That's a great way to describe books, "new lenses to see your world through". It's basically that, we can explore subjects through other people's eyes who care deeply enough to write a book about it.
Me too. I always borrow my books, but I don't want to sell them. I will try to keep them. I'm always returning to books I've read when I need some advice.
I forgot to mention that most of the books I bought are used. They are a lot cheaper sometimes and are in perfect conditions. The last one I've bought, "It's Not How Good You Are, It's How Good You Want to Be" by Paul Arden cost me only 0.01 pounds(without shipping). It is used but like new. Awesome purchase