The seeker has to overcome all the obstetrical by perfect understanding by realizing 'what is truth' and 'what is untruth'.

There are no divisions in the formless soul,which is present in the form of consciousness.  The consciousness pervades everywhere and in everything in all the three states.  The ego or  waking entity is not the base to decide where the presence is and where it is not.  It has to be viewed, judged and concluded on the base of the formless witness (soul) to know there is only unity and the diversity is mere illusion. The  formless soul, which is present in the form of consciousness is all-present and everywhere and in everything and connects everything to everything and finally becomes nothing other than itself.

For those who have learned how to see, and judge the three states on the base of the soul as self, find the truth is perfectly hidden and perfectly revealed in these three states.

The intellect is based on the ‘ego’, which is the false self and so the truth cannot be unfolded. Consequently, the people are caught up in believing the imaginary theories based on the false self as reality.

There are many obstacles in pursuit of truth. The seeker has to overcome  all the obstetrical  by  perfect  understanding by realizing 'what is truth' and 'what is untruth'.   Seeker of truth must accept only uncontradictable truth. 

People believe that only through a guru and his grace will help them to acquire the self-knowledge, and   faith in the revelations made by the Guru and in the scriptures.  In pursuit of truth there is no need for Guru because it is path of verification, whatever is not truth has to be rejected. Thus whatever guru preaches or teaches cannot be accepted blindly without verification. In pursuit of truth, there is no need for guru, the self itself is guru.

Some time seekers inability to understand the revealed truth creates doubts and confusion, but constant pondering by deeper thinking all the doubts and confusion get cleared automatically. 

Seeker must not take the authorship of the inner revelation as his own but always say the inner revelation revealed as such, to get the grace of the Self.   

Without proper conviction the doubts and confusion bound to arise." Doubts regarding the truth of the revelation and by failure to understand and assimilate them. The doubt arises whether there is freedom; and later misunderstanding leads to its denial. These two are sure obstacles to any sincere efforts being made for realization.

Non-dual wisdom refers to a direct realization which is non-dualistic, and contradicts the way in which we ordinarily perceive the world. The experience of ultimate truth is beyond duality. 

Essence from Upanishads:-

Reflection on the nature of the Self as Brahman is the mental world that conforms with the scriptural injunctions. Even this duality in conformity with the scripture is to be renounced after Brahman is realised. This is the direction of the Shruti.

An intelligent person, who has studied the scriptures and has repeatedly practised what they enjoin should renounce them after knowing the supreme Brahman, just as a man throws aside a flaming torch at the end of his journey’. (Amritanada Upanishad)

An intelligent person, who has studied the scriptures and has practised what they enjoin should discard them after experiencing Brahman as his Self, just as a man discards the husk when he has found the grain’. (Amrita-Bindu Upanishad)

A wise man, having experienced Brahman as his Self, should keep his higher intuitive faculty (prajna) united with Brahman. He should not oppress his mind with many words, for they are a mere waste of energy’. (Brihadaranyaka Upanishad)

It has been clearly told in the Shruti: ‘Know that One and give up other talks’ (Mundaka Upanishad) 

‘A wise man should restrain his speech and keep it within the mind’. (Katha Upanishad)

   The duality of the mental creation of man, which is not in conformity with the scripture, is of two kinds, violent and dull. That which gives rise to lust, anger and other passions is called violent and that which gives rise to day-dreams is called dull.

   Before starting the study into the nature of Brahman it is necessary to give up both; for, mental poise and concentration are the two prerequisites for the study of Brahman, so says the Shruti.

In order to achieve and to be established in, the state of liberation these two must be given up. One who is subject to the urges of lust and other passions is unfit for liberation in life.