九流莫难于医，亦莫慎于医，盖人之性命所攸关也。是必奉其传于名师，穷其
理于素习，小其心于临时。一遇其人之病，先审其人之气质，按其人之性情，据其人
之居处、服习，循经辨络，以得其致病之原与夫病之所在，然后随节气，就方舆，
切脉对症而投之以药，无不有随手而效焉者也。顾自张仲景以后，名医代出，其所
着述，几于汗牛充栋。后之学人，于茫茫大海中，非埋首读书、潜心味道、得名师
之指授，而能知三昧者盖寡。余少留心于方书，稍稍知本草，每有疾而不轻服药，
惟恐庸医之误也。
兹奉圣天子命抚粤东。粤东山海 区也，在天文星躔鹑火，其气多燥，而又
近于大海，群山叠抱，其间，溪涧泉窦，莫非潮湿也。以天燥地湿之乡，而人之生
于其中者，苟不自谨，立即致病。其气之壮者，感之轻而发之速，固可不药而愈。
然疾甚者必延医，讵知粤东之医，其能记诵《汤头》，耳熟《脉诀》、者，十无一二，
甚而不解《内经》为何文，《条辨》为何意。略知药性，拘守陈方，究之胸中不
通，指下不明，是以投之剂而多死。今夫病之寒热，有表里之分焉，有疑似之别焉，
有浅深、主客之攸殊焉。其于似热症者辄投凉剂，岂知凡感于寒则为病热，寒郁则
热盛，须温以解者，而凉剂直利刃矣；于似寒症者辄投暖剂，岂知食重内蒸，热极
反寒，六脉全伏，须下以解者，而暖剂尤利刃矣。更可骇者，不论其人之形气与天
行之节候、致病之根源，而擅用桂、附、人参，以为能用贵药者为通方、为老手，
而不知杀人于三指，而卒不自认其罪者，莫若此等庸医之甚也。余抚粤未及三载，
而闻医之杀人者不可数计，殊悯粤人之甘心送命于庸医而不自知也。比山阴余子
庵来粤，携函秘藏《辨证录》一书，余假一观，真有仲景诸公所未及者，而辨证折
衷补求，诚为仁人济世寿物之至宝。即为捐俸授梓印本普行，愿吾粤之医家熟读精
思，悟其今之所是，故不惮琐琐以为之序。
大清雍正三年岁次乙巳中 钦命巡抚广东等处地方
提督军务兼理粮饷都察院右副都御史广宁年希尧撰
九流百家之中，没有比医学更难的了，也没有比医学更需谨慎的了，因为人的生命性命系于其中。因此，必须向名师请教以传承医术，通过长期学习来穷尽医理，在临证时要保持谨慎小心。一旦遇到病人患病，先审视病人的体质，探察病人的性情，依据病人的居住环境和生活习惯，沿着经络进行辨析，从而找到致病的根源和病变的部位，然后结合节气变化、地理环境，通过切脉对症用药，没有不随手见效的。
然而自从张仲景以后，名医代代涌现，他们的著作多得像堆满屋子、牛马出汗一样（形容书籍极多）。后世的学医者，在浩瀚如海的医籍中，如果不是埋头苦读、潜心体会医理、得到名师指点，能够真正掌握精髓的人是很少的。我年轻时留心于方书，稍微了解本草知识，每次生病都不敢轻易服药，唯恐庸医误人。
如今奉圣天子之命巡抚粤东。粤东是山海相连的地区，在天文星宿划分中属于鹑火分野，气候多燥，但又靠近大海，群山环绕，其中的溪涧泉眼，无不潮湿。在这天燥地湿的地方生活的人，如果不自加谨慎，立即就会致病。那些正气壮盛的人，感邪轻而发病快，本来可以不药而愈。但是病情严重的必须延请医生，谁知道粤东的医生，能背诵《汤头歌诀》、熟悉《脉诀》的，十个人里不到一两个，甚至有的人连《内经》是什么文章、《伤寒条辨》是什么意思都不懂。略微知道一点药性，就拘泥守旧地使用成方，结果心中不通医理，指下不明脉象，所以开出的药方导致很多死亡。
现在的病症，寒热有表里的区别，有疑似的不同，有浅深、主客的根本差异。对于看似热症的患者，往往投用凉剂，岂不知凡是感受寒邪则表现为热病，寒邪郁结则热势亢盛，需要用温法来解除，而凉剂简直如同利刃；对于看似寒症的患者，往往投用暖剂，岂不知饮食积滞内蒸，热极反而出现假寒，六脉完全伏匿，需要用下法来解除，而暖剂更是如同利刃。更可骇异的是，不顾病人的形体气质、天时节候以及致病的根源，擅自使用桂枝、附子、人参等贵重药物，以为能用贵药的就是通晓大方、是老手，却不知道这种杀人于无形（三指切脉之间），最终还不承认自己罪责的，莫过于这些庸医了。我巡抚广东不到三年，听说医生杀人的案例不可胜数，非常怜悯广东百姓甘心送命于庸医而不自知。
后来山阴余子庵来到广东，携带并秘密珍藏《辨证录》一书，我借来观看，发现确实有张仲景等前辈所未及之处，其辨证折衷、补求完善，确实是仁人志士济世救人的至宝。于是捐出俸禄刻印此书广泛流行，希望广东的医家们熟读精思，领悟其中正确的道理，所以不怕琐碎地写了这篇序言。
大清雍正三年岁次乙巳年，钦命巡抚广东等处地方、提督军务兼理粮饷、都察院右副都御史、广宁人年希尧撰写。
Among the nine schools of thought, none is more difficult than medicine, nor is any more demanding of caution, for human life and destiny depend upon it. Therefore, one must receive transmission from a master teacher, exhaustively study principles through long-term practice, and maintain a humble and cautious mind during clinical application. Upon encountering a patient's illness, one must first examine the individual's constitution, assess their temperament, and consider their living environment and habits. By tracing the meridians and collaterals, one identifies the root cause of the disease and its location. Subsequently, by aligning with seasonal changes and geographical conditions, and prescribing medication based on pulse diagnosis and symptoms, efficacy is invariably achieved promptly.
