Many critics see the parallel between Duncan's death and disorder in nature as an affirmation of the divine right theory of kingship.
As we witness in the play, Macbeth's murder of Duncan and his continued tyranny extends the disorder of the entire country.
We cannot blame him for becoming king (it is his Destiny), but we can blame him for the way in which he chooses to get there (by his own free will).
Kingship and Natural Order is set in a society in which the notion of honor to one's word and loyalty to one's superiors is absolute.
With an unpredictable swing up or down, one could equally easily crash to the base of the wheel. In a fatalistic universe, the length and outcome of one's life (destiny) is predetermined by external forces. The play makes an important distinction: Fate may dictate what will be, but how that destiny comes about is a matter of chance (and, in a Christian world such as Macbeth's) of man's or free will.
Although Macbeth is told he will become king, he is not told how to achieve the position of king: that much is up to him.
Gender Roles Lady Macbeth is the focus of much of the exploration of gender roles in the play.
As Lady Macbeth propels her husband toward committing Duncan's murder, she indicates that she must take on masculine characteristics.
Once the sense of guilt comes home to roost, Lady Macbeth’s sensitivity becomes a weakness, and she is unable to cope.
Significantly, she (apparently) kills herself, signaling her total inability to deal with the legacy of their crimes.