Breakfast with Solomon - Proverbs 9:9
"Give instruction to a wise man and he will be still wiser, teach a righteous man and he will increase his learning."
This is one of the litmus tests of whether you have really arrived at a point of being wise. Are you capable of being corrected and incorporating the correction into your thinking, life, and design?
The word instruction is not in the original Hebrew and so the sentence is really given to a wise man, and he will be still wiser. The verse is in the context of rebuke and reproof so that the translators put the italicized word in to help bring about understanding. The Hebrew word natan is here translated give. What is the wise person given in this proverb? People who are not wise despise this: a set back; a criticism; an obstacle; a difficulty. God gives these sometimes, and only the wise realize that they are gifts.
The New Testament echoes this sentiment in James 1:2,3: Count it all joy my brothers when you encounter trails as they come to test your faith.
The second phrase (teach a righteous person and he will increase in his learning), two ideas are here. Teach means to share new information or new methods. If a person is really righteous, then they can be shown new information or methods, and they will add it to their collective knowledge.
If you try and teach a person who is not righteous, they will often reject the information. Too many men are too proud to really grow from information that was given in a rebuke.
This is evidence that wisdom involves a level of humility; be ready to learn, even if the information comes from an enemy.
When was the last time you paid attention to what a critic was saying? Wise men do.
To be wiser means that one can make better choices and apply the information they have; it is to increase in learning so as to have more information.