To understand,  the ability to realize each aspect of a situation and accept it.
Now, do I understand myself?  Does anybody?  No... well, I don't.
I have the ability to confuse myself on levels beyond reach but I grasp the idea of the mystery.
Who am I? Will I be able to ever understand me?
I don't think anybody will ever understand themselves, yet, we still try to, only to cause self destruction.
Self destruction?  You ask wondering how the discovery of oneself can destroy them, but the reality of it all is that somethings should be kept hidden, buried, indiscernible to prevent something disastrous from erupting on the inside of us.
No one understands how dangerous the human mind can be; we are atomic bombs waiting to explode and the detonator would be the discovery of oneself BUT we are forever in the dark... keep it that way.
The key to understanding yourself is realizing you need to remain a mystery.