In the Aristotelian tradition, there are two broad answers to the basic question "What is soul?" On the one hand, the soul can be described by what it does. From this perspective, the soul seems to be composed of various different parts or powers (potentiae) that are the principles of its various actions. On the other hand, the soul seems to be something different, namely, the actual formal principle making embodied living substances to be the kinds of things that they (...) are. Contemporary Aristotelians are split on how to interpret Aristotle: Anna Marmodoro (2013, 18), Thomas Johansen (2012, 81), and most others argue that the soul is nothing but a kind of cluster or group of powers. Rebekah Johnston (2011), however, strongly disagrees and argues that the soul is only the actual principle of embodied substance. Aquinas provides a novel and neglected solution to this problem and would argue that both sides are partly right but that either side is insufficient without the other. (shrink)