I read Watership Down as a break from heavy philosophical research I’m doing for the next book in my Cluster series.  Little did I know that one of the rabbits, Fiver, had a touch of Phillip K. Dick in his blood.  In my metaphysics, the quantum strings of the physical universe are looped through similar strings in the spiritual universe.  In Perturbations Of The Reality Field my characters use the borderland “between” the two in order to travel faster than the speed of light (FTL).  Now I am about to send them deeper into that spiritual universe, a wild place and very unsafe, as Fiver says.  Forgive the long quote from Watership Down, by Robert Adams, but it contains several very interesting ideas I intend to explore.
“You’re sure we are here then?” asked Fiver. … “Well, there’s another place – another country, isn’t there? We go there when we sleep; at other times, too; and when we die.  El-ahrairah comes and goes between the two as he wants, I suppose, but I could never quite make that out, from the tales. Some rabbits will tell you it’s all easy there, compared with the waking dangers that they understand.  But I think that only shows they don’t know much about it.  It’s a wild place, and very unsafe.  And where are we really – there or here?”