What happens to Macbeth in Act 3 and why?
In Act 3 of Macbeth, a change happens which affects the whole course of the play and leads to Macbeth’s downfall. The couple begin to drift apart. Together they have achieved a result:
“Nought’s had, all’s spent.” mourns lady Macbeth.
Macbeth invites Banquo to attend his banquet and elicits the information that Fleance will accompany Banquo on his ride that day. He hides his murderous intentions towards them in pleasantries and tells his wife to pay special attention to Banquo, hinting at bloody deeds to come. Now troubled that things are going too far, she tries to soothe him......
“You must leave this...”
But Macbeth is beginning to slide away from her sphere of influence. The banquet displays, for all to see, the divide between them--and Macbeth’s outer representation of madness. Up until now, the couple have worked as a team albeit with one partner more dominant than the other as Lady Macbeth has been the power behind the throne.
Macbeth’s peace of mind is now destroyed however, and guilt-ridden nightmares have stolen his ability to sleep. The restorative properties of a good night’s sleep can soothe a troubled mind but a person who lacks sleep for long enough will surely lose his sanity: he will lose the power of rational judgement.
It is in this act that we see Macbeth starting to lose his power. After he learns that Banquo died as planned but not Fleance, Macbeth begins to see Banquo's ghost at his banquet table. In addition, Macbeth notices Macduff's absence at the banquet. People are beginning to realize that Macbeth is probably up to something, and that realization doesn't sit well with Macbeth. He decides to again turn to the witches for a prophecy of things to come. Macbeth loses most of his rational reason in this act, something that will eventually lead to his own death.
A lot of things have taken place by the time we come across Macbeth in Act 3. King Duncan has been killed and the prime suspects are his two sons, Donaldbain and Malcolm, who have fled the country. Macbeth had been crowned King of Scotland and the coronation ceremony was held at Scone. Macduff makes no excuse of hiding his doubts about Macbeth's involvement in the sudden change of political standings. Banquo has his suspicions over Macbeth as well, but does not talk to anyone about it. Macbeth decides to kill Banquo and his son Fleance, and he appoints two murderers for this. However the murder does not go as planned, as Fleance flees the scene and is saved, thus giving way to worry in Macbeth's mind.
It is the banquet scene where we finally see Macbeth completely losing control of his emotions and his true sense of purpose. His sub conscience has clearly dominated his conscious mind and making him do and say things that he would later regret. The fear and quilt of his actions take the form of the ghost of Banquo that he sees sitting at the table on which the feat has been laid out to all his quests. Macbeth, unable to tolerate it, starts uttering nonsense and makes a complete fool of himself, so mch so that Lady Macbeth begins to tell the guests that he has had this 'illness' since the beginning, and ultimately asks them to leave for fear of them finding out about their involvement in Duncan's murder.