The Clarendon Aristotle Series is designed for both students and professionals. It provides accurate translations of selected Aristotelian texts, accompanied by incisive commentaries that focus on philosophical problems and issues. The volumes in the series have been widely welcomed and favourably reviewed. Important new titles are being added to the series, and a number of well-established volumes are being reissued with revisions and/or supplementary material.This volume presents a new translation by Thomas Kjeller Johansen of Aristotle's Metaphysics Books A and α, a signature text within Aristotle's writings, of immense importance for the formation of Western metaphysics and for our understanding of early Greek philosophy. Aristotle's Metaphysics was the first work to define metaphysics.