In his Yoga Sutra, Patanjali explains the two distinctive aspects of samadhi: samprajnata, where you question, discriminate, and have feelings of amazement; and asamprajnata, where there is no pulsation of thought, no awareness.
In the first stage of samadhi, when the mind gains
one-pointedness it gets an experience of sudden questioning: ‘What is this?’ Up
until now the mind was cognizing many things, multiple perceptions, ideas,
images — the mind was dwelling on them. When you silence and resolve them, you
experience a kind of amazement, a kind of wonderment — ‘What is this?’ When a
man who had never seen an ocean saw it for the first time, he opened his mouth
and said: ‘What is this?’ It happens just like this. There you ask yourself:
‘What happened to all those things which I had been seeing until now?’ The
memory is there, the questioning, the discrimination, these things shine before
the mental horizon.
The second stage of samadhi comes due to purification, with
more concentration, more steadiness:
‘By the constant practice of cessation of all mental activity, in which the
mind-stuff retains only the unmanifested impressions.’ Then the questioning,
the discrimination stops, everything is silenced. That experience, as described
earlier, is as when you go to the top of a mountain, lie flat on your back,
look at the sky when there are no clouds, no birds flying, when you see
nothing, only expanse, or space, pure and simple, blank, the mind takes that
form for the time being — there is nothing visible except space; all are
silenced; no thoughts, no images, no clouds, no birds, no moon, no sun, only
the vast sky.
The mind takes that form in the second stage of samadhi.
When this comes, what actually happens?
All mental impressions are silenced, because of purity of mind obtained through
constant detachment from all other thoughts, all other impressions. What are
the thoughts and impressions that have been gathered by you from childhood up
until now? They are not you, they are not part of your being; they have come
from outside, are due to knowledge and experience combined. All the thoughts
and ideas and impressions are there, they are silenced now. You don’t remove
them, you become detached, you become unconcerned, unrelated, they do not drag
you, you become strong; due to will power you control your mind completely, you
say: ‘Nothing doing’. In that stage everything is submerged, the thoughts and
impressions go down.
Source - Light on Patanjali – IV by Swami Sarvagatananda published in Prabuddha Bharata Magazine November 2008 issue.