Acharya Prashant addresses the nature of the ultimate truth, asserting that it cannot be a personal opinion or something that varies between individuals. He explains that the truth is beyond words and expressions because every word depends on its opposite, whereas the truth has no opposite and does not change. It is characterized by a deep, unreasonable peace that does not depend on external causes or justifications. This truth is not a conclusion to be reached or a memory to be stored; it is the underlying reality that runs the entire world and is the ultimate aim of all human desires and actions.