This book offers a novel account of Aquinas's theory of the human act. It argues that Aquinas takes a human act to be a composite of two power-exercises, where one relates to the other as form to matter. The formal component is an act of the will, and the material component is a power-exercise caused by the will, which Aquinas refers to as the 'commanded act.' The book also argues that Aquinas conceptualizes the act of free choice as a hylomorphic composite: it is, materially, an act of the will, but it inherits a form from reason. As the book aims to show, the core idea of Aquinas's...