In Arthur Miller's play The Crucible, John Proctor knows he has done wrong by his affair with Abigail Williams, yet he is still trying to blame others for his own actions. He becomes angry with his wife, Elizabeth, claiming that she is judging him and that she needs to learn charity. Instead of accusing him, he says, she should look for the good in him.
Elizabeth counters, “I do not judge you. The magistrate sits in your heart that judges you.” In other words, John's conscience is judging him, and it is yelling, “Guilty! Guilty! Guilty!” John knows exactly what he has done wrong, but he is trying hard to excuse himself and blame Elizabeth. Yet it isn't working, and Elizabeth knows it. John's conscience, that little judge inside of him, is poking at him, and John does not want to acknowledge it.
On another level, Elizabeth may also be referring to God, for he is the one who places people's consciences within their hearts and programs them to know right from wrong, no matter how hard they try to deny it. Some Christian saints and scholars have called the conscience “the little voice of God within.” John is hearing that little voice loud and clear, but he would much rather not, so he begins yelling at Elizabeth to try to drown it out. Of course, he fails.