"Fair is foul, and foul is fair"(Act I, Scene I).
The witches utter this paradoxical phrase, of which repeats in various forms throughout the play. This is an introduction the theme of equivocation. It suggests that things may not always be as they seem, and foreshadows the deceit that will take place. "If chance will have me king, why, chance may crown me" (Act I, Scene III).
This quote illustrates Macbeth’s ambition, which is immediately stirred after he discovers he has been given the title of Thane of Cawdor. This unchecked ambitions and desire for power corrupts Macbeth’s mind, as he contemplates committing ill against the king.
“Unsex me here, And fill me from the crown to the toe top-full of direst cruelty” (Act I, scene V)
The idea of masculinity, as strong and hard-hearted is conveyed throughout Macbeth. Lady Macbeth calls upon a divine power to remove all womanly compassion that may have existed within her, giving her the malice of a man. This portrays the belief of the time that a woman could not be so cruel as to commit murder, as well indicating Lady Macbeth’s expectations of her husband.
"Yet do I fear thy nature; it is too full o' the milk of human kindness." (Act I, Scene V)
Lady Macbeth fears that her husband lacks a callous brutality, of which she deems a significant attribute of a man. She expresses her belief of women being compassionate, and kind-hearted. In the following scenes, Lady Macbeth uses this common belief to challenge Macbeth’s masculinity.
"Look like the innocent flower, but be the serpent under 't." (Act I, Scene V)
As Lady Macbeth tries to convince Macbeth to murder Duncan, she advises him to act guiltless. Deceit and the idea of concealing one’s intent under a mask of goodness are common themes that take place throughout the play, as Macbeth and Lady Macbeth use malevolence to rise to power.
If it were done when ’tis done... that but this blow might...