Interpenetrating Planes

Two or more planes of existence
might interpenetrate, with each loca-
tion in one world corresponding to a
similar location in all the others. Such
realms are generally distinct from one
another, and invisible to each other’s
inhabitants – although some gifted
people, such as mediums and seers,
might be able to perceive more than
one reality at a time. Perhaps even
ordinary people can occasionally see
the inhabitants of the other realms,
but regard them as ghosts.
This is a common way to look at
“dream,” “phantom,” and “spirit”
realms in fiction. Often, travelers to
such planes do not go anywhere; they
just shift their perceptions.