Yogi is unaware of the ‘Self hidden by the world in which he exists.+

Patanjali warns against sleep as a hindrance to yoga, he means when it occurs in the early stages of the practice. Yogi is unaware of the ‘Self hidden by the world in which he exists.

For only when all is known can all be known to be but ideation. Hence yogis blotting all out in samadhi cannot lead to Advaitic Gnana.

Ashtavakra says:~"This is your bondage, that you practice Samadhi or meditation.”

Remaining thoughtless in the waking experience is yogic Samadhi. Yogic Samadhi is not the Advaitic wisdom

Brih Upanishad: page 32. "Yoga does not yield truth or liberation."

                                                                 

One who is in Samadhi will not know that this universe as the consciousness; therefore yoga is not the means to Self- knowledge or Brahma Gnana or Atma Gnana.

 In Samadhi the yogi knows nothing, sees no universe; so if there is nothing but blankness. The blankness is not the Advaitic wisdom.

The yogi does not know the nature of the universe. If the universe is not seen in the Samadhi then there is no need to use the word Atman and Brahman.  The yogi is unaware of the truth, which is beyond the form, time and space. 

By shutting his eyes in Samadhi, the yogi does not know the universe, which confronts him. Hence the universe can't be known as the Soul or the consciousness through yoga.

One is in a non-dual condition in deep sleep or Samadhi, One without a second, true, but he did not know it at the time. He says only in the waking experience afterward. Hence, there must be an inquiry so that you find non-duality whilst you are awake so that you can see nonduality at the time not afterwards. Hence, too the need for inquiring into the nature of the universe and knowing it as the Soul or the consciousness whilst one is awake, and not during sleep or Samadhi.

Advaitic truth is the ultimate truth.  Yogis, mystics and religious teachers do not accept the path of wisdom because it pries into the truth, the source and the validity of the knowledge they claim. Therefore, it is the most difficult part of the study of Advaita.

That is why Sage Sankara said: ~ “Without causing the objective universe to vanish and without knowing the truth of the Self, how is one to achieve Liberation. -63- (VC)” 

The universe in which we exist will not remain as reality when wisdom dawns. The universe is a mere mirage created out of the consciousness and there is a conscious awareness of unity in diversity because there is no second thing exists other than the consciousness.

Remember:~

Lord Krishna confesses that the oldest wisdom of India (Advaitic wisdom) has been lost: people misinterpret and falsify it today as they did then. It is not yoga but philosophic truth. But nobody knows it. The teachers of philosophy and leaders of mysticism or religion do not want to inquire into truth and have no time for it. (Gita –Chap- IV-v.2)

In Gita Chap.IV where Lord Krishna says: ~ "This yoga has been lost for ages" the word yoga refers to Gnana yoga, not other yogas: the force of the word this is to point this out.

Lord Krishna describes some of the other yogas but devotes this chapter separately to Gnana Yoga. So one sees even in those ancient days people did not care for Advaita; they wanted religion; hence Gnana got lost. That is why Krishna calls it "the supreme secret." Krishna points out that the yoga must see "Brahman in action."

Mystics who promise a Garden of Eden, a joyous outlook on life, do not see that this must be a Seen, an object which is seen and must inevitably vanish. How long can it last? We Vedantins regard peace as higher, because it is apart from joy or sorrow, ecstasy or pain, and because it belongs to the  Maya and is therefore unbroken, permanent.

In the dream you know that the dream figures are also mind(universe), not different from it; similarly, when you know that everything is Brahman, there is no need for yogic control of the mind. Control presupposes second, a duality. Hence yoga is in the sphere of duality and is unnecessary to one who knows non-duality.

Advaita requires one to be active in order to examine the world and discriminate. Hence Advaitic awareness means knowing that there are no ideas different from Self, as the dream mountain is not different from the Self, knowing which they automatically come under control.  Advaitic awareness is different from Patanjali Yogic Nirvikalpa samadhi, which is only a deep sleep.

There is nothing to drive out. Even the yogi's ecstasies may be retained, provided you do not let yourself be deceived about them and accept them like everything else, as part of Brahman.

The mystic who sees God in vision has seen Him during the waking state: but as Reality is not in a state, therefore he is in the world of Seen.

The Yogi wants to do something, some action, even that of sitting still, to control this or concentrate that. This means he is still attached to the body. He wants his body to be quiet. He is still thinking of the illusory body. He does not start with Vedanta's idea that the body is but an idea. On the contrary, he takes it for reality.:~Santthosh Kumaar