Here is a good place to start, take a look at this book. Some might say that this topic more correctly belongs in Ghosts and spirits, but the lack of understanding of the base connectivity of the phenomena in the hard 'physical-multidimensional-scientific knowledge base'..could be at the heart of such a separation of the whole interconnected mess. Only one part of the whole.
It's the usual bunch of blind men touching different parts of the elephant syndrome-and coming to isolated and partial solutions, to some extent. I don't exempt myself from such, as I've found that the idea of 'perfect knowledge' is..shall we say..not really effectively allowed 'here', with respects to the idea of those who have most of it..aren't here any more. Part of the nature of the system. There are also other aspects, which can't be voiced in tiny bits of text on forums. They need years of daily communication, in person, to have any effective value.:
Journey Of Souls
This is an awesome book, and I'd think it's actually worth tracking down at the local bookshop or finding on a day trip to Regina. The synopsis states that '29' people's stories of regression are within the text. This fails to take into account Dr. Newton's 7800+ forays into exactly that within the context of the work. This is the 29 out of the 7800+..that are in the book.
I've spoken with a few classically trained modern shamen on a specific mailing list..who's presence on the list was shall we say....muted. I was attempting to explain to a given list member what goes on in dream and 'ethereal' communications vis-a-vis the idea of multidimensional reality and non-linear time. How to understand the validity of a potential precognitive dream.
What I stated was, that as the given person begins the conscious journey of attempting to understand the unconscious..that the layers of 'dream' and 'allegorical, or 'visions' of reality, or symbolic dreaming..all source form the idea of the mind itself trying to make sense of what it is receiving.
For example, dreaming of a given person who one does not really know..in the precognitive sense, this 'visited' being might have a flavour of character and birth time that is close to that of a friend or family member..so the brain interprets the 'visited' being or 'energy' as the family member or friend. The brain is well known for this capacity in all of the psychological sciences.
Once again, we all know that manufactured reality takes place in our lives (every minute, every second), the life reading this text right now-every day - but few will concentrate on dealing with it, and fixing it..as it is generally..quite painful. And this will separate one from the herd. That is painful for most, even those kinds of individuals who spend time here. Then the group mind consensus reality also rears it's head. How to stay 'sane'

, when one is attempting to 'go clear'? Friends and family get worried, and can even attempt to commit one to an institution...when one is only trying to clear their mind from the large pile of crap that western society and modern man has inflicted on the idea of the 'core' of the being that resides within.
In essence, beings in dreams are not what you think they are. Dreams of friends and family can also be not what you think they are (but not necessarily so). The whole thing is symbolic, visions, voices, alternate realities, etc, all symbolic, until one learns how to slowly peel back the layers of 'manufactured reality' that are superimposed on the visions-by the mind...and see the alternate dimensions and truth behind the multi-dimensionality as it truly is. This is a slow and steady trick to learn.
And thus..Ghosts and fairies, UFO's, aliens, dragons, daemons, spirits, angels, Dimensional traveling, telekinesis, ESP, PSI, etc...all really belong squarely in the realm of science...in the end. All connected together. All one thing...
But only when the the mind's masking is taken off.
Then one gets to see it for what it really is. But then..you don't really belong here anymore..so you go. You leave. Of one's one volition.
When I explained this to the list, in general..A shaman whom I've never heard of..stepped forward and was quite interested in the fact that I'd worked to do this and understand this important facet by myself, and thought it was refreshing that someone without the guidance of other shamen..could make it to that fundamental point all by themselves. To Clarify, I mean that I learned not just the point, but the peeling back of the minds layering and to see the reality of the things, on their own. To truly understand and get past the depth of the interpretive and layering system of the human mind's workings.
I had one foot in each 'world'....but pulled back from leaving, as I surmised that I was not done here yet. I submersed myself back into 3-d reality, I stepped away from leaving...and let me tell you, that was not fun. I came back for a reason, one that is not 100% entirely clear,as of yet. I've been told my soul is complete, and this is all 'old hat' for me - that I've come back for...something. Like anyone else...I am relatively blind 'here'. The price of incarnating.
Edit: Extensive, for content, speling and grammer.