Ashtavkara Gita page 224:- It is not the absence of buddhi that can grasp Advaita but the man who possesses the highest intellect. Brains are necessary. Such a man, by merely hearing the truth mentioned will know it.
Avadhuta Gita:-“The Atman cannot be purified through the practice of the six limbs of the yoga, or through the annihilation of the mind, or through the instruction of a teacher. The Atman is the Reality Itself and It is Purity Itself."
Where people cannot and do not think, they follow others. A Gnani will see the world and get to know it is only an illusory appearance. He is not blind; he sees three states or objects as it is, but he knows it is only falsehood. Just as you see a mirage, the Gnani sees the mirage of this universe too; but he is not deceived by it. So long as one is ignorant, he will have the idea that God has created this world because the causal notion will be there. Nobody wants to suffer, and while the notion that suffering can be got rid of by appealing to God these wishes will sway the mind to believe in God. For them religion will arise, but for the man who wants truth, religion offers no consolation.
One has to inquiry into the mind or the world and its nature i.e. matter, there can be no such thing as non-dual wisdom or Gnana without understanding what is mind or the universe. Seeker of truth will not be able to find answers in the path of religion and yoga are based on blind belief or imagination because they think the mind is within the body.
The yogi or religionists may just by saying “I know” and not explain how one knows the ultimate truth. Because he has read it in the book or scriptures or his guru may have told him “yogic Samadhi is liberation.
The self-deluded believers tell others the same, because he has not investigated if it is right. People give lectures and write books on yoga and eastern philosophy.
Some may say for many years they are enjoying mystic exaltation, trances, meditations and peace but they have verified what they experienced is really truth. . Then this state is not permanent because when this state passes away again they enter into duality. This state, which is impermanent is not Gnana or self—awareness. This proves he had attained a yogic condition, but not Gnana.
Yogic Samadhi vanished because it was not the highest insight. The Gnani, however never loses his Gnana. Dislodging a Gnani from his insight is an impossibility. Once he has thoroughly seen the truth he simply can't fall away from it.
Many enjoying a similar sort of mystic exaltation and peace, but whether it passes away soon or endures the whole of life, it is not Gnana, because it did not come through striving to investigate the nature of the mind or world, it came only through meditation on the self; that is the yogic reward for such meditation but it is only one half.
The Gnani not only gets inner peace but also truth because he also has grasped the truth about the matter, which is as much consciousness as his- innermost self.
It is not possible to stop thought process for more than a half-second whilst in the waking experience. If one succeeds in controlling thought and then banishes it, one passes into yogic Nirvikalpa Samadhi, which is identical with deep sleep. The only difference between ordinary deep sleep and Samadhi therefore is that the ordinary man falls asleep involuntarily whereas the yogi has the satisfaction of knowing that he has passed into sleep by his own effort of will in banishing thoughts. Thoughtless states not wisdom because thoughts rise to the false self within the false experience. There is no use of struggling to stop the thoughts which belong to the falsehood? One has to trace the source of the falsehood which is not the form of mind or universe to unfold the reality of the true existence.
Thoughtlessness is not wisdom and thoughtlessness is not Gnanic or Brahmic truth. The Soul, which is present in the form of consciousness, is the innermost self. Consciousness is the witness that experiences the action, the actor, and the world of separate things. It is like a light that illuminates everything in a theatre, revealing the master of ceremonies, the guests, and the dancers with complete impartiality. Even when they all depart, the light shines to reveal their absence.
There is only need to realize the whole universe in which we exist is created out of consciousness (soul or Atman), the innermost self. On the standpoint innermost self, the universe is mere illusion created out of consciousness. Thus on the ultimate standpoint no second thing exists other than consciousness. Thus consciousness is ultimate truth or Brahman.
What is not consciousness (formless) in the experience of diversity (waking or universe)? The waking and the dream cease to exist without consciousness. The seeker, seeking and his destination all are one in essence.