Franz Kafka says

If the book we are reading does not wake us, as with a fist hammering on our skulls, then why do we read it? Good God, we also would be happy if we had no books and such books that make us happy we could, if need be, write ourselves. What we must have are those books that come on us like ill fortune, like the death of one we love better than ourselves, like suicide. A book must be an ice axe to break the sea frozen inside us.