This came up earlier. I don't know if the Johari window is still taught in introductory psych courses. It's a fairly simple concept.

Imagine a square. In that square is everything there is to know about you.
Imagine a horizontal bar in that square. Above the bar are the things you know about yourself. below that bar are the things you don't know about yourself. There are a million things you don't know about yourself. Some are obvious: how you will act under pressure you have never experienced; things you have never learned to see. Some bring up some deep denial: all the things you think are cool but annoy others; all the times you are playing to an imaginary audience as you interact in life.
Imagine a vertical line in the square. All the things on the left are the things that others know about you. All the things on the right of the line are the things that they do not know. You deeper dreams and fantasies and history and...

It is important to realize that others know things about you that you do not. Who you think we see and who we actually see are not the same and often the person on the outside sees more accurately. the one on the outside doesn't see the voices in our heads making excuses and creating false explanations and rationalizations. They just see what we do.
So the window divides into four quarters, the relative size of each section different for each person:
The things that only we know about ourselves.The things that everyone knows.The things that others know and we do not.The things that no one knows.

On that level, the quest in life is the same: to open the window and see as much about ourselves as possible. We can't see our own blindspots and it is only through friends (or sometimes enemies) that tell us what they see that we get anywhere on our quest.