱菔子麦芽。越鞠丸加减亦治之。
水谷进入胃中。其中浑浊的部分成为渣滓，向下通过幽门，到达大肠和小肠，形成粪便，从肛门排出。其中清灵的部分，迅速转化，依托脾气的升清作用向上输送到肺。其中最为清灵精微的物质，由肺输布灌溉到四肢百骸，化为汗液、津液和唾液，辅助血脉运行，补充气力，这是生命生生不息的运作机制。其中清中之浊的部分，向下进入膀胱，形成尿液。这是虞天民在《医学正传》中的论述，他关于水谷消化过程的阐述非常清晰，因此全文抄录于此。
凡是食物不能消化的，责任在于脾，用六君子汤主治。水液不能代谢的，责任在于肺，用二陈汤，加防己、桑白皮、桔梗、木通来治疗。消渴病是肺火所致，用甘露饮加天花粉治疗。消谷善饥（吃得多饿得快）是胃火所致，用白虎汤，加黄连、人参、枳壳、厚朴、生地黄治疗。喝得多尿得也多，属于下消，是肾虚所致，用肾气丸主治。食入即吐，是火气上逆所致，用泻心汤加生姜、竹沥治疗。只是用水漱口，而不想喝水的，多是经脉中有瘀血，宜用四物汤，加红花、血竭、干漆、冰片、葱白、桃仁治疗。食物吃下去很久，发生翻胃吐出，或者不消化而完谷不化的泄泻，是脾不能磨化食物，用六君子汤，加肉豆蔻、补骨脂、吴茱萸、五味子治疗。
人之所以能够消化食物并产生食欲，完全依赖胃中的津液。我在总论中已经详细论述过。有津液就能消化食物，能接纳食物；没有津液则食物停滞不化。观察停食病，食物吃进去反而呕吐，大便像羊屎一样干燥，就可以知道没有津液则食物不能消化的缘故了。观察噤口痢，咽喉干燥津液枯竭，食物无法咽下，就可以知道没有津液则食物不能接纳的缘故了。痢疾证候中出现噤口不食的，另在便血门中详细说明。膈食不化，以及血虚津枯导致不思饮食的，宜用左归饮，加天花粉、人参、玉竹、党参、莲子、白芍、芝麻治疗。
一般普通人内伤饮食，多表现为中焦虚寒导致的洞泄（急迫的水样腹泻），治疗宜用理中汤、平胃散，以温燥之法治疗。如果是失血之人，内伤饮食，则反而多出现壅滞实热之证，往往伴有手足潮热、口干、气逆、冲脉上逆致咳等症状。如果使用温燥的药物，不仅饮食不能消化，而且会加重壅热。此时用小柴胡汤，加枳壳、厚朴、大黄。病情轻的加莱菔子、麦芽。越鞠丸加减也能治疗。
When food and water enter the stomach, the turbid portion becomes dregs. It passes downward through the pylorus to the large and small intestines, forming feces, which are expelled from the anus. The clear portion transforms rapidly; relying on the ascending function of Spleen Qi (Spleen Qi), it rises to the Lung. The most pure and refined substances are irrigated by the Lung to the four limbs, transforming into sweat, body fluids (Jin-Ye), and saliva, assisting blood vessels and replenishing qi strength. This is the continuous operation of life. The turbid part within the clear portion descends into the bladder to form urine. This discussion is from Yu Tianmin's *Zhuan* (General Treatise) of *Yi Xue Zheng Zhuan* (Correct Transmission of Medical Learning). His explanation of the digestion pathway of food and water is very clear, so it is recorded in full here.
