It’s a slippery slope. There’s no sense or consistency to allowing books of religion but not books of philosophy, which are also often not credible. Some new age manosphere grifter would love to get their trash into jail. Or whatever’s going as the celestine prophecy or the secret these days.

Since they’re westerners there at the jail in Kentucky, I’d like some David Hume or John Locke. Kant is good, requires a lot of focus, might get you twisted up with anxiety, Marx or Hegel if you’re even more masochistic. it would be amazing to sneak in some 20th century Spanish antifascist text, but that might turn out to be anachronistic. I’d say you need a dictionary for much of this, but same with the bible.