Ian Edwards:
Does this sound about right?
There's really no corroborating different people's impressions or descriptions of the changes that occur going from one jhana to the next as sometimes it happens so quickly that the details become muddled in the process. What matters most is that you yourself have determined that each shift has occurred and have been able to discern something that informs you of such.
In other words, I wouldn't describe my experience in quite the words you have outlined here. Quite frankly, I'm not sure how some of the descriptions you've used relate to the cessation of jhana factors which informs the standard description of moving between the first, second, third, and fourth levels of the
rupa jhanas. Nowhere in the standard descriptions (coming from the discourses themselves) are there any descriptions that bring out "a feeling of disconnectedness or separateness from body," as a factor in the transition between jhanas. This may be a distinctive way that you yourself perceive this process, attributable only to your own unique perception. Or, maybe with additional detail you might add something that I could relate to in some way that would give me the impression of something that, upon further reflection, I could relate to.
At any rate, don't discount any impression you have, as with time it may change and become modified. In time, one's discernment sharpens and one sees things later that one didn't (or wasn't able to) discern earlier for one reason or the other.
Ian Edwards:
If so I would conclude that there are not very clear lines between the jhanas and they kind of meld into each other.
It took me a couple of years to really get a clear handle on the transitions involved, so don't be discouraged if you are similarly having difficulty discerning these changes, too. I think it happens to all of us who attempt to practice this very subtle meditative practice.
What I would say about this impression that you have brought up is that after a certain point, when your practice in jhana has matured and you find entering jhanic meditation as easy as breathing, that you may find it difficult to discern the transition from first to fourth jhana. In my own practice, I have found this to be true, leading me to the impression that one can go from first to fourth in the blink of an eye. Fourth is where all the "magic" happens in terms of insight recognition. And by "magic" I don't mean to imply anything metaphysical. The magic I'm speaking about is the increased level of concentration that occurs in the fourth jhana. That increased concentration accompanied by the overall impression of relative mental ease allows the mind to view "things (
dhammas) as they are," which in turn provides the impetus for the change in one's mental outlook about reality.
So with the above comment in mind, yes, I can agree with the statement you've made here that each jhana "kind of meld(s) into the next." That impression is not foreign to me.