A distinguished group of Aristotelian scholars and contemporary metaphysicians discusses Aristotle's theory of the unity and identity of substances. The questions of ontology, explanation, and methodology with which they deal remain central to metaphysics today. This book sets a new agenda for Aristotelian metaphysics.

This volume presents fourteen essays by leading figures in the fields of ancient philosophy and contemporary metaphysics, discussing Aristotle's theory of the unity and identity of substances, a topic that remains at the center of metaphysical enquiry. The contributors examine the nature of
essences, how they differ from other components of substance, and how they are related to these other components. The central questions discussed are: What does Aristotle mean by "potentiality" and "actuality?" How do these concepts explicate matter and form, and how are they related to the
actuality of a substance? What is the role of actuality in accounting for the unity and identity of substance? These questions are crucial to an understanding of the unity of composite substances and their identity over time. The aim of the volume is both exegetical and philosophical: to give
answers to central problems in Aristotle's metaphysics, and also to stimulate further investigation of the problems defined and the controversies embodied.

Most of the articles are forward-looking, concerned to tease out new problems and explore fresh responses.