However, since Zhang Zhongjing, renowned physicians have emerged generation after generation, and their written works are as numerous as books filling warehouses or causing oxen to sweat (a metaphor for an immense volume of literature). For later scholars immersed in this vast sea of medical texts, unless they bury themselves in reading, deeply contemplate the underlying meanings, and receive guidance from a master teacher, few can truly grasp the essence. In my youth, I paid attention to prescription books and gained some knowledge of materia medica. Whenever I fell ill, I refrained from taking medicine lightly, fearing misdiagnosis by incompetent physicians.
I was now appointed by the Holy Son of Heaven to serve as Governor of Guangdong. Guangdong is a region characterized by mountains and seas. In astronomical star divisions, it corresponds to the Chunhuo sector; its climate is predominantly dry, yet being close to the ocean and surrounded by layered mountains, its streams, ravines, and springs are inherently damp. In such a place where the sky is dry and the earth is damp, those who live there without self-discipline will immediately fall ill. Those with robust vital energy may experience mild pathogenic invasion with rapid onset, potentially recovering without medication. However, severe cases require medical intervention. It is surprising that among physicians in Guangdong, fewer than one in ten can recite *Tangtou Gejue* (Song Formulas) or are familiar with *Maijue* (Pulse Rhymes); many do not even understand what the *Neijing* (Inner Canon) is or the meaning of *Tiaobian* (Delineations). Slightly knowing drug properties, they rigidly adhere to old prescriptions. Lacking internal understanding and clear diagnostic skills, their prescriptions often result in death.
Current diseases involve distinctions between cold and heat, exterior and interior, similarities and differences, and variations in depth and primary versus secondary factors. For symptoms resembling heat, cool formulas are often administered. Yet, one must realize that pathogenic cold manifesting as heat requires warming methods to resolve; administering cool formulas is akin to wielding a sharp blade. For symptoms resembling cold, warm formulas are often used. However, food stagnation causing internal steaming can lead to extreme heat presenting as false cold, with all six pulses hidden; this requires purgative methods. Administering warm formulas here is even more like wielding a sharp blade. What is most shocking is the indiscriminate use of expensive herbs such as Guizhi Tang (Cinnamon Twig Decoction), Fuzi (Prepared Aconite Root), and Renshen (Ginseng Root), regardless of the patient's constitution, seasonal climatic factors, or the root cause of the disease. Physicians believe that using expensive herbs signifies mastery and experience, unaware that they are killing patients under the guise of treatment while refusing to acknowledge their guilt. Such incompetence is unparalleled.
During my less than three years as Governor of Guangdong, the number of deaths caused by physicians has been incalculable. I deeply pity the people of Guangdong for blindly entrusting their lives to incompetent physicians without realizing it. Later, Yu Zi'an from Shanyin arrived in Guangdong, bringing with him a secret copy of *Bianzheng Lu* (Record of Syndrome Differentiation). I borrowed it to read and found that it contained insights surpassing those of Zhang Zhongjing and other predecessors. Its syndrome differentiation, compromise, and supplementation constitute a supreme treasure for benevolent individuals seeking to save the world. I therefore donated my salary to have this book printed and widely distributed, hoping that physicians in Guangdong would study it diligently, comprehend its correct principles, and thus I have not hesitated to write this preface despite its triviality.
Written by Nian Xiyao, a native of Guangning, Right Vice Censor-in-Chief of the Censorate, Imperial Commissioner Governing Guangdong and Other Regions, Commander-in-Chief of Military Affairs, and Administrator of Grain and Supplies, in the year Yisi of the third year of the Yongzheng Reign of the Great Qing Dynasty.