Books are said to be a wonderful thing. With all the thoughts of mankind contained on hundreds of pages, neatly put between protecting covers. Which appear like walls, protecting the precious content, or eventually protecting the world from the dangerous content, written on those pages.
Limit #20 Thinking Between Covers
And there's another, yet invisible wall, arising by books, separating those who can read from those who can't. Those who agree with the content, and those who don't. Even worse, our brain is filtering pretty much everything to its liking, no matter what the input is. Words are a strong weapon, but thinking is even stronger.