Incompetence is certainty in ...

Incompetence is certainty in the absence of expertise.  Overconfidence is certainty in the presence of expertise.
Incompetence is certainty in the absence of expertise. Overconfidence is certainty in the presence of expertise.

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I was constantly told and challenged to live my life as a warrior. As a warrior, you assume responsibility for yourself. The warrior humbles himself. And the warrior learns the power of giving.
 Billy Mills
A warrior takes responsibility for his acts, for the most trivial of acts. An average man acts out his thoughts, and never takes responsibility for what he does.
The fixed determination to have acquired the warrior soul, to either conquer or perish with honor, is the secret of victory.
 George S. Patton
I developed the concept of the Happy Warrior as a rallying cry for those of us who want to restore America to its great foundational principles: individual freedom, personal responsibility, fiscal restraint, and economic liberty.
 Monica Crowley
See first with your mind, then with your eyes, and finally with your body.
 Yagyu Munenori

Quotes from the same author

My writing model is my mother, who is a writer as well. She always valued clarity and simplicity above all else. If someone doesn't understand what you're writing, then everything else you do is superfluous. Irrelevant. If any thoughtful, curious reader finds what I do impenetrable, I've failed.
We vary greatly in the natural advantages that we've been given. The world's not fair
We sometimes think of being good at mathematics as an innate ability. You either have "it" or you don't. But to Schoenfeld, it's not so much ability as attitude. You master mathematics if you are willing to try.
That fundamentally undermines your ability to access the best part of your instincts. So my advice to those people would be stop thinking and introspecting so much and do a little more acting.
You need to have the ability to gracefully navigate the world.