The 'I am' is the essence of the five elements and three qualities that make up the body and mind and all these are unreal. Why are they unreal? Because they are interdependent, constantly changing and the real is not dependent and never changes. This essential knowledge 'I am' has become a root habit with you and misled you into believing that you are a person with a body born in this world who will die one day. This root habit has got so deeply ingrained into you that it is very difficult to disbelieve it.