The intellectual ferment and cultural turmoil of the fifth and sixth centuries B.C. in Greece have hidden more than they have revealed in the inner history of humanity. The Mysteries, despite sincere devotees and widespread public piety, were in precipitous decline. Practical application of mathematical relationships – originally formulated from the spiritual ontology and ethical mathematics of the Pythagoreans – encouraged concretization in thought and materialization of science. An unhealthy scepticism mocked reticent feeling and sensitive intuition rather than raising fundamental questions. An indiscriminate grounding in the traditional poets, who were of uneven quality, without the hidden keys required to grasp their best work, was the mark of the cultivated individual. Emphasis had shifted decisively towards outward social activity and away from inward spiritual regeneration. In this climate of spiritual decay, even as Hellenic civilization was on the verge of 'the Golden Age', a few philosophers attempted to understand and articulate the ultimate nature of things, man's place in the order of the universe and the crucial imperatives of ethical conduct. Some were Initiates who knew far more than their pledges would permit them to say; others, less wise, were only too ready to succumb to the crude empiricism of the day. All sought after the simplest possible explanatory devices which would do justice to Man and Nature.

The thought of Heraclitus survives only in tantalizing fragments, pregnant, puzzling and suggestive. Even in his own time he was called 'the Dark One', 'the Obscure', one who spoke in riddles. So little was known of him that ancient writers felt compelled to fill in details where none were available; disagreement over what he meant – or even said – persists into the present. Like others who have used the mind-arousing images of the poets or the code-language of the Sages, Heraclitus was frequently quoted out of context to prove the conflicting points of others. According to Diogenes Laertius, Heraclitus was born in Ephesus, an Ionian city twenty-five miles north of Miletus, and flourished there in the sixty-ninth Olympiad (about 504-500 B.C.). The eldest son of an ancient and noble Ephesian family, it fell to him to assume the office of 'king' – a title applied to one who had particular social and religious duties in the community. These included presiding over certain religious sacrifices. Heraclitus rigorously opposed any externalization or profanation of the Mysteries, and he resigned this prestigious position in favour of his younger brother. When the Ephesians exiled his friend Hermodorus, on the ground that he excelled his peers to so great a degree that it was unpalatable to the democratic social structure of the city, Heraclitus withdrew from public life and participated only as an uncompromising critic. The Ephesians retaliated by spreading false stories about him, some of which have found their way into his biography.

Heraclitus was familiar with the philosophies of the Milesian schools, and he also knew of the Zoroastrian fire-philosophy. He was a contemporary of Darius the Persian, whose empire covered the region from Ephesus to India. Indians came to mainland Greece in the reign of his successor Xerxes, so Heraclitus may have had some contact with Indian thought. Apocryphal accounts suggest that he was undergoing a Zoroastrian cure for dropsy when he died. His thinking reveals a pithy originality which lent itself to aphoristic prose, resembling the Tao te ching in style and substance. He wrote one book, known though misunderstood in antiquity, from which quotations in and out of context alone survive. It was divided into three parts dealing with the universe, politics and ethics.

For Heraclitus, Nature is a mystery which veils its secrets even when seeming to reveal them. Clement of Alexandria said that Heraclitus "loved to conceal his metaphysics in the language of the Mysteries", and in so doing he made language conform to the subject. "The lord whose oracle is at Delphi", he wrote, "neither speaks nor conceals, but gives signs." Heraclitus refused to develop a systematic cosmogony or a schematic science. Rather, he offered suggestions and intimations about the inner order of things. "Nature loves to hide", and so "eyes and ears are bad witnesses for barbarian souls". Amassing observations will not avail understanding unless one has cultivated the potential for soul-knowledge. Not events, but their meanings count. Nevertheless, "eyes are more accurate witnesses than ears", and one should look for oneself into all matters. "Men who love wisdom should acquaint themselves with a great many particulars." If data without discrimination is empty of meaning, high-flown theories without recognizable application are useless. "Let us not make arbitrary conjectures about the greatest matters", for even "much learning does not teach understanding". If both crude empiricism and pure rationalism are to be shunned, is there a way to know?

Heraclitus held that though the external world displays a hidden harmony, its key could not be found in the mere concatenation of things and the cacophony of events. To know, one would have to turn within. "I have searched myself", and seen that "it pertains to all men to know themselves and be temperate". In inner discovery, one finds the truth; in temperate conduct, one exhibits it so that all may see it. One lives the hidden harmony. "To be temperate is the greatest virtue. Wisdom consists in speaking and acting the truth, giving heed to the nature of things." If one practised this method even a little, one would begin to sense the real nature of the cosmos – a universe of ceaseless flux suffused and governed by the Logos.

Although this Logos is eternally valid, yet men are unable to understand it, not only before hearing it, but even after they have heard it for the first time. That is, although all things come to pass in accordance with this Logos, men seem to be quite without any experience of it, at least if they are judged in the light of such words and deeds as I am here setting forth. My method is to distinguish each thing according to its nature, and to specify how it behaves; other men, on the contrary, are as forgetful and heedless in their waking moments of what is going on around them as they are during sleep.

