When Paul received an abundance of revelations, having been caught away to the third heaven and to Paradise, God was concerned that he might become proud (2 Cor. 12:1-7). Therefore, Paul was given a thorn in his flesh by a messenger of Satan. This was permitted by God, and it was a real perfection to Paul, who had not yet been purified and could have become proud. Thus, God purified him, perfected him, by an affliction in his body. This is God's economy. Our God is omnipotent, yet for us He has to be very patient and do things slowly.
Second Corinthians 4 tells us that "though our outer man is decaying, yet our inner man is being renewed day by day" (v. 16). Day after day our outer man is decaying, being consumed, and our inner man is being renewed. This indicates that it is not easy for God to renew us. This cannot be accomplished just by our prayer. God needs to use His "therapy" to renew us.
Now we can see the place of the book of Proverbs in God's economy. According to His economy Proverbs should not be used to build up the old man. The big proverbs, like nuggets, and the small ones, like gems, are not for us to build up our old man, to cultivate our self and our natural man. Rather, they are for us to build up our new man. It is for this purpose that they are useful. While we are still living in this body, we need Proverbs to give us instructions on how to live rightly in so many aspects, in order to build up our new man.