A marquis who retired from court life at Versailles to pursue scientific discovery. His pet project is the idea of fluidum vitale, or the idea that the earth contains poisonous gases that can do damage, while places and items that are "earth-removed" (places with high elevation, or birds) are healing. Grenouille provides the perfect example of his theory in action when he comes to the marquis' attention after spending seven years in a cave. The marquis uses Grenouille to support his theory, gives several lectures, and pays Grenouille for being a research subject. The marquis eventually decides to climb the highest mountain in the Pyrenees, from which he will return a man aged 20 thanks to the healing powers of the fluidum vitale at the high elevation, but he never returns.