疟之病，热气舍于营，寒气居于卫。寒居于卫，则束其营之热，不得外越；热舍于营
，则阻
其卫之寒，不得内乘。气相抑而适相持，是以伤寒易变，而疟病不迁也。疟邪不能自发，必
得人之正气而后发，故曰卫气之所在，与邪气相合则病作。
疟邪外不在皮肤，内不在脏腑，是以汗之而不从外泄，下之而不从里出也。
风气常在，疟有时而休。常在者，其气舒；蓄而作者，其气暴，故工不能治其已发也。
疟发已而邪递浅者，其作日蚤；发已而复伏愈深者，其作日晏。日蚤者易已，日晏者难
已。
其始晏而终蚤者，邪气下行极而之上也。是以疟病欲愈，一日反二三发，其邪愈浅，辄与卫
气相簿故也。
疟之为病，邪正分争，往来不已，有战之义也。治之必先助其正气，或急去其邪气。盖
正旺
则邪自解，邪去则正亦安也。今有人体虚患疟，不数日而作渐晏，势渐衰，神气反昏而不可
救，非正虚而邪陷之故欤？
阴阳交之病，古有其名，而无能抉其义者。愚谓“交”非交通之谓，乃错乱之谓也。阴
阳错
乱，而不可复理，攻其阴则阳捍之不得入，攻其阳则阴持之不得通，故曰交者死也。郭白云
所谓即是两感之病，盖从汗出而热不退处悟入。然两感究竟是阴阳齐病，而非阴阳交病，是
以与先表后里，或表里并治之法，以其未尝混合为一也。
疟疾这种病，是热气潜伏在营分，寒气停留在卫分。寒气停留在卫分，就会束缚住营分的郁热，使其不能向外发散；热气潜伏在营分，就会阻碍卫分的寒气，使其不能向内侵袭。气机相互抑制且恰好势均力敌，所以伤寒容易发生变化，而疟疾的病位则相对固定不移。疟邪不能独自发作，必须依赖人体的正气才能引发疾病，所以说，当卫气运行到某个部位，与邪气相搏结时，疾病就会发作。
疟邪在外不在皮肤表层，在内也不在脏腑深处，因此用发汗法治疗，邪气不会从体表排出；用泻下法治疗，邪气也不会从体内排出。风邪之气常存于体内，但疟疾却有间歇期停止发作的时候。常存的风气其势舒缓，蓄积后爆发的疟邪其势猛烈，所以医生难以在疟疾发作正盛时进行治疗。
疟疾发作后，如果邪气逐渐变浅，那么下次发作的时间就提前；如果发作后邪气再次潜伏且变得更深，那么下次发作的时间就推迟。发作时间提前的容易治愈，发作时间推迟的难以治愈。
如果起初发作时间推迟，最后却变得提前，这是邪气下行至极点后转而向上的表现。所以疟疾想要痊愈时，会出现一天内反而发作两三次的情形，这是因为邪气已经变浅，频繁地与卫气相搏结的缘故。
疟疾这种疾病，是邪气与正气分争，往来不休，具有交战的意义。治疗它，必须先扶助人体的正气，或者迅速祛除邪气。因为正气旺盛则邪气自然解除，邪气去除则正气也能安宁。现在有人体质虚弱患疟疾，没过几天发作时间逐渐推迟，病情势头逐渐衰退，但神志反而昏沉无法救治，这难道不是正气虚衰而邪气内陷的缘故吗？
阴阳交这种病，古代虽有名称，但没有能透彻阐明其含义的人。我认为“交”不是交通、交流的意思，而是错乱的意思。阴阳错乱，就无法再理顺，攻伐阴分则阳分会抗拒使药力不得进入，攻伐阳分则阴分会牵制使药力不得通行，所以说“交”意味着死亡。郭白云所说的就是两感证（表里同时受邪），大概是从他观察到出汗后热势不退这一现象中领悟到的。然而两感证终究是阴阳两经同时患病，而不是阴阳交病，因此可以采用先治表后治里，或表里同治的方法，因为它们尚未混合为一团。
Malaria is a disease where pathogenic heat resides in the Ying (Nutrient) level, and pathogenic cold dwells in the Wei (Defensive) level. When cold dwells in the Wei level, it binds the heat of the Ying level, preventing it from dispersing outward; when heat resides in the Ying level, it obstructs the cold of the Wei level, preventing it from invading inward. The Qi mutually suppresses each other and remains in a stalemate; therefore, Shanghan (Cold Damage) tends to change frequently, whereas malaria remains relatively fixed in its location. Malaria pathogens cannot manifest spontaneously but must rely on the body's Zheng Qi (Upright Qi) to trigger the disease. Thus, it is said that when the Wei Qi reaches a certain area and combines with the pathogenic factor, the illness arises.
The malaria pathogen is neither on the exterior at the skin level nor on the interior within the Zang-Fu organs. Therefore, diaphoresis (sweating therapy) does not expel it from the exterior, and purgation (draining therapy) does not eliminate it from the interior. Wind pathogens are often present, but malaria has periods of remission. The ever-present wind Qi is gentle, while the accumulated malaria Qi is violent; thus, physicians find it difficult to treat the disease during its acute attack phase.
If, after an attack, the pathogen becomes shallower, the next attack occurs earlier; if, after an attack, the pathogen retreats deeper, the next attack occurs later. Attacks occurring earlier are easier to cure, while those occurring later are harder to cure.
If the onset time initially delays but eventually advances, it indicates that the pathogen has descended to its extreme and is now moving upward. Hence, when malaria is about to heal, it may occur two or three times in one day because the pathogen has become shallow and frequently clashes with the Wei Qi.
Malaria involves a struggle between pathogenic factors and upright Qi, characterized by continuous alternation, akin to battle. Treatment must first assist the Zheng Qi or rapidly eliminate the pathogenic factors. When Zheng Qi is robust, the pathogen resolves itself; when the pathogen is removed, the Zheng Qi remains secure. Now, consider a person with weak constitution suffering from malaria: within a few days, the attacks occur progressively later, the condition weakens, yet the spirit becomes confused and beyond salvation. Is this not due to deficiency of Zheng Qi leading to the sinking of the pathogen?
The disease known as Yin-Yang Jiao (Intermingling of Yin and Yang) existed in ancient texts with its name, but no one could fully elucidate its meaning. I believe "Jiao" does not mean communication or interaction, but rather disorder or confusion. When Yin and Yang are disordered and cannot be restored to order, attacking the Yin allows the Yang to resist, preventing entry; attacking the Yang allows the Yin to hold back, preventing passage. Thus, it is said that "Jiao" implies death. Guo Baiyun stated that this is essentially the same as Liang Gan (Double Exposure/Simultaneous Affection of Exterior and Interior), likely deduced from observing cases where fever persists despite sweating. However, Liang Gan ultimately refers to simultaneous disease of both Yin and Yang meridians, not the specific pathology of Yin-Yang Jiao. Therefore, treatments such as treating the exterior first then the interior, or treating both simultaneously, can be applied, as they have not yet merged into a single indistinguishable entity.