The information about what Pythagoras said is missing.

big flaws, like hubris (arrogance) - you don't need the parenthetical reference to arrogance.

no explanation for any basic (and advanced) science - it can be assumed that if they don't have the basic, they won't have the advanced either.

They saw the sun, they saw a ball - I believe you need a "When", and there is technically nothing wrong with a ball of fire :)

Very interesting topic, but I think your essay would be better served if you limited the # of things to talk about (literature, society, geography, studying, and mythology) and add how other pre-socratics were influenced by those subjects. In each paragraph you seemed to only mention one philosopher for each category, but you're making the argument that these topics influenced all of the pre-socratics more broadly, so find a few more who were influenced by that same topic.

Your argument about mythology influencing them is a little weak, perhaps that should be the first to go?

I'm not an English teacher, so I can't say much else to how well the essay is written, but I enjoyed it :)