Thanks, Korpo. I gave it a good read now. I also started today skimming over part 5 dealing with higher / mental or 'cosmic' bodies. I am only half through it as I think it also gets a bit complicated then (also my thinking capacity isn't the best today). However, this is not the interesting point now. I've come to the point when he says that we have two bodies available per subplane, he describes them using the old Sanskrit labels:

[T]here are two bodies associated with each plane. Hence we have the ordinary astral body, which is an adhibhautika body, and a meta-astral body, which is an ativahika body.
The word adhibhautika means “composed of the elements of,” and so refers to an astral body that is made up of the matter of a particular astral subplane and therefore confined to it. The word ativahika means “going onward or beyond,” hence free of any particular subplane and therefore able to perceive and travel within all levels of the astral plane–hence a meta-astral body."
- Kurt Leland
Well, what astonishes me from reading about this, is this: Tonight, I had a dream. Much of it was confusing and memory is overall very hazy. I remember one scene clearly, though:

I was driving home with a bike from a bigger town (nearby) to my (now again!) hometown. (I do have this dream quite often, btw.). I was having trouble as the bike I was driving did not move properly or fast enough (but it did, I shall say).
Another cause for the difficulty of cycling was that for some unknown reason then to me, I was actually driving with two bikes! That's possible, although not easy to do; and I remember doing this as a youth when I transportet a bike to a buddy of mine, fortunatley along 2 streets only.

So in the dream, as back then, on one hand I was steering the bike I was sitting on with the right hand on the right side of the handlebar, while I was holding with my left hand (arm stretched out) the right handlebar of another bike, balancing it, getting it dragged along, rolling next to me. There was a time jump (or I don't remember the in-betweens) and then I was home, leaning both bikes (iirc) against the wall of our house in the garden.

Well, I need to stress again that I had this dream tonight BEFORE I read this article today! It might be accident and there's no correlation. It might be another precog vision of just reading about this information today. I do have precogs a lot now. So... be that what it may have been ... it's at least very interesting.

And maybe there is more to it than just another nice precog: I assume the bike is (as sometimes my car) a metaphor for my energy body. Maybe this IS to show and/or reassure me that (although with great difficulties) I am in the process of making the 'second bike' available to me ... for use ... one day. I have it brought home already, so to speak, although maybe it's only the knowledge of its existence now, or of it standing there ready to jump on (or not?) in my garden, when I am 'ready' to use it. I don't rememer if it was damaged (flat tyre etc.) or not, however.

Anyway, I might be over-interpreting again ... but in case I'm right then it is an encouraging dream (plus the precog into the bargain ).