景岳子曰∶痘之与疹原非一种。虽痘之变态多证，而疹之收敛稍易。然疹之甚者，其势
凶危亦不减于痘。最为可畏盖疹毒痘毒本无异也。第古人重痘而忽疹，多不详及，使后人
无所宗法，余实怅之。自得罗田万氏之刻，见其理透法精，鄙念斯慰。今悉从其训，备述于
此，虽其中稍有裁订，亦不过正其疑似，详其未详耳。使此后患疹者幸获迷津之指南，亦以见万氏之功为不少矣。
疹者痘之末疾，惟二经受证，脾与肺也。内应于手足太阴，外合于皮毛肌肉，是皆天地
间戾不正气，故曰疹也。（音同疠）然其名目有异，在苏松曰痧子，在浙江曰 子，（音同
错）又曰 子，在江右湖广广东安徽曰麻子，在山陕曰籽疮，曰糠疮，曰赤疮，在北直曰疹
子，（音同轸）名虽不同其证则一。但疹在痘前者，痘后必复出疹，惟痘后出疹者，方为正疹结局。
万氏曰∶疹以春夏为顺，秋冬为逆。以其出于脾肺二经，一遇风寒，势必难出，且多变
证，故于秋冬为不宜耳。夫天行不正之气，致为人之疡疹。然古人于痘、疹二字始终归重于
痘，并不分别。疹为何物，岂可以二证归于一证耶。想当时重痘不重疹，故尔略之，致使后
人不得心法，因而害事者往往有之。今以吾家四代传流，以及今日心得之法开载于后，用此
应治，定不瘥矣。敢有毫厘隐秘，天其鉴之。
Zhang Jingyue stated: Smallpox (Dou) and measles (Zhen) are originally not the same disease. Although smallpox presents with more varied syndromes, measles is slightly easier to resolve (recover). However, severe cases of measles can be equally perilous in their progression as smallpox. What is most feared is that the toxin of measles and the toxin of smallpox are essentially no different. It is merely that ancient physicians valued smallpox while neglecting measles, rarely discussing it in detail, leaving later generations without a standard to follow, which I truly regretted. Since obtaining the printed work by Master Wan from Luotian, seeing its profound principles and refined methods, my concerns were alleviated. Now, fully adhering to his teachings, I elaborate here. Although there are slight adjustments, they serve only to correct ambiguities and detail what was previously omitted. May those who suffer from measles in the future find guidance through this confusion, thereby acknowledging the significant merit of Master Wan.
Measles is considered a terminal ailment related to smallpox, primarily manifesting in the Spleen and Lung meridians. Internally, it corresponds to the Hand-Taiyin (Lung) and Foot-Taiyin (Spleen) meridians; externally, it combines with the skin, hair, muscles, and flesh. These are caused by malignant and abnormal Qi (vital energy) in heaven and earth, hence it is called Zhen (pronounced similarly to "Li," meaning pestilence). However, its names vary: in Suzhou and Songjiang, it is called Shazi; in Zhejiang, it is called Lizi (pronounced similarly to "Cuo") or Lizi; in Jiangxi, Huguang, Guangdong, and Anhui, it is called Mazzi; in Shanxi and Shaanxi, it is called Zichuang, Kangchuang, or Chichuang; in Zhili, it is called Zhenzi (pronounced similarly to "Zhen"). Although the names differ, the syndromes are identical. If rash appears before smallpox, smallpox will inevitably reappear after the initial eruption; only when rash appears after smallpox does it constitute the proper conclusion of measles.
Master Wan stated: Measles appearing in spring and summer is favorable (Shun), while appearing in autumn and winter is unfavorable (Ni). Since it originates from the Spleen and Lung meridians, once exposed to wind-cold, it becomes difficult to erupt and prone to complicated syndromes, making autumn and winter unsuitable seasons for its appearance. This abnormal atmospheric Qi causes ulcers and rashes in humans. However, ancients consistently emphasized smallpox over measles, failing to distinguish between them. What exactly is measles? How can two distinct conditions be merged into one? It seems that due to valuing smallpox over measles at that time, it was overlooked, causing later generations to miss the essential methods, leading to frequent harm. Now, recording the four generations of family transmission along with my own insights for future reference, using these methods for treatment ensures recovery. If I conceal even a slightest detail, may Heaven witness it.