Libation Bearers: Theme Analysis

Restoration of Lawful Government and War Between the Sexes
Two other themes play a part: the theme of the need to reverence, and restore if need be, lawful government, and the theme of the horror of a world where the sexes are at war, where women kill men, where the bonds of kinship and marriage are destroyed. Part of the reason Orestes is seen as acting out of duty, rather than as becoming a snake, or a Fury, is that part of his motivation is to restore lawful government and the right relationship of the sexes. These themes are harder for a modern audience to resonate with, perhaps, but it’s worth the stretch.
To quote from the plot summary, “Once reverence for the king ruled the people, but now fear rules.” The difference between monarchy and tyranny may not seem great, in the aftermath of a revolutionary age that rejected monarchy as tyranny, but that quotation may help us feel the essence of that difference. Consider also that a personal bodyguard is the mark of a tyrant; a true king reverences law and custom, listens to his counselors, and has no need of a bodyguard. The love for Agamemnon expressed at the beginning of the Agamemnon by the guard who watches from the roof of the palace for the beacons signaling the fall of Troy—that is the reverence and love of a rightful king. The old counselors who form the Chorus in the Agamemnon feel it. The slave-women who form the Chorus in The Libation Bearers feel it. And Orestes’ desire to reclaim his inheritance and become king is not simply a desire for his “possessions” (301), it is the desire “not to leave the citizens of the most glorious city upon earth” subject to tyranny, and to the worst kind of tyranny—“subject to a pair of women” (304). Which brings us to the second theme.
The larger belief behind the theme that “Justice will be done, those who transgress will suffer,” is that there is order and law in the universe. In our day, that order has been called into question in many ways, but many still have the sense that if human beings upset the balance of nature, they will suffer—that belief may help us understand the larger belief Aeschylus holds. Part of the order of the universe is that the sexes must come together in order to create new life; from the Greek point of view, that coming together would only be harmonious and fruitful and in accord with the order of the universe if the male ruled, since men were felt to be less apt to be swept away by the passions that make human beings forget their common humanity and do harm to themselves and others. A woman who nurses hatred for her husband, whatever the reason for that hatred, and then traps him like a beast and kills him—she may be an instrument of Justice in punishing her husband, but she is also a horror. A woman like Electra who joyfully accepts a man taking the lead represents a return to sanity. As the third play of the trilogy shows, Aeschylus had a more balanced (from our point of view) understanding of the right relationship of the sexes than most men of his time, but he still shared the basic belief. And he could certainly expect his audience to resonate with Orestes’ words shortly before he is driven out by the Furies, which are summarized thus: “What do you think of the woman who used this to kill her husband, to whom she had borne children? If she had been a snake, her touch would have been enough to poison. Rather than have such a wife, I would ask the gods to let me die without children!”
Yet no matter what Orestes’ motivation, no matter to what degree his actions have restored right order, they have also violated it. What can restore the balance when a man has killed his mother? Must he die or be driven mad by the Furies, no matter what his motivation was? And if Apollo can simply purify him, is not the order of the universe threatened?  
Learning Through Suffering
The big question about the main theme of The Libation Bearers could be put this way: is it the same as the main theme of the Agamemnon? The main theme of the Agamemnon is rather a dilemma than any positive message. The short version is, Justice will be done, those who transgress will suffer, but woe be to those who carry out that justice by taking vengeance—they will, almost inevitably, transgress in their turn, and so they will have to suffer. Yet the taking of vengeance seems to be the only way that justice can be done. The dilemma seems hopeless.
The theme of The Libation Bearers is subtly different. Let’s just change the last sentence above: “The dilemma would seem hopeless, if it were not for those who suffer even as they take vengeance, who take vengeance primarily because of a sense of duty. They are the ones who will eventually find a better way. By suffering, we learn.”
But at the end of The Libation Bearers is it still not clear what we could learn that would represent a good way out of the dilemma.  Perhaps therefore it would be more appropriate to say that the theme of The Libation Bearers, like the theme of the Agamemnon, is a question, “Must there not be some way that human beings as right-minded as Orestes can learn from all this suffering?”
The theme of “love-in-hate” applies to Orestes and Electra. Loving their mother, they hate her not simply because she has killed their father, but because she has chosen Aegisthus over them. They are filled with jealousy and resentment. It is the sort of emotion that leads Clytemnestra to kill Cassandra as well as Agamemnon in the first play, and thus to reveal the extent to which she has lost her humanity; Electra, on the other hand, undertakes no violence at all herself, and Orestes goes no further than the vengeance that is his duty.
Following the Command of Apollo
Following the command of Apollo is the crucial element that is utterly new in this play when compared to the Agamemnon. No god told Clytemnestra to kill Agamemnon. But Apollo has even threatened Orestes with horrible suffering if he does not carry out his duty to his father by killing his mother and Aegisthus. At the moment when Orestes almost draws back from killing his mother, his friend Pylades speaks with the voice of Apollo and decides him to go through with it. And it is Apollo who gives Orestes the hope of purification.