Diseases of Shanghan (Cold Damage) are common among people. Among the books on Shanghan, Zhang Zhongjing's work is considered the most authoritative. Although a single disease encompasses 397 methods and 113 prescriptions, making it already quite detailed, one might ask what more could be expanded. It is unknown that Zhang Zhongjing's book was based on the *Neijing* (Classic of Internal Medicine), specifically the *Re Lun* (Treatise on Heat Diseases). His discussion on the transmission of the Six Channels (Liu Jing) was indeed clear and distinct. Zhang Zhongjing further extended this into a comprehensive work; consequently, Wang Shuhe added to it, and Cheng Wuji provided annotations. Thus, the more it is expanded, the broader it becomes. Therefore, my effort to fill gaps and correct errors in this book is not without justification.

Furthermore, Shanghan diseases often arise from seasonal qi (vital energy). Therefore, the four seasons, eight solar terms, twenty-four jieqi (solar terms), and seventy-two five-day periods must be explained in detail. Since Shanghan diseases inevitably transmit through the meridians, the distribution of the Twelve Primary Meridians on the hands and feet must be illustrated. As Shanghan presents with various syndromes, the 397 methods and 113 prescriptions must be thoroughly investigated, deduced, and supplemented. Shanghan treatment occasionally involves acupuncture, a method rarely seen in recent times; thus, the 59 acupoints for heat diseases must be fully recorded.

I find it strange that contemporary physicians only rely on Li Zhongzi's (Jie'an) compilation, likely due to its simplicity. However, ancient formula discussions contain profound principles. Failing to deeply examine these meanings can lead to slight deviations resulting in life-or-death consequences. I am not afraid of trouble; rather, I detest those who prefer simplicity at the expense of patients' lives, often causing death through misdiagnosis. Thus, the value of this book in supplementing previous works and elucidating unexplored aspects cannot be overstated.

The term "Shanghan" here does not imply cold pathogenicity. Logically, cold diseases are treated with hot-natured agents, and heat diseases with cool-natured agents. Although named "Shanghan," the manifestations are predominantly heat syndromes. I fear future practitioners may mistakenly administer hot-natured drugs due to the name "Shanghan"; hence, I state that "Shanghan is not cold." Cases involving true cold pathogens penetrating deeply into the Three Yin channels account for only ten to twenty percent. In such cases, symptoms are purely cold, distinct from heat syndromes; these are termed "True Cold" and are compiled separately.

Preface by Wang Hu (Courtesy Name: Lingyou) of Changzhou, on the Double Ninth Day of the Gengshen Year of the Kangxi Reign.