 Śaṅkara views witnessing consciousness as invariable despite the fluctuations of mental modes. One foundational argument for this is his analysis of waking, dreaming, and deep dreamless sleep states based on the Bṛhadāraṇyaka and Māṇḍūkya Upaniṣads. He considers these three mental states as exhaustive of human experience, and claims that consciousness persists constantly through all three despite their mutual exclusivity. When awakening from a dream state, though the dream world and dream body discontinue, there is no rupture to the continuity of one’s consciousness. Consciousness continues seamlessly even in deep dreamless sleep where ego and agency resolve into an unmanifest state and subject-object distinctions collapse.