百物与人殊体，而人借以养生却病者，何也？盖天地亦物耳，惟其形体至大，则不能无
生。
其生人也得其纯，其生动物也得其杂，其生植物也得其偏。顾人之所谓纯者，其初生之
体然
耳。及其感风寒暑湿之邪，喜怒忧思之扰，而纯者遂漓；漓则气伤，气伤则形败。而物之杂
者、偏者，反能以其所得之性补之、救之。圣人知其然也，思救人必先知物。盖气不能违理
，形不能违气，视色别味，察声辨奥，权轻重度，长短审形之事也；测时令，详嗜好，分盛
衰，别土宜，求气之术也。形气得而性以得。性者，物所生之理也，由是而立本草、制汤剂
以之治人。有余泻之，不足补之，寒者热之，热者寒之，温者清之，清者温之，从者反治，
逆者正治。
或以类相从，或畏忌各矫其弊以复于平。其始则异，其终则同。夫天地生之，圣人保之，
造
化之能，圣人半之，天地不能专也。汉末张仲景《金匮要略》及《伤寒论》中诸方，大半皆
三代以前遗法，其用药之义，与《本经》吻合无间。审病施方，应验如响。自唐以后，药性
不明，方多自撰，如《千金方》、《外台秘要》之属，执药治病，气性虽不相背，而变化已
鲜沿及。宋元药品日增，性未研极，师心自用，谬误相仍。即用本经诸种，其精微妙义，多
所遗漏。是以方不成方，药非其药，间有效用，亦偶中而非可取。必良由本经之不讲故也。
余窃悲焉！欲详为阐述，其如耳目所及无多，古今名实互异，地土殊产，气味不同。且近世
医人所不常用之药，无识别而收采者。更有殊能异性，义在隐微，一时难以推测，若必尽解
全经，不免昧心诬圣。是以但择耳目所习见不疑，而理有可测者，共得百种，为之探本溯原
，发其所以然之义。使古圣立方治病之心，灼然可见，而其他则阙焉。后之君子，或可因之
而悟其全，虽荒陋可嗤，而敬慎足矜也。
乾隆元年岁在柔兆执徐余月上弦松陵徐大椿题于扬子江舟次
万物与人的形体不同，但人却借助它们来养生祛病，这是为什么呢？大概天地也是万物之一，只因为它的形体极其巨大，所以不能没有生命。
人类禀受了天地之气而生，其气最为纯正；动物禀受之气较为驳杂；植物禀受之气则更为偏颇。然而，人所认为的“纯”，仅仅是指刚出生时的身体状态罢了。等到人体感受了风、寒、暑、湿等外邪的侵袭，以及喜、怒、忧、思等情志的干扰，这种纯正的状态就会变得淡薄流失；一旦淡薄流失，元气就会受损，元气受损则形体就会败坏。而那些禀气驳杂、偏颇的植物和动物，反而能够以其所禀受的偏性来补益人体、挽救危局。
圣人深知其中的道理，想要救人必须先了解药物。元气不能违背自然之理，形体不能脱离元气。观察颜色辨别气味，倾听声音分辨质地，权衡轻重度量长短以审察形态，这是认识药物形体的方法；推测时令变化，详查生长习性，区分盛衰规律，辨别适宜土壤，这是探求药物元气的途径。当形体和元气被掌握后，药物的本性也就随之明确了。本性，就是药物生成的内在规律。基于此，才制定了《本草》书籍，配制汤剂来治疗人类疾病。对于有余的病证予以泻除，对于不足的病证予以补益，寒证用热药治疗，热证用寒药治疗，温证用清法处理，清证用温法调理，顺从病势的反治法，逆抗病势的正治法。
或者依据药物性质相似而归类，或者利用药物间的畏忌关系来纠正弊端，从而使人体恢复平衡。起初看来药物与人似乎异质，最终目的却是相同。天地化生万物，圣人加以保存和利用，造化的能力，圣人占了一半，天地并不能独占其功。
汉末张仲景在《金匮要略》及《伤寒论》中的许多方剂，大半都是夏商周以前遗留下来的古法，其用药的原理，与《神农本草经》完全吻合，毫无间隙。仔细辨证施方，疗效迅速如回声响应。自从唐代以后，对药性的理解不再明晰，方剂多由医家自行创制，如《千金方》、《外台秘要》这类著作，虽然执药治病时药性与病情大体不违背，但其中细微的变化已很少沿袭古法。宋元时期药品日益增多，但对药性的研究并未达到极致，医家往往主观臆断，谬误接连出现。即使使用《神农本草经》中记载的药物，其中精妙深奥的含义也多有遗漏。因此，方剂不成其为良方，药物也不得其真用，偶尔有效，也只是偶然命中而非值得推崇的方法。这必定是因为不讲求《神农本草经》的缘故啊。
我私下对此感到悲痛！想要详细阐述，无奈限于见闻不多，古今名称与实际不符，产地不同导致药材差异，气味也有所不同。而且近代医生不常用的药物，缺乏识别而被采集者甚少。更有那些具有特殊才能和性质的药物，其义理隐微难测，一时难以推测，如果一定要完全解释整部经典，难免会违背良心诬蔑圣人。因此，我只选择那些耳闻目睹习以为常且道理可以推究的，共选取一百种药物，为它们探究本源追溯起源，阐发其所以然的意义。使得古代圣人创立方剂治疗疾病的用心，清晰可见，而对于其他未能理解的则暂时阙疑。后来的君子，或许可以由此领悟全书的精义，虽然我的论述荒疏浅陋令人嗤笑，但那份恭敬谨慎的态度足以自矜。
乾隆元年（1736年），岁次柔兆执徐（丙辰年）余月（农历四月）上弦日，松陵人徐大椿题写于扬子江舟中。
All things differ in form from humans, yet humans utilize them to nourish life and eliminate disease. Why is this? It is because Heaven and Earth are also among the myriad things; only because their forms are extremely vast can they possess life.
