Ghosts: lost souls, a phenomenon, or just a fairy tale?

For historical examples of Ganymede, I highly recommend checking out the Icelandic sagas! Almost every saga mentions the resurrection of the dead, magical tricks, and so on, among completely ordinary things (these sagas are truly the pinnacle of realistic prose). It makes a strong impression.

It would be interesting to hear about the phenomenon itself... Although it's understandable that it must be very difficult to talk about – it's hard to remember, and even harder to reproduce, and almost impossible to convey...