Abstract

Laennec was a master of pathological anatomy and his invention of the stethoscope helped to ensure the relevance of this science to bedside medicine, but his scientific manuscripts reveal that he saw limitations to the anatomo-clinical method. He designed a classification of disease to compensate for the shortcomings in pathological anatomy. This classification was based on identifiable changes, or 'lesions', in what he considered to be the three components of the human organism: solids (organs), liquids and vital principle. He intended the diagnosis of disease to be made by objective identification of the associated 'lesion', regardless of its location in the organs, liquids or vital principle. Thus, in addition to pathological anatomy, diagnosis would require an application of contemporary experimental work in chemistry, physics and physiology to clinical medicine. Laennec thought that 'lesions' in body fluids and in the vital principle could be the detected and quantified by new developments in these sciences