"The night is long which never finds the day"

John Singer Sargent, "Ellen Terry in the role of Lady Macbeth" (detail), 1889Tate, London

Metaphors of light and darkness are used in Macbeth by William Shakespeare to illustrate important themes such as evil and dishonest gain.

For example, Shakespeare uses the metaphor of darkness to illustrate Macbeth's slide towards depravity. He cannot face his deeds but needs the dark to hide what he is doing:

  Stars, hide your fires

  Let not light see my black and deep desires

  (i.iv.50-51)