夫痘，胎毒也。伏于有形之始，因感而发，为生人所不能免。然其发也，或染时气，
或感风寒，或因饮食，或由惊恐，以病引病，为患多端，更改莫测。且其间顺吉者少，险
逆者多，有千方百计而不能冀其愈于万一者，此其所以为难也。古有种痘一法，起自江右，
达于京畿。究其所源，云自宋真宗时，峨眉山有神人出，为丞相王旦之子种痘而愈，遂
传于世。其说虽似渺茫，然以理揆之，实有参赞化言之功，因时制宜之妙。盖正痘感于
得病之后，而种痘则施于未病之先；正痘治于成病之时，而种痘则调于无病之日。自表
传里，由里达表，既无诸证夹杂于其中，复有善方引导于其外，熏蒸渐染，胎毒尽出，又
何虑乎为患多端，更改莫测，以致良工束手于无可如何之地耶！此诚去险履平，避危就
安之良法也。然种痘一科，多口传心授，方书未载，恐后人视为虚诞之辞，相沿日久，无
所考稽，使至理良法，竟置无用之地，神功湮没，岂不大可惜哉！今将种痘一法，细加
研究，审度精详，纂辑成书，永垂千古，庶为种痘之津梁，咸登赤子于寿域也。
尝考种痘之法，有谓取痘粒之浆而种之者；有谓服痘儿之衣而种之者；有谓以痘痂
屑干吹入鼻中种之，谓之旱苗者；有谓以痘痂屑，湿纳入鼻孔种之，谓之水苗者。然即
四者而较之，水苗为上，旱苗次之，痘衣多不应验，痘浆太涉残忍。故古法独用水苗，盖
取其和平稳当也。近世始用旱苗，法虽快捷方式，微觉迅烈。若痘衣、痘浆之说，则断不可从。
夫水苗之所以善者，以其势甚和平，不疾不徐，渐次而入，既种之后，小儿无受伤之处，
胎毒有渐发之机，百发百中，捷于影响，尽善尽美，可法可传，为种痘之最优者。其次
则旱苗虽烈，犹与水苗之法相近，儿体壮盛，犹或可施。至若痘痂之何以为顺？选苗之何
以善藏？天时之何以得正？种期之何以为吉？调摄之何以合宜？禁忌之何以如法？形气之
何以可种？与痘衣痘浆之弊，一一条分缕晰，细列于后。学人必细心体阅，则中有灼见，不
致有他岐之惑，庶种法既善，而成功可必矣！
痘症，是胎中携带的毒邪。它在胎儿形成之初便潜伏体内，因感受外邪而发作，这是人类出生后无法避免的。然而痘症的发作，有的因感染时行疫气，有的因感受风寒，有的因饮食不当，有的因惊恐刺激，以病引病，导致祸患多种多样，变化难以预测。而且其中顺证吉兆者少，险证逆证者多，即使想尽千方百计也难以希望其万分之一痊愈，这就是痘症之所以难治的原因。古代有一种种痘的方法，起源于江西（江右），传播到京城地区。探究其源头，据说自宋真宗时期，峨眉山有神人出现，为丞相王旦的儿子种痘而治愈，于是流传于世。这种说法虽然似乎渺茫不可信，但从道理上推究，确实有参赞天地化育之功，因时制宜之妙。因为自然感染的正痘是在得病之后才发生，而人工种痘则是在未病之前施行；自然正痘是在成病之时治疗，而人工种痘则是在无病之日调理。自然发病是由表传里、由里达表，既没有各种夹杂症状在其中，又有良方在外部引导，通过熏蒸渐染，使胎毒全部排出，还担心什么祸患多样、变化莫测，以至于让高明医生束手无策呢！这确实是去除危险踏上平坦、避开危难走向安全的良法。然而种痘这一科，大多口传心授，医书典籍未曾记载，恐怕后人将其视为虚妄荒诞之辞，沿袭日久，无所考证，使得真理良法竟被弃置无用之地，神功湮没，难道不是太可惜了吗！现在将种痘这一方法，仔细加以研究，审慎度量精详，编纂辑录成书，永垂千古，希望成为种痘的津梁，让所有婴儿都能登上长寿的境界。
曾经考察种痘的方法，有说取痘粒中的浆液来接种的；有说服用出过痘的婴儿穿过的衣服来接种的；有说将痘痂磨成细粉干燥后吹入鼻中接种的，称为“旱苗”；有说将痘痂细粉湿润后纳入鼻孔接种的，称为“水苗”。然而比较这四种方法，水苗最好，旱苗次之，痘衣法大多不灵验，痘浆法太过残忍。所以古法独用水苗，大概是取其和平稳当的缘故。近代才开始使用旱苗，方法虽然快捷，但略微显得迅急猛烈。至于痘衣、痘浆的说法，则绝对不可采纳。水苗之所以好，是因为它势头非常和平，不急不缓，逐渐进入人体，接种之后，小儿身体没有受伤之处，胎毒有逐渐发作的契机，百发百中，见效极快，尽善尽美，值得效法并传承，是种痘中最优的方法。其次是旱苗，虽然药性较烈，但仍与水苗之法相近，如果小儿体质壮盛，或许还可以施用。至于痘痂如何才算顺证？选苗如何善于储藏？天时如何求得端正？种痘日期如何选择为吉？调护摄养如何合乎适宜？禁忌如何符合规范？形气如何可以接种？以及痘衣痘浆的弊端，一一条理分明地分析清楚，详细列在后面。学习的人必须细心体察阅读，心中就会有真知灼见，不至于有其他歧途的困惑，这样种痘方法既然良好，成功就必然能实现了！
Smallpox is the fetal toxin. It lies dormant from the beginning of physical formation and erupts upon exposure to pathogens; it is unavoidable for all humans. However, its eruption may be triggered by contracting seasonal epidemics, catching wind-cold, improper diet, or fright. One illness induces another, leading to diverse complications and unpredictable changes. Moreover, favorable cases are few while dangerous and adverse ones are many; even with every possible effort, recovery is rarely hoped for in one out of ten thousand instances. This is why smallpox is considered difficult to treat. In ancient times, a method of variolation originated in Jiangxi (Jiangyou) and spread to the capital region. Tracing its source, it is said that during the reign of Emperor Zhenzong of Song, a divine being appeared on Mount Emei and inoculated the son of Chancellor Wang Dan, curing him, thus passing the method down to the world. Although this account seems vague, reasoning suggests it indeed possesses the merit of assisting the transformative powers of nature and the subtlety of adapting measures to specific conditions. Natural smallpox occurs after infection has taken place, whereas variolation is administered before illness arises; natural smallpox