This is a very good question.
We are a nonphysical being (soul/spirit) having an excursion in physicality. Our whole being (Oversoul, Soul Family, SELF) has many aspects in various dimensions (Ds). Our self is one of these aspects.
The self is the mechanism through which we experience individuality. It is, as Deepak Chopra noted what enables us to say, I’m eating an apple. instead of, An apple is being eaten. Experiencing individuality affords us learning experiences we can't have in other Ds.,
HS is the first portion of our soul (upper 4th D- 1-12D) that isn’t affected by earthly travails.
Multidimensions.com has allot of information on the Ds & our journey through them-
http://www.google.com/search?ie=UTF-...dimensions.com