This book explores a range of traditional and contemporary metaphysical themes that figure in the writings of E. J. Lowe, whose powerful and influential work was still developing at the time of his death in 2015. During his forty-year career, he established himself as one of the world's leading philosophers, publishing eleven single-authored books and well over two hundred essays. His scholarship was strikingly broad, ranging from early modern philosophy to the interpretation of quantum mechanics. His most important and sustained contributions were to philosophy of mind, philosophical logic, and above all metaphysics. E. J. Lowe was committed to a systematic, realist, and scientifically informed neo-Aristotelean approach to philosophy. This volume presents a set of new essays by philosophers who share this commitment, addressing interrelated themes of his work. In particular, these papers focus upon three closely connected topics central not only to Lowe's work, but to contemporary metaphysics and philosophy of mind in general: ontology and categories of being; essence and modality, and the metaphysics of mental causation.