I am a teacher, and a bookworm, and a nerd (possibly in that order) and so when I want someone to understand something, I will usually hand them a book. You want to understand the Crusades? Book. You can't figure out how to reconcile the one and the many? Book. How should you raise kids? Here's a book. The Bible is one of them, of course, but God has been kind enough to let us copy his method of communication about innumerable things.
But this leads to a problem: how do you decide which books to read? There are probably now more books about, say, WWII than any one person could, quite literally, read in a lifetime! With all this information wandering about, how do you select and shape your reading?