A Gnani is the one who has that wisdom - hence from his self-analysis and understanding he realizes the non-dual truth – Atman alone is real and the true self is that Atman.
The one who acquired physical based wisdom is called genius, on the base of in physical dimension. The one who acquired self- knowledge or non-dual wisdom is called Gnani, in Spiritual dimension.
It is quite evident that no seeker of truth would conceive of a freedom from experiencing duality as reality without the transcendence of individuality, i.e. giving up the holding the ‘I’ as self. Since everyone is trying to view and judge the truth on the standpoint of the false self, it becomes difficult understand and assimilate the non-dual truth. Non-dual wisdom is not based on the physical experience, because the true self is beyond physical/individual experiences. On the standpoint of the formless soul the innermost self (Atman) all experiences are mere mirage, thus the non -dualistic or Adriatic truth has to be grasped and realized.
How can the ‘I’ know the truth, when ‘I’ itself is false? Since, many teachings hold ‘I’ as self and physical body as false and the world as reality, it becomes very difficult to understand and assimilate the non-dualistic truth. That is why step by step one has to remove all his accumulated ideas and obstacle and move towards his nondual destination. It is easy to assimilate the truth for one who is free from religious/philosophical/yogic/theoretical knowledge.
The Atman only knows the Atman. The Atman is the knower not the known. The physical body and the world are known; therefore they are a mere mirage on the standpoint of Atman as self.
Many people give the impression that "they know the Atman; the Atman exists prior to the body and the universe, thus the knower is apart from the known. But he knower is within the known as its formless substance and it is without the known as its formless witness.
Till one takes the whole known to be Atman the Atman cannot be grasped and realized.
The seeker should take a few moments and think what he states and its implications before saying ‘I’ am Atman or ‘I’ am that, without verifying and assimilating what it is. It is not the man who has to realize the self, but it is the mind that has to realize it is not a man, but it is the spirit.