The supernatural in hamlet and macbeth

A.C. Bradley, Shakespearean Tragedy (on the Witches)
Bradley in Shakespearean Tragedy begins his discussion of the Witches in Macbeth by observing that they have a more powerful effect on the imagination of a reader of the play than on a spectator (430, note 6). This sounds surprising at first, since Shakespeare’s plays were certainly not written to be read but to be performed on stage as live public entertainment. But if you are prepared to recognize that the imagination often produces more vivid images and effects than real life (consider, for instance, fear of the dark or sexual fantasies), it does make sense. It is a well-known principle of writing that you can frighten or titillate your reader much more effectively by suggestion than by spelling things out.
Bradley calls the Witches the most potent agency in Macbeth for exciting “the vague fear of hidden forces operating on minds unconscious of their influence” (271), forces that sound very much like the “vaster power” he identifies behind the events in Hamlet. He grants that the Witches’ “contribution to the ‘atmosphere’ of Macbeth can hardly be exaggerated,” but he thinks that they are generally given far too much credit for influencing the action of the play, especially, of course, of Macbeth (271). He also sees a contradiction between the credit the Witches are given for influencing the action and the often-made claim that they are not real beings but “merely symbolic representations of the unconscious or half-conscious guilt in Macbeth himself” (272).
Bradley wants to do two things. He wants to show that although the Witches’ prophecies do influence Macbeth, they are not the decisive influence (any more than Lady Macbeth is [301]), and that the decisive influence comes from within Macbeth himself. Bradley also wants to show that the Witches cannot be taken “merely as symbolical representations of thoughts and desires which have slumbered in Macbeth’s breast and now rise into consciousness and confront him” (275-276). They are an objective outside force that Shakespeare wants the audience to feel combines with forces from inside Macbeth to produce his tragedy.
In showing that the Witches’ prophecies are far from being decisive in influencing Macbeth’s actions, Bradley begins by arguing that although Shakespeare drew on contemporary witch lore like Reginald Scot’s Discoverie of Witchdraft and King James’s Daemonologie for his conception of the Witches, he chose to emphasize only those things that “could touch the imagination with fear, horror, and mysterious attraction,” and disregarded everything else (272). The result is that the Witches are nothing more than “poor and ragged, skinny and hideous,” spiteful old women (272). But while they are old women and “not goddesses, or fates, or, in any way whatever, supernatural beings,” they are old women who “have received from evil spirits certain supernatural powers,” including the power to see into the future (272). They are “instruments of darkness” (273), not darkness themselves.
They can see into the future but, within the world of the play, Bradley argues, what is foreknown is not fixed. That is because, in spite of what Macbeth misleadingly refers to as “supernatural soliciting” (I.3.130), none of the things the Witches foreknow is an action, and the responsibility for the choices that lead to the actions that bring about the fulfilment of the prophecies is entirely Macbeth’s (274, 275). Without Macbeth’s freely-willed choices and actions, “for all that appears, the natural death of an old man might have fulfilled the prophecy any day” (274).
Are the Witches only symbolic representations of the dark side of Macbeth’s soul? Bradley answers no, and for two reasons. First, such an explanation does not match with prophecies that in no way can be thought of as projections of Macbeth’s desires (“shalt be king hereafter!”) or fears (“beware Macduff”), prophecies like the ones about Birnam Wood and “none of woman born” which “answer to nothing inward” (276). Secondly and even more importantly, the creation of a sense of “vaster powers” from outside conspiring with the dark forces operating on Macbeth from within to push him in the direction he takes is essential to the play’s overall tragic effect of fear, horror, and mystery (277). "The words of the Witches are fatal to the hero only because there is in him something which leaps into light at the sound of them; but they are at the same time the witness of forces which never cease to work in the world around him, and, on the instant of his surrender to them, entangle him inextricably in the web of Fate" (277).