The saguna brahman is to be understood.
Nirgunam brahman is atma alone, neither subject, nor object, non dual, unchanging , of the nature of
'satchitanantha'.
The word sat alone cannot be used to reveal one vastu, as sat can mean just plainly 'is'. Any object also 'is', subject also 'is', thereby we need to say 'anantam sat', neither subject nor object, and 'is'.
Also chit alone cannot be used for one vastu, since I 'is', and other people also say ' I is'. (I am). So here also we need to say anantam chit, the chit not limited to or associated to a particular body mind self complex.
Again, just anantam sat doesnt reveal that there is one vastu alone, as chit I is there. Also that chit I is there doesnt reveal that one vastu, as there is a sat vastu.
Satchitananta together however reveals I, chitatman, as sadatman, which is anantam satchit.
So at once, it reveals that I am the vivarta kAranam, being the non dual satchitananta atman.
It covers my understanding of ishvara and self. Both subject and object get swallowed in understanding of satchitananta. The name and form dont have to disappear. In understanding of clay, the pot doesnt disappear. The pot is a name and form, and pot knowledge when we say, knowledge is brahman. So pot knowledge when we say brahman is knowledge, pot being name and form. There is a sat which is jnanam, and pot is a name and form.
Same way there is a knower, knower is sakshi chaitanyam, pure chit, happens to be a knower. Is brahman, brahman is knower, knowledge and known all the three. Rest is name and form.
With regard to objects, it is knowledge and known.
With regard to entry, it is knower.
The one brahman appears to be siimultaneously knower, known and knowledge , as though three due to associating with name and form.
This name and form is in unmanifest state, wherein brahman is not differentiated as knower, known and knowledge. Brahman is undifferentiated as in sleep for example.
This brahman alone manifests this universe, as akasha, vayu, tejah, apah, pruthvi etc. wherein these are all brahman with name and form. This is saguna brahman. Here brahman is manifesting with its maya shakti, which is iccha shakti, kriya shakti and jnana shakti.This shakti or maya is non separate from brahman, which enables brahman to manifest and appear as though as 3.
This manifestation is mithya in terms of reality, being name and form having its being in nirguna brahman.