Identify the source of this metaphor.
Input: "All the world's a stage, and all the men and women merely players."
The source of this metaphor is William Shakespeare's play "As You Like It" (Act II, Scene VII).
This metaphor is from a famous saying by William Shakespeare, "All the world's a stage, and all the men and women merely players." It is found in his play, As You Like It, (Act 2, Scene 7).