The impulse to pick up a book implies humility, defined in this paraphrase from Webster’s as “Knowledge of one’s shortcomings; lack of pretension, modesty.” When you make a serious effort to read, you are tacitly admitting that you do not know everything. You don’t have to state it; you don’t have to consciously think about it. Merely having books on display is very different, maybe the opposite, if you have no intention of reading them, but there is an honest, courageous, healthy humility in giving sustained attention to another person’s words.
I pick up a book on philosophy or religion, because I sense my own limitations. I read about science or another culture, because I am aware of my relative ignorance on a given subject. I read a biography or maybe even something on business, because I believe I can benefit from someone else’s experiences.
This goes for fiction as much as for non-fiction. I can’t read a story without submitting to the author’s world-building, saying, “Ok, you’re in charge for a while.” (Maybe this is why some folks “can’t” read scifi/fantasy; they are not willing to journey that far outside themselves.) The curiosity and patience required to follow fictional characters around and experience the unfolding of their stories is a humble act, as it is the opposite of “I can learn nothing from this” or “This is not worth my time”. It is said God will not deal with the proud – well, neither will Frodo Baggins.
This is doubly true (and more difficult) if the book, whether fiction or nonfiction, has a perspective very different from your own. Perhaps when we read, we hope to have our assumptions and beliefs confirmed. That is definitely not ideal, but even looking for assurances is a step up from “I am the smartest person, and I already know all the things.” That is the way of the non-reader. The knowledge, wisdom, experiences and stories which can be found in books are of no interest to the blusterer who is oblivious to his own limitations. It’s not confidence; it is fear. It takes courage to challenge your internal paradigms.
If you are a reader, you have that courage. Your honesty and humility give you a long-term growth advantage over the fool who will not learn, will not listen, will not accept the challenge of being shaken. Sure, not all books are created equal, but every time you pick up a new one, some deep part of you is saying “I could be better”. In that moment, you are.