Jeremiah 9:23-24 (NIV)
This is what the Lord says: "Let not the wise man boast of his wisdom or the strong man boast of his strength or the rich man boast of his riches, but let him who boasts boast about this: that he understands and knows me, that I am the Lord, who exercises kindness, justice and righteousness on earth, for in these I delight," declares the Lord.
Men are proud. It is easy to feel pretty good about ourselves when we have plenty of wisdom, strength or riches. If you can put that combination together, the world would say you have arrived. These are all temporary however. To know and understand God, now that's something to talk about! God delights in mercy because he saves undeserving sinners. God delights in justice because he is holy and saved us without compromising his holiness by offering himself as a sacrifice on our behalf. God delights in righteousness because he clothes us with his righteousness. No amount of wisdom, strength or riches can do those things.