As this play chronicles the transition of society from its dark and primitive origins to its new civilized and illuminated state, it is natural that the motif of light and dark should occur throughout the play. The house of Atreus has sat under a dark clo ud for many generations, beset by misery and bloody murder again and again. However, as the chorus joyously states, Orestes will be a savior and bring light back into their lives. He is able to do this because he is backed by Apollo, who is th e god of the sun and all things associated with illumination, including civilization itself. The Furies on the other hand, are associated with death and everything else that lurks beneath the ground. They wear black and are able to drag people down in to madness, which is also associated with darkness. Under their law, no light ever shines through the clouds, as the blood must continually flow. In order to break free of its dark and bloody past, the house must also sever ties with the Furies that have lurked around it for so long.
The net is the most important metaphor that runs through the Oresteia. Net imagery is used to represent treachery, confusion, and entrapment. Nets' binding powers associate them with snakes, who strangle their victims to death. In the Agamem non, Cassandra has a vision of a net and realizes that it is Clytamnestra herself, closing in around her prey. The physical manifestation of Clytamnestra's devious plot is the robe of Agamemnon, which Orestes calls a net at the end of the play. Just as one weaves words in order to persuade someone of something, so Clytamnestra and Orestes weave plots in order to trap their enemies. Nets are naturally cunning devices, as one usually does not see the net closing in until it is too late. We c an understand this metaphor in opposition to a spear or sword metaphor, which would imply direct and open contact with the enemy. A net is like a trap that is laid well in advance. For this reason, it is associated with all kinds of plotting and deception .