幼科谓婴儿生下三十二日为一变，六十四日为一蒸。变者，变生五脏；蒸者，蒸养六腑，长气血而生精神、
益智能也，积五百七十六日而毕。凡遇变蒸，必有身热，或有惊惕，而口面唇舌俱不变色，身热或重轻，而精
神与常无异，口中气出温和，三四日间自愈；或有热不退，乳母宜服小柴胡则安，此犹为幼科中杰出者之言也。
乃考其变蒸方中，有用褊银丸之巴豆、水银、黑铅、京墨、麝香之类而峻下之者。夫既曰长气血、生精神、益
智能，惟宜助其升生可也，顾且用毒劣，灭其化元，不几于非徒无益而又害之耶？据其说，以周天三百六十五
度，应人身三百六十五骨节，内除手足四十五余骨外，止三百二十数，以生下一日主十段，十日百段，三十二
日则三百二十段为一变。而以天一生水，地二生火为次序，则一变肾，二变膀胱，三变心，四变小肠，五变肝，
六变胆，七变肺，八变大肠，九变脾，十变胃，虽无实据，而理有可取，即令以此为准，变见确然不易之法。
乃又有以木火相生为言者，则似为一肝、二胆、三心、四小肠、五脾、六胃、七肺、八大肠、九肾、十膀胱矣。
复有以木金相克为言者，则又为一肝、二胆、三肺、四大肠、五心、六小肠、七脾、八胃、九肾、十膀胱矣。
夫小儿脏腑骨度，生来已定，毫不可以移易者，则变蒸应有定理。今则各逞己见，各为臆说，然则脏腑竟可以
倒置，骨度亦可以更张，是非真伪，从何究诘？谓天一生水者为是，则木火相生，木金相克者非也；谓木火相
生，木金相克者为是，则天一生水者非矣。徒滋葛藤，迄无定论，将使来学何所适从？所幸变蒸非病，可任其
颠倒错乱，假如变蒸为病，率宜根据经用药者，岂不以脾病而治肾，膀胱病而治胃乎？总之，此等固执之言，不
可为训。盖天地阴阳之理数，可限而不可限。如五运六气为一定不易之规，而有应至不至，不应至而至，往来
胜复，主客加临，有应不应之殊。天地尚且如斯，而况婴儿之生，风土不侔，赋禀各异，时令有差，膏藜非一，
而以此等定局，以限其某时应变，某时应蒸。予临证四十余载，从未见一儿根据期作热而变者，有自生至长，未
尝一热者，有生下十朝半月，而常多作热者，岂变蒸之谓乎？凡小儿作热，总无一定，不必拘泥。后贤毋执以
为实，而以正病作变蒸，迁延时日，误事不小，但根据证治疗，自可生全。
张景岳曰∶小儿变蒸之说，古所无也，至西晋王叔和始一言之，自隋唐巢氏以来，则日相传演，其说益繁。
然以予观之，则似有未必然者，何也？盖儿胎月足离怀，气质虽未成实，而脏腑已皆完备；及既生之后，凡
长养之机，则如月如苗，一息不容有间，百骸齐到，自当时异而日不同，岂复有此先彼后，如一变肾，二变膀
胱，及每变必三十二日之理乎？又如小儿之病与不病，余所见者、治者，盖亦不少，凡属违和，则不因外感，
必以内伤，初未闻有无因而病者，岂真变蒸之谓耶？又见保护得宜，而自生至长，毫无疾病者不少，抑又何也？
虽有暗变之说，终亦不能信，然余恐临证者，有执迷之误，故道其愚昧若此，明达者以为然否？
中医儿科认为，婴儿出生后三十二天为一次“变”，六十四天为一次“蒸”。“变”是指五脏功能的生成变化；“蒸”是指六腑的滋养发育，以此增长气血、产生精神、增进智力。这一过程累计五百七十六天完成。凡是遇到变蒸时期，必然会出现身体发热，或者伴有惊悸恐惧，但口、面、唇、舌的颜色均不发生改变。身体发热的程度有轻有重，但精神状态与平常无异，口中呼出的气息温和，经过三四天即可自愈；如果发热不退，乳母适宜服用小柴胡汤（Xiao Chai Hu Tang，小柴胡汤）调理即可安宁。这还算得上是儿科中较为出众的说法。
然而考察其变蒸方剂中，有用到含有巴豆、水银、黑铅、京墨、麝香等成分的褊银丸（Bian Yin Wan，偏银丸）进行峻猛泻下的。既然说是为了增长气血、产生精神、增进智力，只应当帮助其升发生长才是，反而使用毒烈之药，毁灭其生化之源，这不就是不但没有益处反而有害吗？根据他们的说法，以周天三百六十五度对应人身三百六十五个骨节，除去手足四十五个多余的骨节外，仅剩三百二十个数字，以出生第一天主十段，十天一百段，三十二天则三百二十段构成一次“变”。并按照“天一生水，地二生火”的顺序，那么第一次变肾，第二次变膀胱，第三次变心，第四次变小肠，第五次变肝，第六次变胆，第七次变肺，第八次变大肠，第九次变脾，第十次变胃。虽然缺乏确凿证据，但道理似乎可取，即使以此为准，作为变蒸确实不易改变的方法。
但又有主张以木火相生来解释的，那就似乎是第一次变肝，第二次变胆，第三次变心，第四次变小肠，第五次变脾，第六次变胃，第七次变肺，第八次变大肠，第九次变肾，第十次变膀胱了。还有主张以金木相克来解释的，那就又是第一次变肝，第二次变胆，第三次变肺，第四次变大肠，第五次变心，第六次变小肠，第七次变脾，第八次变胃，第九次变肾，第十次变膀胱了。
