Quote by Chandogya Upanishad: “Tat tvam asi — That thou art.”

One of the most radical statements in any philosophical tradition: you and the ultimate reality of the universe are not separate. The awareness inside you and the awareness that underlies all existence are the same thing. The boundary between self and cosmos is an illusion.

The Chandogya Upanishad was composed during the late Vedic period in ancient India, when forest sages were beginning to shift philosophical inquiry away from ritual sacrifice toward the nature of consciousness and ultimate reality. This mahavakya — great saying — became one of the pillars of Advaita Vedanta philosophy over the following two millennia.

One of the principal Upanishads of ancient Indian philosophy, believed to have been composed between 800 and 600 BCE during the Vedic period. It contains some of the most important early formulations of Vedantic philosophy, including the mahavakya (great sayings) that became central to Advaita thought. The text is embedded in the Sama Veda tradition.