For those who cannot digest food, the responsibility lies with the Spleen; Liu Jun Zi Tang (Six Gentlemen Decoction) is the primary treatment. For those who cannot metabolize water, the responsibility lies with the Lung; Er Chen Tang (Two Aged Decoction) combined with Fang Ji (Stephania Root), Sang Bai Pi (Mulberry Root Bark), Jie Geng (Platycodon Root), and Mu Tong (Akebia Stem) is used for treatment. Xiao Ke (Wasting-Thirst Syndrome) is caused by Lung Fire; Gan Lu Yin (Sweet Dew Drink) combined with Hua Fen (Trichosanthes Root) is used for treatment. Xiao Gu (Consuming Grain/Hyperphagia) is caused by Stomach Fire; Bai Hu Tang (White Tiger Decoction) combined with Huang Lian (Coptis Rhizome), Ren Shen (Ginseng Root), Zhi Qiao (Bitter Orange Fruit), Hou Po (Magnolia Bark), and Sheng Di Huang (Rehmannia Root) is used for treatment. Drinking much and urinating much is called Xia Xiao (Lower Wasting-Thirst), caused by Kidney Deficiency; Shen Qi Wan (Kidney Qi Pill) is the primary treatment. Vomiting immediately after eating is due to rebellious Fire; Xie Xin Tang (Drain the Epigastrium Decoction) combined with Sheng Jiang (Fresh Ginger) and Zhu Li (Bamboo Juice) is used for treatment. Merely rinsing the mouth with water but having no desire to drink indicates mostly stasis of blood in the meridians; Si Wu Tang (Four Substances Decoction) combined with Hong Hua (Safflower), Xue Tong (Draconis Sanguis/Blood Dragon Blood), Gan Qi (Dry Lacquer), Bing Pian (Borneol), Cong Bai (Scallion White), and Tao Ren (Peach Kernel) is indicated. Food remaining in the stomach for a long time, leading to fan Wei (rebellious vomiting/regurgitation), or undigested food causing Sun Xie (undigested stool diarrhea), is due to the Spleen's inability to grind food; Liu Jun Zi Tang (Six Gentlemen Decoction) combined with Rou Dou Kou (Nutmeg), Po Gu Zhi (Psoralea Fruit), Wu Zhu Yu (Evodia Fruit), and Wu Wei Zi (Schisandra Berry) is used for treatment.
The reason humans can digest food and have an appetite relies entirely on the Jin-Ye (Body Fluids) in the Stomach. I have discussed this in detail in the General Treatise. With Jin-Ye, one can digest and accept food; without Jin-Ye, food stagnates and fails to digest. Observing Ting Shi (Food Stagnation) disease, where food eaten is vomited back up and feces are dry like sheep droppings, reveals the reason why lack of Jin-Ye prevents food digestion. Observing Jin Kou Li (Jin-Kou Dysentery/Anorexic Dysentery), where the throat is dry and Jin-Ye is exhausted, preventing food intake, reveals the reason why lack of Jin-Ye prevents food acceptance. Cases of dysentery presenting as Jin Kou (unable to eat) are detailed separately in the Men of Bian Xue (Blood in Stool Chapter). For Ge Shi (Diaphragmatic Obstruction/Regurgitation) with undigested food, as well as cases of Bu Si Yin Shi (loss of appetite) due to Blood Deficiency and Jin-Ye Dryness, Zuo Gui Yin (Left Restoring Drink) combined with Tian Hua Fen (Trichosanthes Root), Ren Shen (Ginseng Root), Yu Zhu (Polygonatum Odoratum Rhizome), Dang Shen (Codonopsis Root), Lian Mi (Lotus Seed), Bai Shao (White Peony Root), and Zhi Ma (Sesame Seed) is used for treatment.
Generally, ordinary people suffering from internal injury due to diet often present with Zhong Han Dong Xie (Middle Jiao Cold causing urgent watery diarrhea); treatment should employ Li Zhong Tang (Regulate the Middle Decoction) and Ping Wei San (Calm the Stomach Powder) to warm and dry. However, for persons with lost blood who suffer internal injury due to diet, they more often present with symptoms of stagnation, excess, and heat generation, such as tidal fever in the hands and feet, dry mouth, rebellious qi, and cough due to Chong Mai (Penetrating Vessel) rebellion. If warming and drying herbs are used, not only will the food fail to digest, but the stagnation and heat will increase. In such cases, Xiao Chai Hu Tang (Minor Bupleurum Decoction) combined with Zhi Qiao (Bitter Orange Fruit), Hou Po (Magnolia Bark), and Da Huang (Rhubarb Root) is used. For milder cases, Lai Fu Zi (Radish Seed) and Mai Ya (Barley Sprout) are added. Yue Ju Wan (Relieving Depression Pill) with modifications is also effective.