I can’t remember where I heard this, but recently, I heard something that may seem obvious to most, but had totally escaped me. The reason we’re afraid of ghosts is that they’re lost souls, they’re all crazy because they’re trapped here - someplace they shouldn’t be. And we instinctively know that - that since they are trapped, caught and bound to a place that is in opposition of what they have become, they are driven insane.
What a disturbing thought. When I die, if things go wrong, I may spend the rest of eternity being crazy. My existence could become the embodiment of a paradox, driving sanity from my mind and soul (body is gone at that point).
The story I’m working on right now plays on this idea, that ghosts are crazy. The most dangerous of these, to me, would be the ones who don’t even know they are dead.