Macbeth, is a story of a man who's ambitions have brought him to commit treason and murder. Visions of power grew within his head until his thirst for power causes him to lose that very source of his ambition to the blade of Macduff's sword. It is the ironic and symbolic elements such as this in the play which contribute to much of the acceptance the work has enjoyed for centuries.
Three forms of irony may be found in the play, Macbeth: Dramatic irony, being the difference between what the audience knows and what a character knows to be true; Verbal Irony, being a difference between what is said and what is meant; and Situational Irony, a difference between what happens and what is expected to happen. I will attempt to show examples of each of these forms of irony and explain their relevance to the characters and the plot.
There are many examples of dramatic irony in the play which we might discuss. A major example is where Lennox asks Macbeth whether the king is to leave Macbeth's castle for home,
Lennox: "Goes the king hence today?"
Macbeth: "He does: he did appoint so." (II,iii,54-54)
Obviously Macbeth is lying through his teeth, for the audience was fully aware that he planned to murder King Duncan that night. But if one takes Macbeth's reply literally, Duncan did "plan" to leave the castle the next day; there is no lie to be found in that.
One can look back on the porter's hidden truths at the beginning of the scene,
Porter: "Knock, knock! Who's there, i' the other devil's name! Faith, here's an equivocator, that could swear in both the scales against either scale; who committed treason enough for God's sake, yet could not equivocate to heaven: O! come in, equivocator." (II,iii,7-11)
Macbeth is playing the part of the equivocator again; equivocation being a form of double talk in which a remark is considered true if it could be argued as true from one viewpoint.
One of my favorite examples of dramatic irony is the porter scene in Act II,iii because of the hidden truths the stuporous drunk revealed. The porter acts the part of the porter at hell-gate in line 2,
Porter: "If a man were porter of hell-gate, he should have old turning the key."
and continues to dramatize through line 17,
Porter: "But this place is too cold for hell. I'll devil-porter it no further..."
After the king's murder is discovered, it is almost comedic the way Lady Macbeth responds to the announcement of King Duncan's murder. First she enters in mock confusion questioning,
Lady Macbeth: "What's the business, That such a hideous trumpet calls to parley
The sleepers of the house? speak, speak!" (II,iii,84-86)
One can imagine the actor portraying Lady Macbeth embellishing her performance almost to be point at which it might be called over-acting. Then with Macduff's reply refusing to tell her what has happened for "The repetition in a woman's ear Would murder as it fell," one can not help but...