You know yourself through your choices.
A Choice implies a thing not chosen.
You know yourself only by distinguishing what you are not.

To "exist" is to "stand out" from a background. “Is” is defined by “not”.

A drop of water does not exist in the ocean; it must stand out from what it is not.
A written word does not exist until a reader distinguishes it from the page.
A signal does not exist until it can be differentiated from noise.

‍Existence extends only as far as Consciousness, for nothing can stand out without its illumination.

‍To recognise yourself is to recognise all that you are not. As you are manifest in your choices, so is all of Existence.