Pang stated: Hardworking people often suffer from warm-heat diseases in spring and summer, all caused by contracting cold pathogenic toxins during winter. Warm diseases occurring from spring until before the Summer Solstice are what *Suwen* (Plain Questions) and Zhang Zhongjing referred to as Shanghan (Cold Damage). If one is affected by unseasonal warmth during winter, this condition is named "Winter-Warmth Poison" (Dongwen Zhi Du), which is vastly different from Shanghan; if a warm disease manifests immediately at that time, it is a Tianxing (epidemic) disease.

During the warm days of winter, if a person contracts climate qi that violates the seasonal norms without immediate onset, and later in spring is suppressed by accumulated cold, causing the internal toxins to fail to dissipate, then when the weather becomes hot, the warm toxin erupts, leading to ulceration and maculation of the muscle tissue. Furthermore, if one directly contracts aberrant qi in the four seasons, resulting in zang-fu yin-yang warm toxins, then in spring there is the syndrome of green sinew traction (Qing Jin Qian), in summer the syndrome of red vessel spasm (Chi Mai Ji), in autumn the syndrome of white qi stagnation (Bai Qi Yu), in winter the Black Bone Warmth (Hei Gu Wen), and during the transition of seasons, the Yellow Flesh Following (Huang Rou Sui). These conditions have their own distinct treatment methods.

*Nan Jing* (Classic of Difficult Issues) records five types of Shanghan, stating that the pulse of warm disease travels through the various meridians. One must not know which meridian is moving, but rather select treatment points based on the location of the meridian involved. Wind-strike corresponds to Wood, Cold Damage corresponds to Metal, Heat Disease corresponds to Fire, Damp-Warmth corresponds to Water, and Warm Disease corresponds to Earth. The practitioner should select the corresponding meridians for each. According to *Nan Jing*, warm disease originally belongs to four types of Shanghan, transforming into warm disease due to the contraction of abnormal qi. Earth has no fixed form and is named because of Fire, hence Warmth is placed after Heat. Earth resides in the four corners (Si Wei), thus attaching itself to Metal, Wood, Water, and Fire to generate diseases. Therefore, Wang Shuhe said: When the Yang pulse is floating and slippery, and the Yin pulse is soggy and weak, further encountering wind-heat transforms it into Fengwen (Wind-Warmth); when the Yang pulse is surging and rapid, and the Yin pulse is solid and large, further encountering heat transforms it into Wendu (Warm-Toxin), which is the most severe among warm diseases; when the Yang pulse is soggy and weak, and the Yin pulse is string-like and tight, further encountering dampness transforms it into Shiwen (Damp-Warmth); when both Yin and Yang pulses are full and vigorous, and one re-contracts cold, it transforms into Wen Nue (Warm Malaria). These are cases where the same disease has different names, and the same pulse arises from different meridians. Therefore, for Fengwen, one selects the Foot-Jueyin Liver Meridian and Hand-Shaoyin Heart Meridian; for Wendu, one exclusively selects the Hand-Shaoyin Heart Meridian; for Wen Nue, one selects the Hand-Taiyin Lung Meridian; for Shiwen, one selects the Foot-Shaoyin Kidney Meridian and Hand-Shaoyin Heart Meridian. Thus it is said to select points according to the location of the meridian.

Tianxing diseases, if severe, spread toxicity throughout the world; if moderate, they affect one region; if minor, they affect one township; if slight, they affect only one household. All are caused by the depression and eruption of Qi movement, with excess and latent factors, shifts in dominant Qi positions, and variations in timing. The interaction of the nine chambers of heaven and earth causes ascending Qi to be blocked from moving forward and descending Qi to be blocked from moving down, resulting in the non-interaction of Heaven and Earth Qi, leading to instability in the transformation of all things. Consequently, specific sectors (Gongfen) inevitably suffer from this harmful Qi, which Zhuangzi referred to as the leakage of movement. Moreover, human fate involves varying encounters, and times fluctuate between obstruction and smoothness, allowing the disease to affect only one household. Since heaven and earth produce such harmful Qi, they also provide substances born of heaven and earth to prevent it; this is called the wise person knowing the method (Xianren Zhifang).