The Subtle Body

Mother and Sri Aurobindo spoke quite clearly of the subtle body and subtle world.
But in order to avoid it remain an intellectual knowledge one needs to prove it to himself.
After all it is not about learning but -being- that transformation and knowledge.
So we don´t have any other option then discover it of first hand.
It also means not being afraid to investigate the eventual value of any other useful information.
I found myself a lot of help in the teaching of the Agni Yoga, based almost in its totality on teaching released on subtler levels, with words as "the Subtle Realm" and "the Fiery Realm", which, to a no-discriminating mind may immediately recall its resonance with the "subtle world" and "supermental world" of Sri Aurobindo.
The reason why it ought to be so are evident but is not of our momentary concern, as we are talking of the subtle body.
When I started to experience "conscious sleep", it was evident a number of things.
The first was that the physical body was sleeping.
The second, was that the subconscious as well was dreaming.
If I wanted to, I could see it as a lower mental appendix of my consciousness, attached to me, but with a certain degree of reciprocal independence.
I was not affected at all for the dreams the subconscious was dreaming, I could see them as on a screen if I wanted to see them, but I could just ignore my subconscious and continue with my experiences.
So, I left behind physical body and subconscious.
Then, I found myself as a nucleus of consciousness, a mental being.
I had all the mental faculties of normal wake consciousness  plus this condition of lack of physicality.
But it was not only -who- I was, but also -where- I was.
It was certainly a space, but not a physical space, rather a mental space, without true objects and dimensions but certain basic blue hues everywhere which was not a flat thing but a "space". It was "things" in its potentiality, they weren't there, but at any moment that space would open on something one has to know or remain just as an unseen possibility.
I would not see any subtle envelope of this mental body/mental being which I was, and yet, in some occasion, if the circumstance needed it, a subtle replica of my physical body would be formed, otherwise, the tendency was getting back to formless mental substance.
That subtle body was not a temporary invention, but had a complete reciprocity with the physical body.
Something like you can fold out and unfold at request, but not of an -essential- presence: to be just that nucleus of consciousness was pretty enough for whatever.
It also gained somehow, as it seemed to share some kind of superior intuition, and even subtler senses, which infallibly told the truth of anything happening there.
I normally did not see either a "body of light", or a "nervous body", or any subtle envelope for the circulating prana and the chakras, though this too, would appear in some concrete occasion, otherwise its presence would remain occult.

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As a consequence of my own perception, (then having value only for me), had I to make parallelism with the descriptions in the integral yoga, I would say that the mental body or mental being of this yoga, was without doubt my own experience of being that formless consciousness.
The "subtle physical" of the integral yoga, would specifically refer to that subtle replica of my physical body and even that "body of light", which would or not appear as necessary, but the word -subtle body- would not refer to something in itself but -the totality- of these more subtle parts.
So that a -subtle body- in itself do not exist, but refers to that larger compendium.
At least, those my own conclusions.