The quote that best illustrates the theme of "The Monkey's Paw" is:
"The first man had his three wishes. Yes," was the reply; "I don't know what the first two were, but the third was for death. That's how I got the paw."
This quote highlights the cautionary nature of the story's theme, which warns about the consequences of tampering with fate and the inherent dangers of wishing for more than one is meant to have. It suggests that while wishes may seem enticing, they can lead to dire outcomes, ultimately showing the tragic repercussions of seeking to control one's destiny.