I dispute the very concept of "human nature", it implies a platonic "human", a base which we can only uncover the details of. While in reality there doesn't appear to be such a thing.
> I mentioned the authors as evidence that the stuff they taught about human nature still applies.
It kind of does, changes in the "public consciousness" are more often subversive than radical, a lot of concepts Shakespeare popularised or came up with are still in common use, however it's not because he's unlayering the onion of "the human" concept, but because these concepts are useful and haven't been subverted or forgotten.
> When you said when we only understand them in a limited way I took that to mean you disagreed with me that the books have practical value still, and thus were not a good marker of an unchanging human nature. But that's mere contradiction of a claim, you didn’t argue anything directly to show that old authors are in fact hard to understand etc.
They of course still have practical value, when I say "in a limited capacity" I mean it in a more "glass-half full" way, a lot of context for these works has been lost forever and how a person reading a text understands a word relies more on his entire lifetime of experience than it does on the authors intent, good authors can generally bridge the gap easily, dead authors can't. So information is lost.
> We can likewise read Sun Tzu and recognize ourselves and our psyches in his stories. There is no cultural continuity with European authors there.
Unless you've brushed up on your ancient Chinese that's not really true, the cultural continuity here is the translator.