The three pieces which form the trilogy of Aeschylus, are the _Agamemnon_, the _Choephorae_ or, we should call it, _Electra_, and the _Eumenides_ or _Furies_. The subject of the first is the murder of Agamemnon by Clytemnestra, on his return from Troy. In the second, Orestes avenges his father by killing his mother: _facto pius et sceleratus eodem_. This deed, although enjoined by the most powerful motives, is, however, repugnant to the natural and moral order of things. Orestes, as a prince, was, it is true, called upon to exercise justice, even on the members of his own family; but we behold him here under the necessity of stealing in disguise into the dwelling of the tyrannical usurper of his throne, and of going to work like an assassin. The memory of his father pleads his excuse; but however much Clytemnestra may have deserved her death, the voice of blood cries from within. This conflict of natural duties is represented in the _Eumenides_ in the form of a contention among the gods, some of whom approve of the deed of Orestes, while others persecute him, till at last Divine Wisdom, in the persona of Minerva, balances the opposite claims, establishes peace, and puts an end to the long series of crime and punishment which have desolated the royal house of Atreus.
A considerable interval takes place between the period of the first and second pieces, during which Orestes grows up to manhood. The second and third are connected together immediately in order of time. Upon the murder of his mother, Orestes flees forthwith to Delphi, where we find him at the commencement of the _Eumenides_.
In each of the two first pieces, there is a visible reference to the one which follows. In _Agamemnon_, Cassandra and the chorus, at the close, predict to the haughty Clytemnestra and her paramour, Aegisthus, the punishment which awaits them at the hands of Orestes. In the _Choephorae_, Orestes, upon the execution of the deed of retribution, finds that all peace is gone: the furies of his mother begin to persecute him, and he announces his resolution of taking refuge in Delphi.
The connexion is therefore evident throughout; and we may consider the three pieces, which were connected together even in the representation, as so many acts of one great and entire drama. I mention this as a preliminary justification of the practice of Shakspeare and other modern poets, to connect together in one representation a larger circle of human destinies, as we can produce to the critics who object to this the supposed example of the ancients.