The Chandogya Upanishad's great teacher, whose lessons to his son Shvetaketu — using a banyan seed and a pinch of salt in water — remain among the tradition's clearest teachings on the nature of the self.
उपनिषद काल · Upanishadic era
Uddalaka is described guiding his son Shvetaketu back to a humbler starting point after the young man returned home from years of Vedic study proud of his learning but, his father found, missing its essential point.
His teaching culminates in the phrase 'tat tvam asi,' thou art that, repeated across the Chandogya Upanishad's ninth chapter as a direct pointer to the identity of the individual self (atman) with the universal reality (Brahman) — one of the four mahavakyas, great sayings, at the heart of Advaita Vedanta.