For 10 points, name this author of  Meditations on First Philosophy .
This philosopher used a pressure-pad-activated statue of Neptune that threatened oncomers with his trident as a model for the mechanistic nature of the body. This philosopher described spatial extension as the primary attribute of matter. He used the dismissal of the Scholastic concept of "heaviness" to explain the interaction of two distinct substances in a letter to Elisabeth of Bohemia. In his  Treatise on Man  and (*)   Passions of the Soul , this philosopher described how the flow of animal spirits from the pineal gland controls one's senses and actions. He had a "clear and distinct idea" of the mind as a thinking thing, which led him to embrace mind-body dualism. For 10 points, name this author of  Meditations on First Philosophy .
This philosopher used a pressure-pad-activated statue of Neptune that threatened oncomers with his trident as a model for the mechanistic nature of the body.
René  Descartes 