Link:- The Lord in the next verse, describes that the Knowable Who, ought to be (Known.
jneyam yattatpravaksyami yajjnstvamrtamainute
anadimatparam brahma na sattannasaducyate
I shall descrihe at length that which is fit to be known, and by knowing which, one attains immortality. It is the supreme Brahma Who is without beginning and Who is said to be, neither existent nor non-existent. 12
Jneyam yattatpravaksyami:- The Lord, promises that He will describe at length that Brahma or God, for Whose realization this human body has been bestowed, and Who has been described in the scriptures.
By the term 'Jneyam' He means that having known all other subjects, sciences and arts of the world, something else remains, to be known. Moreover, worldly knowledge cannot make one free from the cycle of birth and death. But, by knowing God, nothing else remains to be known, and the cycle of birth and death, also comes to an end. Therefore, in the world, there is nothing worth knowing, except God.
Yajjnatvamrtamasnute:- By knowing God, one attains immortality, and then nothing remains to be known, to be done and to be acquired.
In fact, a man (self) is immortal, but by assuming his identity with a body, he regards the death and birth of the body, as his own birth and death. By knowing the Lord, this error is rectified, and he realizes the self or his immortality.
Anadimat:- The entire universe, emanates from the Lord, remains established in Him, and merges in Him, while He remains the same. So He is called, without beginning.
Param brahma:- Prakrti (matter), as well as Veda is called Brahma, but 'Parama Brahma', is the Absolute, formless Brahma, or God Who is all-pervading and ever remains, the same. None is superior to Him in pervasiveness, purity and eternity. He is called 'Parama Brahma'.
Na sattannasadueyate:- God, cannot be called, either existent or non-existent. He cannot be called existent, because something can be existent, in relativity with something else, which is non-existent.