This quote is a reference to the Salem Witch Trials, an infamous event in early American history in which various women in and around the village of Salem, Massachusetts, were accused of witchcraft. Some of them were executed after being found guilty, though the means and methods by which their guilt was determined were considered suspicious and injust by people even in that time period; for example, some suspects were unable to speak English, which was held against them as a claim that they refused to speak before the court.

An aspect of this story is told in the play "The Crucible", which is a common reading piece in high school literature and may provide further insights into the event.

One distinct takeaway from the trials is that there was almost certainly no actual witchcraft taking place, and the trials were instead the byproduct of family feuds and mass hysteria. However, by giving himself the title "grandmaster of witches", this throws the historical account into confusion - it may be that the Devil is confirming that these women were indeed witches, and the popular understanding of their innocence was the result of the Devil's trickery. It may also mean that the women were indeed innocent, but that the Devil was their "master" in that he ensured they would be executed, if for no other reason than to entertain himself.