Qian Yi (around 1032 to 1113) was a famous pediatrician in Shandong during the Northern Song Dynasty. The Key to Therapeutics of Children's Diseases written by Qian Yi is the first pediatric book extant in China, which for the first time summarizes therapy treatment based on differentiation of pediatric syndromes, thus developing pediatrics into an independent branch of knowledge. The later generations regarded it as a classic pediatric work and honored Qian Yi "the Sage of Pediatrics" or "the Originator of Pediatrics".

Qian Yi was diligent and studious since young. He studied intensively the ancient medical books and collected all data about pediatrics in ancient or modern times for his study. There was not much data left about pediatric diseases before his time. However, his efforts were rewarded. He put the elicitations acquired from the ancient books into clinical practice and achieved much effect. Moreover, Qian also fished out the "Differentiation Methods in Five Viscera" for curing pediatric diseases based on his own practices and Zhang Zhongjing's theory of treatment based on differentiation of syndromes.

During decades of clinical practice, Qian Yi accumulated rich experience, especially in pediatrics with much innovations and gains. He then combined his experience with classic medical works including Inner Canon of Huangdi, Treatise on Cold Pathogenic Diseases and Miscellaneous Diseases and Shennong's Classic of Materia Medica into his pediatric book Key to Therapeutics of Children's Diseases.