医有成法、有活法，成法师古不可悖，活法因时不可拘。古方切中人病，自有定见。品味及分
两，皆按君臣佐使，不可漫为增减，其制丸散，用服时候，悉有肯綮。盖心肺居上属阳，治心肺，
药必大丸调化，或汤散，或噙咽，皆使易化，必饭后临睡服之，欲其药气恋于心肺也。肾肝居下属
阴，治肾肝，药必细丸吞服，以炼蜜、酒糊、黄蜡等为丸，皆使迟化，必早空心服，更以干物压之
，欲药气令直达于肾肝也。脾为中州，药须细丸，或水叠、或蒸饼糊、或枣肉、或饭丸，服于半饥
半饱巳时之分，使药气正归中州也。如风、火、寒、暑急证，欲取功速者，及走表四达者，皆以汤
散为主。汤者荡也，取其荡涤；散者散也，欲其疏散。如虚损淹延之病，不能一时奏效者，主以丸
，丸者缓也。令其从容培植，各有定格。常见时俗，心肺丸方减数味，加肝肾病之药；肾肝丸方减
数味，入心肺病之饵。上下混淆，皆不奏功。虚费药本为轻，迁延病深为重，若此者，须分二方早
晚各服为是。
病有寒有热，有似寒实热、似热实寒者，皆须细审。经曰∶诸躁狂越，惊惑悲笑，属于热。喘
呕吐酸，暴注下迫，诸禁鼓栗，皆似寒实热，治以凉药。诸病上下所出水液，澄彻清冷，面青肢厥
，属于寒；面红不热，躁渴，不喜冷冻饮料，欲坐卧泥水、井中，皆似热实寒，治以热药。心盛则生热
，肾盛则生寒，心虚则热攻于内，肾虚则寒动于中。此热清，寒温，虚补，实泻也。有初感热病，
因过服寒剂及生冷之类，遂变而为寒者；有初感寒病，因过服热药及姜、椒之类，变而为热者。不
知用药之法，中病即止，治之太过则病外添病矣。如病家不知脉理，欲辩寒热，但看病患畏热恶火
，怕日色暖气，口渴思饮冷汤水，大便闭结，小便短赤，心烦身躁，多言声响，不寐，仰身挺卧，
喜睡凉处，皆属热证。凡病患畏寒喜暖，口不干，思饮热汤，大便利，小便长，口鼻气冷，懒言蜷
卧，皆属寒证。热多属实，寒多属虚，仿此推之，寒热虚实，皆可辩矣。
医生治病既有固定的法则，也有灵活的方法。遵循古法师承前人，但不能违背原则；运用活法顺应时势，也不能拘泥不变。古代方剂切合病人的病情，自有其确定的见解。药物的种类及剂量，都按照君、臣、佐、使的配伍原则，不可随意增减。制作丸剂、散剂，以及服药的时间，都有关键要点。
因为心和肺位于上部，属于阳，治疗心肺疾病，药物必须制成大丸剂以便调化，或者使用汤剂、散剂，或者含咽，都是为了让药物容易消化，必须在饭后和临睡前服用，目的是让药气留恋于心肺部位。肾和肝位于下部，属于阴，治疗肾肝疾病，药物必须制成小丸剂吞服，用炼蜜、酒糊、黄蜡等作为粘合剂制丸，都是为了让药物缓慢释放，必须在早晨空腹时服用，并用干粮压住药力，目的是让药气直接到达肾肝部位。脾脏位居中焦（中州），药物需要制成细丸，或者用水泛丸、蒸饼糊丸、枣肉丸、饭丸等形式，在巳时（上午9-11点，半饥半饱之际）服用，使药气正好归于中焦。
如果是风、火、寒、暑等急症，想要快速见效，以及病邪在体表四肢扩散的情况，都以汤剂和散剂为主。“汤”的意思是荡涤，取其清除病邪之意；“散”的意思是疏散，取其发散透达之意。如果是虚损且病程迁延的疾病，不能一时奏效的，以丸剂为主，“丸”的意思是缓和，让它从容地培植正气。这都有固定的格式。
常见世俗做法，在治疗心肺病的丸方中减去几味药，加入治疗肝肾疾病的药；在治疗肝肾病的丸方中减去几味药，加入治疗心肺病的药。上下混淆，都不能取得疗效。浪费药费是小事，延误病情导致病邪深入才是大事。像这种情况，应该分为两个方子，早晚分别服用才是正确的。
疾病有寒证，有热证，还有看似寒证实为热证、看似热证实为寒证的情况，都必须仔细审察。《内经》说：各种烦躁狂乱、惊惧迷惑、悲伤或无故发笑的症状，都属于热证。气喘呕吐酸水，突然腹泻且里急后重，各种口禁、鼓颔战栗的症状，都看似寒证实为热证，治疗要用凉性药物。各种疾病从上下排出的水液，清澈透明且寒冷，面色青紫、四肢厥冷，属于寒证；面色红赤但不发热，烦躁口渴，却不喜喝冷冻饮料，反而想坐在泥水或井水中降温，都看似热证实为寒证，治疗要用热性药物。心气盛则产生热，肾气盛则产生寒，心气虚则热邪攻冲于内，肾气虚则寒邪动扰于中。这是热证用清法，寒证用温法，虚证用补法，实证用泻法。
有的起初感受热病，因为过量服用寒凉药剂及生冷食物，于是转变为寒证；有的起初感受寒病，因为过量服用温热药物及生姜、花椒之类，转变为热证。如果不了解用药的法度，中病即止（见效就停药），治疗过度就会给病人增添新的病症。
如果病人家属不懂脉理，想要辨别寒热，只需观察病患是否畏热恶火，害怕日光和暖气，口渴想喝冷饮，大便闭结不通，小便短少色赤，心烦身躁，多言声高，失眠，仰卧伸肢，喜欢睡在凉快地方，这些都属热证。凡是病患畏寒喜暖，口不干，想喝热汤，大便通畅，小便清长，口鼻呼出气体寒冷，懒言蜷卧，这些都属寒证。热证多属实证，寒证多属虚证，仿照此理推演，寒热虚实都可以辨别了。
Physicians employ both fixed rules and flexible methods. Following ancient traditions requires adherence to principles without deviation, while applying flexible methods demands adaptability to changing circumstances without rigidity. Ancient prescriptions are tailored to patients' conditions, possessing inherent rationale. The selection of herbs and their dosages strictly follow the hierarchy of Sovereign (Jun), Minister (Chen), Assistant (Zuo), and Envoy (Shi) [Jun-Chen-Zuo-Shi], and should not be arbitrarily added or removed. The preparation of pills and powders, as well as the timing of administration, have specific key points.
