Some ideas are not easy to grasp when you have no practical experience and you are not sensitive, sometimes you read the same Book but you get a different meaning depending on your state of mind , sometimes you can only get a literal superficial meaning sometimes you they can sea things deeper.
But the best book it’s everyone’s own day to day experience when interaction with the other, what we you feel, what you think, listening and watching the nature see, hear,feel everything as it is not according to someone else’s ideas
If you are not aware that your mind is conditioned, a book is useful that help you to see that your mind is conditioned, once you see it book is no longer need it, the purpose of that book is over and now you are free to be your own teacher and your own pupil