We can certainly substitute water with body, but the same problem remains. One perceives body, as that which is body.
One assumes/conceives that body.
That body is perceived, and you cannot see the body without the perception, thus it is a PERCEIVED-BODY, not just a body.
( Excuse the capital letters, I’m not shouting)
One cannot ‘ACCESS’ the body without perception.
Can you imagine a body, without in some way perceiving it?
No matter how fanciful ones imagination of a body, it’s still perceived through thought.
The body (not the perceived-body) cannot even be thought; i.e the thought of body is also not that body, it still is perceived-body( which is being perceived because of the inaccessible body).
The body is inaccessible to you, even in thought. It is thus inconceivable when one directly knows/remembers the understanding/abhijanati of this.
But one must always also be careful not to assume that "the thought that the body is inaccessible"is that body.
The inaccessible-body-knowledge reveals what anicca-dukkha-anatta means i.e it appeared, and it will disappear without your ability to do anything about it; it persists in an inaccessible situation beyond my control; it increases and decreases without concern for ‘me’.
As regards the basic elements, these are a description of the most general elements,in an unproliferated sense. Modern science has discovered many more particular elements but they are all constitutes of the general basis.
Modern times are more proliferated into the world of particulars, and therefore we are further away from discerning these GENERAL phenomena, whereas , in the time of the Buddha,the general background phenomena were more easily discerned and that would explain the perfect conditions for the appearance of a Buddha and the ease by which some others understood him.
One could say that in fact, we have descended/proliferated further into the senses and so it will be harder to ascend.
The mind is a general background phenomena, thoughts are more particular, but are more general than what you see or touch.
The body is also a much more general thing, our perceptions of it are more particular. Therefore we cannot know the general body through the particular perception, for wherever we look, we find a perception.
Thus, having such knowledge repeatedly, one stops even trying to conceive the body.
If the general inaccessible body is understood and no longer conceived as accessible (mine in whatever way), what is to say for all the more particular things based on body.
If the very base of my existence is not mine, then all other things cannot possible be mine. They never were and never will be.
). I’m finding it tends to have quite a deconstructive impact on perceptions of self (driving home that I have about as much fundamental control over external water in rivers as internal water/fluids in the body etc.). You seem to be taking this deconstructive light and shining it on perception itself, which seems good to me. Though, on the other hand, I guess while there’s still a body there’s still going to be perception going on.