All the scriptures indicate that Atman is Brahman, and Brahman is ultimate truth.

People are ignorant and they are unaware of the reality of their true existence. Man and his experience of universe is simply a mirage created out of   the consciousness.  Consciousness is the innermost Self. On the standpoint of the innermost self , the universe is mere illusion.  thus the illusion is created out of single stuff (consciousness)  therefore no second thing exists other than consciousness. Thus  consciousness is ultimate truth or Brahman.  The ultimate truth is  God.

Mundaka Upanishad:- The rituals and the sacrifices described in the Vedas deal with lower knowledge. The sages ignored these rituals and went in search of higher knowledge. ... Such rituals are unsafe rafts for crossing The sea of samsara, of birth and death. Doomed to shipwreck are those who try to cross The sea of samsara on these poor rafts. Ignorant of their own ignorance, yet wise In their own esteem, these deluded men Proud of their vain learning go round and round Like the blind led by the blind.

All the scriptures indicate that Atman is Brahman, and Brahman is ultimate truth. Therefore the soul, which is present in the form of consciousness, is ultimate truth or Brahman.  Thus to realize the ultimate truth is the prime goal.   A well-directed inquiry, analysis and reasoning will lead one to his non-dual destination. 

Self-Realization is direct realization of the ultimate truth or real god, in contrast with traditional paths, which are indirect. And the other paths cannot lead to the ultimate destination because they are based on the false self, which they hold as real self and false experience as reality. 

Until and unless one overcomes physical shackle it is impossible to understand and assimilate the non-dualistic or Advaitic truth, which is beyond the physical existence or the universe.  Consciousness itself is lord of itself though not of the universe. And having nothing it has all.

Common people and primitive minds fall into faulty thinking through their inherited conditioning , such faulty thinking and reasoning  makes them accept the experience of birth, life and death as reality ; taking what one sees through  the senses  as real, taking what is apparent obvious and superficial as true because it is less troublesome.

Many People adopt the attitude that what   they know is truth. And what others say id false. This attitude makes them not to verify anything other then what they know.   One needs to be rational, not merely logical. Logic is has its value only in physical plane.

As one advances towards spiritual plane he sees the logic underlying experience and becomes more rational. His reasoning is two-fold--implicit and explicit.

There is a need of facts of physical proof in scientific invention, whereas in pursuit of truth the proof has to be grasped mentally and realized.  Therefore, the truth is realized only by few who take this mental pursuit.  “Whatever facts revealed, which is un-contradictable has to be accepted as truth.

The truth based on the formless soul,the innermost self is worthwhile; without it, one has something else, not truth.  Most people refuse to venture into pursuit of truth; because they do not want to go into the root of things.

The seeker of truth has to study, inquire and reason in the beginning of the pursuit of truth, because it is absolutely necessary in pursuit of truth.

One has to know the true self is not physical but the formless spirit.  The spirit or soul or the self is in the form of consciousness. Consciousness gives one the awareness of the three states. 

The ignorance of the true self is the cause of experiencing the duality as reality.  The ignorance vanishes through realization of the true Self, which is the soul or consciousness or spirit. 

The true the Self   does not lie in our body, in our brain, or our ego, but it is the essence of the dual and non-dual experiences, which comes and goes as waking dream and deep sleep.

The Self of all makes the senses flow outward,
Therefore one seeks outside of oneself.
Only the wise, seeking the immortal amidst mortality,
Turn their gaze away from the world
And look inward – to find the Self.

- Katha Upanishad

The individual experience within the dream is reality with in the dream. Therefore waking reality is also is reality within the waking. This waking is parallel dream and dream is parallel waking. Only when self-wakes up in waking the dream becomes unreal. When the self-consciously wakes up in its formless non-dual true nature in the midst of waking experience  then all the three states are  mere mirage created out of its formless soul or consciousness(the innermost self).

The form time and space within the dream are falsehood when waking takes place. Similarly the form, time and space of the waking are also falsehood when wisdom dawns. The wisdom dawns only when one realize the self is neither the waking entity nor the dream entity. Thus it is erroneous to judge and reason and conclude the ultimate truth on the base of waking entity and waking world because waking experience itself is illusion.

Suppose you were holding the same view in the dream, all your experiences and views are reality within the dream. The dream becomes unreal when waking takes place. Similarly the waking becomes unreal when you become aware the fact that, the self is not an individual.  Thus whatever individual experiences experienced within the waking is as unreal as dream.

 Until one thinks body as body and world as world it is impossible to grasp non-dual truth, because his views and judgments are bases on physical self with the physical existence.  The individuality is reality with the waking experience but the waking experience itself is false hood. Thus holding the view as an individual within the false experience is erroneous on the ultimate point of view.  The waking is parallel dream and dream is parallel waking experience.

In waking the universe comes: in deep sleep   the waking goes. In waking is one born; in waking one dies.

In waking one lives, in Waking one suffers. In Waking one earns, in Waking one enjoys. In Waking is one truthful or lies like a liar. In Waking one reflects on Virtue and Sin. In Waking do one lands in Heaven and Hell. In Waking is one happy, in Waking in sorrow. In Waking does one lose the distinctions of caste and creed. In Waking is one wise; in Waking is one unwise.

In Waking one has an urge to know the truth. In Waking one is in the illusion; in Waking is one shadowed by Doubts and confusion, in waking one thinks of reincarnation and rebirth.  In waking one thinks that he is born in this world and world existed prior to him. In waking one is in ignorance of the true self, which is consciousness. If one spots out the true self within the three states, one realizes the way to freedom.

One is in action in Waking. In Waking one is bound by form, time and space. Waking is in the form of mind. Mind appears and disappears as waking or dream.  If there is no mind then there is no waking or dream. Waking or dream is born out of ignorance of the true self. Getting rid of the ignorance through wisdom is   the way to the release. In Waking or dream, one follows the Writ of habit. Waking or dream is a chronic malady; but within it also is its remedy. 

The true Self is not perceptible to the senses. It is perceived by Reason. It is not perceptible as a thing with form and attributes. To those whose attention is fixed on the body and the world, it is very difficult to attain Self-knowledge. It is also very difficult for them to see the consciousness as self. The attention towards the universe (mind) should be lessened by realizing the self is not the body. The attention has to be focused on the formless substance and witness of the universe (mind) should be increased. So long as the attention is directed towards the universe, the experience of birth, life and death will prevail as reality. But when the attention is directed towards the formless substance and witness of the mind, the ignorance vanishes and the sense of reality of the duality will disappear. Then there is unity in diversity.

There are only two mistakes one can make along the road to truth:
not going all the way... and not starting.
— Buddha