Around 1833–early in his career and two years after Michael Faraday’s discoveries about how electricity flows were announced–Guillaume-Benjamin-Amand Duchenne (1806–1875), a French neurologist, began experimenting with a form of acupuncture that employed electric currents. A decade later and working in Paris, Duchenne continued to refine his process of “electrotherapy,” which he believed could help in the treatment of nervous and muscular disorders and to clarify the relationship between musculature and emotion. By the 1860s and after learning the basics of photography, Duchenne began to take still-startling images to document his research on subjects ranging from the physiognomy of smiles to the nature of paralysis. His sitters included patients, actors, indigents, and children and photographs of them were collected in an influential book, Mécanisme de la physionomie humaine (Mechanism of Human Physiognomy), in 1862. A decade later, Charles Darwin included some of Duchenne’s images in The Expression of Emotion in Man and Animals–one of the first widely distributed and photographically illustrated science books–which traced the connection and evolution of mental states to neurological organization, bodily gestures, and movement.