By renouncing the worldly life and surrendering to the physical guru one will never be able to acquire self-knowledge.***

The seeker of truth ought not to renounce from the practical life within the practical world like ascetics by renouncing it, but he has to strive to understand the true nature of the world and thus conquer it by self-knowledge by  fully engaged in practical life within the practical world.  The universe is in the form of mind. Thus the universe is the mind itself.  The universe or mind appears as waking or dream (duality) and disappears as deep sleep (non-duality). By renouncing the worldly life  and surrendering to the physical guru one will never be able to acquire self-knowledge.    

That is why Swami Vivekananda said: - “You have to grow from the inside out. None can teach you, none can make you spiritual. There is no other teacher but your own soul.” 

Without inquiry into the external world and its nature that is matter, no one can acquire non dual wisdom. The Yogi cannot answer objections raised by critics; he can but say “I know” and not explain how he knows. A Gnani can.  

That is why Sage  Sri, Sankara Says: -  63 (VC). Without causing the objective universe to vanish and without knowing the truth of the Self, how is one to achieve Liberation by the mere utterance of the word Brahman? — It would result merely in an effort of speech.  

He who has realized the ultimate truth or Brahman transcends the duality or mind where he sees no second thing other than consciousness.   The yogi who sees the universe as reality may try to deny it because he thinks thoughtlessness is Brahman.  The yogi sees the universe as a second thing and he wants to banish the universe in Samadhi, because he does not know that in non-duality there is no need to deny the universe. But he has to realize the fact that, the universe is not something different from the self, which consciousness. Those who cannot grasp and realize this position, misunderstand it, and wrongly hold it be yogic Samadhi where there is only blankness.  

The presence of the universe is no obstacle to Gnani‘s realization; he does not need yogic Samadhi.  But yogi has imagined Brahman as blankness or thoughtlessness thus he is still in the grip of duality.  Thus Yogis Brahman is but a thought.  Brahman is not a thought but Brahman is prior to any mind or universe.  Thus one has to know what is prior to waking experience.  

The yogi who wrongly thinks there is Brahman to be got , may attempt to do so, and may think he sees it, but all the time he under the delusion of duality because he bases his- self  on the physical body, thinking Brahman to be something different from the soul, which is the true self.

When one becomes aware of the fact all the experiences of the three states and all the thoughts and words are Mind and mind in turn is consciousness then he has transcended thinking faculty. 

The Yogi' believes mystic experience is liberation.” His followers too believe in  their gurus experience as true and being self-deluded when honest and tells others the same, because he has not investigated if it is right. The Gnani, however never loses his Wisdom.  Dislodging a Gnani from his insight is an impossibility. Once he has thoroughly seen the truth he simply cannot fall away from it. 

Yogi enjoys a sort of mystic exaltation and peace, but whether it passes away soon or endures the whole of life, it is not non dual Wisdom, because it did not come through striving to investigate the nature of the three states, it came only through meditation on the self; that is the Yogic reward for such meditation but it is only one half.  

Sage Sri, Sankara says (VC) 56. Neither by Yoga, nor by Sankhya, nor by work, nor by learning, but by the realization of one's identity with Brahman is Liberation possible, and by no other means.  

A Gnani not only gets such inner peace but also truth because he has turned outwards also and grasped the truth about the matter, which is the Atman in its essence.  Thus he is fully aware of the fact that everything in the whole experience of diversity is nothing but Atman.  Thus he finds unity in diversity. 

The Yogi and mystics dip into their selves but they do not understand that that is only one half of the truth and that this dipping is also a mental discipline to fit their minds to understand the true nature of the world confronts  them, which understanding they must next get if they are to become Gnani.  

Sage Sri, Sankara says: - [AA] 88. When the whole universe, movable and immovable, is known to be Atman [consciousness], and thus the existence of everything else is negated, where is then any room to say that the body is Atman?

The knowledge of both matter and soul is the true knowledge. Seeker living as the in the world, and he has to live, move and work in the external environment. He cannot get away from it. It is his life within the waking experience. Therefore, seeker ought to know, understand and grasp its meaning. The Yogi or mystic who refuse to do so is refusing to face the whole of reality.