O'Neill's "Mourning Becomes Electra" transplants the themes of the Oresteia to a post-Civil War New England setting to explore the destructive forces of:
1
External political conflicts and their impact on family life.
2
Repressed desires, familial curses, and the psychological burdens of guilt and revenge.
3
The rigid social conventions and moral codes of Puritan society.
4
The supernatural and the inescapable influence of fate on human actions.