Actually it means most people don't know their own faults.
Frederick Douglas would rather that people treat him with contempt than conforming to other's desires, thus betraying himself and his values. This shows that he wants to be true to himself, and in a world where other people's opinions matter more than your own, that is a very bold statement. Some people have beliefs that are very valuable to them, yet they consider abandoning them for the sake of popularity or preventing ridicule.
The style that focused on heroic and mythological stories was The Grand Manner.
