夫两手肘，两足膝是为四关，盖脏腑有十二原，出于四关，故四关之痘，最为紧
要，身体之痘虽佳，而肘膝处或有变异，则周身之痘亦变而不能成浆矣。何也？盖机关
阻塞，气不流行，则三百六十五穴皆闭矣。故四关，或有贼痘，成紫陷者，疔肿须急挑
去，吮出恶血，以药封之，否则，诸痘尽变，或以四肢为卒伍，卑贱之属而忽之。如
果则验疾病安危者，何独于两手三部及两足之冲阳太溪太冲也？
夫痘初发，起于肾，二日传肝，三日传心，四日传脾，五日传肺，肺复传肾，周而
复死。几十三时，二刻而移经，故五日半为一周。如同房有未出痘者，或近五日半而
发，次则十一日，又次则十六日半，又次则二十二日，又次则二十七日半而发，宜察其
形容，视其耳纹，详其诸候，按其热势而定以日期，传变此谓肾、肝、心、脾、肺者、
取相生之义也。有谓肾、心、脾、肝、肺者，取相克所以相成，脾居四脏之中也。
男面黄兮女面赤，喘急增寒又项急，口中气热呵欠频，此是伤寒莫误识。腮赤燥兮
多喷嚏，四肢皆冷兼惊悸，鼻尖耳尖及尻凉，耳后红丝皆痘意。
一凡忽于禁处，多生如鸡子大肿毒，色黑紫而发喘者。
一凡勿泻鲜血，或如死鸡肝色者。
一凡唇青黑缩，咽喉肿闭，而口舌喉生黑白色疮者，
一凡忽被外风，手足搐搦，口吐涎沫，直视不醒，甚或肌肉而色青黑，口作鸦声者。
一凡肚胀如鼓，气喘烦躁，大热发渴，口鼻出血者。
一凡疮紫黑者。
一凡疮子出后，遍身忽肿如瓜，气喘急促者。
一凡面耳口鼻俱黑，四肢逆冷，项软忽出大汗者。
一凡手足身体俱冷如冰，肾中黑缩，口吐腥臭气者。
一凡忽被外风，喉中痰锯，目闭多睡，头上汗出如珠者。
一凡大热燥烦喘急，服药不退，反见面黑者，并皆不治。
一凡沉重痘症，投剂而顿效者，须防有变。盖服药不应，固为不治，然服剂而顿见
骤效者，因根本萎尽，药力易于感动也。若药势一缓，或脏腑真气不能发生，则初服暂
得一效，继进便难见功，况万物发得早者萎亦早，成得快者，败亦速，如杯水易涸易
盈，长河难消难长也。故凡治疗必渐获效者，根深蒂固，永保无虞，不惟痘疮即诸症
皆然也。此（张）临症屡验，敢附说于后。
两手肘部和两足膝部被称为“四关”，这是因为脏腑的十二原穴都出于四关，所以四关部位的痘疹最为紧要。虽然身体其他部位的痘疹看起来很好，但如果肘膝处出现变异，那么全身的痘疹也会随之变化而不能化脓成浆。为什么呢？因为如果关节机关阻塞，气机不能流通，那么全身三百六十五个穴位都会闭塞。因此，在四关部位如果有“贼痘”（指形态异常的痘疹），呈现紫色凹陷的，必须立即挑破，吸出恶血，然后用药物敷封，否则，所有的痘疹都会发生变证。有的人认为四肢是士兵和步兵，属于卑贱的部位而忽视它们。如果要通过诊察来判断疾病的安危，为什么只关注双手的三部脉（寸、关、尺）以及双足的冲阳、太溪、太冲脉呢？
痘疹初发时，起于肾，第二天传至肝，第三天传至心，第四天传至脾，第五天传至肺，肺再传回肾，如此循环往复直至死亡（注：此处原文“死”通“已”或指周期终结，结合上下文“周而复始”之意，但原文用字为死，按字面意译并保留语境）。大约经过十三时辰，每二刻钟转移一经，所以五天半为一个周期。如果是未曾出过痘的人，或者接近五天半的时间发病，其次是十一天，再次是十六天半，再次是二十二天，再次是二十七天半才发病。应当观察其神色形态，查看耳纹，详细审察各种征候，按压热势的程度来确定日期。这种传变称为肾、肝、心、脾、肺，是取五行相生的意义。也有说是肾、心、脾、肝、肺，这是取五行相克以相成的道理，因为脾居于四脏之中。
男性面色发黄，女性面色发红，气喘急促，怕冷加重且颈部僵硬，口中气息热，频繁呵欠，这是伤寒的症状，不要误认为是痘疹。腮部红赤干燥，多打喷嚏，四肢冰冷兼有惊悸，鼻尖、耳尖及尾骨部位发凉，耳后有红丝，这些都是痘疹的征兆。
凡是忽然在禁忌之处生出像鸡蛋大小的肿毒，颜色黑紫且伴有气喘的。（此为死候）
凡是大便排出鲜血，或者颜色像死鸡肝一样的。（此为死候）
凡是嘴唇青黑收缩，咽喉肿痛闭塞，且口舌喉部生出黑白色疮疡的。（此为死候）
凡是忽然被外风侵袭，手足抽搐痉挛，口吐涎沫，两眼直视不醒人事，甚至肌肉颜色青黑，口中发出类似乌鸦叫声的。（此为死候）
凡是腹部胀大如鼓，气喘烦躁，高热口渴，口鼻出血的。（此为死候）
凡是痘疮颜色紫黑的。（此为死候）
凡是痘疹发出后，全身忽然肿胀像瓜一样，气喘急促的。（此为死候）
凡是面部、耳朵、口、鼻全部发黑，四肢逆冷，颈部软弱忽然出大汗的。（此为死候）
凡是手足身体全部冰冷如冰，肾囊收缩发黑，口中吐出腥臭气味的。（此为死候）
凡是忽然被外风侵袭，喉中痰声如锯，眼睛闭合嗜睡，头上出汗如珠状的。（此为死候）
凡是高热燥烦，气喘急促，服药后不退烧，反而见面色发黑的，以上情况都属于不治之症。
凡是病情沉重的痘症，投药后立刻见效的，必须防备病情突变。因为服药无效，固然属于不治；然而服药后立刻见到骤效的，是因为根本元气已经枯竭，药力容易触动虚弱的正气。如果药势一缓和，或者脏腑的真气不能生发，那么初次服药暂时得到一点效果，继续进药就很难见效了。况且万物发得早的枯萎也早，长得快的败亡也快，就像一杯水容易干也容易满，长河难以消退也难以增长一样。所以凡是治疗必须逐渐获得效果的，才是根深蒂固，永远保持没有忧患。不仅痘疮是这样，所有病症都是如此。这是我（张氏）临证多次验证的经验，敢附说在后面。
The two elbows and two knees are referred to as the "Four Passes" (Sì Guān). This is because the Twelve Yuan-Source points of the Zang-Fu organs originate from the Four Passes; therefore, the variola lesions at these sites are of utmost importance. Although the lesions on the rest of the body may appear favorable, if variations occur at the elbows and knees, the lesions throughout the entire body will also change and fail to suppurate and form pus. Why is this? Because if the joints become obstructed and Qi circulation is impeded, all three hundred and sixty-five acupoints will be closed. Thus, if there are "Thief Lesions" (Zéi Dòu, referring to aberrant or malignant lesions) at the Four Passes that present with purple coloration and depression, they must be immediately pricked, the foul blood sucked out, and sealed with medicinal paste. Otherwise, all lesions will undergo pathological transformation. Some regard the four limbs as soldiers and infantry, belonging to humble categories, and thus neglect them. If one seeks to verify the safety or danger of a disease through pulse diagnosis, why focus solely on the three positions (Cun, Guan, Chi) of both wrists and the Chongyang, Taixi, and Taichong pulses of both feet?
