Importance of Kettle

When Reverend Parris discovers his niece, Abigail, and daughter, Betty, dancing in the woods with several other girls and the slave Tituba, Tituba is standing over a boiling kettle. This insinuates a traditional vision of witchcraft, and Abigail is later questioned what was in the kettle and if any creatures were put in it. Abigail admits that a frog leapt in, but of its own accord.