Heraclitus' account of the cosmos is an evolution and involution out of his one eternal principle of Fire, - at once the one substance and the one force, - which he expresses in his figurative language as the upward and downward road. "The road up and down" he says "is one and the same." Out of Fire, the radiant and energetic principle, air, water and earth proceed, - that is the procession of energy on its downward road; there is equally in the very tension of this process a force of potential return which would lead things backward to their source in the reverse order. In the balance of these two upward and downward forces resides the whole cosmic action; everything is a poise of contrary energies. The movement of life is like the back-returning of the bow, to which he compares it, an energy of traction and tension restraining an energy of release, every force of action compensated by a corresponding force of reaction. By the resistance of one to the other all the harmonies of existence are created.
We have the same idea of an evolution of successive conditions of energy out of a primal substance-force in the Indian theory of Sankhya. There indeed the system proposed is more complete and satisfying. It starts with the original or root energy, mula prakriti, which as the first substance, pradhana, evolves by development and change into five successive principles. Ether, not fire, is the first principle, ignored by the Greeks, but rediscovered by modern Science [Now again rejected, though that does not seem to be indubitable or final.]; there follow air, fire, the igneous, radiant and electric energy, water, earth, the fluid and solid. The Sankhya, like Anaximenes, puts Air first of the four principles admitted by the Greeks, though it does not like him make it the original substance, and it thus differs from the order of Heraclitus. But it gives to the principle of fire the function of creating all forms, - as Agni in the Veda is the great builder of the worlds, - and here at least it meets his thought; for it is as the energetic principle behind all formation and mutation that Heraclitus must have chosen Fire as his symbol and material representative of the One. We may remember in this connection how far modern Science has gone to justify these old thinkers by the importance it gives to electricity and radio-active forces - Heraclitus' fire and thunderbolt, the Indian triple Agni - in the formation of atoms and in the transmutation of energy.
But the Greeks failed to go forward to that final discrimination which India attributed to Kapila, the supreme analytical thinker, - the discrimination between Prakriti and her cosmic principles, her twenty-four tattwas forming the subjective and objective aspects of Nature, and between Prakriti and Purusha, Conscious-Soul and Nature-Energy. Therefore while in the Sankhya ether, fire and the rest are only principles of the objective evolution of Prakriti, evolutionary aspects of the original phusis, the early Greeks could not get back beyond these aspects of Nature to the idea of a pure energy, nor could they at all account for her subjective side. The Fire of Heraclitus has to do duty at once for the original substance of all Matter and for God and Eternity. This preoccupation with Nature-Energy and the failure to fathom its relations with Soul has persisted in modern scientific thought, and we find there too the same attempt to identify some primary principle of Nature, ether or electricity, with the original Force.
However that may be, the theory of the creation of the world by some kind of evolutionary change out of the original substance or energy, by pari\,nama, is common to the early Greek and the Indian systems, however they may differ about the nature of the original phusis. The distinction of Heraclitus among the early Greek sages is his conception of the upward and downward road, one and the same in the descent and the return. It corresponds to the Indian idea of nivritti and pravritti, the double movement of the Soul and Nature, - pravritti, the moving out and forward, nivritti, the moving back and in. The Indian thinkers were preoccupied with this double principle so far as it touches the action of the individual soul entering into the procession of Nature and drawing back from it; but still they saw a similar, a periodic movement forward and back of Nature itself which leads to an ever-repeated cycle of creation and dissolution; they held the idea of a periodic pralaya. Heraclitus' theory would seem to demand a similar conclusion. Otherwise we must suppose that the downward tendency, once in action, has always the upper hand over the upward or that cosmos is eternally proceeding out of the original substance and eternally returning to it, but never actually returns. The Many are then eternal not only in power of manifestation, but in actual fact of manifestation.
It is possible that Heraclitus may so have thought, but it is not the logical conclusion of his theory; it contradicts the evident suggestion of his metaphor about the road which implies a starting-point and a point of return; and we have too the distinct statement of the Stoics that he believed in the theory of conflagration, - an assertion which they are hardly likely to have made if this were not generally accepted as his teaching. The modern arguments against enumerated by Mr. Ranade are founded upon misconceptions. Heraclitus' affirmation is not simply that the One is always Many, the Many always One, but in his own words, "out of all the One and out of One all." Plato's phrasing of the thought, "the reality is both many and one and in its division it is always being brought together," states the same idea in different language. It means a constant current and back-current of change, the upward and downward road, and we may suppose that as the One by downward change becomes completely the All in the descending process, yet remains eternally the one everliving Fire, so the All by upward change may resort completely to the One and yet essentially exist, since it can again return into various being by the repetition of the downward movement.
All difficulty disappears if we remember that what is implied is a process of evolution and involution, - so too the Indian word for creation, srishti, means a release or bringing forth of what is held in, latent, - and that the conflagration destroys existing forms, but not the principle of multiplicity. There will be then no inconsistency at all in Heraclitus' theory of a periodic conflagration; it is rather, that being the highest expression of change, the complete logic of his system.