We should let ourselves be guided by what is common to all. Yet, although the Logos is common to all, most men live as if each of them had a private intelligence of his own.

Logos can mean 'word' or 'speech', 'reason' or 'account', 'definition', 'the rational faculty' and 'proportion'. Heraclitus leaves the term suggestively vague, like the enigmatic activity of nature, since the whole range of possible meanings becomes relevant to his root-idea. Whatever the Milesians had meant, Heraclitus knew that their philosophic speculations were enlisted in reductionist explanations of the origin of the universe. Rather than see nature reduced to water or air or earth, Heraclitus rejected all genetic accounts of the cosmos and declared that it was uncreated. The universe is eternally reformed in accordance with the Logos which guides and pervades every portion and particle of it. The Logos conceived as an ontological principle has no attribute subject to anthropomorphic characterization. It is intelligent in its operations and intelligible to one who has turned within. Since it is everywhere, it is surprising that men do not witness it even when they have heard of it. Since it is within, the pulsating core of the soul is the Logos. Thus it is accessible to all who would rely on what is common to all human beings. Men do not recognize the Logos without or within because they desire to reify and quantify it. Yet in its being, it is more like fire than a tangible substance, and in its activity it is more like an intelligent formula than a visible force. It is accessible to the consciousness capable of discerning the hidden harmony in the universal flux, to intuition rather than discursive thought.

The universe is concealed Fire. When unobstructed by temporary form, it shines on its own, bright as the day sky, filling the bowls of the sun and moon, ungraspable because it is pure transformation. The Logos appears as cosmos in its aspect of archetypal matter which is Fire. Though earth is the opposite pole from Fire, seemingly solid and unmoved, it is only an aspect of Fire itself, real in its own nature, but illusory to the extent that it seems stable. Water mediates between earth and Fire, and it too is only Fire in its inner nature, for it can 'die' by becoming either earth or Fire.

There is exchange of all things for fire and of fire for all things, as there is of wares for gold and gold for wares. This universe, which is the same for all, has not been made by any god or man, but it always has been, is, and will be, an ever-living Fire, kindling itself by regular measures and going out by regular measures. It throws apart and then brings together again; it advances and retires. The transformations of Fire are: first, sea; and of sea, half becomes earth and half prester. Fire lives in the death of earth, air in the death of Fire, water in the death of air, and earth in the death of water. The thunderbolt pilots all things.

Fire is the real value of each thing, not simply its material substratum. Fire is self-sustaining and therefore prior to any form it can assume. As the profound myth of Prometheus suggests, Fire is the root of mind and therefore of all consciousness and intelligence. When Fire moves from the gaseous or aetheric to the aqueous state, then in transforming itself into the earthy, it also releases prester, a tremendous transforming force which is like both Fire and water, combining an upward and downward motion. As the thunderbolt, it guides all things. Heraclitus suggests that the real elements are states of the aetheric Fire rather than different kinds of substance. Pre-Socratic philosophers ignored Heraclitus' dynamic analysis and spoke instead of fire, air, water and earth, thus compelling Greek thinkers to postulate a fifth element, aether, which was held to exist in and beyond the other four. By holding that there is only one element in three forms, Heraclitus drew attention to the points of transition between them, those critical states where each 'dies' into the others.

In addition to its pure unmanifest being and its material appearance as Fire, the Logos exhibits activity as its third aspect. The Logos in action manifests through pairs of opposites – beginning and end, day and night, hot and cold, life and death – unified by a single principle, eris or strife. "Everything flows and nothing abides; everything gives way and nothing stays fixed." Whatever exists is changing into its opposite – what is young is becoming old, what is dead is becoming newborn, what is cold is warming up, what is moving is slowing down. Visible nature is depicted in one striking image, rhoe, a stream or flux. "You cannot step twice into the same river, for other waters are continually flowing on." The term suggests, but does not entail, becoming (genesis), change (metabole) and movement (kinesis). Eris, the ceaseless tension between the opposites, rules the manifest universe, and if it were to cease for even a moment, the universe would perish. Each pair of opposites is one, since either half of the pair can be understood only by knowing the other half. "It is by disease that health is pleasant; by evil that good is pleasant; by hunger, satiety; by weariness, rest." There is thus a harmony between all the opposites, so that universal flux is also dynamic balance. Order is not stasis, an unchanging arrangement of things, but a balance between all transformations at every changing moment. There is a balance between that which never manifests and that which ever changes, and this is the real hidden harmony. "It is in changing that things find repose."

