The Phoenix Pre-Socratic series is designed for modern students of the Pre-Socratic philosophers. This volume provides the Greek text of Heraclitus with a new, facing page translation together with a commentary outlining the main problems of interpretation and the philosophical issues raised by Heraclitus' work. The volume also contains an English translation of substantial material from the ancient testimonia concerning Heraclitus' life and teaching, and offers selective bibliographic guidance.

While much of the commentary follows lines of interpretation that have won general acceptance, it differs from many in its claim that the logos of which Heraclitus speaks in fragments 1, 2 and 50 means, essentially, 'statement.' This statement, uttered in words by Heraclitus, reflects that statement everlastingly uttered by the cosmos itself, which descriptively tells of how things are and prescriptively lays don patterns of cosmic activity that serve as the basis for human laws (fragment 114).