The Mahavakya 'Tat Tvam Asi' (That Thou Art) is one of the four great Upanishadic declarations, first appearing in the Chandogya Upanishad (6.8.7) where the sage Uddalaka Aruni instructs his son Shvetaketu on the identity of the individual self (Atman) with the ultimate reality (Brahman). This dhyana mantra is a contemplative formulation used in Advaita Vedanta and certain Tantric traditions to internalize this non-dual truth. The mantra consists of three Sanskrit words: 'Tat' (That, referring to Brahman), 'Tvam' (Thou, the individual self), and 'Asi' (Art, indicating identity).
Phonetically, 'Tat' contains the dental 't' and short 'a', evoking stability and transcendence; 'Tvam' combines the labial 'v' and nasal 'm', suggesting immanence and inwardness; 'Asi' ends with the sibilant 's' and short 'i', conveying direct realization. According to the Advaita tradition, as expounded in Shankara's commentaries, the purpose of this mantra is to remove the ignorance that veils the unity of Atman and Brahman, leading to liberation (moksha). The Mantra-Yoga-Samhita prescribes its repetition during meditation on the non-dual self, ideally at dawn or dusk in a quiet space, with a count of 108 or 1008 repetitions using a rudraksha mala.
The Devi Mahatmya, while focused on the Goddess, also acknowledges the power of such Mahavakyas in destroying the ego. Practitioners are advised to approach this mantra with a qualified guru, as its contemplation can destabilize conventional identity and requires proper guidance. No specific cautions are given beyond the need for sincerity and purity of intent.
This mantra is not chanted for worldly gains but solely for self-realization, and is often integrated into Vedantic study retreats and satsangs.
That thou art.