For those interested in Kierkegaard's realms, Walker Percy's The Last Gentleman is absolutely worth a read (no pun intended). Percy, a Christian and a big fan of Kierkegaard's, plants a main character squarely inside each realm, and leaves the protagonist to agonize over which to ground himself in. There's an interesting struggle with how passive the leap to the religious realm is, with one character insisting he must be acted upon by the absolute (and ending up in pretty sad shape).
Also, to get us ready:
(From Maira Kalman's The Principles of Uncertainty)