In generating humans, [Heaven and Earth] imparted pure Qi; in generating animals, the Qi is mixed; in generating plants, the Qi is biased. However, what humans consider "pure" refers merely to the state of the body at birth. Once affected by pathogenic factors such as Wind, Cold, Summer-heat, and Dampness, or disturbed by emotional fluctuations like Joy, Anger, Worry, and Overthinking, this purity becomes diluted. When diluted, Qi is injured; when Qi is injured, the physical form deteriorates. Conversely, those things with mixed or biased natures can instead use their acquired characteristics to tonify and rescue [the human body].
The Sages understood this principle. To save people, one must first know the medicinal substances. Qi cannot violate natural principles, and form cannot depart from Qi. Observing color to distinguish taste, examining sound to identify texture, weighing weight and measuring length to assess shape—these are methods for understanding the physical form of substances. Predicting seasonal changes, detailing habits, distinguishing flourishing and declining states, and identifying suitable soils are methods for seeking the Qi of substances. Once form and Qi are grasped, the Nature (Xing) of the substance is obtained. Nature is the underlying principle of a substance's generation. Based on this, Materia Medica was established and decoctions formulated to treat human diseases. Excess is drained, deficiency is tonified, cold is treated with heat, heat is treated with cold, warmth is cleared, coolness is warmed, following the disease with contrary treatment, and opposing the disease with orthodox treatment.
Sometimes substances are grouped by similarity, sometimes fears and taboos are used to correct imbalances and restore equilibrium. Initially different, ultimately the same. Heaven and Earth generate these substances, and the Sages preserve and utilize them. The power of creation is shared equally between Heaven and Earth and the Sages; Heaven and Earth do not monopolize it.
During the late Han Dynasty, Zhang Zhongjing’s *Jin Gui Yao Lue* (Essential Prescriptions of the Golden Cabinet) and *Shanghan Lun* (Treatise on Cold Damage) contained many prescriptions that were largely remnants of pre-Shang-Zhou methods. The rationale behind their medication usage aligned seamlessly with the *Shennong Bencao Jing* (Divine Farmer's Materia Medica). Careful diagnosis guided prescription selection, yielding results as immediate as an echo. Since the Tang Dynasty, however, understanding of drug properties has become unclear. Prescriptions were often self-composed, such as in *Qianjin Fang* (Prescriptions Worth a Thousand Gold) and *Waitai Miyao* (Secret Essentials from the Imperial Library). While the drug properties generally did not contradict the conditions being treated, the subtle variations of ancient methods were rarely followed. During the Song and Yuan dynasties, the number of medicinal materials increased daily, but their properties were not thoroughly researched. Physicians relied on subjective judgment, leading to persistent errors. Even when using substances recorded in the *Bencao Jing*, their profound and subtle meanings were often overlooked. Consequently, prescriptions failed to be effective formulas, and drugs lost their true efficacy. Occasional successes were mere coincidences rather than reliable methods. This was undoubtedly due to the neglect of the *Bencao Jing*.
I privately lament this! I wish to elaborate in detail, but my observations are limited. Ancient and modern names differ, geographical origins vary, and flavors and odors diverge. Moreover, medicines rarely used by contemporary physicians lack identification and collection. Some possess unique abilities and natures, with principles hidden and obscure, difficult to deduce at present. If I were to attempt explaining the entire classic, I would risk acting against my conscience and misrepresenting the Sages. Therefore, I have selected only those hundred substances that are familiar through observation and whose principles can be reasoned out. For these, I trace the origin and explore the fundamental reasons, elucidating the rationale behind their use. Thus, the intent of the ancient Sages in creating prescriptions to treat diseases becomes clearly visible, while other aspects remain unexplained. Future scholars may perhaps comprehend the whole through this, and although my humble and crude work may invite ridicule, my reverence and caution deserve respect.
Written by Xu Dachun of Songling, aboard a boat on the Yangtze River, during the first half-moon of the fourth month of the year Bingchen (1736), the first year of the Qianlong reign.