By this time Macbeth senses that the witches' prediction are legitimate, however he feels a disastrous downfall. He perceives this way because he assumed to become king promptly. His high expectations were destroyed. The King's son, Malcolm was appointed heir to the throne. Malcolm had got into the way of Macbeth's ambition to be king. Which shows In act 1 scene 7 when Macbeth is thinking about killing King Duncan he talks about his 'vaulting ambition' in lines 27 - 28: "Vaulting ambition which o'er leaps itself and falls on th'otherâ€¦"/" The Prince of Cumberland, that is a step On which I must fall or else o'er leap". What Macbeth means in this quotation is that his excessive ambition is like a horse that tries to jump too high and falls on the other side of the fence. Macbeth may realise that killing Duncan may be a bit far-fetched and his plan will not work - the audience will find out what he has done if he is to go through with the murder. The second quote shows that, Macbeth already sees Duncan's son as an obstacle to his destiny. Ominously, Macbeth adds "Stars, hid your fires! Let not light see my black and deep desires;" Moreover, this shows how eager Macbeth is to hide his dark and bloody desires and give a face of pleasances.
What Macbeth lacks in decisiveness, Lady Macbeth makes up for in bloodthirsty lust for power and wealth. Swearing off her femininity at the beginning of the play, Lady Macbeth manipulates her husband powerfully to follow through with his plans to kill Duncan. After the act of regicide, it is Lady Macbeth who has the soundness of mind to plant the incriminating evidence on Duncan's guards. And yet, her firmness disintegrates gradually as the play progresses, leading to nightmares that haunt her and ultimately drive her to suicide. In this regard, Lady Macbeth appears to switch characters with Macbeth midway through the play. Although most famous for her cruelty and lines such as "unsex me here," the decline of Lady Macbeth is also of great interest and certainly a mysterious aspect of Macbeth .