Heraclitus was a Presocratic Greek philosopher of Ephesus, who lived about BCE. 535-475. The date of Heraclitus is roughly fixed by his reference in the past tense to Hekataios, Pythagoras, and Xenophanes (fr. 16), and by the fact that Parmenides appears to allude to him in turn (fr. 6). This means that he wrote early in the fifth century BCE. He was an Ephesian noble, and had a sovereign contempt for the mass of mankind. He lived during the time of the first Persian domination over his native city. As one of the last of the family of Androclus, the descendant of Codrus, who had founded the colony of Ephesus, Heraclitus had certain honorary regal privileges, which he renounced in favor of his brother. He likewise declined an invitation of King Darius to visit his court. He was an adherent of the aristocracy, and when, after the defeat of the Persians, the democratic party came into power, he withdrew in ill-humor to a secluded estate in the country, and gave himself up entirely to his studies. In his later years he wrote a philosophical treatise, which he deposited in the temple of Artemis, making it a condition that it should not be published till after his death. He was buried in the marketplace of Ephesus, and for several centuries later the Ephesians continued to engrave his image on their coins.

His great work "On Nature" (peri phuseos), in three books, was written in the Ionian dialect, and is the oldest monument of Greek prose. Considerable fragments of it have come down to us. The language is bold, harsh, and figurative; the style is so careless that the syntactical relations of the words are often hard to perceive; and the thoughts are profound. All this made Heraclitus so difficult a writer that he went in antiquity by the name "the Obscure" (skoteinos), and Lucretius attacks him on the ground (i. 638-644). From his gloomy view of life he is often called "the Weeping Philosopher," as Democritus is known as "the Laughing Philosopher." It is above all in dealing with Heraclitus that we are made to feel the importance of personality in shaping systems of philosophy. But it was not only the common run of men that Heraclitus despised; he had not even a good word for any of his predecessors. He agrees, of course, with Xenophanes in criticizing Homer, but Xenophanes himself falls under an equal condemnation. In a remarkable fragment (fr. 16) he mentions him along with Hesiod, Pythagoras, and Hekataois as an instance of the truth that much learning does not teach men to think. The researches of Pythagoras, by which we are to understand his harmonic and arithmetical discoveries, are rejected with special emphasis (fr. 17). Wisdom is not a knowledge of many things; it is the clear knowledge of one thing only, and this Heraclitus describes, in true prophetic style, as his Logos (word/fire), which is 'true evermore', though men cannot understand it even when it is told to them (fr. 2). Perfect knowledge is only given to the gods, but a progress in knowledge is possible to men. We must try, then, to discover, what Heraclitus meant by his Logos, the thing he felt he had been born to say, whether anyone would listen to him or not.

As fire is the primary form of reality, the process of combustion is the key both to human life and to that of the world. It is a process that never rests; for a flame must always be fed by fresh exhalations as fuel, and it is always turning into vapor or smoke. The steadiness of the flame depends on the 'measures' of fuel kindled and the 'measures' of fire extinguished in smoke remaining constant. Now the world is 'an everliving fire' (fr. 20), and therefore there will be an unceasing process of eternal flux (panta pei). For Hereclitus, everything is in this process of flux, and nothing therefore, not even the world in its momentary form, nor the gods themselves, can escape final destruction. That will apply to the world at large (macrocosm) and also to the soul of humans (microcosm). Concerning the larger world, 'You cannot step twice into the same river' (fr. 41); concerning the human soul, it is just as true that 'we are and are not' at any given moment. As fire changes continually into water and then into earth, so earth changes back to water and water again to fire. The world, therefore, arose from fire, and in alternating periods is resolved again into fire, to form itself anew out of this element. The division of unified things into a multiplicity of opposing phenomena is "the way downwards," and is the consequence of a war and a strife. Harmony and peace lead back to unity by "the way upwards." Nature is constantly dividing and uniting herself, so that the multiplicity of opposites does not destroy the unity of the whole.

A glance at the fragments will show that the thought of Heraclitus was dominated by the opposition of sleeping and waking, life and death, and that this seemed to him the key to the traditional Milesian problem of the opposites, hot and cold, wet and dry. He finds these opposites both at the level of the human soul and the larger cosmos. At the human level, the soul is only fully alive when it is awake, and that sleep is really a stage between life and death. If we look next at the macrocosm, we shall see the explanation is the same. Night and day, summer and winter, alternate in the same way as sleep and waking, life and death, and here too it is clear that the explanation is to be found in the successive advance of the wet and the dry, the cold and the hot. The existence of these opposites depends only on the difference of the motion on "the way upwards" from that on "the way downwards"; all things, therefore, are at once identical and not identical. The principle of the universe is "becoming," which implies that everything is and, at the same time, is not, so far as the same relation is concerned. 'The way up and the way down', which are 'one and the same' (fr. 69) are also the same for the microcosm and the macrocosm. Fire, water, earth is the way down, and earth, water, fire is the way up. And these two ways are forever being traversed in opposite directions at once, so that everything really consists of two parts, one part traveling up and the other traveling down.

Paradoxically the everlasting fire of the world which creates its flux, also secures its stability. For the same 'measures' of fire are always being kindled and going out (fr. 20). It is impossible for fire to consume its nourishment without at the same time giving back what it has consumed already. It is a process of eternal 'exchange' like that of gold for wares and wares for gold (fr. 22); and 'the sun will not exceed his measures; if he does, the Erinyes, the auxiliaries of Justice, will find him out' (fr. 29). For all this strife is really justice (fr. 22), not injustice, as Anaximander had supposed, and 'War is the father of all things' (fr. 44). It is just this opposite tension that keeps things together, like that of the string in the bow and the lyre (fr. 45), and though it is a hidden attunement, it is better than any open one (fr. 47). For all his condemnations of Pythagoras, Heraclitus cannot get away from the tuned string.

With all his originality, Heraclitus remains an Ionian. In a sense, Heraclitus substituted fire for the 'air' of Anaximenes, who in turn had substituted 'air' for the water of Thales. Also, Hereclitus' notion of flux is a development of that Anaximenes' notion of rarefaction and condensation. Although Hereclitus has a doctrine of the soul, his fire-soul is as little personal as the breath-soul of Anaximenes. Some fragments superficially appear to assert the immortality of the individual soul. But, when we examine them, we see they cannot bear this interpretation. Soul is only immortal in so far as it is part of the everliving fire which is the life of the world. Seeing that the soul of every man is in constant flux like his body, what meaning can immortality have? It is not only true that we cannot step twice into the same river, but also that we are not the same for two successive instants. That is just the side of his doctrine that struck contemporaries most forcibly, and Epicharmos already made fun of it by putting it as an argument into the mouth of a debtor who did not wish to pay. How could he be liable, seeing he is not the same man that contracted the debt?

Excerpt from the Encyclopedia Britannica without permission.