I think books are like people, in the sense that they'll turn up in your life when you most need them. I firmly believe there are books whose greatness actually enables you to live, to do something. And sometimes, human beings need story and narrative more than they need nourishment and food.
It is indeed impossible to describe reality 'in itself', but that does not mean that our lives are answerable to nothing but our own conventions and commitments. They are answerable to a way of things that transcends the reach of our conceptual schemes.