单方者，药不过一二味，治不过一二症，而其效则甚捷。用而不中，亦能害人，即世所
谓涨上方者是也。其原起于本草。盖古之圣人，辨药物之性，则必着其功用，如逐风、逐寒、解
毒、定痛之类。凡人所患之症，上一二端，则以一药治之，药专则力浓，自有奇效。若病兼
数症，则必合数药而成方。至后世药品日增，单方日多，有效有不效矣。若夫外内之感，其
中自有传变之道，虚实之殊，久暂之别，深浅之分。及夫人性各殊，天时各异，此非守经达
权者不能治。若皆以单方治之，则药性专而无制，偏而不醇，有利必有害。故医者不可以此
尝试，此经方之所以为贵也。然参考以广识见，且为急救之备；或为专攻之法，是亦不可不
知者也。
天地有好生之德，圣人有大公之心，立方以治病，使天下共知这，岂非天地圣人之至愿
哉
之高下，以为效验，故或用之而愈，或用之而反害，变化无定，此大公之法也。若禁方者，
义有所不解，机有所莫测。其传也，往往出于奇人隐士，仙佛鬼神，其遇之也甚难，则爱护
之必至。若轻以授人，必生轻易之心，所以方家往往爱惜，此乃人之情也。一则恐发天地之
机也。禁方之药，其制法必奇，其配合必巧，穷阴阳之柄，窥造化之机，其修合必虔诚敬慎
，少犯禁忌，则药无验。若轻以示人，则气泄而有不神，此又阴阳之理也。《灵枢》禁服篇
∶黄帝谓雷公曰∶此先师这所禁，割臂歃血之盟也。故黄帝有兰台之藏，长桑君有无泄之戒
，古圣皆然。若夫诡诈之人，专欲图利，托名禁方，欺世惑众。更有修炼热药，长欲导淫，
名为养生，实速其死。此乃江湖恶习，圣人之所以诛也。又有古之禁方，传之已广，加载医
书中，与经方并垂，有识者自能择之也。
单方，是指药物不超过一两味，治疗的病症不超过一两种，但其疗效却非常迅速。使用得当则有效，若使用不当不能对症，也会伤害人体，这就是世人所说的“涨上方”（指夸大疗效的方子）。单方的起源可以追溯到《本草》。大概古代的圣人辨别药物的性质时，一定会注明其功效，比如祛风、散寒、解毒、止痛之类。凡是人们所患的病症，只要有一两个主要症状，就用一味药来治疗，因为药味专一，药力就浓厚，自然会有奇效。如果病情兼有多种症状，就必须合并多种药物组成方剂。到了后世，药品日益增多，单方也越来越多，有的有效，有的无效。至于外感六淫和内伤七情等因素，其中自有传变规律，有虚证和实证的差异，有病程久暂的区别，有病位深浅的不同。再加上每个人的体质各不相同，天时气候各有差异，这些不是那些能够坚守常法又能灵活变通的医生是不能治疗的。如果都用单方来治疗，那么药性虽然专一但缺乏制约，药力偏颇而不纯正，有利必有弊害。所以医生不可以拿这个去尝试，这就是经方（经典方剂）之所以珍贵的原因。然而，参考单方以拓宽见识，并且作为急救的备用；或者作为专门攻邪的方法，这也是不可不知道的知识。
天地有好生之德，圣人有公正无私之心，创制方剂来治疗疾病，使天下人都知道，这难道不是天地和圣人的最大愿望吗？（通过比较方剂）的高下，来判断疗效，所以有的用了痊愈，有的用了反而受害，变化没有定规，这是大公无私的治法原则。至于禁方，含义有不理解的地方，机理有无法推测之处。它的传承，往往出于奇人隐士，或是仙佛鬼神，遇到它很难，所以必定会极度爱惜。如果轻易传授给别人，必然会产生轻慢随意的心理，所以医家往往十分爱惜，这是人之常情。一方面是因为担心泄露天地的机密。禁方的药物，其制作法则一定奇特，其配伍一定巧妙，穷尽阴阳的要旨，窥探造化的玄机，其炮制配合必须虔诚恭敬谨慎，稍微触犯禁忌，药效就没有验证。如果轻易展示给人看，那么药气就会泄失而不再神奇，这又是阴阳的道理。《灵枢·禁服篇》记载：黄帝对雷公说：“这是先师所禁止传授的，是割臂歃血结盟才能得到的秘密。”所以黄帝有兰台之藏（收藏珍贵医籍之所），长桑君有无泄（不得泄露）的告诫，古代圣人都这样做。至于那些诡诈之人，专门想要谋取利益，假托名为禁方，欺骗世人迷惑大众。更有甚者修炼温热药物，长期想要引导淫欲，名义上是养生，实际上是加速死亡。这是江湖上的恶劣习气，是圣人所以要谴责的。又有古代的禁方，流传已经很广泛，收录在医书中，与经方一起流传下来，有见识的人自然能从中选择适用的。
Single-herb prescriptions (Danfang) refer to formulas containing no more than one or two herbs, treating no more than one or two symptoms, yet their efficacy is remarkably rapid. If used inappropriately, they can also harm the body; this is what the world calls "Zhangshangfang" (prescriptions with exaggerated claims of efficacy). Their origin lies in Bencao (Materia Medica). Generally, ancient sages, when distinguishing the properties of medicinal substances, would necessarily record their functions, such as expelling wind (Zhufeng), dispelling cold (Zhuhan), resolving toxicity (Jiedu), and relieving pain (Dingtong). Whenever a patient suffers from a condition with only one or two primary manifestations, a single herb is used for treatment. Because the prescription is specialized, its therapeutic force is concentrated, naturally yielding miraculous effects. However, if a disease involves multiple symptoms, several herbs must be combined to form a formula. In later generations, as the number of medicinal substances increased daily, so did the number of single-herb prescriptions, resulting in some being effective and others ineffective. Regarding external pathogens and internal injuries, there are inherent laws of transmission and transformation, distinctions between deficiency (Xu) and excess (Shi), differences in duration (acute vs. chronic), and