Advaitic truth is uncontradictable truth and rational truth and scientific truth, and ultimate truth.+

Many people quote Advaita without understanding it really in its highest aspect. They declare themselves as Gnanis, but their knowledge is really mysticism.

Sage  Sankara says: ~ What is accepted without a proper inquiry will not lead a person to the final goal. On the contrary, such acceptance will result only in evil, something which is detrimental to our spiritual progress.

Seekers of truth should not believe blindly in traditional orthodox nonduality without verifying all the facts from every angle. One has to reflect through reasoning, over and over again without getting tired of the process.

There is no hope for those who call themselves realists because they are unwilling to make inquiry into what is real. The true seeker of truth analyses and inquires, not relying on first impressions, and hence he is fit for the path of Advaitic wisdom.

They have to know that what they are saying is true. There are so many conflicting teachings by many gurus, one gets confused as to which are true.

They will be unable to prove because they do not know the proper test of truth they preach what is written is books with their own interpretation without verifying them.

Why does one start by assuming that anything he knows is true? Many things he regards many things unconsciously as true because he enjoys them or is pleased or satisfied with them. But without verification, nothing has to be accepted as truth. 

Advaitic truth is uncontradictable truth and rational truth and scientific truth, and ultimate truth.

To realize the Advaitic truth is the seeker's aim, which is quite different from the opinions of dualistic egocentric schools. Advaitic truth is Soulcentric truth and uncontradictable truth. 

All the various views are mere opinions and have nothing to do with the ascertainment of the ultimate truth, which is beyond the experience of birth, life, death, and the world.

In the Advaitic path, the seeker of truth has to analyze the whole world; think consistently about it. He has to exercise his thinking faculty and inquire continually; discrimination is essential; this practice is the only way to grasp the Advaitic truth.

Gnana is that knowledge, knowing which everything else becomes known. Truth can be known by its being impossible of any contradiction and depending entirely on what is not the self. 

The seeker of truth has to go to the very root of things. He rejects everything which is untrue by Soulcentric reasoning.

Katha Upanishad (1.2.5) says; -"Caught in the grip of ignorance, self-proclaimed experts consider themselves learned authorities. They wander about this world befooled, like the blind leading the blind.

Perfect understanding and assimilation of ‘what is what’ helps you to unfold the mystery of your true existence.

Remember:~

The seeker has to make his discoveries through the process of rational thinking and reasoning.

That is why Sage Sankara says:~VC-65- As a treasure hidden underground requires (for its extraction) competent instruction, excavation, the removal of stones and other such things lying above it, and (finally) grasping, but never come out by being (merely) called out by name, so the transparent Truth of the self, which is hidden by Maya and its effects, is to be attained through the instructions of a knower of Brahman, followed by reflection, meditation and so forth, but not through perverted arguments.

It means searching for the truth independently on your own therefore there is no need for any teacher or teaching. The truth has to be ascertained by the seeker himself. 

Until the seeker realizes the truth, how can he know what is untruth?  How can one know the teacher knows the truth or teaching speaking of the truth?  

The seeker should not accept anything as truth without deeper introspection. Only uncontradictable truth has to be accepted as the ultimate truth of Brahman. The path of truth is the path of verification. Nothing has to be accepted as truth without verification.

The Guru is useless so long as the ultimate truth is unknown, and the guru is equally useless when the ultimate truth or Brahman has already been known. A guru is needed in the religious and yogic path.  There is no need for a guru to acquire Self-knowledge.

That is why Sage Sankara himself says:~ VC- 59. The study of the Scriptures is useless so long as the highest Truth is unknown, and it is equally useless when the highest Truth has already been known.

60. The Scriptures consisting of many words are a dense forest that merely causes the mind to ramble. Hence, men of wisdom should earnestly set about knowing the true nature of the Self.

61. For one who has been bitten by the serpent of Ignorance, the only remedy is the knowledge of Brahman. Of what avail are the Vedas and (other) Scriptures, Mantras (sacred formulae), and medicines to such a one?

62. A disease does not leave off if one simply utters the name of the medicine, without taking it; (similarly) without direct realization one cannot be liberated by the mere utterance of the word Brahman.

63. 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.

Self-Knowledge or Brahma Gnana or Atma Gnana is achievable without the grace of any physical guru or the conceptual God or the mercy of some Godmen. The seeker has to wake up to reality, which is the formless substance and witness of the unreality (universe).

At the end of the quest, the seeker becomes aware of the fact that the true self is the soul or consciousness.  There is nothing that exists other than consciousness. Thus,  the soul, which is present in the form of consciousness is the ultimate reality or Brahman or God in truth.

The Soul, the Self is being identified by another name "Nothingness", because truly if there was Nothingness in the end, there must be one "final witness" to that Nothingness.:~Santthosh Kumaar