If we take Plato’s cave to be the mind, and the projections upon the wall to be reality’s impressions upon our mind transformed into stimuli, then I don’t believe anyone could have ever left that cave anymore than anyone could have ever stepped their consciousness outside of their own brain to verify how well reality correlates to their mind’s interpretation of it.

Regardless, all this this conjecture is invariably happening within the boundaries of our minds, which seems to be composed entirely of physical phenomena.