Many men through the ages have sought happiness by seeking to obtain earthly riches. Many have even killed in search of gold and precious stones. However, when they obtained these riches, they were still not fulfilled, because real happiness and peace come only by knowing God. When we accept Jesus as our savior and repent of our sins, we are given a peace that passes all understanding. It is a gift of God. The kind of peace and joy that one receives by knowing Him is not based on circumstances, or how much material wealth we might have, or lack of it. It is based on our relationship with Jesus. When we know Him, we have access to all things that we might need in this life.
Verse 18 says that "Wisdom" is a "tree of life" and all that really grab hold of her and keep her will experience a joy and happiness in this life. Since Jesus is ultimate wisdom, we realize as we embrace Him and His ways, we experience His life in all we do. Jesus and His word is that "tree of life." As a tree continues growing, all who commit to the Lord and obey His word will continue to grow in Him.