As was mentioned in the previous post, Reverend Hale visits John Proctor's home to gather additional evidence that suggests witchcraft is present throughout Salem's community. To ensure that the Proctors are upright Christians, he asks Elizabeth and John if they can recite the Ten Commandments. John Proctor is able to name nine of the commandments but forgets the commandment forbidding adultery. While John is attempting to remember the last commandment, Elizabeth intervenes and says, "Adultery, John" (Miller, 67). Proctor forgetting the commandment regarding infidelity is significant because it represents his affair with Abigail Williams. John Proctor's marriage is struggling because of his infidelity, and he feels extremely guilty for his past sin. Even though Elizabeth gently reminds her husband of the commandment dealing with adultery, she has been unwilling to forgive John for his affair with Abigail. Proctor's inability to remember the last commandment relates to his affair with Abigail Williams.
At the point where Elizabeth says this, John Proctor has just recited the Ten Commandments at the request of Reverand John Hale. The only problem is that he has recited one of them twice and the ironic thing is that he has forgotten to mention the one commandment - "Thou Shalt not commit adultery" - that he has borken when he had the affair with Abigail Williams. Elizabeth mentions this line as gently as she can to remind John of his infidelity to her and that he has done a great wrong by her.