She (Uma) said to him, "This" is the "Eternal-Tattva" (Brahman).
It is the victory of 'Brahman' in which you will attain glory."
Only then he came to know that it is 'Brahman'.
That is why these gods-Agni, Vayu and Indra, are higher than all other gods, because they got the closest touch of that 'paratattva'...
Due to some mistake of the ancient reciters or the later scribes, the rest of this mantra completely got contaminated.
It means-"that he first came to know that it is 'Brahman'".
This feeling is neither factual, meaningful, nor grammatical.
The last part of the third mantra has taken its place by entering the last part of the text of the second mantra.
Therefore Indra is higher than all other gods, because he came closest to his touch, because he first came to know that he was Brahman.
It is the instruction of 'That',... like the flashing of electricity or like the blinking of an eye, so is the Super divine feeling.
Now the spiritual sense as the movement of this mind seems to attain 'Him' (the other essence) and thereafter the contemplative resolution from it constantly remembers 'Him'
The name of 'That' (Paratattva) is 'That Anand' (Blissfulness), 'That Anand' should be worshiped only in the form of 'Anand' (Bliss).
One who knows him as such is specially desired by all beings.
You said - "discourse on the Upanishads"; Upanishad has been preached for you.
Certainly, it is the Brahmi (theological) Upanishad that we have preached.
Upanishad means intuition, that knowledge which penetrates into the Absolute Truth and is established in it.
Tenacity, self-conquest (Dum) and action are the basis (Pratishtha) of this intuition, Vedas are its parts, Truth is its abode.
The one who knows this intuition, after getting rid of his sins, becomes established in that greater world and eternal heaven, he definitely becomes established.