Zhang Ji (Simplified Chinese: 张机; Traditional Chinese: 張機; pinyin: Zhāng Jī, 150 - 219), style name Zhang Zhongjing (Simplified Chinese: 张仲景; Traditional Chinese: 張仲景; pinyin: Zhāng Zhōngjǐng; Wade-Giles: Chang Chung Ching), an Eastern Han (Traditional Chinese: 東漢; pinyin: Dōng Hàn) physician and author of the Shanghan Zabing Lun (Traditional Chinese: 傷寒雜病論; pinyin: Shānghán Zábìng Lùn, lit. "Treatise on Cold Pathogenic and Miscellaneous Diseases"), was one of the most eminent Chinese physicians during the later years of the Eastern Han era. He lived in today's Nanyang in Henan Province. During his time, with warlords fighting for their own territories, many people were infected with febrile disease. Zhang's family was no exception. He learned medicine by studying from his townsfellow Zhang Bozu, assimilating from previous medicinal literature, and collecting many prescriptions elsewhere, finally writing the medical masterpiece Shanghan Zabing Lun. Unfortunately, shortly after its publication the book was lost during wartime. Due to Zhang's contribution to Traditional Chinese medicine he is often regarded as the sage of Chinese medicine.
Zhang's masterpiece was collected by later people and compiled into two books, namely the Shanghan Lun (in full, Shanghan Zabing Lun or "Treatise on Febrile Diseases") which was a discourse on how to treat epidemic infectious diseases causing fevers prevalent during his era, and the other, highly influential doctrine Jingui yaolue (金匱要略, "Synoptic Essentials from the Golden Cabinet"), a compendium of his clinical experiences. He established medication principles and summed up the medicinal experience up until the Han Dynasty, thus making a great contribution to the development of Traditional Chinese Medicine.
Though extremely well known in modern Chinese medicine and considered one of the finest Chinese physicians in history very little is known of his life. Zhang Ji is considered to have founded the Cold Damage or "Cold Disease" school of Chinese medicine and is widely considered the seminal expert to this day. For more information on Zhong Ji it is best to refer directly to the Shang Han Lun.