Shakespeare often uses darkness and will frequently set the scene as a dark and stormy night. This depicts that evil happenings are occurring or are about to take place. There are at least three examples of this in "Macbeth". "The night has been unruly: where we lay,/Our chimneys were blown down; and, as they say,/Lamentings heard i' the air; strange screams of death,..." (Act 2 scene 3 line 54-56). "Three score and ten I can remember well;/Within the volume of which time I have seen/Hours of dreadful and things strange, but this sore night/Hath trifled former knowings." (Act 2 scene 4 line 1-4). Both these quotes are talking about the night of Duncan's death. They are showing the comparisons between the natural unruliness and the anomalous disaster. "And yet dark night strangles the travelling lamp." (Act 2 scene 4 line 7) is a metaphor for both the murder of Duncan and the night in which it transpired. A dark and stormy image is also portrayed when pernicious characters (ie. the witches, Macbeth and the murderers) meet.
The witches play a very important role in "Macbeth", as they initiate the evil plot. Even from the prologue we can see the witches are evil. "Fair is foul, and foul is fair:" (Act 1 scene 1 line 11). They uphold their evil status throughout the play although their power is not fully demonstrated until the prophecies come true and also later where they conjure up the three apparitions. The witches are truly evil and love evil for its own self unlike Macbeth. "Spiteful and wrathful; who. as others do,/Loves for his own ends, not