Acharya Prashant explains the structure of the human mind using a model of four concentric layers. The outermost layer is the conscious mind where thoughts reside, followed by the subconscious mind containing tendencies and habits. The third and deepest layer is the 'I-tendency' or ego, which is synonymous with fear. At the absolute center lies the source, truth, or freedom from all tendencies. He emphasizes that deeper layers always prevail over superficial ones; therefore, intellect and thought, being on the surface, can never defeat fear, which is rooted much deeper in the ego. Only the power of the source or truth, which is deeper than fear, can overcome it through surrender.