“A being who is not what he is and is what he is not”

To think you have individual thought is not possible because as a child you learned that this is this and that is that. You were taught that you do not defecate in your pants because you are supposed to use the potty. It is NOT your idea to do so yet you do it every day. On the other hand you do not think yourself to be like someone you despise because they have qualities you don’t have. But at the same time they despise you for despising them, so therefore you have mutual dislike. There for you have similar qualities and are THUS you are alike.

So what you think you ARE, you are not; and what you are NOT is what you truly are.

My attempt at trying to understand the existentialist perspective on the quote in the first line.