There are four clear states of knowledge and understanding in which you can find yourself.
1. You know something and know that you know it.
2. You know something, but you don't know you know it.
3. You don't know something, but you don't know that you don't know it.
4. You don't know something, but you know that you don't know it.
All of us live part of our personal and professional lives in each of there areas at one time or another. They each have their advantages and disadvantages. If you know something and know that you know it you can act with confidence and profit from the experience; however. it is important to not rest in this knowledge as the state of the art will always change, and the rate of change is accelerating daily. People who know a computer program and knows that they know it will be forced to upgrade their skills as new generations of software are developed, or they will be left behind.
All of us from time to time, know something but don't know that we know it. This is caused by a lack of perspective. There is probably a piece of property near where you live that you have driven by countless times. Then, all of a sudden, it becomes extremely valuable and is developed in such a way that the owner or speculator profit greatly. If you will look back at the situation, you may realize that, had you thought about it from a different perspective, you knew - or at least should have known-that that property would increase in value. You simply didn't compile the knowledge in such a way that you could recognize the value and act upon it.
The most dangerous people in the world are those who don't know something but they don't realize that they don't know it. These are the people who go through life and fall into every pitfall and obstacle along the way. They think they know it all, but in reality, they only learn from the mistakes that their ignorance causes them to make. They are over-confident, and you simply can't tell them anything. The best you can do for them is to stand back and help pick them up after the inevitable crash and burn.
The greatest potential is held by those people who don't know something but understand that they don't know it. This is a powerful concept that they can understand that there is something they don't know and recognize that they need to know it. These individuals rarely make mistakes, and they are always growing and developing. The world doesn't belong to them yet, but it probably will someday.
As you go through you day today, act on the things you know and build on the things you don't know.
source: Excerpt from the book "Today's the Day, Jim Stovall, 2007