Most events in this scene occur past midnight. The moon and stars have all set, signaling the end of King Duncan’s reign. The mood is tense and suspenseful. Banquo has obsessed and fretful over the witches’ prophecies. His nerves are so on edge that he almost draws his sword when an intruder startles him. The intruder is Macbeth, and had Banquo drawn his sword, the ramifications would have been devastating because Macbeth would have thought that Banquo wanted him dead. Unlike the audience, Banquo is not aware of Macbeth’s intention to murder King Duncan. This is one of several instances of dramatic irony throughout the play.
In all of Shakespeare’s works, Macbeth’s dagger speech remains one of the most famous. It is a scintillating display of stage psychology. Its nature and flow showcase Macbeth’s mental disturbances that permeate the play. It also intensifies the play’s suspenseful mood, which Macbeth reinforces when he says, “I see thee still… I see thee yet… I see thee still!” Moreover, Macbeth experiences a disconnect from his body as he prepares to murder King Duncan. “Mine eyes,” he says, “are made the fools of the other senses.” He goes on: “It is the bloody business which informs thus to mine eyes.” Macbeth knows what he is about to do is wrong, ugly, and heinous. However, he also knows King Duncan’s murder is inevitable.
In the time that has passed since he heard the witches’ prophecy, Macbeth’s eagerness to occupy the throne has increased. As the scene goes on, Macbeth sees himself as King Duncan’s murderer. Macbeth has a vision of himself taking the stairs to the king's chamber to kill him. Macbeth’s disposition parallels his tone, revealing his ruthless and malevolent side. He no longer fears taking another person’s life. Macbeth’s final line makes clear Shakespeare’s distinction between speech and action. Although many people do not always do what they say, Macbeth has become determined to follow through on his speech. He evolves from a mindset of hesitant ambition to coldblooded murder.