So this, the Brahman, is the very fabric of reality….and yet not reachable and at another place in the same Upanisad  the famous neti neti (not this not this) argument sums this up – ‘ Now therefore there is the teaching, not this not this for there is nothing higher than this, that He is not this. Now the designation for him is the truth of truth. Verily, the vital breath is truth, and He is the truth of that.◊ This limit which is inherent in the nature of things was tackled by the minds of a whole bunch of scientists like Bohr, Pauli, Schrödinger, Heisenberg, Dirac, De-Broglie which led to the development of Quantum Mechanics – this is best excerpted in the words of John Wheeler (1911 – present), (a physicist, who worked with Niels Bohr the main force behind of QM) writes….
(See Appendix – ‘Poetry’ – ‘Brahma’ by Ralph W. Emerson)
“Nothing is more important about the quantum principle than this, that it destroys the concept of the world as ‘sitting out there’, with the observer safely separated from it by a 20 centimeter slab of plate glass. Even to observe so minuscule an object as an electron, he must shatter the glass. He must reach in. He must install his chosen measuring equipment. It is up to him whether he shall measure position or momentum. To install the equipment to measure the one prevents and excludes his installing the equipment to measure the other. Moreover, the measurement changes the state of the electron. The universe will never afterwards be the same. To describe what has happened, one has to cross the old word ‘observer’ and put in its place the new word ‘participator’. In some strange sense the universe is a participatory universe.”
Fritjof Capra writes in The Web of Life……… …..
“This is how quantum physics shows that we cannot decompose the world into independently existing elementary units. As we shift our attention from macroscopic objects to atoms and subatomic particles, nature does not show us any isolated building-blocks, but rather appears as a complex web of relationships between the various parts of a unified whole.”
◊ The Upanisadic concept of Ātman was now touched upon by the West. To truly understand this let us start with the words of S. Radhakrishnan… “as Brahman is the eternal quiet underneath the drive and activity of the Universe, so Ātman is the foundational reality underlying the conscious powers of the individual”…The various Hymns of Creation in vedic writings dwell on this Brahman – Ātman dichotomy in a variety of ways – it is like a matrix of metaphysical concepts. The author-rishīs tip-toe through ontological and conceptual difficulties with the help of myths and metaphors. Dr. Paul Deussen gives an extensive review of the vedic literature and says…… “The motive of the conception that dominates all these passages may be described to be the recognition of the first principle of the universe as embodied in nature as a whole, but especially and most of all in the soul (the universal and the individual) Hence the idea arose that the primeval being created the universe, and then as the first born of the creation entered into it.”
(See Appendix –‘Poetry’ – “MAN” by A.C. Swinburne)
Let us first look at a part of Brihad-āranyaka Up. 1.4.10 – The First adhyāy belongs to the Madhukānd – and its fourth Brāhmana is titled “The Creation of the World fom the Self” by S. Radhakrishnan….
Indeed, this world was in the beginning Brahman itself, which alone knew itself. And it realized : “I am Brahman !” – Through that it became this world. And whoever among the gods became aware of this (through the knowledge : ‘I am Brahman’), he became just the same; and so also among the Rsis (seers) as also among men. Realizing this, Vāmadeva, the Rsi exclaimed :-
“I was once Manu, I was once the Sun.” And also even today he, who realizes this “ I am Brahman,” becomes this universe: and also the gods have no power to produce that which he will not. Because he is the soul (Ātman) of the same. Now he, who adores any other godhead (than the Ātman, the self) and says :”It is different, and I am different”, does not know; he is just like a domestic animal of the gods…..
This shlöka includes the second of the Māhāvākyas . It very succinctly relates the Unknown, Brahman to the Ātman. This, the individual consciousness, realizes “Itself” as the central, “I”, …..Douglas R. Hofstadter explains this beautifully when he introduces M. C. Escher’s ‘The Drawing Hands’ as, what he calls, the Tangled Hierarchy…….
Here a left hand (LH) draws a right hand (RH), while at the same time, RH draws LH. Once again , levels which ordinarily are seen hierarchical – that which draws, and that which is drawn – turn back on each other creating a Tangled Hierarchy. Note, that behind this lurks the undrawn but the drawing hand of M. C. Escher, creator of both the LH and RH.
Thus there are three hands in this lithograph – Brahman the undepicted hand of the artist ; LH and RH both simultaneously appearing as Ātman, the soul, the participator and “I”, the individual consciousness, the observer.
◊ Let us quickly look at the ‘etymology’ of aham  …..it is given in explicit detail in the Aitareya Āranyaka in the 2nd part, 3rd adhyāy, 6th to the 8th verse. The ‘Hymn of Creation’ comes next, which is the Aitareya Upanisad itself, from the 4th to the 6th adhyāy of the Āranyaka.…
……. ‘a’ is the whole of speech and being manifested through the mutes and the sibilants it becomes manifold and various. If uttered in a whisper it is this prāna, if forcefully, that body – śarīra. Therefore it is hidden, as hidden as the previous body encapsulated in this prāna . But spoken forcefully it is that body and visible, for body is visible.