books and great books.
I mean there are Jewish books that are not great. Even bad. [What happens when you read book is your stream of consciousness is focused into what the book is saying. And if it is bad it can affect you badly. And some of it might even seep into your sub level subconscious]
My orientation is as a Rationalist. But that does not cancel out the fact that I believe knowledge is available by non rational non perceptive means.
I have great respect for the Ari (Isaac Luria)and Rambam
The general rule of thumb I would like to suggest is that people learn the great books of Torah that are original, fresh, powerful, i.e. The Torah, Talmud (Gemara, Rashi, Tosphot).