尝为种痘之法，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，谓之旱苖者，有谓以痘痂屑湿纳入鼻孔种之，谓之水苖者，然
即四者而较之，水苗为上，旱苖次之，痘衣多不应验，痘浆太涉残忍，故古法独用水
苗，盖取其和平隐当也，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，则旱苖虽烈，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，形气之何以可称，与痘衣痘浆之弊，一一条分缕晰，细列于后，
学者必细心体阅，则中有灼见，不致有他歧之惑，庶种法既善，而成功可必矣。
苗者痘之痂也，种痘者，全资乎此以为胎毒之引导，关系匪轻，选苗时宜留神细
察，不可轻忽，其中有可用者，有不可用者，惟在痘之顺与不顺别之，痘之不顺者出不尖圆，色
不红润，浆不充满，所落之痂，温暗而薄，此天人合病，内外合邪所致，即幸而得愈
，亦不过良工之善为调治，非天然之美，此等痘痂，断不可用，痘之顺者，始终无夹
杂之证，出则尖圆，色则红润，浆则充满，所落之痂，苍蜡光泽，肥大厚实，此得天
地阴阳之正气，极顺之苗也，收而用之，效如响应，但此痂甚少，所遇无多，或不能
亲其事而假手他人，亦必令彼身亲目见方可，否则宁置而不用，切勿滥用，种者审之。
我曾经研究过种痘的方法，有人说取痘粒中的浆液来接种，有人说穿患痘婴儿的衣服来接种，有人说将痘痂的碎屑干燥后吹入鼻中接种，这叫做“旱苗”；有人说将痘痂的碎屑湿润后塞入鼻孔接种，这叫做“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，所以古法只用水苗，大概是取其平和恰当。近代才开始使用旱苗，虽然方法快捷，但药性略微迅疾猛烈。至于痘衣和痘浆的说法，则绝对不可采纳。
水苗之所以好，是因为其势态非常平和，不急不缓，逐渐进入体内。接种之后，小儿不会受到损伤，胎毒有逐渐发散的契机，百发百中，见效极快，尽善尽美，值得效法并流传，是种痘的最优方法。其次，旱苗虽然猛烈，但仍与水苗之法相近，如果儿童体质壮盛，或许还可以施用。至于痘痂如何才算顺证，选苗为何要妥善收藏，天时如何求得正宜，接种日期如何选择吉利，调护摄养如何合乎适宜，禁忌事项如何符合规范，形体气质如何可称适宜，以及痘衣、痘浆的弊端，我将一一条理清晰地分析，详细列述在后面。学者必须细心体察阅读，心中就会有真知灼见，不至于产生其他歧途的困惑，这样既然种痘方法优良，成功就必然有了保证。
所谓“苗”，就是痘的痂皮。种痘完全依靠它作为引导“胎毒”的手段，关系重大。选苗时应当留神仔细察看，不可轻率疏忽。其中有可以使用的，有不可以使用的，关键在于辨别痘疹是顺证还是逆证。痘疹属于逆证的，出痘时形状不尖圆，颜色不红润，浆液不充满，脱落的痂皮色泽晦暗且薄，这是天人合病、内外邪气相合所致。即使侥幸痊愈，也不过是良医善于调治的结果，并非天然之美。这种痘痂绝对不可使用。痘疹属于顺证的，从头到尾没有夹杂其他证候，出痘时形状尖圆，颜色红润，浆液充满，脱落的痂皮苍蜡色且有光泽，肥大厚实，这是得天地阴阳的正气，是最为顺遂的苗种。收集起来使用，效果如回声般迅速响应。但这种痂皮很少，遇到的机会不多。如果不能亲自处理而假手他人，也必须让他人亲眼目睹方可，否则宁可放置不用，切勿滥用，种痘者务必审慎。
I have studied the method of variolation. Some advocate using the pus from pockmarks for inoculation; others suggest wearing clothes worn by an infant who has had smallpox. There are those who dry the scabs of smallpox and blow them into the nose, a method called "Dry Seedling" (Han Miao); and those who moisten the scabs and insert them into the nostrils, called "Wet Seedling" (Shui Miao). Comparing these four methods, the Wet Seedling is superior, followed by the Dry Seedling. The clothing method is mostly ineffective, and the pus method is excessively cruel. Therefore, ancient methods exclusively used the Wet Seedling, likely because it is considered balanced and appropriate. In recent times, the Dry Seedling began to be used; although this method is rapid, its action is slightly swift and intense. As for the theories regarding clothing and pus, they should absolutely not be followed.
The reason the Wet Seedling is excellent is that its momentum is very gentle, neither too fast nor too slow, entering gradually. After inoculation, the child suffers no injury, and the fetal toxin (Tai Du) has the opportunity to dissipate gradually. It is successful every time, effective as quickly as an echo, perfect in every way, worthy of emulation and transmission, making it the optimal method for variolation. Secondly, although the Dry Seedling is more intense, it is still similar to the Wet Seedling method; if the child's constitution is robust, it may perhaps be applied. Regarding how scabs constitute a favorable course, why seedlings must be stored properly, how to align with correct seasonal timing, how to select auspicious dates for inoculation, how to ensure care and nursing are appropriate, how to observe taboos correctly, what constitutes suitable physical constitution, and the drawbacks of clothing and pus, I will analyze them one by one in detail below. Scholars must carefully study and read this; then they will have clear insights and avoid confusion from divergent paths. Thus, with a good method, success is assured.
The term "Seedling" refers to the scab of smallpox. Variolation relies entirely on this to guide the fetal toxin, a matter of significant importance. When selecting seedlings, one must pay close attention and examine carefully, without negligence. Among them, some are usable, and some are not; this depends on distinguishing whether the smallpox eruption follows a favorable or unfavorable course. Unfavorable eruptions do not appear sharp and round, lack ruddy color, and have insufficient pus. The fallen scabs are dull and thin. This results from the combination of heavenly and human factors, and internal and external pathogens. Even if recovery occurs by chance, it is merely due to the skillful treatment by a competent physician, not natural perfection. Such scabs must absolutely not be used. Favorable eruptions have no mixed syndromes throughout their course; they emerge sharp and round, with ruddy colors and full pus. The fallen scabs are pale yellowish-white, glossy, large, thick, and substantial. These possess the righteous qi of heaven and earth yin and yang, representing the most favorable seedlings. Collected and used, their efficacy is immediate like an echo. However, such scabs are rare and encounters are infrequent. If one cannot handle the process personally but delegates to others, one must ensure they witness it with their own eyes. Otherwise, it is better to discard them than to use them indiscriminately. Practitioners must exercise caution.