In William Shakespeare's Macbeth, there are three key factors that contribute to Macbeth's downfall. These factors are the prediction foretold by the 3 witches to Macbeth, Lady Macbeth's strong influence over her husband and, most important of all, Macbeth's ambition and hunger for power which all lead him down to despair and ultimately death. These three factors have one root - evil.
At the very beginning of the play, Macbeth is portrayed as a brave and honest soldier to the audience, and his character is seen as one of goodness and righteousness. They see him as a courageous, loyal and chivalrous subject of the king.
"...brave Macbeth - well he deserves that name..." [I, ii, 16]
What they don't see, however, are the flaws in his character. Macbeth, though basically a good man, is also extremely ambitious, weak and has a tendency to self-doubt. Though overall we see Macbeth as an "evil" character, he is set apart from other villains because he is consummated by evil rather than being truly evil, and this is shown mainly in the first Act of the play.
Macbeth's praiseworthy reputation is maintained until he comes across the three witches. The witches represent supernatural evil in the play. They predict of Macbeth not only becoming Thane of Cawdor, but also King of Scotland.
"All hail, Macbeth! hail to thee, Thane of Cawdor!" [I, iii, 49] ~ Second Witch
"All hail, Macbeth! that shalt be King hereafter." [I, iii, 50] ~ Third Witch
Not only does Macbeth dwell on the idea that he may become king, but his thoughts are also driven to the idea of how he might get there and he wonders about his future. Soon after his meeting with the witches, Macbeth is honoured with the title of Thane of Cawdor,