variations in depth of pathology. Furthermore, human constitutions vary, and climatic conditions differ. These complexities cannot be treated by those who do not adhere to fundamental principles while exercising flexibility (Shoujing daquan). If single-herb prescriptions were used universally, the specific nature of the herbs would lack regulation, leading to biased but impure actions, where benefits inevitably bring harms. Therefore, physicians should not experiment with them casually; this is why Jingfang (Classic Prescriptions) are so highly valued. Nevertheless, consulting single-herb prescriptions broadens knowledge and serves as a reserve for emergency situations; or as methods for targeted attack on pathogenic factors, this is also knowledge that cannot be ignored.
Heaven and Earth possess the virtue of loving life, and sages possess a heart of great impartiality. Creating formulas to treat diseases and making them known to all under heaven—could this not be the greatest wish of Heaven, Earth, and the Sages? By comparing the superiority and inferiority of formulas to assess efficacy, some cures the disease while others cause harm; changes are unpredictable. This represents the method of great impartiality. As for Jin Fang (Forbidden Prescriptions), their meanings may be unclear, and their mechanisms unfathomable. Their transmission often comes from eccentric hermits, or even immortals, Buddhas, ghosts, and gods. Encountering them is difficult, hence they are cherished intensely. If given away lightly, people would develop a casual attitude, which is why practitioners often guard them closely; this is human nature. On one hand, it is feared that the secrets of Heaven and Earth might be revealed. The preparation methods of herbs in forbidden prescriptions are invariably unique, and their combinations ingenious, exhausting the principles of Yin and Yang (Yin-Yang) and peering into the mechanisms of creation. Their compounding requires utmost sincerity, reverence, and caution; any violation of taboos renders the medicine unverified. If shown to others lightly, the vital energy (Qi) leaks, and the efficacy becomes ineffectual; this is again the principle of Yin and Yang. The *Lingshu* (Spiritual Pivot), chapter *Jinfu*, records: Huangdi (Yellow Emperor) said to Leigong, "This was prohibited by former masters, obtained through an oath of cutting arms and drinking blood." Thus, Huangdi had the Lantai Cang (Lantai Treasury), Changsang Jun had warnings against leakage, and ancient sages acted similarly. As for deceitful individuals seeking profit, they falsely claim "forbidden prescriptions" to deceive the public. Worse still, some cultivate hot-natured drugs to induce lust under the guise of health preservation, actually accelerating death. This is a vicious habit of the Jianghu (unorthodox medical circles), which sages condemn. There are also ancient forbidden prescriptions that have spread widely, recorded in medical texts alongside classic prescriptions; those with insight will naturally select appropriately.