"a sort of magic circle"
The Magic Circle (1886)
Public DomainThe Magic Circle (1886) - Credit: John William Waterhouse

Before practicing their magical arts, witches are said to create a ritual space for themselves by drawing a magic circle on the ground around them, sometimes marking it out with chalk or salt. The magic circle is supposed to create a portal in which supernatural energies can be concentrated, but it also has a protective function. Witches summoning up dangerous spirits had to remain within the safety of the circle: even flailing an arm outside it laid them vulnerable to the grabbing hands of the demons they had conjured. Magic circles could also be formed by a coven of witches joining hands and dancing around in a ring, focusing their powers at its center. Because of this, it’s equally possible to read into this simile the implication that Hester is a witch or that the townspeople who resolve into a circle are so themselves.