In Act 3, scene 4, the ghost of Banquo appears to Macbeth at his banquet.
Ironically, at that moment that the ghost appears, Macbeth is telling the other lords who are present that he is sorry that Banquo has not arrived. The lord, Ross, says:
“His absence, sir,
Lays blame upon his promise,”
suggesting that only Banquo is to blame for his absence, whereas the audience knows that Macbeth is the one who should be blamed, as he was the one who ordered Banquo’s murder. Shakespeare uses this dramatic irony in order to show the lords’ ignorance of the King and Queen’s unholy doings, which is a contrast to later in the play, when most of the lords (including those present at this scene’s banquet) know that it is Macbeth who has ‘broken his promise.’ Whilst, Ross was merely referring to Banquo’s promise to dine, Macbeth, as King, made a promise to serve his country and his subjects, but instead, has resorted to killing them so that he has a better life.
When Banquo appears, the tension starts to build as Macbeth is confronted by what he has done; the audience may start to wonder how long Macbeth can continue lying about King Duncan’s murder, and whether Macbeth’s actions will be the undoing of his mind. This is further shown in scene 2 of Act 3, when he begins to fear anyone who could be in his way. Shakespeare, once again, uses the metaphor of a snake; instead, this time it is Macbeth’s enemies (Banquo and Fleance) who are the snake, and not Macbeth himself. Macbeth says, “We have scorched the snake, not killed it:” when he is referring to his be troubles involving Banquo and Fleance. The tables have turned as Macbeth is worrying that the nobles who seem to respect him might be planning his death and downfall, whereas beforehand, he himself was making the deception of being the “innocent flower”, whilst plotting to kill the previous king. Macbeth feels that he cannot even trust his wife enough to tell her his plans now, even though it was she at first who told him to put on the pretence of being a safe companion for Duncan. In Act 1, scene 5, she says thus:
“ To beguile the time,
Look like the time. Bear welcome in your eye,
Your hand, your tongue: look like the innocent flower
But be the serpent under ‘t.”