(περὶ φύσεως)

The philosophical system of Heracleitus was contained in a work which received various titles from the ancients, of which the most common is (περὶ φύσεως).

From the obscurity of his style, Heracleitus gained the title of σκοτεινός, and, with his predilection for this method of writing, was probably connected his aristocratical pride and hauteur (whence he was called ὀχλολοίδορος), his tenacious adherence to his own views, which, according to Aristotle, had as much weight with him as science itself (Eth. Nic. 7.5), his contempt for the opinions of previous writers, and the well-known melancholy of his disposition, from which lie is represented in various old traditions as the contrast to Democritus, weeping over the follies and frailties at which the other laughed. (See Juv. 10.34.) With regard, however, to his obscurity, we must also take into account the cause assigned for it by Ritter, that the oldest philosophical prose must have been rude and loose in its structure; and, since it had grown out of a poetical style, would naturally have recourse to figurative language. He starts from the point of view common to all the Ionian philosophers, that there must be some physical principle, which is not only the ground of all phenomena, but is also a living unity, actually pervading and inherent in them all, and that it is the object of philosophy to discover this principle. He declared it to be fire, but by this expression he meant only to describe a clear light fluid, " self-kindled and self-extinguished," and therefore not differing materially from the air of Anaximenes. Thus then the world is formed, " not made by God or man," but simply evolved by a natural operation from fire, which also is the human life and soul, and therefore a rational intelligence, guiding the whole universe. While, however, the other Ionian philosophers assumed the real existence of individual things, and from their properties attempted to discover the original from which they sprang, whether it were water or air, or any other such principle, Heracleitus paid no regard to these separate individuals, but fixed his attention solely on the one living force and substance, which alone he held to be true and permanent, revealing itself indeed in various phenomena, and yet not permitting them to have any permanence, but keeping them in a state of continual flux, so that all things are incessantly moving and changing. In the primary fire, according to Heracleitus, there is inherent a certain longing to manifest itself in different forms, to gratify which it constantly changes itself into a new phenomenon, though it feels no desire to maintain itself in that for any period, but is ever passing into a new one, so that "the Creator amuses himself by making worlds " is an expression attributed to Heracleitus. (Procl. ad Tim. p. 101.) With this theory was connected one of space and motion. The living and rational fire in its perfectly pure state is in heaven (the highest conceivable region), whence, in pursuance of its wish to be manifested, it descends, losing as it goes the rapidity of its motion, and finally settling in the earth, which is the furthest possible limit of descent. The earth, however, is not to be considered immovable, but only the slowest of motions. Previous, however, to assuming the form of earth, fire passes through the shape of water; and the soul of man, though dwelling in the lower earthly region, must be considered a migrated portion of fire in its pure state, and therefore an exception to the general rule; according to which, fire by descending loses its etherial purity. And this, as Ritter remarks, appears an almost solitary instance of Heracleitus condescending to mould his theory in any respect according to the dictates of sense and experience. The only possible repose which Heracleitus allowed the universe was the harmony occasionally resulting from the fact, that the downward motion of some part of fire will sometimes encounter the upward motion of another part (for the living fire, after manifesting itself in the lower earthly phenomena, begins to return to the heaven from which it descended), and so must produce for some time a kind of rest. Only we must remember that this encounter is not accidental, but the result of law and order. Ultimately, all things will return into the fire from which they proceeded and received their life. The view that all things are arranged by law and order is also the foundation of his moral theory, for he considered the summum bonum to be contentment (εν̓αρέστησις), i.e. acquiescence in the decrees of the supreme law. The close connection of his physical and moral theories is farther shown by the fact that he accounted for a drunkard's incapacity by supposing him to have a wet soul (Stob. Serm. 5.120), and he even pushed this so far as to maintain that the soul is wisest where the land and climate is driest, which would account for the mental greatness of the Greeks. (Euseb. Praep. Evang. 8.14.) There is not to be found in Heracleitus any dialectical exposition of the sources of our knowledge. He held man's soul to be a portion of the divine fire, though degraded by its migration to earth. Hence he seems to have argued that we must follow that which is commonly maintained by the general reason of mankind, since the ignorant opinions of individuals are the origin of error, and lead men to act as if they had an intelligence of their own, instead of a portion of the Divine intelligence. " Vain man," he said, "learns from God as the boy from the man " (Orig. c. Cels. 6.283), and therefore we must trust this source of, knowledge rather than our own senses, which are generally (though not invariably) deceitful. He considered the eyes more trustworthy than the ears, probably as revealing to us the knowledge of fire. The connection of pantheism and atheism is well illustrated by the system of Heracleitus; nor is it difficult to see how the doctrine of an all-pervading essence, revealing itself in various phenomena, might serve possibly for the origin, and certainly for an attempt at a philosophical explanation of a polytheistic religion.

Letters attributed to Heracleitus

The Greek letters bearing the name of Heracleitus are the invention of some later writer.