Termed a tragedy of the imagination, the drama of Macbeth reverberates with predictions and with the phantasmagoric, a constantly shifting complex of things seen and unheard. In Act III, Scene 4 when the ghost of Banquo appears to him, Macbeth is greatly disturbed because of his guilt and because he perceives a disturbance in the natural order of things.
Having heard the predictions of the three witches, Macbeth has given credence to their words. In so doing, he acts upon these predictions, but he is ill-equipped for the psychic consequences that come from seeking to rise above his place as a man in the Chain of Being in which the spiritual world is above Man. As a result of Macbeth's tragic overreach in taking upon himself the fulfillment of the prediction that he would become king, he attempts to direct by himself his own fate.
In Act III, Scene 4, the setting of a bounteous, rich, orderly banquet is transformed into a horrible parody of itself by the actions of Macbeth. When he enters the room, feigning that he will "play the humble host" for his honored guests, his imagining that the ghost of Banquo in his place at the banquet table destroys the orderliness of this occasion.
Speaking so that only Macbeth can hear her, Lady Macbeth tells him he is simply seeing the bloody dagger again. In other words, Macbeth is allowing his fears to dominate him.
Macbeth replies that it used to be that when a man was killed, that was the end of him.
...But now they rise again
With twenty mortal murders on their crowns
And push us from our stools. This is more strange
Than such a murder is. (3.4.83-86)
Macbeth is haunted by the ghost of Banquo and greatly disturbed. This scene plays into the Elizabethan belief that ghosts of dead people could return to earth and appear to whomever they wanted. Moreover, ghosts were especially likely to return when they were troubled.
At this point Macbeth's paranoia grows as he fears the appearances from the preternatural world, believing that Banquo's ghost has come back for revenge: "It will have blood, they say: blood will have blood" ( 3.4.128).
In Macbeth, Act 3, Scene 4, Macbeth arrives to join the banquet table, only to see all the seats are full. Lennox points out a seat, saying that it has been reserved for Macbeth. To Macbeth's surprise, the 'empty' seat actually is occupied by the ghost of Banquo.
Macbeth has only just learned that Banquo's murder has been successful. For him suddenly to see the ghost of the man whose murder he arranged startles Macbeth. He suspiciously reacts to the crowd at the table, accusing "which of you have done this?" (48)
Banquo's ghost, however, is not a practical joke or a set up, and Macbeth's guilt at having ordered the man's death overwhelms him. He denies his role to the ghost, "thou canst say I did it; never shake thy gory locks at me" (46). He refuses to take responsibility for his actions, even to the man he condemned to death.
His reactions to the ghost, whom no one else can see, are so bizarre that Lady Macbeth has to pretend he is having a fit, merely to justify his erratic behavior to the dinner guests.