Tat Tvam Asi (Devanagari: तत्त्वमसि, Vedic: tát túvam ási), a Sanskrit phrase, translated variously as "Thou art that," (That thou art, That art thou, You are that, or That you are, or You're it) is one of the Mahāvākyas (Grand Pronouncements) in VedanticSanatana 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, Atman.
Shuddhadvaita - oneness in "essence" between 'tat' and individual self; but 'tat' is the whole and self is a part.
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'.
^Raphael, Edwin (1992). The pathway of non-duality, Advaitavada: an approach to some key-points of Gaudapada's Asparśavāda and Śaṁkara's Advaita Vedanta by means of a series of questions answered by an Asparśin. Iia: Philosophy Series. Motilal Banarsidass. ISBN81-208-0929-7, ISBN978-81-208-0929-1. Source:  (accessed: Tuesday April 27, 2010), p.Back Cover