朱 曰。养生至宝书云。近秽气。触真气。近死气。乱生气。深有旨哉。孙真人云。乘马远行。
至暮。当沐浴更衣。方可近婴见处所。若感其气。则为急惊风搐。又曰。步践粪秽之履。勿使近
婴儿。若感其气。则为天吊。伤寒大汗将出。当以艾灸席隅。以避其气。不然。感其汗气。则传染
矣。所以多染侍奉劳役之人者。由其神虚气怯。易为扰乱故也。如剥死马者。感其毒瓦斯。而为马气
之疾。其理同焉。（以上汗气传染）或曰。伤寒只传足经。不传手经。何也。曰。伤寒之邪。多于
足经。而其病甚。少于手经。而其病微。故不特言手经。但寄于足经而已。（手足经辨）外有风寒
暑湿。内有饥饱劳逸。或曰。劳役。非也。劳、倦也。逸、闲逸也。西山记曰。久劳则安闲以保极
力之处。久逸则导引以行积滞之气。（内外伤辨）
夫寒者。天地杀厉之气也。秋之雾露。冬之霜雪。
皆寒邪也。是以辛苦之徒。起居不节。饮食不时。感雾露之气。则邪浅。感霜雪之气。则邪深。
感而即病。名曰伤寒。不即病者。寒邪藏于肌肉之间。伏于荣卫之内。至春因温暖之气而发。名温
病。至夏因暑热之气而作。名热病。一理而已。若疫疠。稍有不同者。盖因春宜温而反凉。夏宜热
而反冷。秋宜凉而反热。冬宜寒而反温。四时不正之气也。感春夏不正之气为温疫。感秋冬不正之
气为寒疫。其经络传受。表里受症。与伤寒同。俗云时气病。经总之曰伤寒。所以谓大病者。害人
甚速也。轩岐后。得其治法之秘者。仲景一人。守真先生。
不遵桂枝发表之法。自制双解通圣辛凉之剂。非不同也。时有异也。五运六气有所更。世态居民有
所变。天以常静。人以常动。动属阳。静属阴。清平之世。同水化也。虽有辛热之药。不生他症。
扰攘之世。同火化也。若用辛热。则发黄出斑。成坏病矣。盖人内火既动。外火又侵。所以辛热发
汗。不如辛温。辛温发汗。不如辛凉。以辛热发汗。轻者必危。重者必死。可不慎哉。（理伤寒
总论）
Zhu stated: The *Book of Supreme Treasures for Health Preservation* records, "Approaching foul odors will touch and disturb the body's true Qi; approaching death qi will disrupt vital energy." The profound significance of this is great. Sun Simiao said, "After traveling far on horseback, when evening arrives, one should bathe and change clothes before approaching areas where infants are present. If one contracts this qi, it will cause acute convulsive wind (Ji Jing Feng Chu)." He also said, "Do not allow shoes that have stepped in feces or filth to approach infants. If they contract this qi, it will result in Tian Diao (a type of convulsive disorder)." When a patient with Shanghan has profuse sweating about to occur, moxibustion should be applied to the corners of the mat to avoid the pathogenic qi. Otherwise, contracting the sweat qi will lead to transmission. Therefore, those who serve patients or engage in laborious work are easily infected because their spirit is deficient and their Qi is timid, making them susceptible to disturbance. Just as those who skin dead horses contract toxic vapors and suffer from diseases related to horse qi, the principle is the same. (Regarding the transmission via sweat qi)
Someone asked, "Shanghan transmits only through the Foot meridians and not the Hand meridians. Why is this?" The answer is: The pathogen of Shanghan is more prevalent in the Foot meridians, and the disease is severe; it is less prevalent in the Hand meridians, and the disease is mild. Thus, the Hand meridians are not specifically mentioned, but are merely implied within the discussion of the Foot meridians. (Differentiation of Hand and Foot Meridians)
Externally, there are Wind, Cold, Summer-heat, and Dampness pathogens; internally, there are factors such as hunger, fullness, fatigue, and rest. Some argue that "laborious work" is incorrect. Here, "Labor" refers to fatigue/exhaustion, and "Rest" refers to leisure/idleness. The *Xishan Ji* states, "After long periods of labor, one should maintain tranquility to preserve the areas of extreme physical exertion; after long periods of idleness, one should practice Daoyin (guiding and pulling exercises) to move stagnant Qi." (Differentiation of Internal Injury)
Cold is the killing and fierce qi of Heaven and Earth. Autumn fog and dew, and winter frost and snow, are all Cold pathogens. Therefore, among those who endure hardship, if their daily routine is irregular and meals are untimely, contracting fog and dew qi results in shallow pathogenesis, while contracting frost and snow qi results in deep pathogenesis. If illness occurs immediately upon contraction, it is named Shanghan. If illness does not occur immediately, the Cold pathogen hides between the muscles and lies dormant within Ying and Wei. In spring, triggered by warm qi, it erupts and is named Wenbing (Warm Disease). In summer, triggered by heat qi, it arises and is named Rebing (Heat Disease). The underlying principle is the same. Epidemic diseases differ slightly, generally occurring because spring should be warm but is instead cool, summer should be hot but is instead cold, autumn should be cool but is instead hot, and winter should be cold but is instead warm. These are the abnormal qi of the four seasons. Contracting abnormal qi in spring and summer is called Wenyi (Warm Epidemic); contracting abnormal qi in autumn and winter is called Hanyi (Cold Epidemic). Their meridian transmission patterns and exterior-interior symptom manifestations are the same as Shanghan. Commonly known as Shiqi Bing (Seasonal Qi Disease), the classics summarize it under Shanghan. It is called a major disease because it harms people very rapidly.
Since Huangdi and Qibo, only Zhang Zhongjing mastered the secrets of treatment. Liu Wansu (Mr. Shouzhen) did not follow the method of releasing the exterior with Guizhi Tang (Cinnamon Twig Decoction) but independently created cooling agents like Shuangjie San (Double Resolution Powder) and Tongsheng San (Universal Benefit Powder). This is not due to difference in theory, but difference in times. The Five Movements and Six Qi undergo changes, and social conditions and resident constitutions vary. Heaven remains constantly still, while humans are constantly moving. Movement belongs to Yang, stillness belongs to Yin. In peaceful times, the environment resembles Water transformation; even if acrid-hot medicines are used, no other syndromes arise. In turbulent times, the environment resembles Fire transformation; if acrid-hot medicines are used, jaundice and macules will appear, resulting in complicated diseases. Because internal fire is already active and external fire invades, using acrid-hot medicine to induce sweating is inferior to using acrid-warm medicine; using acrid-warm medicine to induce sweating is inferior to using acrid-cool medicine. Using acrid-hot medicine to induce sweating will endanger mild cases and kill severe cases. Can one not be cautious? (General Discussion on Managing Shanghan)