Think of a two dimensional example:
When you look from a three dimensional standpoint at a two-dimensional figure, like a square, for example, you simultaneously see what is inside and outside it. Granted, the observer would have to be outside the square's plane for this to work.
Same would work for 4D to 3D.
When you add "Density" to those Dimensions it's no longer simple, osit.
I just think there's so much more we (3D) have yet to encounter, all there is to be aware of in 3D. (not to sound like word salad but it's short and I'm not good at explaining things in details). Shoot! If, I'm suppose to have graduated from 1-2D, than why can't I "know" them? "Guardian" to me, she/he seems to display some of that knowingness/awareness than I, osit. Does graduating to 4D imply learning all the lessons of 3D, excludes or does it accommadate 1D,2D as well?
okiron
As for the question why we can't see the 4D objects and beings, there is a reference from the RA material about this:
Questioner: Is an entity in the fourth density normally invisible to us?
Ra: I am Ra. The use of the word “normal” is one which befuddles the meaning of the question. Let us rephrase for clarity. The fourth density is, by choice, not visible to third density. It is possible for fourth density to be visible. However, it is not the choice of the fourth-density entity to be visible due to the necessity for concentration upon a rather difficult vibrational complex which is the third density you experience.
Even though we can't perceive four spatial dimensions (at least, not yet), there is a possibility that we could see projections of 4D objects, if they happen to intersect with our space (kind of like their shadows), but perhaps that reference from the RA material explains why we don't see them either.
