Tat Tvam Asi — Thou Art That
The Teaching
"Bring me a fruit of the Nyagrodha tree." "Here it is, Sir." "Break it." "It is broken, Sir." "What do you see in it?" "Very small seeds, Sir." "Break one of them." "It is broken, Sir." "What do you see in it?" "Nothing, Sir."
Then his father said: "My son, that subtle essence which you do not perceive there — in that very essence stands the being of this great tree. That is the True. That is the Self. That is Brahman. And thou, Shvetaketu, art That — Tat Tvam Asi."
Commentary
Tat Tvam Asi, Thou Art That, is one of the four Mahavakyas, the Great Sayings of the Upanishads. It is the direct assertion that the individual self (Atman) is identical with the universal ground (Brahman).
When Jesus says 'I and the Father are one' (John 10:30) he is making the same statement. When Al-Hallaj says 'Ana al-Haqq, I am the Truth' he is executed for the same claim.
The tree story is brilliant teaching methodology, showing through the invisible essence of a seed that reality's ground is beyond sensory perception and yet is the very basis of everything perceivable. This is also Meister Eckhart's entire project: to show that the divine ground is identical with the ground of the human soul.