In the Upanishadic vision, Ātman is the innermost Self, the true essence of a person that is pure consciousness, eternal, and unchanging. It is distinct from body, senses, mind, and ego, serving as the silent witness of all states of experience. This Self is unborn, undecaying, and immortal, and it represents one’s deepest spiritual identity rather than any passing role or attribute. Described as beyond all change and limitation, Ātman is not something one “has” but what one fundamentally “is” at the most profound level of being.

Brahman, by contrast, is spoken of as the ultimate reality: infinite, eternal, and the ground of the entire universe. It is the absolute, formless, and all-pervading consciousness that underlies and sustains all existence, beyond name, form, and all conceptual categories. This reality is characterized as the unchanging, transcendent source in which all phenomena appear and disappear. Though described in many ways, Brahman is consistently portrayed as the supreme, non-dual reality that is both immanent in the world and beyond it.

The heart of the Upanishadic teaching lies in the recognition that Ātman and Brahman are fundamentally identical. The individual Self is not a separate entity standing over against a cosmic principle; rather, the true Self is non-different from that ultimate reality. Classical declarations such as “Tat tvam asi” (“That thou art”), “Aham Brahmāsmi” (“I am Brahman”), and “Ayam ātmā brahma” (“This Self is Brahman”) give voice to this non-dual insight. What appears as an individual consciousness is, in truth, the one absolute reality manifesting through various forms.

The perceived gap between the individual and the absolute is attributed to ignorance (avidyā), often associated with the power of illusion (māyā), which veils the Self’s real nature and creates the sense of separateness. As long as consciousness is entangled in identification with body, mind, and ego, the unity of Ātman and Brahman remains obscured. Liberation (mokṣa) is described as the direct realization of this unity, a transformative knowledge (jñāna) in which the false identification with the limited self falls away. Through deep inquiry, meditation, and spiritual understanding, the seeker awakens to the fact that the innermost Self has always been none other than Brahman, the one, non-dual reality, and this realization is held to be the highest goal and the end of suffering.