How the soul moves the body: the nature of pneuma as an instrumental cause in Philoponus’ Commentary on Aristotle’s On the Soul

In his commentary on Aristotle’s On the soul Philoponus claims that each part of the soul relates to its own underlying body as a form to matter. Philoponus insists, that the vegetative soul relates to a solid body, whereas the irrational soul relates to a pneumatic body. At the same time the irrational soul is the first mover for the solid body. In the paper, I consider the problem of the relationship between the irrational soul and an organic or solid body. Philoponus claims, that the irrational soul needs a pneumatic body to be the mover and entelecheia of a solid body. For this reason I describe how Philoponus understood the nature and function of pneuma and I reveal the role of pneuma as instrumental cause of bodily movement and therefore as a mediator between the irrational soul and the solid body.