The introduction describes the scholastic Latin debate over the relation between the soul and its powers in the late thirteenth and early fourteenth century. It shows that this debate concerned the question of how a living being’s natural kind, which is determined by its soul, and its kind-specific powers are related. Is a living being’s soul the very same thing as its kind-specific powers, or is its soul perhaps something more basic upon which its kind-specific powers depend? The introduction shows that there were two overarching answers to this question in the thirteenth and fourteenth century: the identity theory, according to which the soul and its powers are identical, and the distinction theory, according to which the soul is distinct from its powers. The introduction first highlights that the debate between identity and distinction theorists already arose in the twelfth century in response to Augustine’s doctrine of the image of the Trinity. It then traces, in broad strokes, the development of the debate from the twelfth century until 1250. Finally, it discusses the phase between 1250 and 1320 focusing on the reception of Aristotle’s theory of the soul in the Latin West.