 It is as God says, by the prophet Jeremiah in chapter 17, the heart is deceitful above all things and desperately sick who can understand it. So how can we, whose hearts are by nature sick beyond understanding, obtain a righteousness that exceeds that of the Pharisees, that is a righteousness that makes the heart pure? Let us listen to a former Pharisee who exchanged his lacking righteousness with the only kind that gives eternal life.