The second event is when Uddalaka’s distinguished disciple Yājñavalkya, in the Bṛhadāraṇyaka Upaniṣad, lays out a simple algorithmic rule to get to ‘That’. The formula is: ‘It is not this! It is not this!’ [Neti, Neti].
The exact word used is Ātman, a term synonymous with ‘That’ in the verses and related to the English word ‘Animate’: to come alive, [the Latin Anima Mundi]. Ātman is simply ‘That which animates Life’.
What is ‘It’? And why is the Rule repeated twice? The common interpretation is that this was a sweeping rejection of ‘World as Object’ and a relapse to an ‘Inner Self’ in line with the terminus of the Chandogya Upanishad. An emphatic repetition of the Rule in a linear sealing of the formula.
The Rule is not the revelation: ‘I am not this potted plant’. The Rule is about the claimant, the speaker with the revelation: ‘I am not this potted plant’.
The ‘It’ refers to the Subject making the claim. The rule properly interpreted is a self-scuttling circular loop. ‘The Backward Step’ designed to scuttle the presumed Subject and not a forward sweep for locating a new Object [such as an imagined ‘That’].
Used as linear unfolding Yājñavalkya’s Rule has no natural convergence and will enter into an insidious spin. No amount of negating will lead to convergence unless the negating finally turns in on itself. And the reel will spin forever if you don’t at some point see that you are part of the movie.
The formula completes, the circle is rounded only when the aim, act and agent of negation are themselves consumed in full self-scuttle. It is a meta-statement; an assertion about an assertion. Yājñavalkya’s Rule, properly rounded becomes: ‘It is not this! It is not: ‘It is not this!’.
When properly rounded Yājñavalkya’s Rule becomes the first formulated Self-Negating Expression and the earliest definition for the Symbol ‘0’.
But the most accurate articulation of the rounded Yājñavalkya’s Rule appears almost 500 years later in the rightly celebrated Vajrachedika Sūtra, in English, the ‘Diamond’ [or ‘Diamond-Cutter’] Sūtra.
Yājñavalkya has a fairly long list of credits. The earliest implicit reference to the ‘Axioms of ‘Self’. The most compact definition for ‘Not-Two’. And more.
‘Hinduism’ in its original intent is simply the proper unwinding of Yājñavalkya’s Rule [although I see an outraged reaction to that summary]. The first temples weren’t built until well past the 2nd Century, the popular Puranas remained unwritten until the 5th Century, the practice of the domesticated Puja begun even later. See the Posts on Hinduism, the Vedanthins and Yagñá.