The revolutionary heart of Advaita is expressed in four Mahavakyas (great statements) from the Upanishads. "Tat Tvam Asi" (Thou art That) from Chandogya Upanishad reveals that your essential self (Atman) is identical with ultimate reality (Brahman). "Aham Brahmasmi" (I am Brahman) from Brihadaranyaka Upanishad is direct declaration of this identity. "Prajnanam Brahma" (Consciousness is Brahman) from Aitareya Upanishad equates pure consciousness with ultimate reality. "Ayam Atma Brahma" (This Self is Brahman) from Mandukya Upanishad identifies the innermost self with the infinite. These are not metaphors or aspirational goals but statements of present fact requiring recognition. The Atman is not a small soul inside you that will merge with a larger Brahman after death—that would still be dualism. Rather, the consciousness reading these words right now, stripped of all limiting adjuncts (upadhis), IS Brahman. Ignorance (avidya) alone creates the appearance of separation. Liberation is not achieving something new but recognizing what always was true.