What is the advantage of gaining unitary vision? This is the important teaching in Hinduism.
The Upanishads answer:
When there is duality, as it were, then one smells another,
one sees another, one hears another, one speaks to another, one thinks of
another, one knows another.
But when everything has become the Self, then what should
one smell and through what, what should one see and through what, what should
one hear and through what, what should one speak and through what, what should
one think and through what, what should one know and through what; through what
should One know That owing to which all this is known, through what, my dear,
should one know the Knower?’ (Brihadaranyaka Upanishad, 2.5.6)
‘Mrityoh sa mrityum prapnoti
ya iha naneva pashyati;
He goes from death to death who sees multiplicity here.’ (Katha Upanishad, 2.1.10–11.)
‘Yasminsarvani bhutanyatmaivabhudvijanatah. tatra ko mohah
kah shoka ekatvamanupashyatah;
He who perceives all beings as the Self, for him how can
there be delusion or grief, when he sees this oneness (everywhere)?’ (Isha Upanishad, 7.)
‘Tarati shokam atmavit
The knower of Atman crosses over sorrow.
‘Yo va etadaksharam gargyaviditvasmallokatpraiti sa kripanah,
atha ya etadaksharam
gargi viditvasmallokatpraiti sa brahmanah;
He, O Gargi, who departs from this world without knowing
this Immutable, is miserable. But he, O Gargi, who departs from this world
after knowing this Immutable, is a knower of Brahman.’ (Brihadaranyaka Upanishad, 3.8.10.)
Why should an intelligent human being, in the light of this
understanding, waste one’s precious life running after secular knowledge which cannot
remove sorrow, amass wealth and possession which cannot give immortality, and
go crazy after worldly enjoyments which while dragging the mind away from the
Self, are ephemeral and result only in the loss of vigour of the senses? The problem
is this: while we boast about knowing much about things surrounding us very
near, even within us, and even far away as the distant galaxies, we do not know
the Self which lies hidden in us. This is our tactical error for which we are
paying a heavy price.
Atma va are drashtavya shrotavyo mantavyo nididhyasitavyah;
Verily, my dear Maitreyi, it is the Self that should be
realised—should be heard of, reflected on and meditated upon. By the
realisation of the Self, my dear, through hearing, reflection and meditation,
all this is known. (Brihadaranyaka Upanishad, 2.4.14 .2.5.6)