The play "Macbeth" gives the audience plenty of opportunities to consider the reasons for the main character's actions. Such as his ambition, which drives him to do things he wouldn't otherwise consider, his wife's help in pushing along his ambition along with his influence by evil forces.
It is clear that at the beginning of the play Macbeth is a brave war hero. We find this out in Act 1 Scene 2 Line 16 and that he is also the king's cousin. Is it possible that he has gotten fed up with simply being a warrior? It's been a question hovering in my mind as to why he would kill his own cousin who has given him many awards already, even when his cousin is the King of his country. If he is gotten fed up with being a warrior, the witch's prophecy of Macbeth going to be king might sound very promising. In Act 1 Scene 3 Macbeth has a great willingness to believe the witches. Macbeth clearly feels that he has to kill Duncan after meeting the witch's. Surely if he believed the witches he would allow fate to take its course. He clearly realizes that killing Duncan is an option. Shakespeare's use of soliloquies to allow us to see this from Macbeth and his other thoughts. During the soliloquies Macbeth talks to himself about what the witch's had to say to him and he debates the need to kill Duncan.
" Present fears Are less than horrible imaginings: My thought, who murder yet is but fantastical, Shakes so my single state of man that function Is smother"d is surmise; and nothing is But what it not. ".
(Act 1 Scene 3 Line 147 - 152).
In Act 1 Scene 4 Macbeth is able to be kind to the King, which is contrary to his up coming betrayal of King Duncan. He admits that he is thinking of murder. In Act 3 Scene 1 Macbeth shows his cold heartiness by setting up the murder of Banquo, and to follow up he ensures the death of Lady MacDuff.
It is also clear to the audience that from the moment Lady Macbeth receives the letter from Macbeth she also begins to plan the murder of Duncan.