Ubik, by Philip K. Dick, is all about the nature of reality and the soul.  If I had read Ubik before plunging half-way through his Exegesis I would have missed much of the meaning.  Even so, this is a complicated book that could be analyzed indefinitely.  It begins with a relatively simple concept of frozen bodies in “coldpacs” so that their souls continue in “half-life” before fading away towards heaven or hell.  Sort of a high tech purgatory?  When one character, Runciter, visits his half-dead wife to speak with her about how to handle problems in their joint business venture, a problem arises.  He is told, “She exists.  She just can’t contact you.”  He replies, “A metaphysical difference which means nothing to me.”  Metaphysical details dominate the rest of the story, although they are well hidden behind the bizarre plotline.  xxx