How is Sophocles' Electra similar to that of Aeschylus' Libation Bearers?
Sophocles' Electra was composed about 40 years or so after Aeschylus' Libation Bearers first appeared in 458 BCE. Although Sophocles changes many of the details within the play, Sophocles follows the story's basic outline. Both plays deal with the revenge Orestes seeks against Aegisthus and Clytemnestra for the murder of Orestes' father Agamemnon. Both plays contain a recognition scene in which Orestes, who has been in exile, returns to Mycenae and is reunited with Electra. In both plays, Orestes conspires with Electra to bring about the deaths of Aegisthus and Clytemnestra. Also, in both plays Orestes pretends to be dead. Finally, Orestes' vengeance is motivated by an oracle from Apollo commanding him to take vengeance against those who killed his father:
I have gone to the Oracle of Apollo and asked the god how I should avenge the death of my father. His answer was that I should go about it on my own and with my own hand, without armies or shields and, secretly extract the bloody Justice. (George Theodoridis translation)