Neti Neti (नेति नेति) is a sanskrit expression which means “not this, not that (न इति न इति)”.
Neti Neti is the method of understanding the nature of the Atman (Self) by negating everything that is not Atman (non-Self).
Non-Self includes physical body, name, wordly titles, senses perception and the obejcts associated with it. When non real is negated what remain is abosulte Atman.
Neti Neti used twice in Brihadaranyaka Upanishad 2.3.6 and 4.5.15
- अथात आदेशः—नेति नेति, न ह्येतस्मादिति नेत्यन्यत्परमस्ति
Now therefore the description (of Brahman): ‘Not this, not this.’ Because there is no other and more appropriate description than this ‘Not this.’
- येनेदं सर्वं विजानाति तं केन विजानीयात्? स एष नेति नेत्यात्मा, अगृह्यो न हि गृह्यते, अशीर्यो न हि शीर्यते, असङ्गो न हि सज्यते, असितो न व्यथते, न रिष्यति; विज्ञातारमरे केन विजानीयात्, इत्युक्तानुशासनासि
Through what should one know that owing to which all this is known? This self is That which has been described as ‘Not this, not this.’ It is imperceptible, for It is never perceived; undecaying, for It never decays; unattached, for It is never attached; unfettered—it never feels pain, and never suffers injury.