is treated when the disease is established, while variolation regulates health when no disease is present. Natural onset involves transmission from exterior to interior and vice versa, often accompanied by mixed symptoms. Variolation, guided by effective prescriptions externally and through gradual fumigation and absorption, allows the fetal toxin to be completely expelled. Why then worry about diverse complications and unpredictable changes that leave even skilled physicians helpless? This is truly an excellent method to remove danger and step onto safety, avoiding peril for peace. However, the art of variolation was mostly transmitted orally and heart-to-heart, not recorded in medical texts. Fearing that later generations might regard it as absurd fiction, and with long-standing tradition lacking verification, causing this profound truth and excellent method to be abandoned as useless, obscuring its miraculous efficacy—would this not be a great pity? Now, having carefully studied and meticulously examined the method of variolation, I have compiled it into this book to last forever, hoping it serves as a bridge for variolation, enabling all infants to attain longevity.
Upon examining methods of variolation, some suggest using the fluid from smallpox pustules for inoculation; others suggest wearing clothes worn by children who had smallpox; some suggest blowing dried powder of scabs into the nose, called "dry seedling" (Hanmiao); others suggest inserting moistened scab powder into the nostrils, called "wet seedling" (Shuimiao). Comparing these four methods, wet seedling is superior, dry seedling is second best, wearing infected clothes is often ineffective, and using pustule fluid is excessively cruel. Therefore, ancient methods exclusively used wet seedling, likely because it is peaceful and steady. In recent times, dry seedling began to be used; although fast, it is slightly rapid and intense. The theories of wearing infected clothes and using pustule fluid should absolutely not be followed. The reason wet seedling is good is that its action is very gentle, neither too fast nor too slow, entering gradually. After inoculation, the child suffers no injury, and the fetal toxin has a mechanism to emerge gradually. It is highly effective, swift in results, perfect in quality, worthy of emulation and transmission, making it the optimal method of variolation. Second is dry seedling; although more intense, it is still similar to the wet seedling method and may be applied if the child's constitution is robust. Regarding how scabs constitute a favorable condition, how to select and store seeds properly, how to align with correct heavenly timing, how to choose auspicious dates for inoculation, how to regulate care appropriately, how to observe taboos correctly, and under what physical conditions inoculation is suitable, as well as the drawbacks of wearing infected clothes and using pustule fluid—all are analyzed clearly and listed in detail below. Students must study these carefully to gain clear insight, avoiding confusion from divergent paths, so that with a good method, success is assured.