We generally experience ourselves as our body, life and mind. When we injure our body, we say that we have hurt ourselves. When there are hunger pangs, we say that we are hungry. When we experience an emotion, we say that we have become angry, or are in love, or are feeling lonely or depressed. Rene Descartes famously stated “I think, therefore I am”, showing his sense that he was identified with his mental consciousness. When the body dies, we believe that we die.
The Taittiriya Upanishad goes through an exercise to show us that we are not solely the body, the life-force or the mind, but that these are stages in our self-awareness that lead us eventually, with concentration, to the true causative levels of knowledge and bliss. The Kena Upanishad makes it clear that the powers of body, life and mind, represented by Agni, Vayu and Indra, are not supreme and that their powers are nullified when faced with the Supreme. Yoga texts speak about the separation of Purusha and Prakriti, the witness consciousness and the active nature. Other Upanishads speak of two birds on a common tree, one observing while the other eats of the fruit.
All of these observations are confirmed in the actual experience when an individual slips into the status of the witness himself, and experiences that he can view his body, his life and his mind as something separate and external to him, as if watching a motion picture. The power of detachment from total immersion in the outer, external being represents a stage of the development of consciousness as it prepares to break out of the limits imposed by the ego-consciousness tied to the body-life-mind complex.
Dr. Dalal observes: “(e) In the normal state, consciousness is involved and identified with its instruments — the body, the vital nature and the mind; one feels oneself to be the body, thoughts and feelings. As consciousness evolves, it experiences itself more and more as detached and separate from the outer physical, vital and mental nature. Instead of being identified with the movements of the outer nature, it observes them as a detached witness — Sakshi, to use a term of the Gita.”
Sri Aurobindo writes: “It [consciousness] can be detached, it can be involved. In the human consciousness it is as a rule always involved, but it has developed the power of detaching itself — a thing which the lower creation seems unable to do. As the consciousness develops, this power of detachment also develops.”
Sri Aurobindo and the Mother, Growing Within: The Psychology of Inner Development, Introduction, pg. viii