Heraclitus c. 540 B.C.–c. 480 B.C.
One of the most powerful Greek thinkers and prose artists of the archaic age, Heraclitus has been described by Charles H. Kahn as "perhaps the only pre-Socratic philosopher whose thought is of more than historical interest today." A lover of metaphor and paradox, he embodied his theories concerning man's role within the universe, and the nature of knowledge and meaning in a collection of aphoristic passages, approximately 125 of which have been culled from the writings of subsequent authors who quote Heraclitus's lost work. He is best known for developing the concept of logos (often translated as "reason" or "proportion") as the governing principle of the cosmos and for the view that the natural world is in a state of constant flux. As a result of his deliberately obscure and oracular literary style, Heraclitus continues to engender a great deal of commentary among contemporary scholars and philosophers.
Virtually nothing is known with certainty about the facts of Heraclitus's life. From the meager evidence contained in his philosophical fragments, scholars believe that he belonged to an aristocratic family in Ephesus and that he resigned in his brother's favor the hereditary office of king, which is believed to have been an honorary title. There is no evidence that he ever traveled beyond Ephesus, although he clearly was conversant with the flowering of natural philosophy in the Ionian region and with the thought of such philosophers as Thales of Miletus, Xenophanes, and Pythagoras. Most scholars believe that Heraclitus responded to the questions posed by his philosophical contemporaries in a single short work which according to Aristotle, he deposited in the temple of Artemis in Ephesus. This book has not survived, and all that we know of Heraclitus's theories derives from quotations and paraphrases preserved in later writers from Plato through the early centuries of Christianity.
Scholars maintain that the unique achievement of Heraclitus was to articulate a philosophy that presented seeming opposites and contradictions as reflections of the fundamental unity of the universe. Kahn has stated that the central insight of Heraclitus was the "identity of structure between the inner, personal world of the psyche and the larger natural order of the universe." From what survives of his thought, scholars believe that Heraclitus was essentially concerned with elucidating the nature of the human condition in such a manner that life and death, youth and old age, sleeping and waking could be reconciled by a single principle. At times Heraclitus calls this unifying principle both fire and logos, a virtually untranslatable term that encompasses such meanings as speech, reason, thought, and proportion. Among the most commented upon of Heraclitus's statements are the fragments "The way up and down is one and the same" and "The sea is the purest and foulest water: for fish drinkable and life-sustaining; for men undrinkable and deadly." While he believed that there was unity in the cosmos, Heraclitus also stressed the fluid, ever-changing nature of reality. He is perhaps best known for the statements "All things flow" and "It is not possible to step into the same river twice"—statements which some scholars do not believe Heraclitus actually wrote.
The obscurity of Heraclitus's literary style has made him the source of heated inquiry for centuries. Scholars believe that Heraclitus was viewed as a seminal thinker by the time of his death. The fact that crucial Heraclitean fragments are contained in the works of Plato and Aristotle has been considered as evidence that the philosopher had acquired authoritative status early on. The Stoic philosophers particularly claimed allegiance with his philosophy and believed that his conception of the place of logos in the universe prefigured their own cosmology. Heraclitus's writings were often quoted by early Christian writers; Clement of Alexandria considered the philosopher to have been a pagan prophet of the Last Judgment, and Hippolytus of Rome saw him as a source of heresy. In the nineteenth century, Heraclitus became a serious topic of study for such philosophers as Hegel and Nietzsche. After reading the surviving fragments, Hegel exclaimed, "Here we see land! There is no proposition of Heraclitus which I have not adopted in my logic." The twentieth-century German philosopher Martin Heidegger was particularly influenced by Heraclitus and wrote extensively on him and other Presocratic thinkers. Throughout the twentieth century there has been an increasing amount of scholarly activity devoted to Heraclitus by Anglo-American classical scholars and philosophers. Much of this scholarship has been concerned with placing his work in historical context as well as with understanding him on his own terms. Consequently, the primary thrust of recent critical activity has been devoted to elucidating precise meanings for such key Heraclitean concepts as fire, change, the soul, and logos.