The chorus asks how long they will have to wait until they can exercise their power of speech in celebration of Orestes. They then call on the Earth that lies over Agamemnon's corpse to help them, for now is the time when Persuasion must come to the aid of Orestes. They also call on Hermes to bring about the deadly confrontation between Orestes and the murderers.
Orestes's nurse Cilissa enters in tears, and the chorus asks her where she is going. The nurse describes how Clytamnestra ordered her to fetch Aigisthos, feigning sadness while laughing inside at the news. For the house, this message spells ruin. Aigisthos will certainly rejoice when he hears of Orestes's death.
The nurse laments the grief she has had to suffer over the years, saying that this new sorrow is by far the worst. She reared Orestes from birth, pacing back and forth throughout the night to quiet his crying. One must tend carefully to a baby, as it has no speech to ask for what it wants. She was a prophet to his desires, but was mistaken many times. Both washerwoman and wet-nurse, she cared for his every need. She was the one who took him from his father's arms, and now he is dead. But now she must bring this news to the man who destroyed the house.
The chorus interrupts the nurse's dirge to ask whether Clytamnestra told Aigisthos to come with his guard. The nurse replies that she told him to come with his guard. The chorus bids her to alter the message, saying that she should bid Aigisthos to come alone, and happily. For, in the mouth of a messenger, a crooked message can be made strait.
The nurse is shocked that the chorus seems to rejoice over the news. The chorus suggests that she should not give up hope for Orestes yet. The nurse remains confused, but the chorus tells her to get on with it.
Once the nurse leaves, the chorus makes a prayer to Zeus, asking him to safeguard Justice. They also call on the spirits of the house to conspire with them, to come and wash the blood from the halls with Justice. With Orestes's act, they trust that Murder will cease to stalk the palace halls. Furthermore, they pray to Apollo, asking him to grant that the house may look up from its veil of gloom and see freedom's bright light.
Soon, the chorus sings, there will be cause for rejoicing. "But you," they say, meaning Orestes, "when your turn in the action comes, be strong." When Clytamnestra cries out "Son!", he must reply, "Father!" Doing this, he may commit the awful deed in innocence.
The chorus opens this section with an ambiguous phrase, asking either how long they will have to wait before they can sing in honor of Orestes, or how long they will have to wait before they can use their speech to aid him in his quest. If the latter is the case, then their wish is immediately granted, as they tell the nurse to tell Aigisthos to come without his bodyguards. This would be consistent with the trend in the Libation Bearers of immediate wish fulfillment. However, even if the latter is the case, the former will also come about, as by instructing that Aigisthos come alone, the chorus ensures that Orestes will be victorious.
Cilissa's role in the play, while brief, is crucial to the plot. On the most obvious level, she brings an altered message to Aigisthos, omitting Clytamnestra's command that he bring his guards. In telling her to do this, the chorus continues its invasive role in the tragedy, operating as actors as well as commentators.
Just as significant, however, is the information that Cilissa gives us about Orestes's upbringing. She says that she cared for Orestes from birth, meaning that she was much more of a mother to him than Clytamnestra ever was. While this custom has been common practice in royal houses throughout history, Aeschylus emphasizes it here in order to discredit Clytamnestra's role as a nurturing mother. As she did not care for Orestes herself, she has far less of a claim on his affections. Orestes feels little to no filial bond with his mother. He is his father's son only.
Cilissa also tells us that Clytamnestra was feigning sadness upon hearing of Orestes's death. While this statement is only an opinion and not necessarily the truth, it does affect our perceptions of Clytamnestra. We are told yet again that we cannot trust her words or gestures. The chorus and the nurse together do everything in their power to discredit Clytamnestra in our eyes, so that we see her not as a mother but only as a cold hearted and manipulative murderer.
After Cilissa's departure, the chorus's prayer serves as a reminder to the audience of all the deities who have played a role in bringing Orestes back home in order to avenge his father. Hermes was his guide, Zeus reminded him of the duties of Justice, and Apollo threatened him with horrible diseases and exile if he did not comply.
The house spirits are slightly more complicated. They represent the bloody destiny of the house, which compels the killing to continue, with Orestes as its agent. The chorus does not seem to fully understand what they are asking for, as they call on the house spirits to wash away old blood with new blood shed in the name of Justice. They conclude this little section with a prayer that murder breed in the palace no more. From this we understand that they expect the killing to stop with Clytamnestra and Aigisthos. Orestes will murder the murderers, and everything can go back to normal. But what of the consequences for Orestes? We will see at the end of the play that he too is expected to pay for his crimes. The cycle of murder does not automatically end with Orestes's action.
The chorus also anticipates Orestes's state of mind at the crucial moment when he is about to kill Clytamnestra. As we will see, he hesitates for a moment when Clytamnestra implores him to respect the relationship between mother and son. The chorus confronts this possibility by urging Orestes to think of himself as Agamemnon's son only, and not Clytamnestra's. In this way, he will be able to kill his mother while still remaining innocent, as she is not really his mother at all. We will also see that this rather simplistic solution will not be enough, and Apollo will have to intervene.