Since the Heart and Lungs reside in the upper body and belong to Yang, treatments for Heart and Lung diseases require large pills for easy dissolution, or decoctions (Tang) and powders (San), or lozenges held in the mouth. These forms facilitate digestion. They must be taken after meals and before sleep, aiming to retain the medicinal qi within the Heart and Lungs. Conversely, the Kidneys and Liver reside in the lower body and belong to Yin. Treatments for Kidney and Liver diseases require small pills swallowed whole, bound with refined honey, wine paste, or beeswax to ensure slow release. They must be taken on an empty stomach in the morning, followed by dry food to press the medicine down, aiming to direct the medicinal qi directly to the Kidneys and Liver. The Spleen resides in the Middle Jiao (Central Earth). Medicines for the Spleen should be fine pills, such as water-pellets, steamed dough pellets, jujube meat pellets, or rice pellets, taken during the Si hour (9:00–11:00 AM, when hunger is moderate) so that the medicinal qi returns precisely to the Middle Jiao.
For acute conditions caused by Wind, Fire, Cold, or Summerheat, where rapid efficacy is desired, or for pathogens spreading to the exterior and four extremities, decoctions and powders are primary. "Decoction" implies sweeping away; it is chosen for its ability to cleanse and purge. "Powder" implies dispersing; it is chosen for its ability to scatter and diffuse. For chronic deficiency and wasting diseases that cannot be cured instantly, pills are primary. "Pill" implies slowness; it allows for gradual nourishment and support. Each category has a fixed standard.
It is commonly seen in popular practice that in pill formulas for Heart and Lung diseases, several herbs are reduced and replaced with those for Kidney and Liver diseases; conversely, in Kidney and Liver formulas, herbs are swapped for those treating Heart and Lung diseases. This confusion of upper and lower regions results in therapeutic failure. While wasting medicinal resources is a minor loss, delaying treatment leading to deeper disease is severe. In such cases, it is correct to divide them into two separate formulas, taken in the morning and evening respectively.
Diseases present as Cold or Heat, but there are also cases that appear Cold but are actually Heat, and vice versa, all requiring careful examination. The Classics state: Various restlessness, mania, wandering, fear, confusion, sadness, or inappropriate laughter belong to Heat. Wheezing, vomiting of sour fluid, sudden diarrhea with tenesmus, various lockjaw, teeth chattering, and shivering appear as Cold but are actually Heat; these are treated with cooling medicines. Discharges of fluids from above and below that are clear, transparent, and cold, accompanied by a bluish complexion and cold limbs, belong to Cold. A red face without fever, restlessness, thirst, yet a dislike for cold drinks, preferring to sit in mud or wells, appear as Heat but are actually Cold; these are treated with warming medicines. Excess Heart Qi generates Heat; Excess Kidney Qi generates Cold. Deficiency of Heart Qi allows Heat to attack internally; Deficiency of Kidney Qi allows Cold to move internally. This dictates that Heat is cleared, Cold is warmed, Deficiency is tonified, and Excess is purged.
Some initially contract Heat diseases but, due to excessive intake of cold agents and raw/cold foods, transform into Cold diseases. Others initially contract Cold diseases but, due to excessive intake of hot medicines and pungent-warm substances like Ginger and Sichuan Pepper, transform into Heat diseases. Ignorance of medication principles, specifically stopping treatment once the disease is addressed (Zhong Bing Ji Zhi), leads to over-treatment, adding new ailments to the patient.
If family members do not understand pulse diagnosis and wish to distinguish Cold from Heat, they may observe the patient's preferences. If the patient fears heat and fire, dislikes sunlight and warmth, feels thirsty and desires cold drinks, suffers from constipation, short and dark urine, mental restlessness, loud speech, insomnia, lies supine with extended limbs, and prefers cool sleeping places, these belong to Heat syndromes. If the patient fears cold and prefers warmth, has no dry mouth, desires hot drinks, has loose stools, long and clear urination, cold breath from nose and mouth, speaks little, and curls up in bed, these belong to Cold syndromes. Heat often indicates Excess, while Cold often indicates Deficiency. By inferring from this, Cold, Heat, Excess, and Deficiency can all be distinguished.