In Descartes’ theory, how could animal spirits affect bodily movement?

In Descartes' theory, the concept of animal spirits refers to a fluid or ethereal substance that he believed flowed through the body and was responsible for the movement of muscles. He theorized that when these animal spirits moved through the nerves, they would cause a kind of inflation or swelling within the muscles, leading to bodily movement. This idea was part of Descartes’ mechanistic view of the body, where he considered it to operate in a similar way to a machine.

The correct answer illustrates this notion of inflation: when animal spirits reached the muscles, they would create a pressure that would make the muscles contract, thus facilitating movement. This perspective highlighted Descartes' innovative approach to understanding the physiological mechanisms behind movement, setting the stage for subsequent developments in both psychology and physiology.