Verses 1-6 personify wisdom in the figure of a lady preparing a feast and issuing invitations. Verses 13-18 personify folly in the guise of a harlot doing the same thing. The contrasts between these sections are full of nuances. Verses 4 and 16 are almost identical invitations.
In view of what God has revealed so far about wisdom, any person can determine just how wise or how foolish he or she may be. This is not a mystery. It has little to do with intelligence but everything to do with commitment. If a person recognizes divine revelation as such and decides to understand it, submits to it, and lives by it the best he can, he is wise. On the other hand if he rejects God's Word and decides to live his life with no regard to what God has said, he is a fool.