Acharya Prashant explains that Sanatana Dharma and Vedanta are fundamentally the same, focusing on the relationship between the mind and the timeless truth. He classifies existence into three categories: the timeless (Sanatana), the eternal flow of human tendencies (Shashwat), and the time-bound experiences of the mind. The speaker emphasizes that only the truth is truly Sanatana because it exists beyond the reach of time, concepts, and words. He describes the mind as being in a constant state of flux and restlessness, always seeking something beyond itself to find contentment and peace.