Peter Thonemann at the Times Literary Supplement:
Thucydides goes on to give a sombre and terrifying account of the “violent teachings” of civil war: moral chaos, the abuse of political language, the collapse of due legal process. Corcyra, insignificant though it was in the grand scheme of things, turns out to reveal certain dark and permanent truths about human nature.
But what exactly are these truths? Thucydides does not say. Indeed, his analysis of the “meaning” of the Corcyrean civil war is so complex and allusive that one puzzled ancient reader felt compelled to draft his own summary of what he understood Thucydides’ argument about human nature to be. His – certainly wrong-headed – analysis is preserved in all our medieval manuscripts of Thucydides:
“And with civic life at that time so cast into commotion, human nature, naturally prone as it is to injustice and law-breaking, cheerfully revealed itself to be powerless over its passions, too strong for justice, and hostile to all superiority.”
Whatever Thucydides meant to say about human nature, it was certainly not that: he did not believe in the innate viciousness of the human soul. But one can sympathize with this anonymous reader.
more here.