Macbeth: 'Out, out, brief candle! Life's but a walking shadow, a poor player that struts and frets his hour upon the stage. And then is heard no more: it is a tale told by an idiot, full of sound and fury, signifying nothing.'
Uses a metaphor to compare the length of life to the briefness of a candle's burn time
Highlights the theme of mortality because Macbeth's ambition makes him feel empty and realize that everything that happens in life leads to nothing and has no meaning
Highlights the theme of guilt and the consequences of unnatural actions because it underscores the destructive impact of ambition and the destruction of Lady Macbeth's mind
Lady Macbeth: 'Come, you spirits that tend on mortal thoughts, unsex me here, and fill me from the crown to the toe top-full of direst cruelty. Make thick my blood.'