小儿的脏腑和骨度，生下来就已经确定，丝毫不能移动改变的，那么变蒸应该有固定的定理。现在却各自逞强己见，各持臆测之说，既然如此，难道脏腑竟然可以颠倒，骨度也可以更改吗？是非真伪，从哪里去追究质问呢？如果说“天一生水”是对的，那么木火相生、金木相克就是错的；如果说木火相生、金木相克是对的，那么“天一生水”就是错的。徒然增加纠缠不清的争论，始终没有定论，这将使后来的学者无所适从？所幸变蒸不是疾病，可以让它颠倒错乱，假如变蒸是疾病，都依照经典用药的话，岂不是把脾病当作肾病治，膀胱病当作胃病治吗？总之，这种固执的说法，不可以作为准则。
大概天地阴阳的道理和数理，是可以限制的，也是不可以限制的。比如五运六气（Wu Yun Liu Qi, Five Movements and Six Qi）是固定不变的规律，但有应至而未至，不应至而至的情况，往来胜复，主客加临，有应验和不应验的区别。天地尚且如此，何况婴儿的出生，风土不同，禀赋各异，时令有差异，饮食营养不一，而用这种固定的格局，来限制他们某个时候应该变，某个时候应该蒸。我临证四十多年，从未见过一个婴儿严格按照日期发热变蒸的，有的从出生到长大，从未有一次发热；有的出生十几天半个月，却经常多发热，这难道是变蒸吗？凡是小儿发热，总没有一定的规律，不必拘泥。后世的贤者不要固执地认为这是事实，而把真正的疾病当作变蒸，迁延时日，误事不小，只要根据证候治疗，自然可以保全生命。
张景岳（Zhang Jingyue）说：小儿变蒸的说法，古代是没有的，直到西晋的王叔和（Wang Shuhe）才提到它，自隋唐时期的巢元方（Chao Yuanfang）以来，就代代相传演变，说法越来越繁杂。然而在我看来，似乎未必是这样，为什么呢？因为胎儿月份足月离开母体怀抱时，气质虽然尚未成熟坚实，但脏腑都已经完备；等到出生后，凡是生长养育的机理，就像月亮盈亏、禾苗生长一样，一息之间不容许有间断，百骸齐备，自然是每天不同，哪里会有先此后彼，像第一次变肾，第二次变膀胱，以及每次变都要间隔三十二天的道理呢？又如小儿生病与不生病，我所见到、所治疗的，也不少，凡是属于身体不适，要么是因为外感，要么是因为内伤，从未听说过无缘无故就生病的，这难道真是变蒸吗？又看到保护得当，从出生到长大，毫无疾病的不少，这又是为什么呢？虽然有“暗变”的说法，终究也不能相信。然而我恐怕临证医生有执迷不悟的错误，所以陈述我的愚见如此，明智的人认为对吗？
TCM pediatrics holds that thirty-two days after birth constitutes one "Bian" (Transformation), and sixty-four days constitutes one "Zheng" (Steaming). "Bian" refers to the generation and transformation of the Zang organs (Solid organs); "Zheng" refers to the nourishment and development of the Fu organs (Hollow organs), thereby increasing Qi and Blood, generating Spirit, and enhancing intelligence. This process is completed after accumulating five hundred and seventy-six days. Whenever a Bian or Zheng occurs, there must be body heat, possibly accompanied by startle or fear, but the color of the mouth, face, lips, and tongue remains unchanged. The degree of body heat may vary from light to heavy, yet the spirit and mental state remain identical to normal, and the breath exhaled from the mouth is warm; it heals itself within three to four days. If the fever does not subside, it is appropriate for the nursing mother to take Xiao Chai Hu Tang (Minor Bupleurum Decoction) to bring peace. This still counts as an outstanding statement among pediatric theories.
