RALPH: These witches, who seem to have supernatural powers, have encouraged Macbeth to believe that he’ll become king. You would think that a prediction of becoming king would be a good thing. 

DAVINA: That’s right, Ralph.  But then why would Macbeth’s hair stand on end and his heart start to pound?  One possibility is that it immediately leads him to imagining the killing of Duncan, which is a terrifying thought..

RALPH: As Macbeth puts it: “Present fears are less than horrible imaginings”.

DAVINA: In other words, the real situations we face, no matter how threatening, are not as horrible as the things we can imagine.

RALPH: Macbeth’s “fantasy”, his imaginings of the future, are smothering his ability to function in the present.  As he puts it: “Nothing is, but what is not.”

DAVINA:  The only thing that seems real to him is that horrible thought in his imagination.  And all of the real things around him at that present moment seem not real at all.