This question is essentially a theme question. So, what are the major themes of Macbeth?
Ambition is the most prominent theme of the play with several characters working to express this theme, including Macbeth and Lady Macbeth.
In Macbeth, ambition conspires with unholy forces to commit evil deeds which, in their turn, generate fear, guilt and still more horrible crimes.
The first act has many moments where ambition and the lust for power are directly discussed.
Guilt and paranoia both become themes (mutual themes) afterDuncan is killed. Macbeth’s encounters with the supernatural figures of the second act reinforce these themes along with Lady Macbeth’s suicide.
Another theme of the play is responsibility, though more interpretation is required to argue for this theme than the others mentioned. The relationship of Macbeth and Lady Macbeth and their roles in the murder create a complex situation of responsibility regardingDuncan’s murder.
Congrats on reading MacBeth (M)-you have joined a v. long line of other scholars who have read and questioned this amazing play. In any work of literature there is never just ONE main idea. Boring! There are many ideas Shakespeare (WS) is putting out there for us to think about. For me the great ideas M offers me to think about are about POWER, GREED, AMBITION, LOYALTY, FRIENDSHIP, and naturally, LOVE...phew...that's enough for this post. Of course for each of these ideas, WS has created characters to 'carry' the ideas and symbols to 'embody' the ideas and metaphors to 'describe' the ideas. Let's look at the theme (idea) of friendship. When you think of your friendships, who pops into your head? Faces of your pals. Then, what about little items you have exchanged - birthday presents, anniversary presents -symbols of friendship right? Then you might think about places you've been together, things you have done together - incidents, events (plot). So, we've got characters in your theme of friendship, symbols and plot. (MY GOD - look at that:your life is a Shakespearean drama! just kidding) Do the same thing with MacBeth - Banquo (B) and M are WS characters in the theme of friendship, so is DUNCAN (D)! M was friends with D (speech inviting him to his house, hints abou inheriting the crown); There are other events and incidents in the plot to prove (develop) the theme of friendship with B - they were soldiers together, fought side by side (battle scene) looked out for each other (witches scene), celebrated victories together - (banquet scene); liked each others' families (banquet scene with Banquo's son present and Lady M) These guys were through a lot together - these guys were tight! So, what's the point WS is making with this theme (idea) of friendship??? Great question: Let's push pause here and consider what WS was all about. For WS humanity, being human, was endlessly fascinating. He would take characters from history (yes, there was a real M and a real D in oldoldold Scotland) and want to figure out what made them tick, he wanted to know what makes all humans tick, what makes them do what they do. What makes a guy kill his best friend +his little boy? What makes a wife LUST for power to the point she has nothing else in her life? What makes a friend turn on his friend who just happens to be the king???? WS was always exploring, wondering about asking about humans and what makes us tick. OK -to theme of friendship: Look what WS has M do with these friendships....throws them away, brutalizes them, even kills his best friends' child! YIKES! What does that theme, those incidents, those symbols (knives, ghosts) tell us about M the man.What does it reveal about his character? It reveals a man easily manipulated (impact of letter from Mrs. M) 'cause he does not have a firm grasp on what is right. It reveals a man who is casually loyal and will turn his back on friends when it suits him (plotting to kill B) It reveals a man who uses friendship for his own ambition-was he friends with Duncan because he truly liked and admired him or because he was going to inherit the crown and his power? The theme of friendship,a major theme explored by WS in MacBeth, allows us to explore the personality of MacBeth,see his motivations and understand that when we give up our friendships for greedy purposes, we are trading our humanity-qualities which makes us human-for something of far less value-fleeting power.