Philosophers and doctors from the period immediately after Aristotle down to the second century CE were particularly focussed on the close relationships of soul and body; such relationships are particularly intimate when the soul is understood to be a material entity, as it was by Epicureans and Stoics; but even Aristotelians and Platonists shared the conviction that body and soul interact in ways that affect the well-being of the living human being. These philosophers were interested in the nature of the soul, its structure, and its powers. They were also interested in the place of the soul within a general account of the world. This leads to important questions about the proper methods by which we should investigate the nature of the soul and the appropriate relationships among natural philosophy, medicine, and psychology. This volume, part of the Symposium Hellenisticum series, features ten scholars addressing different aspects of this topic.