|Lindsay -- this whole series of yours is fascinating.|
My own view is that Heraclitus and Parmenides were mostly good guys who advanced philosophy. They were generally rational intellectuals who continued the fine Milesian tradition, and made human thought more profound and more subtle than ever before.
I view Xenophanes amd Pythagoras very differently. These are the bad guys -- the irrationalists who first gave philosophy a bad name. Altho' their advent was likely ineluctable and even healthy, these are the ones that made it a source of mockery and contempt to the hoi polloi. Just as today, the common-sense, non-ivory tower, man-in-the-street rightly condemned and feared the easy, frequent tendency of the over-brainy, over-educated, sneaky, tricky philosophes slipping into empty double-talk and false, insidious mumbo-jumbo.
I think Pythagoras gave birth to the Sophists and early skeptics, who gave birth to Plato, who gave birth to the Platonists and full skeptics, and who eventually gave birth to Berkeley, Hume, Kant, etc. These early guys also de facto invented "god," and established just about all the metaphysical and epistemological disasters which are still with us.
One point about Dionysus: In my reading of the history of philosophy it was the irrationality and early skepticism of Pythagoras which created the updated/adapted mythology and Eleusinian versions of Dionysus, Orpheus, Demeter/Persephone, etc. It didn't happen the other way around or simultaneously. These Eleusis-based mystery cults eventually became full religion, monotheism, and today's omniscent, omnipotent god.
Pythagoras created the first cult -- not unlike the ARIan group today. He combined real truth with intimidating, meretricious gibberish. And this slick, perverse, intellectual rot was backed with a cult-of-personality, intellectually-seductive, charismatic leader.
...Or at least that's how I see it...