Also externally contracted disease; external contraction. Any disease caused by influences originating outside the body, characterized by heat effusion and a usually rapid stage-by-stage progression. The earliest extant compilation dealing with external febrile diseases, On Cold Damage (伤寒论 shāng hán lùn), written in the Hàn Dynasty, identifies and treats diseases according to their location among the six channels. Further accumulation of experience and developments in medical thought in the ages that followed culminated in the doctrine of warm diseases. On Warm Heat (温热论wēn rè lùn) and Systematized Identification of Warm Diseases (温病条辨 wēn bìng tiáo biàn) are two works of the Qīng Dynasty that further synthesized the laws governing the origin and development of externally contracted febrile diseases into the system known as four-aspect pattern identification and treatment. As a result of these latter-day developments there have emerged two separate schools of thought, the cold damage school and the warm diseases school.