In the Introduction I set out the main argument of the book, namely the demonstration that Empedocles’ doctrine of rebirth is not only a positive doctrine within On Nature, but is central to his physical system. Then, after briefly tracing the history of the reception of Empedocles’ thought up to the modern era and showing thereby the importance of this thinker in the history of ancient philosophy, I discuss the state of the art related to the book’s main argument. Building on Kahn’s fundamental reappraisal of Empedocles’ doctrinal unity, my book considers the Strasbourg papyrus as evidence for a new reconstruction of Empedocles’ physical poem and thus for a rethinking of his philosophy in terms of a unified system of thought. Therefore, by aiming to demonstrate the ways in which Empedocles’ physics integrates, on a textual and contextual basis, the details of his doctrine of rebirth, sometimes even giving the impression of being premised on it, it is argued that this study is also relevant to a reassessment of the nature and intent of ancient Greek philosophy in general.