The basis of neti-neti is that the true Self, what you truly are, can never be objectified.
You objectify the world - there is the Sun, the moon, the trees, the birds... in fact if we look closely with openness, these "appearances" are merely sensory perceptions. Every single one of them.
You also objectify that body - feet, legs, stomach, hands, arms - these also appear as sensory perceptions - you SEE the body. This is the core of Douglas Harding's message of "Having no head." The body also appears as sensations - feelings - the sensation of legs, the sensation of hunger, breathing, heartbeat... These sensations are what we call "body" - yet that "thing" is only ever a bundle of sensations and appearances of perception.
You also objectify the "mind" - the thoughts, images, music, memories, imagination, reasoning... these all appear TO YOU - you are AWARE OF these "sensations" that are conceptualized as "mind". They are objects - objectified to you - the Subject.
So then what are you? What is knowing these things? Where is that knowing happening? Does that knowing appear as another object? If it did, it would be known again by something, so that isn't it.
Something is knowing all these objects. That "knowingness" is what you are. It's been called "awareness" or "consciousness" but those are just more words. The function is obvious if we just look. It cannot be seen, cannot be objectified, just as the eye cannot see the eye.
That activity or fact of knowing is what you are. That isn't an object. That doesn't suffer. That doesn't require Peace or Love. That isn't subject to coming and going. That is there in the presence or absence of any of these other objects.
True Self is simple yet amazingly it is overlooked in the focus and identification with objects. That presence of knowing is what makes it possible for these words to be read - the very light by which the body itself is known.
The "I AM" of identification arises only ever as an object, coming and going within the never-changing and ever-present presence and function of the Knowingness that is your True Self.