"The lips of the wise spread knowledge, but the hearts of fools are not so"
This is another proverb on the observable theme of speech. Verse after verse in Proverbs 15 is about the tongue, the lips, prayer, speech, etc. This chapter could be called “How to Handle Your Tongue” and is the positive counterpart to James, Chapter 2.
It may look like the foolish – those who are selfish, impulsive, and rebellious – are constantly spewing out a stream of information bits and opinions but it is not knowledge. In fact, it is the exact opposite; it is how to mess up your life.
Notice the contrast between the lips of the wise and the hearts of fools. Now this contrast could be in at least three directions:
First: That the wise speak wise things and the foolish do not. It only appears to be wise but is really damaging opinions and falsehoods.
Second: The contrast could be that the speech of a wise person is interspersed with wisdom and should be followed carefully, while the foolish person hides in their heart whatever true knowledge they have in order to use it for their own advantage.
Third: The contrast could be the heart of the fool has no knowledge but are actually cooking up more foolishness and, therefore, in the core of the fool’s being there is not wisdom but an ever increasing amount of foolishness, while the wise person actually has enough wisdom that it is put into play in their life and is spread to others.
The wise want other people to hear and understand wisdom. They try and share information, data, and skills that will help others.