古书言病之遇节即发也，仅见于《巢源·尸注候》，而目见甚多。有发于交节日者，有
发于
交节前后数日者，不必尽是尸注。总之，病根不拔，则愈而复发。其必遇节何也？考万物应
节而来者，莫如八风，以风为中央土气，（本《尚书·洪范》郑注，详前《原风湿》。）土于
五常主信，故至期而不爽，而经谓风者百病之长，是知遇节即发之病必风也。风留经脉，则
随感而作，且五日为候，三候为气，一气者月郭盈亏之大法。人身惟经脉随月郭之盈亏以为
盛衰，故必久风之在经脉中者，方为遇节即发；若病不在经脉中，虽属久风，亦不至遇节即
发也。故遇节即发之状，于风虚劳独多。
前论阳脉候先受，阴脉候后受者，其义本之叔微。叔微于湿温之脉，阳濡而弱，阴小而
急，
则云先受温，后受湿，以彼准此，义当如是，并以知温脉濡弱也。经意谓邪中于人，其兼及
表里者，当阴阳如一，如温疟是。若先受某邪，后又受某邪，则先之兼见于阴者，必退而并
于阳，斯后之独见于阴者，乃得而乘于阳。风温、温毒、温疫脉法皆如是。后者之不得陷于
阳也，以阳有宿邪也；先者之不得越于阴也，以阴有新邪也。新者欲下不得下，宿者欲上不
得上。不得下而因汗之，则宿者随新者以俱升而病剧；不得上而因下之，则新者随宿者以深
入而病变。此二变者皆难治。必明于温热之脉法，而后温病可诊也；亦必明于温病之诊法，
而后温病可治也。所以温病大法禁汗下偏行之治，而宜汗下并行之治，萎蕤汤汗下并行之方
也。由萎蕤而推之他方，思过半矣。
古代医书提到疾病在节气交替时发作的情况，仅见于《诸病源候论·尸注候》中记载，但临床上见到的情况非常多。有的疾病在交节当天发作，有的在交节前后的几天内发作，并不一定都是尸注病。总之，如果病根没有去除，就会痊愈后再次复发。为什么一定要遇到节气才发作呢？考察顺应节气而来的事物，没有比八风（八方之风）更明显的了，因为风被视为中央土气所化生（依据《尚书·洪范》郑玄的注释，详见前文《原风湿》）。土在五行五常中主“信”，所以到了特定时间就不会差误。而经典经文说“风为百病之长”，由此可知，那些遇到节气就发作的疾病，必定与风邪有关。
风邪滞留于经脉之中，就会随着外感而发作。而且五天为一候，三候为一气，一气对应月亮盈亏的大致规律。人体只有经脉会随着月亮的盈亏而发生盛衰变化，所以必须是风邪长久停留在经脉中，才会出现遇到节气就发作的情况；如果病不在经脉中，即使属于久风，也不会遇到节气就发作。因此，这种遇到节气就发作的症状，多见于风虚劳损类疾病。
前文论述阳脉候反映先受邪、阴脉候反映后受邪的观点，其理论本源于戴叔微。戴叔微在论述湿温病的脉象时，提到阳脉濡弱、阴脉小而急，认为这是先受温邪、后受湿邪的结果。用这个例子来类比，道理应当是这样，同时也由此推知温病的脉象表现为濡弱。经文的意旨在于：邪气侵入人体，如果同时涉及表里，那么阴阳脉象应当一致，如温疟病就是这种情况。如果是先受某种邪气，后又受另一种邪气，那么先前兼见于阴脉的邪气，必然会退去并合并到阳脉中，这样后来单独见于阴脉的邪气，才能乘虚侵入阳分。风温、温毒、温疫的脉法都是这样的道理。后来的邪气之所以不能陷入阳分，是因为阳分已有宿存的邪气；先前的邪气之所以不能越过进入阴分，是因为阴分已有新的邪气。新邪想要下行却下不去，宿邪想要上行却上不来。无法下行而强行使用发汗法，则宿邪会跟随新邪一起上升，导致病情加重；无法上行而强行使用攻下法，则新邪会跟随宿邪一起深入体内，导致病变复杂。这两种变证都难以治疗。必须通晓温热病的脉法，然后才能诊断温病；也必须通晓温病的诊法，然后才能治疗温病。所以治疗温病的大法禁止偏重于发汗或攻下的治法，而适宜采用汗法与下法并用的治法，萎蕤汤（Rehmanniae Radix Decoction）就是汗下并用的方剂。由萎蕤汤推广到其他方剂，思考起来就能掌握大半要领了。
Ancient medical texts mention diseases that manifest upon the arrival of solar terms, a phenomenon recorded only in the "Shi Zhu Hou" (Posture and Etiology of Corpse-Infestation) chapter of *Zhu Bing Yuan Hou Lun* (Source Book of All Categories of Diseases), yet it is frequently observed in clinical practice. Some diseases manifest on the day of the solar term transition, while others appear several days before or after; these are not necessarily all cases of Shi Zhu (Corpse-Infestation). In essence, if the root of the disease is not eradicated, it will recur after remission. Why must it manifest upon the solar term? Examining phenomena that respond to solar terms, none is more evident than the Eight Winds (Winds from the eight directions). Wind is regarded as the qi transformation of Central Earth (based on Zheng Xuan's commentary on the *Book of Documents*, detailed in the preceding section "On Wind-Dampness"). Earth governs "Trustworthiness" (Xin) among the Five Virtues; thus, it arrives at its appointed time without error. Since the classics state that "Wind is the leader of a hundred diseases," it can be deduced that diseases manifesting upon solar terms are necessarily related to Wind pathogen.
