I've been trying to find some more information on out of body experiences (OBEs). Certainly I'm not the first person to try and document their experiences.

In the past, I've read through Robert Monroe's books, Robert Peterson, and Robert Bruce (lots of Roberts?). The material is all great, but it still left me with more questions.

The Wikipedia page on Out-of-body Experiences lists a bunch of theories. Here's one that stood out:

Jan Ehrenwald had described the out-of-body experience (OBE) "as an imaginal confirmation of the quest for immortality, a delusory attempt to assure ourselves that we possess a soul that exists independently of the physical body"

I've been thinking about the connection between OBEs and death, since my last experience included seeing my non-physical arm as mist. It was almost comically what you think of as a ghost – translucent cloudy evaporating white stuff.

What surprised me about the experience is that I've had OBEs for 25 years, and I've only experienced my non-physical body as refracting rippling glass (common), or looking exactly like my physical body (rare). Mist is new for me.

Why do we have this idea of ghosts in the first place? Why are ghosts translucent white stuff?

Ancient civilizations had the concept of deceased spirits, but not necessarily white mist. The Greeks described spirits as "shadows", though they maintain the wispy non-physical nature. The Egyptians had the concept of Akh, which was identified with light – though I'm not sure of the interpretation.

Could my experience have been my subconscious trying to assure itself that it exists as a ghost, and is therefore immortal?

It seems almost impossible to tell.

Did humans invent spirits to help us cope with death, or is there a ground truth to us having a spirit, and our beliefs came from this ground truth?

I'm really not sure how people can be so certain in their own beliefs. I find myself constantly questioning the interpretation of what I experience.