Parmenides was a Greek philosopher and poet, born of an illustrious family. He was held in high esteem by his fellow citizens for his excellent legislation, and was admired for his exemplary life.

He believed that truth lies in the perception that existence is, and that error lies in the idea that non-existence also can be. Nothing can exist if it cannot be imagined, therefore to be imagined and to be able to exist are the same thing. He goes on to consider the consequences of saying that anything exists. In the first place, it cannot have come into being. If it had, it must have arisen either from nothing or from something. It cannot have arisen from nothing, for there is no nothing. It cannot have arisen from something, for there is nothing else than what exists. Nor can anything else besides itself come into being, for there can be no empty space in which it could do so. In this way, Parmenides completely refutes all accounts of the origin of the universe.

Quotes:
(Speaking to Socrates) "...similars, for example, become similar, because they partake of similarity; and great things become great, because they partake of greatness; and just and beautiful things become just and beautiful, because they partake of justice and beauty..."

(Speaking to Socrates) "...one and the same thing will exist as a whole at the same time in many separate individuals, and will therefore be in a state of separation from itself."

Ouroboros says, "If these quotations are addressed to Socrates, they are likely the construction of Plato, a character based on the historical philosopher Parmenides, and are therefore suspect."

The first philosophers were storytellers.

Gather around the fire, and listen to some old guy tell a story about the Gods. Thunder is Zeus' wrath. Athena made the flute, but never played it because it made her look silly. It's an easy way of talking about the world when you don't have the benefits of enlightened science.

Parmenides is the harbringer of a shift in storytelling. Telling a story in which you invent the main characters is a fantasy, and fantasies aren't real. So let's tell a story that might be real.

Perhaps it started with a dream — or a nightmare. Parmenides saught the meaning of "to know", and perhaps such truths are so great that they crush the rational thought right out of the person who finds them. In his dreams he found the Goddess of Truth, who told him of three ways.

1. The Way of Truth — This path ends at finding Being, or the "That Which IS" (you can hear the capital letters in the old man's voice). There's only one thing here. No multitude of Gods and Goddesses that bicker and contradict each other can account for the unchanging, objective truth that lies at the end of the Way of Truth.
2. The Way of Nothingness — A path that never starts is not really a path at all. It is a black hole; you can only look at it indirectly by finding at That Which IS and ignoring it. There is no knowledge, no thought, nothing here to look at. Move on, nothing to see here.
3. The Way of Opinion — Where we all are doomed to wander. There are many things around you; but only one Thing That IS. Everything else is a reflection of that one, shining perfection as it muddles with the black hole. The One, stuck in a house of mirrors, is reflected into The Many. "That Which IS And IS NOT," the man says, looking straight at you, "is all we ever see or hear or touch. What is important (that being, That Which IS) is invisible."

"So, if you haven't caught the drift yet," he says, chuckling, "everything around you is full of lies. Turn away from the lies and seek the Truth."

You ask him why he's talking to you, then.

He vanishes in a puff of logic.

That bastard. His written works have all gone the way of Sappho. That we have anything is due to Aristotle's unhealthy fascination with the guy. Aristotle spent a good deal of time systematically refuting this story of Parmenides' with fancy things like logic and, eventually, metaphysics. But the holy trinity of Greek philosophy — Socrates, Plato, and Aristotle — likely only knew Parmenides from his stories.

I say likely because while the chronology doesn't exclude Socrates and Parmenides having a dialogue, like Plato wrote, keep in mind that Socrates is at least twenty years younger than Parmenides. Also, Parmenides lived in Elea (in southern Italy), whereas Socrates lived in Athens. I doubt the two ever met in person.