叶天士出身医学世家，相传其学医求师极为虚心，自述「十年之内，易师十七人」，凡闻某医有一技之长，便虚心求教。他创立「卫气营血」辨证纲领，用以判断温病由表入里、由浅入深的传变规律，是温病学说体系化的关键人物，后世将他列为「温病四大家」之首。其晚年医案由门人整理成《临证指南医案》，学术见解则见于《温热论》。

Born into a family of physicians, Ye Tianshi was famously humble in seeking instruction, reportedly changing teachers seventeen times over ten years, studying with anyone who possessed a particular skill worth learning. He established the "defense-qi-nutrient-blood" framework for tracking how warm-febrile disease progresses from the body's exterior to its interior, becoming the pivotal figure in systematizing Warm Disease theory and earning recognition as foremost among the "Four Great Masters of Warm Disease." His late-career case records were compiled by his students into the Guide to Clinical Practice with Medical Cases, while his theoretical views are recorded in the Treatise on Warm-Heat Disease.