The good and evil is part of the falsehood (duality); pure and impure is part of the falsehood (duality). No one can purify another because the duality is itself is impure and duality is created, sustained and finally dissolves as purity, which is the soul or spirit.
When one starts exploring the mystery of the self, he is still mired in habituated patterns. Limited in perception to a world projected by these patterns, he does not and cannot see things as they are because his understanding is based on the false self(waking entity or ego), whereas the truth is based on the formless soul, the innermost self.
The soul is the subject, and mind is an object. When the understanding is based on the object as subject the realizing the truth is impossibility. Object is unreal created out of the formless subject, which is real.
Mind means ignorance. Overcoming the ignorance through wisdom is the aim of the truth seeker. The Gnani is the one who is fully aware of “What is truth?” and “What is untruth?” in the midst of experience of diversity/illusion.
Gnani is fully aware of the fact that the birth, life and death are mere illusion and views all the pain and pleasure of the life as mere illusion.
The waking rise and man and his experience of the world comes into existence and dissolves into nothing in deep sleep. To the Gnani there is no world, no body, and no ego because the mind is mere mirage for Gnani.
There is nothing as sacred of Self-Knowledge. Realization of self-drives way the ignorance. Self-Awareness frees ‘Self’ from the burden and bondage of illusory duality. It is the self that is in illusion. When it becomes aware of its true nature than the universe is mere mirage to the self which is formless and non-dual in its nature. Thus the thoughts and words are part of the illusory existence.
Many spiritual masters say that sticking to "I am" is way out from the physical shackles. But that "I am" itself is creates the prison. The one, which expresses itself as 'I', is not 'I' but it is formless consciousness. Therefore the ‘I’ or ‘I AM’ is not the self. Considering the ‘I’ or ‘I AM as self is erroneous. The self, which is in the form of consciousness cannot be called anything nor approached because it is prior to anything that exists. When the consciousness is the substance of the whole universe and its contents thoughts and words and it is not a thing or entity or identity within the physical existence but it pervades the whole physical existence than it is erroneous to limit the ‘I’ to the physical entity alone.
The existence of the soul, which is the true self has to be, has to be grasped and assimilated.' I or 'I' am is mere expression.
The whole physical existence or universe is an expression. Thus physical existence or universe is mere illusion. The man and his experience of the world and his belief of god are within the illusory expression. The diversity is created out of single substance and knowing that single substance brings unity in diversity in consciousness.
Thus experience of duality is mere illusion. That is mind is an illusion. The one that has this illusion is the consciousness, which is the innermost self.
Therefore it is erroneous to seek truth on the base of 'I' because 'I' is not self. It very much necessary to rectify the seeking base by proper understanding of the fact that ‘I’ or ‘I AM’ is not the self before indulging in the pursuit of truth.
As long as a person has a firm conviction that 'I' is self, he will not be able to understand ,assimilate and realize the non-dualistic or Advaitic truth, Because whatever knowledge one assimilate he assimilates as a person, which adds to his existing accumulated information. Therefore, seeker has to discover the fact that 'I' is not the self but 'I' is the whole universe, which appears in the form of mind. Universe is mere mirage. The duality is experienced only when the universe is present. Thus universe is duality. Consciousness is formless substance and witness of the universe. Thus consciousness is the true self and cause of the universe but it itself is uncaused because no second thing exist other than it.
It is necessary to have firm conviction 'I' is not self but the formless consciousness is the true self. To understand, assimilate and realize the non-dualistic or Advaitic truth.