Yes, it is essential to know thyself - "gnothi seauton", as the ancient Greek aphorism advises. But it is impossible to know thyself. You can never be the object of knowing. You are the one that knows. You are the eye that sees. Thus knowing thyself is knowing without the separate knower and the known. It is about transcending the dualism of subject and object.
You are not a noun. You are a verb. You are knowing. You are feeling. You are not-knowing. You are no-thing.
You are the moment that arises now. You are the awareness within which this moment arises. You are the "I am" that witnesses this moment as it is.
(photo Sannastinoja, Mikkeli Finland 28.10.2013)