After a glorious performance in battle, Macbeth encounters three witches who foretell his ascent to the throne. He is immediately consumed by a lust for power, but the rational side of his mind continues to bother him:
‘This supernatural soliciting
Cannot be ill, cannot be good. If ill,
Why hath it given me earnest of success,
Commencing in a truth? I am Thane of Cawdor.
If good, why do I yield to that suggestion
Whose horrid image doth unfix my hair,
And make my seated heart knock at my ribs,
Against the use of nature?’
Clearly, he is at an utter loss. If the prophecies from the witches are evil, why do they begin with the truth that he is Thane of Cawdor? But if they are good, why do they stir a passion within his very soul, achievable only through the most bloody of deeds?[1]
Unable to resolve this seeming contradiction, Macbeth places his full trust in his ambition.
‘Stars, hide your fires;
Let not light see my black and deep desires.’
He even fears to witness what he knows he must do.
‘The eye wink at the hand, yet let that be
Which the eye fears, when it is done, to see.’
Macbeth thus demonstrated a principle Dostoevsky wrote about over a century ago. True, what he wanted to do was wrong. But. When reason fails, the devil helps.
[1] I here refer to the murders Macbeth will have to commit if he is to acquire and maintain the crown. I, of course, do not condone his actions.