By saying I know the truth; I know Brahman is not wisdom. The Truth is found only in the Unity of understanding that is the knowledge of both the matter and spirit. That is the matter and the spirit, are one in essence. And that essence is spirit, which is present in the form of the Soul or consciousness.
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."
Upanishad's say:~ "He who thinks he knows, does not know." This means that to know anything implies a second, an object of knowledge, hence duality, i.e. no Gnana.
If you know what is this ‘I’? , then you will know the whole truth of the Oneness, which is hidden by the ‘I’. If you know the world which confronts you is nothing but an illusion then there is nothing else is there for you to seek.
Sage Sri, Sankara says you must first know what is before you. If you cannot know that, what else can you know or understand? If you give up the external world in your inquiry, you cannot get the whole truth.
That is why Sage Sri, Sankara says:~ ~ VC 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.
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 comes 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.
66. Therefore the wise should, as in the case of disease and the like, personally strive by all the means in their power to be free from the bondage of repeated births and deaths.
Buddha:~ There are only two mistakes one can make along the road to truth: not going all the way... and not starting
Jesus said: ~ "Know what is in front of your face, and what is hidden from you will be disclosed to you. (THE GOSPEL OF THOMAS- Saying 5)
Jesus said:~"Those who seek should not stop seeking until they find. When they find, they will be disturbed. When they are disturbed, they will marvel, and will reign over all." (Gospel of Thomas 2)
The Soul, is the innermost Self, the Soul is present in the form of the consciousness. The consciousness is the root element of the universe. From the consciousness the universe comes into existence. In the consciousness the universe resides. And into the consciousness the universe is dissolved. The consciousness is the parent of all that is there is.
The sun, the moon, the stars, planets shine because of the Soul or Spirit. The Soul shines and all things else shine as a result. Everything in the universe reflects but that light of the Soul which is present in the form of consciousness. Merely to know the truth is not enough to escape from the tangle of illusion.