The Mechanism of Human Facial ExpressionIn Mecanisme de la Physionomie Humaine, the great nineteenth century French neurologist Duchenne de Boulogne combined his intimate knowledge of facial anatomy with his skill in photography and expertise in using electricity to stimulate individual facial muscles to produce a fascinating interpretation of the ways in which the human face portrays emotions. This book was pivotal in the development of psychology and physiology as it marked the first time