When a person begins to feel as if they have reached the wisest point in their life, this is perhaps the most ideal time for them to ponder over the words written in wisdom quotes. While a person does gain knowledge as more facts accumulate in their mind, the wise words of another can give them what is needed to apply it to different situations that arise in life. When times of trouble and confusion become overwhelming and too much to bear, a quote that is written from someone else's experience of the same situation can provide a new perspective.
Reference.com Definition of Wisdom
Wisdom on Wikipedia.org