昌性好医，少时诵读之暇，访求名医着述，见外证与小儿痘证两门，生死反掌，非比内
证，尚可延迟待治。闻东台周舒轩先生精医术，昌往从学焉，十余年深究精思，稍知梗概。
继得郑西宾《痘证必读》，虽集腋成裘，而分门析类，了如指掌。又得前明耿仁斋《麻科明
镜》遗稿，惜乎残缺过半，昌为之增着删繁，分列四篇，便于习学，二书皆梓行于世。第外
证一书，汗牛充栋，偏执者多，适中者寡。有同人毕苍霖者，着《外科证治》，阐发透彻，
于外证大有裨益。苍霖甫着两卷，年未三十而卒，书成废帙。昌虽不敏，广集诸名家外科考
证，访求效方，立痈疽就简于各证部之首，分别阴阳脏腑经络，认证医治。历试二十余年，
诊视送药，无不获效，四远就医者，岁无虚日。又增内景、外因、奇证、蛊证、中毒五条，
并立应验药方附于书末，以备急用，共成五卷。非敢问世，聊以备遗忘耳。
许克昌自识
有学问之医，有阅历之医，外科古有专业无专书，故阅历为尤切。汉唐作家十数，然多
亡佚
》，莫详于《外台》。顾闳深奥衍，未易通晓，且时异事殊，即方药所载，或至贵而骤不可
得，或甚贱而莫识其名，是以精而用之者益鲜。自后源流不一，治遂多歧，其专门名家，大
率由阅历而进之学问者也。近世《外科证治》一书，不为高论，一以阴阳虚实为之端，法期
简要，方必中和，深有取于王氏《全生集》，而删繁补缺，几于明备。览之而得其归，用之
而有其效，视他书徒炫名目，侈陈古义，或不甚切于日用者有间。夫自武进曹畸庵有《疡医
雅言》之述，《千金》、《外台》将可以复明于世，独于宋后诸家等之自桧以下，今以此书
为矢，则学问即阅历，阅历亦学问，溯流穷源，庶无遗憾耳。谨识其大概，以谂世之笃
嗜斯道者。
同治乙丑冬孝感屠仁守书于成都寓斋
许昌生性喜爱医学，少年时在诵读之余，四处访求名医的著作。他发现外科疾病与小儿痘疹这两类病症，生死往往在顷刻之间，不像内科疾病那样还可以拖延等待治疗。听说东台的周舒轩先生精通医术，我便前往拜师学习，经过十余年的深入研究和精细思考，才稍微知晓大概要领。
随后我又得到郑西宾所著的《痘证必读》，这本书虽然汇集了众多精华如集腋成裘，但分类清晰，条理分明，让人一目了然。接着我又得到了明代耿仁斋《麻科明镜》的遗稿，可惜残缺过半，我对它进行了增补、撰写和删减繁冗的工作，将其分为四篇，以便于学习和掌握，这两本书都刻印发行于世了。
然而关于外科疾病的书籍，汗牛充栋（形容藏书极多），但偏执己见的很多，适中准确的很少。有一位名叫毕苍霖的同僚，著有《外科证治》，阐述透彻，对外科疾病大有裨益。但他只写了两卷，不到三十岁就去世了，书稿因此被束之高阁废弃。我虽然不聪明，但广泛收集各位名家对外科病的考证研究，访求有效的药方，在各证候章节之首设立“痈疽就简”以简化诊断，分别辨别阴阳、脏腑、经络，从而准确辨证施治。
历经二十多年的临床验证，诊视病人并送药，无不获得疗效，四面八方来就医的人，每年都没有空闲的日子。我又增加了内景、外因、奇证、蛊证、中毒这五个门类，并在书末附上应验的药方，以备紧急使用，最终共成五卷。我不敢说敢以此问世，只是姑且用来防备遗忘罢了。
许克昌自记
有学问的医生，是有阅历的医生。外科在古代虽有专业分工但没有专门的书籍，所以阅历显得尤为迫切重要。汉唐时期的作者有十几位，但大多已经亡佚散失，内容没有比《外台秘要》更详细的了。但是《外台秘要》内容深奥繁杂，不容易通晓理解，而且时代不同情况各异，即使书中记载的方药，有的极其昂贵而突然难以得到，有的极其便宜却没人认识它的名字，因此精研并应用这些方法的人越来越少。
从此以后，学术源流不一，治疗方法也就多种多样。那些专门的名家，大率都是通过阅历进而提升为学问的人。近世的《外科证治》一书，不发表高深空论，一律以阴阳虚实作为开端，方法追求简要，方剂必定平和中正，深深取法于王氏的《全生集》，并且删减繁冗补充缺漏，几乎达到明白完备的程度。阅读它能找到归宿方向，使用它能获得疗效，与其他书籍徒然炫耀名目、奢侈地陈述古义，或者不太切合日常使用的情况相比，有着明显的区别。
自从武进人曹畸庵有了《疡医雅言》的论述，《千金方》、《外台秘要》将可以在世上重新明朗起来。唯独对于宋代以后的各家学说，将其等同于秦桧以下的人物一样看待（意指轻视或否定）。如今用这本书作为标杆/箭靶，那么学问就是阅历，阅历也是学问，追溯源头穷尽本源，或许就没有遗憾了。谨记录其大概情况，以此来告知世上那些笃信喜好此道的人。
同治乙丑年冬天，孝感人屠仁守书写于成都寓所
Xu Chang naturally loved medicine. In his youth, during breaks from reading classics, he sought out the writings of famous physicians. He observed that external diseases (Wai Zheng) and pediatric smallpox/rubella conditions (Xiao'er Dou Zheng) could determine life or death in an instant, unlike internal diseases (Nei Zheng), which allowed for delay and waiting for treatment. Hearing that Mr. Zhou Shuxuan from Dongtai was proficient in medical arts, Xu Chang went to study under him. After more than ten years of deep investigation and refined thinking, he grasped the general outline.
