In Chapter 10, I show how Aristotle attempts to make an empirical advance over the Platonic theory that the soul has determinate spatial-parts in the body. What Aristotle takes over from this theory, I argue, is that the soul has ‘parts’ which exercise powers within the body, but these parts cannot be understood as spatial-parts. Aristotle’s investigation of this puzzle results in the discovery that, while the soul does not have a determinate spatial structure, it does have a metaphysical structure. These discussions, I claim, place a positive constraint on him to adopt the Part-Hood Thesis.