Acharya Prashant explains that duality and the perception of 'the other' arise from ignorance. When one realizes the Self, everything is seen as the Self, and there is no room for attachment or grief because there is no 'other' to mourn or desire. He clarifies that as long as one is in a physical body, the eyes will naturally perceive differences like colors and forms. Unity does not mean becoming color-blind or failing to distinguish between objects; rather, it means that these differences no longer hold personal meaning or exert influence over the individual. The world of nature will always contain variety and division, but one must establish themselves in the realm of the non-dual, which is the Self.