Acharya Prashant explores the fundamental question of identity by establishing a simple criterion: whatever is acquired from the outside cannot be the self. He illustrates this by pointing out that clothes, wristwatches, and even surgically implanted medical devices like pacemakers are external to one's true being. He extends this logic to the physical body, noting that it is built from food, water, and air sourced externally, and even its biological functions and features are not decided by the individual. Similarly, names, religions, and societal roles are all given by external sources and therefore do not constitute the core of who one is.