John Proctor, one of the protagonists in Arthur Miller's play The Crucible, is able to triumph over evil by the end of the action.
John Proctor is facing multiple evils in the play. First, he has committed adultery with Abigail Williams. John must come to terms with the reality that he must admit to the adulterous affair in order to prove that Abigail is not telling the truth about the accusations against the members of Salem.
Second, John must overcome the fact that the town has, basically, gone mad with accusations of witchcraft. His wife, Elizabeth, has been one of the people accused of witchcraft.
The last thing that John must overcome is the communal idea that the Devil is at work in the community.
In order for him to overcome all of the obstacles that he is facing, John must admit to the affair. By admitting to the affair, John will be able to show Abigail for who she really is--a lying and deceptive woman.
His triumph comes from the fact that he does admit, in court, that he had an affair. After admitting to the affair, John faces the fact that he must sign his name to a document declaring his sins. By refusing to sign the paper, John is able to overcome the power of the theocratic government (combination of church and state). His outright refusal to sign allows him to be true to his heart and show his disdain for the court system.