This paper argues that the witches in "Macbeth" are diabolical beings who possess humans. The paper suggests that the characters in the play unconsciously echo the witches in the beginning, though not one of the characters had actually met the witches, suggesting something a little deeper than the average witchery that people think happened in "Macbeth".
From the Paper:
"William C. Carroll's description of the witches in his introduction to Macbeth is that of "malevolent external figures" (Carroll 2) who "symbolize the dark inner mental state of Macbeth himself" (2). The key point in Carroll's argument to be made is that while the witches can influence Macbeth's actions, they cannot compel him to commit evil deeds. The witches represent the dark powers that have the ability to influence men's decisions, but, more importantly, they are an outward representation of Macbeth's inner evil. It is this evilness and greed within his own human nature that persuades him, rather than it being the fate of the witches. The witches represent what Macbeth has hidden inside himself. He has already contemplated killing Duncan, but the witches have given Macbeth a motive for committing the murder."