The poet invokes the Muse to help him tell the story of Odysseus.
We learn that Poseidon, god of the sea, holds
a grudge against Odysseus and is making the
guy's voyage home pretty difficult.
This tells us two very important things: (1) Greek gods
are temperamental, and (2) Poseidon is a powerful guy.
So Poseidon isn't around on Mount Olympus, while the other
gods discuss the fact that this one guy Orestes murdered this
other guy Aigisthos.
Zeus, king of the gods , says that Aeigithus totally deserved it because he had a
long affair with Agamemnon's wife while he was away at Troy and then killed Agamemnon upon returning
home.