Wait, wait, wait, wait. So they're written in a language that Rey can't read? This might be because she's uneducated, but then she's also surprised that threepio can read them. And he says they're written strangely. So...did Luke ever try to read them? Could he? Could anyone? Yoda seems to know what was in them, but how many jedi knew about it?
And you know, originally, I'd just thought, cause of Yoda's comments, that those books were basic knowledge, since, you know, knowledge tends ot grow over time. But now that you've mentioned it, they were in the unknown regions, and they were ancient, like the knowledge Palpatine was after, Luke studied when shifting away from the jedi order, and Snoke knew of. And the "prime jedi" was also on Ahch-To, in the unknown regions, which we're told is the origin of the force. I'm interested now. Can't wait to see where this goes.