act 5 nature

 scene 6 line 33
I looked toward Birnam, and anon, methought, the woods began to move.  Messanger
they where camoed in the forest and it seemed to be mouving

scene 6 line 49
I'gin to be aweary of the sun, and wish the estate of the world were now undone. Ring the alarum bell! Blow wind, come wrack! At least we'll die with harness on our back.  Macbeth
Compares the situation with nature.