There are quite a few quotes from William Shakespeare's tragic play Macbeth which speak to the imagery of darkness. These quotes are important based upon the fact that the play is a tragedy and that the mood of the play (as determined by the opening scene with the three witches is dark and ominous).
Here are examples from the play which exemplify the imagery of darkness.
1. "Stars, hide your fires." (Act I, Scene iv): In this quote, Macbeth is telling the stars to not shine so that he can do what needs to be done regarding taking the throne of Scotland.
2. "Let not light see my black and deep desires." (Act I, Scene iv): Again, as a continuation of the previous line, Macbeth is going on to state that darkness needs to hide what he is planning to do.
3. "The instruments of darkness tell us truths." (Act I, Scene iii): Here, Banquo is considering the fact that the witches, denoted by "instruments of darkness," are speaking truths (something darkness usually does not do). This speaks to the common appearance of paradoxes throughout the play.
4. "Nor heaven peep through the blanket of the dark." (Act I, Scene v): Here, Lady Macbeth is hoping for darkness to shroud what she, and Macbeth, are about to do (kill Duncan). She does not want anyone, even God, to be able to see their plan.
5. "And yet dark night strangles the travelling lamp." (Act II, Scene iv): Here, Ross is speaking with the Old Man about how dark it is outside. Light is unable to exist because the darkness strangles it. (This is also personification.)