Heraclitus (; ; ) was an ancient Greek pre-Socratic philosopher from the city of Ephesus, which was then part of the Persian Empire. He exerts a wide influence on Western philosophy, both ancient and modern, through the works of such authors as Plato, Aristotle, the Stoics, Georg Wilhelm Friedrich Hegel, Friedrich Nietzsche, and Martin Heidegger.
Little is known of Heraclitus's life. He wrote a single work, of which only fragments survive. Even in ancient times, his paradoxical philosophy, appreciation for wordplay, and cryptic, oracular epigrams earned him the epithets "the dark" and "the obscure". He was considered arrogant and depressed, a misanthrope who was subject to melancholia. Consequently, he became known as "the weeping philosopher" in contrast to the ancient atomist philosopher Democritus, who was known as "the laughing philosopher".
The central ideas of Heraclitus's philosophy are the unity of opposites and the concept of change. Heraclitus saw harmony and justice in strife. He viewed the world as constantly in flux, always "becoming" but never "being". He expressed this in sayings like "Everything flows" (, panta rhei) and "No man ever steps in the same river twice". This insistence upon change contrasts with that of the ancient philosopher Parmenides, who believed in a reality of static "being".
Heraclitus believed fire was the arche, the fundamental element of the world. In choosing an arche Heraclitus followed the Milesians before him — Thales of Miletus with water, Anaximander with apeiron ("boundless" or "infinite"), and Anaximenes of Miletus with air. Heraclitus also thought the logos (<small>lit. </small>word, discourse, or reason) gave structure to the world or existed as a kind of divine law.
Life
thumb|Theater in [[Ephesus on the coast of Asia Minor, birthplace of Heraclitus]]
Heraclitus, the son of Blyson, was from the Ionian city of Ephesus, a port on the Cayster River, on the western coast of Asia Minor (modern-day Turkey). In the 6th century BC, Ephesus, like other cities in Ionia, lived under the effects of both the rise of Lydia under Croesus and his overthrow by Cyrus the Great c. 547 BC. Ephesus appears to have subsequently cultivated a close relationship with the Persian Empire; during the suppression of the Ionian revolt by Darius the Great in 494 BC, Ephesus was spared and emerged as the dominant Greek city in Ionia. Miletus, the home of the previous philosophers, was captured and sacked.
The main source for the life of Heraclitus is the doxographer Diogenes Laërtius. Although most of the information provided by Laertius is unreliable, and the ancient stories about Heraclitus are thought to be later fabrications based on interpretations of the preserved fragments; the anecdote that Heraclitus relinquished the hereditary title of "king" to his younger brother may at least imply that Heraclitus was from an aristocratic family in Ephesus. Heraclitus appears to have had little sympathy for democracy or the masses. However, it is unclear whether he was "an unconditional partisan of the rich", or if, like the sage Solon, he was "withdrawn from competing factions".
Since antiquity, Heraclitus has been labeled a solitary figure and an arrogant misanthrope. The skeptic Timon of Phlius called Heraclitus a "mob-abuser" (ochloloidoros). Heraclitus considered himself self-taught. He criticized fools for being "put in a flutter by every word". He did not consider others incapable, but unwilling: "And though reason is common, most people live as though they had an understanding peculiar to themselves." Heraclitus did not seem to like the prevailing religion of the time, criticizing the popular mystery cults, blood sacrifice, and prayer to statues.
Classical philologist Jakob Bernays also wrote a work on Heraclitus. Hermann Diels wrote "Bywater's book has come to be accounted ... as the only reliable collection of the remains of that philosopher."
Continental
thumb|165px|Heidegger believed that the thinking of Heraclitus and Parmenides was the origin of philosophy.
The continental existentialist and philologist Friedrich Nietzsche preferred Heraclitus above all the other pre-Socratics. Nietzsche saw the philosophers before Plato as "pure types" and Heraclitus as the proud, lonely truth-finder. The nationalist philosopher of history Oswald Spengler wrote his (failed) dissertation on Heraclitus.
Phenomenologist Edmund Husserl wrote that consciousness is "the realm of Heraclitean flux". Existentialist and phenomenologist Martin Heidegger was also influenced by Heraclitus, as seen in his Introduction to Metaphysics. Heidegger believed that the thinking of Heraclitus and Parmenides was the origin of philosophy and misunderstood by Plato and Aristotle, leading all of Western philosophy astray.
French philosophers Jacques Derrida and Gilles Deleuze's "differential ontology" is influenced by Heraclitus. According to Deleuze, Michel Foucault was a Heraclitean. The idea that war produces order through strife is similar to Foucault's notion that power is a force dispersed through social relations.
In the 1950s, a term originating with Heraclitus, "idios kosmos", meaning "private world" as distinguished from the "common world" () was adopted by phenomenological and existential psychologists, such as Ludwig Binswanger and Rollo May, to refer to the experience of people with delusions. It was an important part of novelist Philip K. Dick's views on schizophrenia. Those thinkers have relied on Heraclitus's statement that "The waking have one common world, but the sleeping turn aside each into a world of his own."
The Irish author and classicist Oscar Wilde was influenced by art critic Walter Pater, a friend of Bywater's whose "pre-Socratic hero" was Heraclitus. Harold Bloom noted that "Pater praises Plato for Classic correctness, for a conservative centripetal impulse, against his [Pater's] own Heraclitean Romanticism."
Analytic
The British analytic and process philosopher A. N. Whitehead has been identified as a representative of the tradition of Heraclitus. In Bertrand Russell's essay Mysticism and Logic, he contends Heraclitus proves himself a metaphysician by his blending of mystical and scientific impulses. Scholar Edward Hussey sees parallels between Heraclitus, the logos, and the early Ludwig Wittgenstein's linguistic philosophy in the Tractatus (1922).
Aristotle's arguments for the law of non-contradiction, which he saw as refuting the position started by Heraclitus, used to be considered authoritative, but have been in doubt ever since their criticism by Polish logician Jan Łukasiewicz, and the invention of many-valued and paraconsistent logics.
Some philosophers such as Graham Priest and Jc Beall follow Heraclitus in advocating true contradictions or dialetheism, seeing it as the most natural response to the liar paradox.