In a keeping with the view that Shakespeare harbored a sympathetic attitude to Catholic ways of seeing, this essay argues that Macbeth is a study in the dangers of oversimplification and certainty. In contradistinction to how Spenser’s Redcrosse Knight escapes the Cave of Despaire, Macbeth would benefit greatly from probing, questioning, nuancing, and sifting through ambiguity. He needs to examine the particular attenuation of his own moral thinking, and needs to engage equivocation, in the forms of both amphibology and mental reservation.