A person may at first take some external thing as an object
of his meditation, but he should afterwards think of it as existing only in the
form of the mind; and lastly the mind also should be reduced to Brahman which
is pure consciousness. Then alone one is said to have reached the highest goal.
By constant practice of contemplation and discrimination
there dawns on the mind of the aspirant the knowledge that Brahman alone is and
nothing else exists. Thus the ignorance which has so long deluded him by
projecting the world of duality, comes to an end. Thereafter the mind also,
which by destroying ignorance has brought the aspirant so close to Brahman,
vanishes like the fire which after consuming its fuel is itself extinguished,
then Brahman alone shines in Its own glory.
After long practice, the aspirant at first realizes, while
in Samadhi, the presence of Brahman which pervades the inner and the outer
world. But this is not all. He should then hold on this Brahmic consciousness
until he feels his identity with Brahman at every moment and thus becomes
completely free from the bonds of all duality and ignorance. This is the
consummation of spiritual practice.
Source – English translation of Aparokshanubhuti by Adi
Shankaracharya