CHENNAI: Advaita Vedanta posits that there is no fundamental difference between the Absolute Reality (Brahman) and the individual Self (Atman). It is this essential identity that is the crux of the teachings in the Upanishads for their objective is to enable the spiritual seeker to realise His spiritual nature. The essential identity of Brahman and Atman is indicated in the Chandogya Upanishad Mahavakya "Tat tvam asi" (That you are) to show that the Reality behind the entire creation is the same as the Self within the individual.
In his discourse, Sri N.Veezhinathan said man did not realise his essential nature because of ignorance. In the Bhagavad Gita Lord Krishna says, "Knowledge is enveloped with ignorance; hence it is that beings are constantly falling a prey to delusion." While elucidating the Mahavakya Uddalaka Aruni explained to his son Svetaketu how ignorance veils the spiritual nature of the Self with examples. The rivers that merge into the ocean all owe their existence to the ocean (the Sun evaporates the water of the ocean and clouds discharge it as rain, which run as rivers) but they are spoken of as distinct though there is no essential difference (as water) between the rivers and the ocean. So also, an individual identifies himself with the body-mind personality instead of with the Self due to ignorance and thinks he is different from the Reality.
A doubt may arise as to how this manifold universe can manifest from the Absolute, which is described as "subtler than the subtlest." Uddalaka gives the analogy of the tiny seed of a banyan growing into such a big tree. So a spiritual aspirant must have faith in the teaching of the Guru who expounds the spiritual truth, which is subtle. He clarified that the spiritual truth can only be experienced and not taught like other objective sciences by asking Svetaketu to bring some crystals of salt and asked him to drop them into water. The next morning he asked him to take out the salt from the water. When Uddalaka could not, he asked him to taste it and he could taste its salinity. Similarly, he said, Brahman cannot be seen but could be experienced.