Tat Tvam Asi

Tat Tvam Asi (Sanskrit: तत् त्वम् असि or तत्त्वमसि), a Sanskrit sentence, translated variously as "That art thou," "That thou art," "Thou art that," "You are that," or "That you are," is one of the Mahāvākyas (Grand Pronouncements) in Vedantic Sanatana Dharma. It originally occurs in the Chandogya Upanishad 6.8.7, in the dialogue between Uddalaka and his son Śvetaketu; it appears at the end of a section, and is repeated at the end of the subsequent sections as a refrain. The meaning of this saying is that the Self - in its original, pure, primordial state - is wholly or partially identifiable or identical with the Ultimate Reality that is the ground and origin of all phenomena.

Major Vedantic schools offer different interpretations of the phrase:

• Advaita - absolute equality of 'tat', the Ultimate Reality, Brahman, and 'tvam', the Self, Jiva.
• Shuddhadvaita - oneness in "essence" between 'tat' and individual self; but 'tat' is the whole and self is a part.
• Vishishtadvaita - identity of individual self as a part of the whole which is 'tat', Brahman.
• Dvaitadvaita - equal non-difference and difference between the individual self as a part of the whole which is 'tat'.
• Dvaita†† of Madhvacharya - “Sa atmaa-tat tvam asi” in Sanskrit is actually “Sa atma-atat tvam asi” or “Atman, thou art not that”. In refutation of Mayavada (Mayavada sata dushani), text 6, 'tat tvam asi" is translated as "you are a servant of the Supreme (Vishnu)"
• Acintya Bheda Abheda - inconceivable oneness and difference between individual self as a part of the whole which is 'tat'.

††Note: We find pumlinga Sabdās such as Brahman, Ātman, Rājan, Śarman, Varman appearing as Brahmā, Ātmā, Rajā, Varmā, Śarmā in Vishnu Sahasranaamam. Whenever the word "Brahmā" appears, it actually means "Brahman." Similarly, Ātmā means Ātman, Śarmā means Śarman, etc. Even in Sandhya Vandanam, whose mantras are essentially a part of Veda, in the Invocation(Āvāhanam) of Gāyātrī it comes as Brahmaa Śiraha(ब्रह्माशिरः). It does not mean that the mantra means Brahmaa Aśiraha (ब्रह्म+अशिरः); it actually means Brahman Śiraha (ब्रह्मन्+शिरः). Some make such arguments, which are futile, since in the word brahmārpanam, it cannot be split as brahma+ rpanam, but it can only be brahma+ arpanam. One cannot even argue that since rpanam is meaningless, it has to be arpanam. The argument that brahma+arpanam cannot happen is baseless, just as brahma+atat cannot happen is also baseless.