In this paper I offer an analysis of Plotinus’ argument for the existence of a quasi-psychic entity, the so-called ‘trace of soul’, that functions as an immanent cause of life for an organism’s body. I argue that Plotinus posits this entity primarily in order to account for the body’s possession of certain quasi-psychic states that are instrumental in his account of soul-body interaction. Since these quasi-psychic states imply that an organism’s body has vitality of its own , and Platonic souls (...) are no part or aspect of any body, Plotinus draws the conclusion that the soul must be a cause of the body’s life by imparting a quasi-psychic qualification to it. In so doing, Plotinus introduces elements of hylomorphism into Platonist psychology, and addresses a problem for the animation of the body that Platonic soul-body dualism may plausibly be thought to face. (shrink)