Individual consciousness evolves by purifying itself from any sense of duality or separate existence. The purification process happens on its own when the mind perceives itself as whole and undifferentiated.
This drastic purification can only take place as awareness is brought into the core of one’s being. In this state of acute awareness there is no longer any sense of an “I-thought” that is perceived as an external object or phenomenon. Therefore the individual no longer experiences itself as separated from the whole of existence. Thus, one is either self-realized or not self-realized.