Verse 8

8.  That Very Self,  in the realm of sound is the syllable OM,  the above described four quarters of the Self being identical with the components of the syllable,  and the components of the syllable being identical with the four quarters of the Self.
The components of the Syllable are A,  U and M.

"That Very Self,  in the realm of sound is the syllable OM".

"That Very Self"  that has been explained as the  Absolute  "Self"  is all that Consciousness of knowledge from which projects this very material universe and all it contains.
Therefore it is being said,  AUM is the sound of Creation itself forming.  Therefore OM is the gross material realm  "the realm of sound".

"The above described four quarters of the Self being identical with the components of the syllable,  and the components of the syllable being identical with the four quarters of the Self".

As stated,  being referred to here is the above concept of  "quarters"  which were used as an aid for describing the experience,  in consciousness,  of waking sleep,  dream sleep  and profound sleep by the "self",  and therefore also by the Absolute "Self".

Here,  in Universal terms,  Those same  "quarters",  waking state and so forth,  of that same Absolute Universal  "Self"  are being identified with the four states of AUM and the Universe,  because it has been stated that OM is the  "Self".

"The components of the Syllable are A,  U and M".

AUM symbolically encompasses the entirety of created sound which further symbolises or names all forms and states of this Created Universe.