The Buddha famously held his Silence [Mounam, Avyākṛta, Anirvacaniya] to all questions about the nature of his denouement.

This Unformulated Principle‘ says the Diamond Sutra ‘is Uncontainable and Inexpressible’. [Unformulated Principle‘? Formulation is the essence of Principle. Is that a Self-Negating Expression sneaking by?]

Siddhartha Gautama’s chosen name for himself was not as ‘The Buddha’ [a later appellation] but as the Tát-āgathā [literally, ‘That-Gone’] again, the same Tát [‘That’] of the Rig Veda. And it has the same intent as: Tát Tvam Asi [‘That are’t Thou’].

In the highest tradition of the Buddha-Dharma one does not worship The Buddha, which is easy enough. The struggle is to become a Tat-āgatha.

A Tát-āgathā is one: ‘Entered in Tát’ [‘That’]. It says nothing about any ‘Object’ [such as an imagined ‘That’]. It is all about the Subject. Or rather, the absence of it. 

‘Self’ [‘Thou’] as used in the Upanishads was a mystical term [as in the ‘Subtle Inner Essence’ of the Chandogya]. In the Buddhist Sūtric articulation, it is consistently an empirical one. That is, as an identifiable  Subject in counterpoint to an identified Object. And this tilt is what gives the Buddha-Dharma its special flavor [Anātman].