Homesick light

静夜思 "Night Thoughts"
作者：李白 Author: Li Bai

床前明月光 A bed, I see a silver light,
疑是地上霜 I wonder if it's frost aground.
举头望明月 Looking up, I find the moon bright;
低头思故乡 Bowing, in homesickness I'm drowned.

"Night Thoughts" is a famous Chinese poetry by Li Bai.
The poetry talks about the emotion of homesickness: the light from the moon makes the author feeling lonely in a strange place.

"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)