In this passage, Miller uses personification and metaphor to convey the chaotic atmosphere in witch-trial-obsessed Salem. Proctor refuses to give Elizabeth up to the investigators who arrive at their house with a warrant for her arrest:
PROCTOR: I'll tell you what's walking Salem—vengeance is walking Salem. We are what we always were in Salem, but now the little crazy children are jangling the keys of the kingdom, and common vengeance writes the law! This warrant's vengeance! I'll not give my wife to vengeance!
The personification of vengeance as an entity that can “walk” through Salem emphasizes the power of the children’s accusations. Proctor describes vengeance as if it has its own agency, separate from the humans feeling the emotion. As such, he is suggesting that the desire for revenge has become a powerful force controlling the town. Proctor—and, he assumes, the other adults in the room—knows that the “witches” accused are really just townsfolk against whom other Salemites want to take revenge. It’s a legal way to get their property (as convicted witches forfeited their possessions to the commonwealth) or to get revenge for perceived slights. The trials are clearly unjust, given the nature of the accusations and the scant “evidence” behind them. This depiction underscores the danger of allowing personal vendettas to dictate justice, as the rational no longer rule Salem.
The metaphor comparing Salem to a “kingdom” makes this criticism seem even more pointed. Massachusetts was still a British colony at this point, so it was actually still a “kingdom” when Proctor and his neighbors lived in Salem. When Proctor states that the "little crazy children are jangling the keys of the kingdom," he implies that Abigail and her friends, who are making baseless accusations, now hold supreme power over the community. This metaphor suggests a reversal of order, where the people least capable of wielding authority are now in control, “jangling the keys of the kingdom.”