I Don't Know Anything About It... But I Will.
In the "Longstreet" television series that Bruce Lee starred in (as well as co-wrote with his student, screenwriter Stirling Silliphant), Longstreet, a blind insurance investigator, approaches Lee's character to teach him martial arts after Lee rescues him while he is being beaten up by some hoods. Lee initially refuses, and when pressed as to why not, tells Longstreet, "I don't believe in system, mister Longstreet, nor in method. And without system or method, what's to teach?" When Longstreet responds with, "But you weren't born knowing how to take apart three men in a matter of seconds", Lee replies, "True, but I found the cause of my ignorance."
Some people might mistakenly think that Lee was telling longstreet that he was ignorant, but that's not the case at all. The point Lee was making is that while at one time he himself was ignorant about the subject of fighting and how to protect himself, he corrected the situation and eradicated his ignorance.
Ignorance of any kind can restrict our personal growth and limit us. "Finding the cause of your ignorance" simply means developing the necessary sensitivity to become aware of those things of which we're presently unaware of or currently lacking knowledge about which might be hindering our personal growth, and figuring out what can be done to help us improve in those areas. This could relate to anything. For instance, for a martial artist it might mean learning about a particular aspect of combat that he currently knows little or nothing about.
Many people confuse the word 'ignorant' with 'stupid', but they are not at all the same. The word 'ignorant' is defined as, "Having little knowledge, education, or experience... lacking knowledge." We're all ignorant in different areas. I myself could be considered ignorant when it comes to subject of auto mechanics due to the fact that I possess very little knowledge about the subject (It's important to recognize that each of us will be ignorant in some things, and that it's neither possible nor necessary to learn everything about everything).
Unfortunately, some people are ignorant about being ignorant, which is the biggest barrier of all. In addition, there are some individuals in the world who seem to prefer to live in a state of perpetual ignorance. To them, as the old saying goes, "Ignorance is bliss." But ignorance only breeds more ignorance and creates a vicious cycle. Furthermore, such an attitude can be incredibly dangerous. Ignorance can breed fear, which in turn can breed hatred, jealous, prejudice, conflict, etc. Take a look around the world at the current conflicts and see how many people are being led down the path of destrction by manipulative politicians and religious charlatains who prey upon their ignorance.
What does this have to do with you? Perhaps you currently lack the requisite knowledge or skills to do something or get the type of job you would like. Or perhaps your lack of inter-personal realtionship skills is making it difficult for you to interact effectively with other people. Whatever the case may be, if you wish to discover and actualize your full potential, you need to find and eradicate any such ignorance through education and self-knowledge.
Reflect on whatever it is you aspire to do or be and ask yourself, "What is it that I am ignorant of at this moment that might be holding me back or blocking my path to attaining it?" Find the areas of yourself that need to be developed and put in the time and energy necessary to develop them. Commit yourself to personal growth and do the homework required for personal cultivation. Open your eyes to things; read, study, experience, think. If need be, shift your perception so that as opposed to being pissed off or frustrated by your ignorance, you instead realize, "Wow, I don't know about this right now, but I'm going to learn about it and, by the time I'm done, I'm really going to understand and do something great!"