The cyclical nature of blood crimes
The ancient law of the Furies mandates that blood must be paid for with blood in an unending cycle of doom. The chorus states this fact several times throughout the play, most clearly in the first section of the kommos, which is discussed i n the quotes section of this SparkNote. Vengeance is just, they say, and it has been the law of the house for generations. In its opening lines, the chorus describes how "[t]he blood that Mother Earth consumes clots hard, it won't seep through, it breeds revenge and frenzy goes through the guilty" (lines 67–70). Nothing else can wash away a bloodstain but more blood, which in turn requires more blood in order to be cleansed. The chorus offers no solution to this dire situation of violence breeding m ore violence. They merely state it as the natural law and do what is in their power to help Orestes fulfill his role in the divine plan. However, over the course of The Libation Bearers, we get the sense that this time, things will be different . Apollo has promised Orestes that he will not suffer for his crime, and we know that a god is unlikely to go back on his word. The Oresteia as a whole is Aeschylus's way of saying, "the buck stops here." Man cannot hope to build a progressive civilization if he is steeped in a perpetual bloodbath. A way out must be found, a new, more civilized law.
The lack of clarity between right and wrong
At times, one may find Aeschylus rather overwhelming in his complexity. However, it is this complexity that compels us to return to him again and again. One of the manifestations of this complexity is that there are no clear good guys or bad guys, but rat her men and women who are faced with impossible choices. Agamemnon, Clytamnestra, and Orestes are all caught between a rock and a hard place, which we may find to be tragically unfair. Aeschylus is telling us that life is unfair, and that we must develop systems for ourselves so that we can cope with the difficult decisions we will inevitably face.
Orestes's particular situation pits his filial duties to Agamemnon against his filial duties to Clytamnestra. If he does not murder Clytamnestra, the Furies will pursue him. But even when he does murder her, the Furies still pursue him. There is no co mpletely right or wrong answer, Aeschylus tells us, but there are better and worse choices. Since Apollo has thrown his weight behind the path of vengeance, Orestes chooses to comply with his commands. In fulfilling his duty towards Apollo and his fat her, Orestes condemns himself to suffering. He chooses to make this sacrifice, however, in order to preserve the laws of society.
The conflict between new and old gods
At the beginning of The Libation Bearers there is no contradiction between the will of the Furies and the will of Apollo, but by the end of the play we see that a split is developing between these two orders of gods. The Furies represent th e ancient, primitive laws, and demand that blood must always be paid for with blood. Apollo compels Orestes to avenge his father, but then suggests that the cycle of violence will end, as he will not have to die in recompense for his crime. In the Eumenides, this theme is fully developed, as the Furies are tamed and relegated to a far less powerful position in society. It is also significant that that Furies are female deities, while Apollo is masculine, thus equating civilization and progress with male influences. In order for society to prosper, the female powers must be subdued.
The difficult nature of inheritance
The Oresteia teaches us that, while we cannot choose how we are born, we can choose how to approach that birthright. In returning to Argos to pursue a terrible quest, Orestes shows himself to be a noble character. He does not flee from destiny , but calls upon his father's spirit and his mother's resolve in order to do what must be done. As the only son of a murdered father, Orestes is fated to avenge his death. He approaches this fate with sophistication and grace, never wavering in his convic tion that he is doing the right thing, but also never sinking to the point of reveling in the slaughter. Towards the beginning of the play, Orestes states that he has returned to Argos in order to claim his inheritance. By this he means the kingdom that i s rightfully his. However, implicit in this statement is the idea that he must claim his share in the destructive bloodshed that has plagued the house for generations. Clytamnestra had sent him away as a child so that he might escape this fate. But, in order to claim his inheritance and become a man, Orestes must return to the origin of his misery and confront it head on.