Eris is therefore dike (justice), the harmony of all things, and strife is the essence of harmony. "Opposition brings concord. Out of discord comes the fairest harmony." There is one divine law of harmony in nature: the play of the opposites on the one hand, and the eternal motion of Fire on the other. Dike in the universe is not only justice but also compensation, since the 'one law' redresses imbalance. In a world of change, there can be no equality between things, but only a continuous reciprocity between transformations. The State, therefore, should not seek equality among individuals who vary in capacity, perception and wisdom, but should guarantee equal access to the law that justice might be done. If there is to be justice in human society, it will follow the 'one law' as it operates in the human soul.

You could not discover the limits of soul, even if you travelled every road to do so; such is the depths of its meaning. Soul is the fiery vaporization out of which everything else is derived; it is in ceaseless flux, for the moving world can only be known by what is motion.

It is death to souls to become water, and it is death to water to become earth. Conversely, water comes into existence out of earth, and souls out of water. A dry soul is wisest and best. Souls take pleasure in becoming moist. It is hard to fight against impulsive desire; whatever it wants, it will buy at the cost of soul.

The soul of the world is a rate of motion from which everything else spins off. Individual souls are one with the fiery world-soul, but they appear distinct through their separate desires. Desire is always for form, for a lower rate of motion. Dry souls maintain a rate near to that of the world-soul; moist souls slow down. If a soul slows to the rate of water, it 'dies' – it becomes incapable of any understanding or perception beyond the watery sphere – for only the faster movement can encompass the slower. Thus desire gives pleasure, but at the cost of soul, which can be slowed to insensibility. "Immortals become mortals, mortals become immortals; they live each other's death and die each other's life." Since what is generally called 'human' is this desire-infested condition of slow soul-motion, "human nature has no real understanding; only the divine nature has it". Life and understanding depend upon the acceleration of soul, a conscious attempt at balance, but "although intimately connected with the Logos, men keep setting themselves against it". Desire blinds them to their true nature and so they settle for shadows rather than reality. "What is divine escapes men's notice because of their incredulity." Thus while "the most handsome ape is ugly compared with humankind, the wisest man appears as an ape when compared with a god, in wisdom, in beauty and in all other ways". Unaware that the source of redemption lies within, "they pray to images; they as well could talk to walls". Instead of seeking the self-transforming path to the real Mysteries, "what are regarded as mysteries among men are unholy rituals". External gesture replaces inner reform. "When defiled they purify themselves with blood, as though one who had stepped into filth could wash himself clean with filth."

The human soul can be restored to its intimate relation with the world-soul and the Logos, for "the way up and the way down are one and the same".

Thinking is common to all. Men should speak with rational awareness and thereby hold on to that which is shared in common, as a city holds on to law, and even more strongly. For all human laws are nourished by the one divine law, which prevails as far as it wishes, suffices for all things, and yet is something more than they. The best of men choose one thing in preference to all else, immortal glory in preference to mortal goods; whereas the masses simply glut themselves like cattle. To extinguish hubris is more needful than to extinguish a fire. A man's character is his daimon.

Since intelligence is a capacity shared by all human beings, and in a more diffuse degree by all life, men should hold to that which is universal and relinquish all that is personal. Ethical principles and social norms are derived from the one law. Wise men become one-pointed in focussing consciousness upon that law, thereby refining their understanding and purging the soul of scattering tendencies – desires in every form – which retard the soul's speed. Hubris is inertial, resisting change in a universe that is all change. "The sun will not overstep his measures; if he were to do so, the Erinyes, handmaids of justice, would seek him out." Why then should the human being presume to do so? Hubris ends in death. Life is sought by progressively narrowing the range of impulsive desires while focussing on the universal law. This is the middle way of temperance – a moving balance in action wedded to an intuition of the hidden harmony which balance manifests. One is guided in the attempt by one's daimon which is not a semi-spiritual entity outside of oneself, but one's very character, the direction of movement and clarity of vision one has engendered within oneself.

The way up and the way down are one. Precisely because all things are one, the soul can sink to spiritual subsistence and can also be raised up again. "People do not understand how that which is at variance with itself agrees with itself. There is a harmony in the bending back, as in the case of the bow and the lyre. Listening not to be but to the Logos, it is wise to acknowledge that all things are one." The fire within can be kindled to merge into the fire above. One must not, however, become fixed in one's ideas, even of the glorious state of the dry soul. All fixity in thought or action is a resistance to the moving power of the Logos, a subtle form of hubris, a tendency toward self-destruction. Better to remain supple in mind and action, knowing the one law and adhering to it without wavering, while moving freely with external conditions as dictated by the guiding thunderbolt of intuitive consciousness. "Unless you expect the unexpected you will never find truth, for it is hard to attain." With effort one will begin to breathe the freer air of the upper atmosphere, confident that "all things come in their due seasons", wanting nothing and needing nothing which is not provided by Nature whose production is consubstantial with one's needs. In time the soul will learn to flow with the ceaseless flux of life-currents, and also soar into the perpetual motion of the empyrean, close to the highest degree of deific Fire. Then one will know with one's purified senses and not just on hearsay that "the hidden harmony is better than the obvious", that one is the Fire and the light, the fount of Wisdom found within.