It was, for all I know, the first deductive theory of the world, the first deductive cosmology: One further step led to theoretical physics, and to the atomic theory.

Parmenides made it clear for the first time that the Immortal Principle, the One, Truth, God, is separate from appearance and from opinion, and the importance of this separation and its effect upon subsequent history cannot be overstated. It's here that the classic mind, for the first time, took leave of its romantic origins and said, "The Good and the True are not necessarily the same," and goes its separate way. Anaxagoras and Parmenides had a listener named Socrates who carried their ideas into full fruition.

As Parmenides categorically threw out all observation with the senses, so this student of philosophy is inclined to throw out Parmenides as a complete waste of time! His static theories denying motion and change were in direct antithesis to the Kinetic metaphysics of Heracleitus, and his depressing monism was later refuted by the atomists Democritus and Leucippus. In a nutshell; in a word; Parmenides is Pah! — and definitely not a philosopher to take to bed with you on a long winter evening! … Personally speaking the whole thing makes me shudder — although I do acknowledge that paradoxes and riddles are very popular with the average thirteen-year-old school boy. Zeno however, impressed his dialectical ability on Socrates, who then began turning it loose on the average citizen in the Agora (market-place) and in consequence made himself most unpopular. I only think that it is a pity that when they asked Socrates to drink the hemlock in 399 B.C., they didn' t include Zeno and Parmenides in the invitation.

What-is was not generated from what-is-not, because what-is-not cannot give rise to anything in addition to itself. This is the first enunciation of the principle "out of nothing, nothing comes to be,"? which was implicit in earlier Greek thought even as far back as Hesiod and which afterwards, because of Parmenides, became a touchstone for subsequent Greek cosmogonies.These arguments show that coming to be from what-is-not is impossible, which is... relevant in the first stage of a cosmogony. The arguments say nothing of more familiar cases of coming to be, which can be described in terms of changes among already existing things.

I walked on to the next corner, sat on a bench at a bus stop, and read in my new book about Heraclitus. All things flow like a river, he said; nothing abides. Parmenides, on the other hand, believed that nothing ever changed, it only seemed so. Both views appealed to me.

Of the philosophers, Thales is vaguely reported to have taught that souls are immortal. But neither he nor his immediate successors... believed in the immortality of particular souls... This doctrine belongs to the Orphic tradition. In Heracleitus and Parmenides we find the two doctrines of immortality... implicit in mysticism, separated... for the first time. Heracleitus is the champion of the Dionysiac... life and death... in an unending cycle; Parmenides, under Orphic influence, teaches... Soul has fallen from... light and reality to the dark and unreal... bodily existence. This, however, is... only 'the way of opinion'... [Parmenides] feels.... that... substantiality... is not so easily got rid of. But he will not give up... eternal substance. The most interesting fragment of Parmenides... seems to enunciate, for the first time in Greek thought, the mystical doctrine of eternity as a timeless Now, as opposed to the popular... unending succession. 'There remains then only to give an account of one way—that real Being exists. Many signs... showing... it is unborn, indestructible, entire, unique, unshakable, and unending. It never was, and it never will be, since it is all together present in the Now, one and indivisible.' Empedocles... repudiates... Parmenides, probably on the ground that he reduces the world of time and change to nullity... thus leaves no pathway from appearance to reality. His doctrine of the soul’s exile and wanderings is... Orphic doctrine, which Pindar also gives... in the second Olympian Ode. The Soul sins by separating itself from God... from love and a choice of ' strife ’ in the place of harmony. The immortal Soul is... love and strife blended; the body... only an 'alien garment'... perishes at death. ...Empedocles describes the Soul as a ratio, or harmony ...the complex of...'strife'... bound... by the principle of unity...'love'...Parmenides ...may be ...rejects the Pytdhagorean doctrines ...finds truth in static materialism.

What is clear is that Parmenides is making a conscious attempt at some kind of a new start. Like Descartes, he is trying to find an unassailable starting-point on which something further can be built. This search is understandable, given the intellectual situation of the time. The principles of the Milesians had yielded no one clearly true system, but a number of rival ones — in itself a scandal. Heraclitus had made the whole of cosmology suspect by revealing deep-seated contradictions at its heart. In the background, the Pythagoreans were directly or indirectly stimulating new lines of thought and using them, perhaps, for their own mysterious purposes.

Greek philosophy returned for some time to the concept of the One in the teachings of Parmenides... His most important contribution... was, perhaps, that he introduced a purely logical argument into metaphysics. "One cannot know what is not—that is impossible—nor utter it; for it is the same thing that can be thought and that can be." Therefore, only the One is, and there is no becoming or passing away. Parmenides denied the existence of empty space for logical reasons. Since all change requires empty space... he dismissed change as an illusion.

One cannot say that the case for Parmenides is proved. If it is accepted, it is a strange freak of history that so fundamental a discovery should have been made by one for whom the whole physical world was an unreal show.

From this inheritance contemporary philosophers have continued to draw profit. Parmenides is their earliest ancestor whose work contains explicit and self-conscious argumentation. The severe conceptual difficulties posed for the first time in his verses are of perennial interest, and many of them remain in the forefront of discussion today. Recent study has thus brought his thought, in the words of another critic, "astonishingly close to some contemporary preoccupations." He should be viewed not only as "the most original and important philosopher before Socrates" but as the first extant author deserving to be called a philosopher in a present-day sense of the word.