This Chapter is a dialogue from The Yellow Emperor’s Classic of Internal Medicine, exploring the causes and progression of feverish illnesses. Qi Bo, a renowned physician, explains the sequential involvement of different meridians (energy channels) over six days, leading to death if two channels are simultaneously affected by cold. He details symptoms for each affected channel and outlines treatment strategies based on the illness duration, emphasizing avoiding meat consumption during recovery. The discussion also distinguishes between warm and heat diseases depending on their timing relative to the summer solstice and advocates for promoting sweating in heat illnesses.