Macbeth's famous soliloquy at the beginning of this act introduces an important theme: visions and hallucinations caused by guilt. The "dagger of the mind" that Macbeth sees is not "ghostly" or supernatural so much as a manifestation of the inner struggle Macbeth feels as he contemplates murdering Duncan. It "[marshals him] the way [he] was going," leading him toward the bloody deed he will do (II.i 50-54). The same can be said for the ghostly voice Macbeth thinks he hears as he kills Duncan as well as the ghostly vision of Banquo at the feast in Act 3. In fact, almost all the supernatural…
