In the opening scene, the witches portray evil and supernatural, and say the line “fair is foul, and foul is foul is fair.”
This line means that whatever is considered foul to the normal man is considered fair to the witches and vice versa.
It is from the first scene, where the prophecies were introduced, that we see the nature of evil. Macbeth was the most violent and volatile individual in the play, killing many characters.
Lady Macbeth’s first encounter with the nature of evil is when she was reading Macbeth’s letter – she summons evil spirits and persuades Macbeth to kill King Duncan.
It is at this point where we see some of Macbeth’s conscience and it starts to override his ambition, however, Lady Macbeth still convinces him otherwise.
The witches are portrayed throughout the play as ominous representations of the demon throughout the play, and talk about their evil intentions,
Later in the novel, Macbeth mirrors the words that the witches said in the first scene ‘So foul and fair a day I have not seen.’ This shows that his morality has been corrupted, just like the evil witches.
When Macbeth sees the danger, it shows us as the audience that he is starting to recognize evil, yet his ambition is still leading him to kill Duncan and commit the heinous crime of regicide.
When Macbeth has murdered Duncan, he says: “O horror, horror! Tongue nor heart cannot conceive nor name the” (How true the nature of evil is so ruthless and corrupt that a deed so inconceivable could be committed!).