For Shankara's Advaita Vedanta the supreme truth of the three Hindu canons (the Upanishads, Vedanta Sutra and Bhagvad Gita) is the nondual nature of Brahman, Absolute Spirit that is Reality Itself.
Introduction
Shankara's teaching on the Upanishads, Vedanta (Brahma) Sutra and Bhagavad Gita is the very nondual essence of Vedanta, and a sublime contribution to the world's spiritual literature, and to our nondual Great Wisdom Tradition teaching. Shankara (788-820) was the supreme adept-realizer of the Hindu Upanishadic tradition. In his thirty two years this great master and scholar re-established the authority of the Vedas against the prevailing Buddhist ideology of the time.
For the Advaita Vedanta of Shankara, Brahman is the nondual primordial awareness that is Absolute or Ultimate Consciousness Being Itself, “One, without a second,” without limit, empty of all predicates, attributes and qualities, beyond concept and belief, or any subject-object dualism whatsoever. As we have seen, Shankara refers to this prior unity as Nirguna Brahman, the Absolute. Satchitananda however, is usually understood as Saguna Brahman, Brahman with relative qualities, the Great Love that is being (sat), consciousness (chit) and bliss (ananda). Ishvara (usually as the Trimurti) the primordial creator-God or creative principle of Brahman is also Saguna Brahman, the spacetime limited creator God, the cause of the conditional state of ananda/bliss and the object of the spiritual devotion of the devotee. Nirguna Brahman is pure nondual Being Itself; Saguna Brahman is pure Being in the various states and stages of becoming in spacetime reality. These two Brahmans are not separate entities. These two aspects of the one great Reality, are the ontologically prior union of the dualism of being and becoming, of emptiness and form, of the Two Truths that are one absolute reality with its arising, unfolding relative phenomenal appearances. “The One is. The One is not” (Plato, Parmenides). For Shankara then, Nirguna Brahman is the non-experiential, non-conceptual, uncreated nondual Base in whom arises the always present enlightened, pure luminous witness presence, the bright vidya of the Atman-Self that is only Brahman abiding at the heart of all beings. Saguna Brahman is the yogi's great bliss, bhakti, the joyous experiential state of devotion and compassion to God/Ishvara.
If Saguna Brahman is the bliss of conditional savikalpa samadhi, then Nirguna Brahman is the pure, unelaborated, unconditional Primordial Awareness Itself. This pristine nonconceptual, nondual awareness realization of the vidya-Atman presence of that Absolute Reality is nirvikalpa Samadhi. Then, finally sahaj samadhi, paravidya, the yogi's perfect direct realization, the nondual Primordial Awareness Wisdom (jnana/gnosis) that 'I am Brahman,” Tat tvam ami, That I am! This state is the ontologically prior, essential unity of the nondual supreme source and its bright vidya presence in beings, and Brahman is its ground. As savikalpa, nirvikalpa and sahaj samadhi is stabilized in the lifeworld through the spiritual path of the continuous practice of jnana yoga and the other yogas, the ignorance (avidya) that binds us to the wheel of samsara is replaced with vidya, the enlightenment of liberation from this suffering of karma, then the ...