Act 2, Scene 1

Scene I 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 that Macbeth feels as he contemplates the regicide. It "marshal[s] [him] the way [he] was going," leading him toward the bloody deed he has resolved to commit, haunting and perhaps also taunting him (II i 42).