The idea that some parts of reality are fundamental and others derivative was an important one in Aristotle's philosophical system, and is now again of great current interest in philosophy. Michail Peramatzis presents a new account of priority relations in Aristotle's metaphysics, and draws out their continuing philosophical significance.

The main objective of this Element is to reconstruct Aristotle's view on the nature of ontological priority in the Categories. Over the last three decades, investigations into ontological dependence and priority have become a major concern in contemporary metaphysics. Many see Aristotle as the originator of these discussions and, as a consequence, there is considerable interest in his own account of ontological dependence. In light of the renewed interest in Aristotelian metaphysics, it will be worthwhile - both historically and systematically - to return to Aristotle himself and to see how he himself conceived of ontological priority (what he calls 'priority in substance' [proteron kata ousian] or 'priority in nature' [proteron tēi phusei]), which is to be understood as a form of asymmetric ontological dependence.

Cleary discusses the origin, development, and use of the many senses of priority as a central thesis in Aristotle's metaphysics. Cleary contends that one of the most revealing problems for the ambiguity of Aristotle's relationship to Platonism is that of the ontological status of mathematical objects. In support of his claim, Cleary analyzes a curious passage from Aristotle's Topics, where he appears to accept a schema of priorities that makes mathematical entities more substantial than sensible things. How does Aristotle try to reconcile the ordering of things dictated by sciences like mathematics and dialectic with the ordering of sense experience upon which his own physics and metaphysics are based? To find the answer, Cleary reviews three different outlines of the many senses of priority given by Aristotle himself and found in Categories 12-13, Metaphysics Delta 11, and Metaphysics Theta 8. Cleary suggests there is an implicit hierarchy for Aristotle that leads him to posit the Prime Mover at its apex as complete actuality and, therefore, as the focus for the concept of priority. Having reviewed Aristotle's treatment of the many uses of priority, Cleary demonstrates how the concept is used in some typical arguments by Aristotle for his mature metaphysical positions.

Aristotelian (or neo-Aristotelian) metaphysics is currently undergoing something of a renaissance. This volume brings together fourteen essays from leading philosophers who are sympathetic to this conception of metaphysics, which takes its cue from the idea that metaphysics is the first philosophy. The primary input from Aristotle is methodological, but many themes familiar from his metaphysics will be discussed, including ontological categories, the role and interpretation of the existential quantifier, essence, substance, natural kinds, powers, potential, and the development of life. The volume mounts a strong challenge to the type of ontological deflationism which has recently gained a strong foothold in analytic metaphysics. It will be a useful resource for scholars and advanced students who are interested in the foundations and development of philosophy.

Charlotte Witt continues her highly regarded exploration of Aristotle's metaphysics in a book devoted to the ontological distinction between potentiality and actuality. She focuses on Metaphysics book ix, which provides the most sustained discussion of this distinction. Witt rejects the conventional reading of this key text—that Aristotle differentiated between the two concepts solely to further the investigation of substance. Instead, in an original interpretation of his work, she argues that his development of the distinction between "being x potentially" and "being x actually" allowed Aristotle to develop an intrinsically hierarchical and normative vision of reality.For Witt, Aristotle's views about being shed light on his puzzling use of gender language in his descriptions of reality. This language has become an important issue for feminist scholars who have noted that in Aristotle's metaphysics of substance form is sometimes associated with the male, and matter with the female. Witt's interpretation that Aristotelian reality is intrinsically hierarchical and normative, but not intrinsically gendered, offers a new, important understanding of a controversial aspect of Aristotle's metaphysics.

The eighth book of Aristotle's Physics is the culmination of his theory of nature. He discusses not just physics, but the origins of the universe and the metaphysical foundations of cosmology and physical science. He moves from the discussion of motion in the cosmos to the identification of a single source and regulating principle of all motion, and so argues for the existence of a first 'unmoved mover'. Daniel Graham offers a clear, accurate new translation of this key text in the history of Western thought, and accompanies the translation with a careful philosophical commentary to guide the reader towards an understanding of the wealth of important and influential arguments and ideas that Aristotle puts forward.

Michail Peramatzis presents a new interpretation of Aristotle's view of the priority relations between fundamental and derivative parts of reality, following the recent revival of interest in Aristotelian discussions of what priority consists in and how it relates existents. He explores how in Aristotle's view, in contradistinction with (e.g.) Quinean metaphysical views, questions of existence are not considered central. Rather, the crucial questions are: what types of existent are fundamental and what their grounding relation to derivative existents consists in. It is extremely important, therefore, to return to Aristotle's own theses regarding priority and to study them not only with exegetical caution but also with an acutely critical philosophical eye. Aristotle deploys the notion of priority in numerous levels of his thought. In his ontology he operates with the notion of primary substance. His Categories, for instance, confer this honorific title upon particular objects such as Socrates or Bucephalus, while in the Metaphysics it is essences or substantial forms, such as being human, which are privileged with priority over certain types of matter or hylomorphic compounds (either particular compound objects such as Socrates or universal compound types such as the species human). Peramatzis' chief aim is to understand priority claims of this sort in Aristotle's metaphysical system by setting out the different concepts of priority and seeing whether and, if so, how Aristotle's preferred prior and posterior items fit with these concepts.

This volume presents fourteen new essays by leading figures in the fields of ancient philosophy and contemporary metaphysics, discussing Aristotle's theory of the unity of substances. This topic remains at the centre 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 here are: What does Aristotle mean by 'potentiality' and 'actuality'? How do these concepts explicate matter andform, and how are they related to the actuality of substance? What is the role of matter and form in accounting for the unity, identity, and individuation of substances? 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 address central issues in Aristotle's Metaphysics, and to stimulate further investigation of the problems and controversies that arise from these.

Martin Heidegger's reading of Aristotle was one of the pivotal influences in the development of his philosophy. First published in German in 1981 as volume 33 of Heidegger's Collected Works, this book translates a lecture course he presented at the University of Freiburg in 1931. Heidegger's careful translation and his probing commentary on the first three chapters of Book IX of Metaphysics show the close correlation between his phenomenological interpretation of the Greeks (especially of Aristotle) and his critique of metaphysics. Additionally, Heidegger's confrontation with Aristotle's Greek text makes a significant contribution to contemporary scholarship on Aristotle, particularly the understanding of potentiality in Aristotle's thought. Finally, the book exemplifies Heidegger's gift for teaching students how to read a philosophical text and how to question that text in a philosophical way.

Laura Castelli presents a new translation of the tenth book (Iota) of Aristotle's Metaphysics, together with a comprehensive commentary. Castelli's commentary helps readers to understand Aristotle's most systematic account of what it is for something to be one, what it is for something to be a unit of measurement, and what contraries are.