Reading books is somehow inherently comforting. They take us to far away places and let us forget about our troubles. But is it really only that? Actually, the most satisfying books may be the ones that in some way tie in with our own lives.
Novels often* present the idea of an universal truth. The questions a character asks are answered at the end of a book, confusing events start to make sense or the book itself sends out a clear message. Even if that message is that life is a mess, inherently unpredictable or absolutely horrible, the message itself remains solid and true in the universe of the narrative. Granted, it may take the protagonist and/or the reader a while to decipher it, but the truth is always out there.
Moreover, books imply that reality can be captured, presented and ordered in the form of a coherent narrative. Even the most complicated books are in some way “simple”: they guide you through a story, focussing on the scenes that are relevant, only letting you meet people who are in some way part of the story.
Books also encourage us to think of life as something with aesthetic value. Life does not only form a narrative, this narrative is also worth looking at.
Similarly, most novels provide a kind of religious experience – no matter how tough the main character’s struggles become, there is always someone bearing witness to their hard work: the reader. This being is not omniscient, cannot directly influence the narrative universe and may not even be benevolent, but it is there and it cares: if it didn’t it would not be reading the novel. This makes us feel like maybe some nice reader could be following our story too. (I hope I’m not the only one who lives in a novel in their heads sometimes.) Isn’t it the same kind of comforting feeling that something out there cares for you that people find in religion? (Disclaimer: certain kinds of religion)
In short, we read books because they help us to make sense of the world, be it through discovering its potential wonders, exploring its limitations or deepening our understanding of relationships between people. Each book contains a unique outlook on the world in a manageable, even bite-sized form. The more we read the further our perspectives expand. Through this process, we come to assume not necessarily that the world makes sense, but that it is worthwhile to seek to make sense of (elements of) it. Books invite us to try.
*You can count on metafiction, stream of consciousness writing and other experimental works to smash these kind of generalizations.