Power: Macbeth seeks to become king after the prophecy of the witches and when he is encouraged by his wife Lady Macbeth a quote that shows this is:
"All hail, Macbeth, hail to thee, Thane of Glamis! / All hail, Macbeth, hail to thee, Thane of Cawdor! / All hail, Macbeth, that shalt be king hereafter!" (Act 1, Scene 3)
"Stars, hide your fires; / Let not light see my black and deep desires." (Act 1, Scene 4)
When Macbeth becomes king, he becomes more ruthless to maintain his power. He trades his sense of morality for more power.
"Out, out, brief candle! / Life's but a walking shadow, a poor player / That struts and frets his hour upon the stage / And then is heard no more." (Act 5, Scene 5)