In Advaita Vedānta, ātma-vichāra, or self-inquiry, is presented as a direct means of realizing non-duality by turning attention away from all objects of experience toward the very sense of “I” that knows them. Rather than seeking an intellectual definition of the self, the inquiry “Who am I?” is used to redirect awareness from the changing field of body, senses, thoughts, and emotions back to the subject that witnesses them. As this questioning becomes steady, it exposes how identity has been habitually fastened onto what is impermanent and observable. The method of negation, often expressed as “not this, not this,” is applied to each layer of experience so that whatever can be observed is recognized as not the true Self. In this way, the inquiry gradually loosens the grip of identification with the body, mind, intellect, and ego.

As these false identifications are systematically set aside, what stands revealed is a simple, unchanging awareness that does not come and go with thoughts or states of mind. This is recognized as the witnessing consciousness (sākṣin), the pure “I am” that underlies all experiences yet is not itself an object among them. Advaita Vedānta teaches that this innermost Self (ātman) is not a limited, personal entity but is identical with Brahman, the absolute reality. When this is seen, the apparent division between an individual subject and an external world is understood as a product of ignorance, not an ultimate truth. The realization dawns that the same consciousness that appears as the individual knower is the very ground of all names and forms.

Through sustained ātma-vichāra, the sense of being a separate doer and experiencer gradually dissolves, and experiences are no longer owned by an isolated “I.” The duality of seeker, seeking, and sought is undermined as the source of the “I”-thought is traced back to this ever-present awareness. Non-duality is not attained as something newly produced; rather, it is recognized as what has always been the case once superimposed identities fall away. This direct recognition of ātman as Brahman is what is meant by the great saying “That thou art,” indicating that individual consciousness and universal consciousness are one and the same. In such understanding, the illusion of separation between jīva and Brahman is dispelled, and non-dual reality stands self-evident.