Subsequently, he obtained Zheng Xibin's *Dou Zheng Bi Du* (Essential Reading on Smallpox/Rubella). Although it gathered fragments into a whole like collecting armpit fur to make a coat, its categorization was clear, making the content easy to understand at a glance. He also obtained the manuscript of Geng Renzhai's *Ma Ke Ming Jing* (Clear Mirror of Measles) from the previous Ming Dynasty. Regrettably, it was more than half incomplete. Xu Chang added missing parts, deleted redundancies, and divided it into four sections for easier learning. Both books were printed and circulated. However, regarding books on external diseases, there are countless volumes (described as "filling oxen with books and filling cows with manuscripts"), yet many are biased, while few are balanced and accurate.
A colleague named Bi Canglin authored *Wai Ke Zheng Zhi* (Treatment of External Diseases), providing thorough explanations that greatly benefited the field. However, Bi had only completed two volumes before dying at the age of thirty, leaving the manuscript abandoned. Although not particularly intelligent, Xu Chang extensively collected evidentiary studies on external diseases by various masters and sought effective prescriptions. He established simplified guidelines for carbuncles and sores (Yong Ju Jiu Jian) at the beginning of each disease section, distinguishing between Yin and Yang, Zang-Fu organs, and meridians to accurately diagnose and treat.
After more than twenty years of clinical trials, his diagnoses and prescriptions achieved consistent efficacy. Patients came from all directions every day without fail. He further added five categories: Internal Scenery (Nei Jing), External Causes (Wai Yin), Strange Conditions (Qi Zheng), Gu Poison (Gu Zheng), and Poisoning (Zhong Du), attaching verified prescriptions to the end of the book for emergency use, thus completing five volumes. He did not dare to present this to the world, but merely kept it to prevent forgetting.
Xu Chang recorded this himself.
A physician with learning is a physician with experience. In ancient times, surgery had specialized practitioners but no specialized books; thus, experience was particularly crucial. There were over a dozen authors from the Han and Tang dynasties, but most works have been lost. The *Waitai Miyao* (Secret Essentials of the Outer Terrace) is the most detailed. However, its content is profound and complex, difficult to comprehend. Moreover, times and circumstances change; even if prescriptions are recorded, some may be too expensive and suddenly unobtainable, while others are very cheap but their names are unrecognized. Therefore, those who master and apply them are increasingly rare. Since then, sources have diverged, leading to diverse treatments. Most renowned specialists advanced from experience to learning.
The recent book *Wai Ke Zheng Zhi* does not offer high-flown theories but starts with Yin-Yang deficiency and excess. Its methods aim for brevity, and its formulas strive for balance and harmony. It deeply draws from Wang's *Quan Sheng Ji* (Complete Life Collection), deleting redundancy and supplementing deficiencies, nearly achieving clarity and completeness. Reading it reveals the correct approach; using it yields results. Compared to other books that merely dazzle with titles or luxuriously expound ancient meanings without practical daily application, this book stands apart.
Since Cao Jian'an from Wujin published *Yang Yi Ya Yan* (Elegant Words on Surgeon Medicine), the *Qian Jin Fang* (Thousand Gold Formulas) and *Waitai Miyao* can be clarified again in the world. Only the schools after the Song Dynasty are dismissed as inferior (compared to figures below Qin Hui). Now, taking this book as the standard (arrowhead), learning becomes experience, and experience becomes learning. Tracing the stream to its source eliminates regrets. I briefly record the general idea to inform those in the world who are devoted to this path.
Tu Renshou from Xiaogan wrote this in his residence in Chengdu in the winter of the Yichou year of the Tongzhi era.