However, examining the formulas for Bian and Zheng, some use Pian Yin Wan (Pian Yin Pill), which contains Croton Seed (Ba Dou), Mercury (Shui Yin), Black Lead (Hei Qian), Beijing Ink (Jing Mo), and Musk (She Xiang) for drastic purgation. Since it is said to increase Qi and Blood, generate Spirit, and enhance intelligence, one should only assist its ascending and generating functions. Instead, using toxic and harsh substances destroys the source of transformation. Is this not merely ineffective and actually harmful? According to their theory, taking the 365 degrees of the celestial sphere corresponding to the 365 joints of the human body, and excluding more than 45 bones in the hands and feet, leaves only 320 units. Starting with ten segments on the first day of life, one hundred segments in ten days, thirty-two days would result in three hundred and twenty segments constituting one "Bian". Following the sequence of "Heaven generates One with Water, Earth generates Two with Fire," the first Bian affects the Kidney, the second the Bladder, the third the Heart, the fourth the Small Intestine, the fifth the Liver, the sixth the Gallbladder, the seventh the Lung, the eighth the Large Intestine, the ninth the Spleen, and the tenth the Stomach. Although lacking solid evidence, the logic seems acceptable. Even if taken as the standard, it serves as an unchangeable method for Bian and Zheng.
Yet others argue based on the mutual generation of Wood and Fire, suggesting the first Bian affects the Liver, the second the Gallbladder, the third the Heart, the fourth the Small Intestine, the fifth the Spleen, the sixth the Stomach, the seventh the Lung, the eighth the Large Intestine, the ninth the Kidney, and the tenth the Bladder. Still others argue based on the mutual overcoming of Metal and Wood, suggesting the first Bian affects the Liver, the second the Gallbladder, the third the Lung, the fourth the Large Intestine, the fifth the Heart, the sixth the Small Intestine, the seventh the Spleen, the eighth the Stomach, the ninth the Kidney, and the tenth the Bladder.
The Zang organs and bone structure of children are fixed at birth and cannot be altered in the slightest; therefore, Bian and Zheng should have fixed principles. Now, however, everyone promotes their own views and speculates arbitrarily. Does this mean the Zang organs can be inverted and bone structures rearranged? How can we investigate the truth and falsehood? If "Heaven generates One with Water" is correct, then Wood-Fire generation and Metal-Wood overcoming are wrong; if Wood-Fire generation and Metal-Wood overcoming are correct, then "Heaven generates One with Water" is wrong. This merely creates endless entanglements without a definitive conclusion, leaving future students unsure of what to follow. Fortunately, Bian and Zheng are not diseases, so their inversion and confusion can be allowed. But if Bian and Zheng were diseases, and one strictly followed classic prescriptions, would it not mean treating Kidney disease as Spleen disease, and Bladder disease as Stomach disease? In short, such rigid statements should not serve as guidelines.
Generally, the principles and numbers of Heaven and Earth's Yin and Yang are both limited and unlimited. For instance, Wu Yun Liu Qi (Five Movements and Six Qi) is a fixed rule, yet there are times when expected influences do not arrive, and unexpected ones do; there are cycles of excess and recovery, host and guest interactions, with differences in whether they manifest or not. Even Heaven and Earth are like this, let alone infants born into different wind and soil conditions, with varying endowments, seasonal differences, and diverse diets/nutrition. To use such fixed patterns to limit when they should transform or steam is inappropriate. I have practiced clinical medicine for over forty years and have never seen an infant develop fever exactly according to these dates for Bian or Zheng. Some go from birth to adulthood without ever having a fever; others frequently develop fevers within ten days or half a month of birth. Are these really Bian and Zheng? Fever in children generally has no fixed pattern and should not be rigidly adhered to. Later scholars should not stubbornly treat this as fact, mistaking actual diseases for Bian and Zheng, thereby delaying treatment and causing significant harm. Simply treating according to the syndrome will naturally ensure survival.
Zhang Jingyue stated: The theory of pediatric Bian and Zheng did not exist in ancient times; it was first mentioned by Wang Shuhe of the Western Jin Dynasty. Since Chao Yuanfang of the Sui and Tang Dynasties, it has been passed down and evolved, becoming increasingly complex. However, in my opinion, it seems unlikely to be true. Why? Because when a fetus reaches full term and leaves the womb, although its constitution is not yet fully matured, its Zang organs are already complete. After birth, the mechanism of growth and nourishment is continuous, like the waxing and waning of the moon or the growth of seedlings, allowing no interruption for even a breath. All parts develop simultaneously, changing daily. How could there be a sequence where one precedes another, such as the first Bian affecting the Kidney, the second the Bladder, or every Bian requiring thirty-two days? Furthermore, regarding children being sick or healthy, I have seen and treated many cases. Whenever there is discomfort, it is either due to external pathogens or internal injury; I have never heard of illness arising without cause. Could this truly be Bian and Zheng? I also see many children who are well-protected and grow up without any illness. What about this? Although there is a theory of "hidden transformation," I ultimately cannot believe it. However, fearing that clinicians might fall into the error of obsession, I state my humble opinions thus. Will the enlightened agree?