When variola first erupts, it originates in the Kidney, transmits to the Liver on the second day, to the Heart on the third day, to the Spleen on the fourth day, to the Lung on the fifth day, and the Lung transmits back to the Kidney, completing a cycle. This process takes approximately thirteen shichen (two-hour periods), shifting meridians every two ke (forty-eight minutes); thus, five and a half days constitute one full cycle. For individuals who have not previously had variola, eruption may occur close to five and a half days, then eleven days, then sixteen and a half days, then twenty-two days, and finally twenty-seven and a half days. One should observe their complexion and morphology, examine the ear patterns, detail various signs, and palpate the heat intensity to determine the timing. This transmission sequence of Kidney, Liver, Heart, Spleen, and Lung follows the principle of mutual generation (Shēng). Others propose the sequence of Kidney, Heart, Spleen, Liver, and Lung, following the principle of mutual restriction generating harmony (Kè zhōng xiāng chéng), as the Spleen resides in the center of the four viscera.
In males, a yellowish complexion; in females, a reddish complexion; accompanied by rapid breathing, increased aversion to cold, neck stiffness, hot breath, and frequent yawning—this indicates Cold Damage (Shāng Hán), do not misidentify it. Reddish and dry cheeks; frequent sneezing; coldness in all four limbs combined with palpitations; coolness at the tip of the nose, tips of the ears, and the coccyx; red threads behind the ears—these are indications of variola.
Any sudden swelling like an egg in forbidden areas, black-purple in color, accompanied by asthma: [Mortal sign].
Any passage of bright red blood, or blood resembling the color of a dead chicken's liver: [Mortal sign].
Any cyanotic and blackened lips with retraction, swollen and closed throat, and black-white sores appearing in the mouth, tongue, and throat: [Mortal sign].
Any sudden invasion by external wind causing convulsions and spasms of hands and feet, foaming at the mouth, fixed gaze without consciousness, or even bluish-black discoloration of muscles and a crow-like sound from the mouth: [Mortal sign].
Any abdominal distension like a drum, asthma, irritability, high fever with thirst, and bleeding from the mouth and nose: [Mortal sign].
Any lesions that are purple-black: [Mortal sign].
Any general swelling like a melon after eruption, with rapid and urgent breathing: [Mortal sign].
Any blackening of the face, ears, mouth, and nose; cold reversal in the four limbs; sudden profuse sweating with a flaccid neck: [Mortal sign].
Any coldness of hands, feet, and body like ice; blackening and shrinking of the scrotum; foul-smelling breath: [Mortal sign].
Any sudden invasion by external wind, saw-like phlegm sounds in the throat, eyes closed with excessive sleepiness, and bead-like sweat on the head: [Mortal sign].
Any high fever, dryness, irritability, asthma, and urgency unrelieved by medication, especially when the face turns black: All are incurable.
For severe variola cases where immediate efficacy is seen after administering medicine, one must beware of sudden changes. While lack of response to medication is indeed incurable, sudden dramatic improvement often indicates that the root vitality has been exhausted, making the weak vital qi easily stirred by the drug's force. If the drug's effect wanes, or if the true Qi of the Zang-Fu cannot regenerate, the initial temporary improvement will not sustain further treatment. Moreover, things that emerge early wither early, and those that develop quickly perish quickly. It is like a cup of water, which fills and dries easily, versus a long river, which is hard to drain or fill. Therefore, treatments that yield gradual results indicate deep roots and stability, ensuring safety forever. This applies not only to variola but to all diseases. These observations are based on my (Zhang's) repeated clinical verification, and I dare to append this explanation hereafter.