We are not born into the world having a sense of self, it is not innate, but learned through various life experiences and encounters with other people. What does it really mean to know one's self?
In my opinion, it is to know exactly what you stand for, believe in and to have a good understanding about one's own thought processes.
At some point, you get to where you've formed an opinion about yourself that is so solid, you'll never be caught believing the criticisms of those who've constructed nothing.
05.06.14, edited 03.26.18