Charles le Brun's System on Physiognomy. Artworks by the French artist Charles le Brun (1619-1690), showing the first step in a series of stages turning a human face into a pig's face. Le Brun's series of artworks comparing animal and human faces was intended to show similarities and differences, and was used by him in a treatise on the nature of the soul and effect of physical traits on a person's character.