When Wind pathogen remains in the meridians, it manifests with each external contraction. Furthermore, five days constitute one pentad (Hou), three pentads constitute one Qi (solar term period), and one Qi corresponds to the general law of the moon's waxing and waning. Only the human meridians undergo prosperity and decline following the moon's phases. Therefore, only when Wind pathogen has resided in the meridians for a long time will it manifest upon the solar term; if the pathology is not located within the meridians, even if it involves chronic Wind, it will not manifest specifically upon the solar term. Consequently, this pattern of manifestation upon solar terms is most common in conditions of Wind deficiency and consumptive fever (Xu Lao).
The previous discussion regarding Yang pulse indicating prior pathogen invasion and Yin pulse indicating subsequent invasion originates from Dai Shuwei. In his analysis of Wet-Warmth (Shi Wen) pulse patterns, where the Yang pulse is soggy and weak while the Yin pulse is small and rapid, he posited that Warmth pathogen was invaded first, followed by Dampness. By analogy, the principle holds true, and this also indicates that the pulse of Warmth disease presents as soggy and weak. The intent of the classic text is that when pathogens invade the human body and involve both exterior and interior simultaneously, the Yin and Yang pulses should be consistent, as seen in Warm Malaria (Wen Nue). However, if one pathogen is invaded first and another subsequently, the pathogen initially present in the Yin aspect must retreat and merge into the Yang aspect, allowing the later-invading pathogen, uniquely present in the Yin, to penetrate the Yang. This logic applies to the pulse methods of Wind-Warmth, Warm Toxin, and Warm Epidemic. The reason the later pathogen cannot sink into the Yang aspect is that the Yang aspect already harbors residual pathogens; the reason the earlier pathogen cannot transcend into the Yin aspect is that the Yin aspect already contains new pathogens. The new pathogen desires to descend but cannot; the residual pathogen desires to ascend but cannot. If sweating therapy is applied because descent is impossible, the residual pathogen will ascend along with the new pathogen, exacerbating the illness. If purgation therapy is applied because ascent is impossible, the new pathogen will deepen into the interior along with the residual pathogen, complicating the pathology. Both of these two transformations are difficult to treat. One must clearly understand the pulse methods of Warm-Heat diseases to diagnose Warmth diseases; similarly, one must master the diagnostic methods for Warmth diseases to treat them effectively. Therefore, the general principle for treating Warmth diseases prohibits therapies that rely solely on sweating or purging, advocating instead for combined sweating and purging therapies. Wei Rui Tang (Rehmanniae Radix Decoction) is a formula that employs both sweating and purging. By extrapolating from Wei Rui Tang to other formulas, one can grasp the majority of the underlying principles.