What is the significance of the following quote from "Macbeth"?
(act 3, scene 4)
The time has been/that when the brains were out, the man would die/and there and end/but now they rise again/with twenty mortal murders on their
Macbeth utters these words soon after he has seen Banquo's ghost appear at the banquet table. He is quite aghast because he previously confirmed that Banquo had, indeed, been killed. Seeing his spirit is therefore quite disturbing.
The scene is important for a number of reasons. Firstly, it conveys the depth of malice to which Macbeth has sunk—he has had his closest ally and friend murdered because he saw Banquo as a threat. In the second place, it reflects the depth of his guilt. Macbeth is obviously overwhelmed by the magnitude of his evil deed. This is reflected in his earlier statement when he tells the phantom:
Thou canst not say I did it: never shake
Thy gory locks at me.
Added to that, the manifestation ties in with the theme of appearance and reality. Macbeth has been guided by the witches, and, unbeknownst to him, their predictions are not what they seem. The witches have been using paradox and equivocation in their speeches, intentionally misleading him to fulfill their malice. They are servants of evil and have been guiding him toward not only his own destruction but also that of Scotland. Their sole desire is to sow discord and overturn the natural order of things, and they have succeeded most effectively thus far.
The incident also emphasizes the presence and power of the supernatural as another important element in the play. It foreshadows a later event in which the appearance of spirits plays an important role, as when the evil sisters introduce a number of apparitions to strengthen Macbeth's belief that he is invincible. It is this belief that leads him to commit further atrocities and culminates in his death at the hands of Macduff.
Macbeth pays a heavy price for his gullibility and ambition. In the end he loses everything he so maliciously tries to gain.
Macbeth is at the banquet and he has just seen the ghost of Banquo. He is perturbed because, he says, it used to be that when you killed a man, he would just die, and that would be the end of it. This is significant in part because it is Macbeth's guilt that makes Banquo's ghost appear. In the past, Macbeth killed only for his country and had no reason to feel guilty.