In Shakespeare's Macbeth, we find that the author masterfully uses the language to bring the audience into the world he creates with words: specifically imagery. Among the other things Shakespeare's imagery creates are the play's realistic characters, the atmosphere (or mood) and a sense of horror.
Imagery is used early on as the Sergeant describes the valiant way Macbeth (and Banquo) performs on the field of battle in the war between Norway and Scotland. In this case, the descriptions present the admirable qualities Macbeth displays before he decides to kill Duncan, the King. In this passage, Macbeth is described as a man who is not worried for his safety, but "hacks" his way through the battle raging around him until he comes face to face with Macdonwald, a Scottish traitor. Without hesitation, he cuts him open and kills him, and then puts the corpse's head on the castle's battlements.
For brave Macbeth—well he deserves that name—
Disdaining fortune, with his brandish'd steel,
Which smoked with bloody execution,(20)
Like valor's minion carved out his passage
Till he faced the slave,
Which ne'er shook hands, nor bade farewell to him,
Till he unseam'd him from the nave to the chaps,
And fix'd his head upon our battlements. (I.ii.18-25)
There are several examples of setting the mood (or creating an atmosphere). One that I enjoy the best is when the disruption of the order of the universe (because of Duncan's murder) becomes obvious to the casual observer—these are signs that God is displeased that the man he ordained to be King has been killed. Strange things begin to occur in nature. First, Ross indicates the occurrence of an eclipse that now darkens the face of the earth during the daytime. The Old Man talks about a role reversal where the prey becomes the hunter:
Even like the deed that's done. On Tuesday last
A falcon towering in her pride of place
Was by a mousing owl hawk'd at and kill'd. (II.iv.12-15)
Ross then reports that the King's horses, generally gentle creatures, "make war on mankind," going crazy, and the Old Man share a rumor he heard that Ross confirms:
And Duncan's horses—a thing most strange and
Beauteous and swift, the minions of their race,
Turn'd wild in nature, broke their stalls, flung out,
Contending ’gainst obedience, as they would make
War with mankind.
’Tis said they eat each other.
They did so, to the amazement of mine eyes
That look'd upon't. (16-24)
These lines show that the world has turned upside down. A strange and eerie mood is set first with the unnatural darkness that rests over the land and then the unnatural behavior not only of wild animals, but of the King's noble horses that have eaten at each other.
Horror is present when Macbeth returns to his bedroom, covered in blood, still holding the murder weapons. His wife tries to calm his rattled nerves, telling him to wash up, and then—seeing the daggers—to return the weapons to the King's rooms; Macbeth is horrified and refuses:
...Why, worthy Thane,
You do unbend your noble strength, to think
So brainsickly of things. Go, get some water
And wash this filthy witness from your hand.
Why did you bring these daggers from the place?
They must lie there. Go carry them, and smear
The sleepy grooms with blood.
I'll go no more:
I am afraid to think what I have done;
Look on't again I dare not. (II.ii.56-66)
Shakespeare artfully uses language to make his play more realistic.