In this conversation Poe explains to us the positive value of negative emotions.
Anyone ever tell you "be happier," or "Be more positive," right in the moment when you were frustrated, angry, annoyed, sad? In our culture we have a tendency to teach our friends and children to "bear and forebear" (as the stoics say). When we should wallow and understand.
I'd be willing to bet that the parts of your life where you have grown the most are not happy moments. They are moments of sadness, confusion, tragedy, frustration.
Of course, Poe puts it much more eloquently.