In class, we discussed the difference between penance and pentinence. In the book, Dimmesdale yells passionately to Hester that he has had enough penance, but has had no pentinence. By "penance", Dimmesdale is referring to self-imposed suffering. We know that this occurs regularly. He even punishes himself physically by whipping himself in secret. However, he also says that there has been no penitence (feeling regret for one's sin(s)). Right now, he doesn't feel as though he feels sorry enough for his sin. I guess that Dimmesdale will only feel as though there has been pentinence after he confesses his wrongdoing publicly.