What causes the downfall of the White family, and how is it related to the theme of The Monkey's Paw?

The Whites are a content, happy family. They want for nothing, as Mr. White mentions when he thinks of what to make as his first wish. He wishes out of greed, not out of necessity. They face the consequences of upsetting an equilibrium and asking for too much. It is especially telling that Herbert, the one who wants wealth and fame the most, is the one taken by death. Even the second wish is selfish and not rational – it is purely driven by emotion and what Mrs. White wants. This greed leads to disappointment and the downfall of the Whites; greed and lust for something one does not need can lead to tragic consequences.