To know is not so simple as it sounds. "I know it," people often say, but the reality is different. For example, smokers say they know smoking is harmful for their health. But they do not actually quit smoking. They insist that they know that diligence, frugality, and honesty are important in their lives. However, they do not have the three things in their lives.
To truly know something means that it is a part of yourself as completely as part of the body. All you know must be alive in your words, your actions and your life.