Symbolism, Imagery, Allegory
Who doesn't love a good ghost story?
Well, probably Orin Mannon, for one.
Once the unfortunate Ezra Mannon and his murdering adulteress of a wife are out of the picture, ghosts seem to be everywhere in the different parts of Mourning Becomes Electra. When Orin and Lavinia return from their little vacation away from guilt, it's clear from their conversation that Orin's convinced that ghosts live inside that house. Even before they show up Seth and his buddies are talking about all of the dead Mannons that walk the halls of the Mannon estate.
We admit, ghosts are really, really cool, but that's not the only reason why they keep showing up. Think back to Seth's pals and the way they talk about ghosts. Ghosts haunt places where horrible things have happened, usually to the person who's now a ghost. They represent a part of a pretty awful past that just won't stay buried, a terrible secret that just won't die. Particularly angry ghosts, like Patrick Swayze, will even haunt the person who did them wrong in life or refuse to cross over to the Great Beyond until justice is served and the truth about how they died is told.
In Mourning Becomes Electra, ghosts are used to symbolize feelings of guilt and to represent the inescapability of the past.