In Macbeth, Shakespeare uses his considerable genius to express the abhorrent beauty of absolute evil... It's true that lady Macbeth and Macbeth are never more alive than when they contemplate killing the king. They thrill with vitality and excitement. But as soon as they commit the act, they're oppressed with the banality of evil. And I'm not just talking about guilt. To be sure they are both tormented by guilt. But even more afflicting that Macbeth's guilt is his ennui. His awesome will to power, magnificently manifested in Duncan's murder, gives way to an all-consuming listlessness.
He'll murder many more times, but each time it becomes more mechanical, more tiresome, more wearisome. What really wears on Macbeth is the tedium of evil. In his wickedness he cannot find contentment or joy or even desire. There's nothing but this: tomorrow tomorrow and tomorrow creeping at its petty pace to the last syllable of recorded time. And perhaps this is the ultimate truth of the tragedy. When decency and goodwill give way to wickedness and evil, life loses its meaning. It can be no more than a tiresome monotony. A tale told by an idiot, full of sound and fury signifying nothing.
Professor Kent Lehnhof