Aeschylus' Seven Against Thebes was first performed in 467 BCE, as the third play of the trilogy satyr-drama "Sphinx." Unfortunately, we only possess this play from the trilogy, and we do not possess more than one play from any of Aeschylus' other trilogies (with the notable exception of his "Oresteia"). Nonetheless, Aeschylus' seven plays survived thousands of years and multiple empires precisely because of his unique tragic style. He was respected not only by both Romans and later Byzantine empires, but his plays were also considered the core texts all young pupils must learn. Aeschylus' native city of Athens famously allowed his plays to be performed even after his death, an honor no other deceased playwright ever received. Both his language, and his tragic stories, set him apart from virtually every other tragedy writer in the entire western canon. With his reputation established, it is important to note that the play as we have it today has been greatly altered from its original form.
Most modern scholars suggest that Seven Against Thebes was altered in order to more closely align with other plays by Greek tragedy writers such as Sophocles and even Aeschylus' other plays. As a result, the ending in the surviving manuscripts we have today appears to diverge significantly from the plot trajectory of Aeschylus' original play. Setting aside the interpretive issues the altered ending creates, the play's simple trajectory and plot make it an easy introduction to Aeschylus and Greek tragedy in general.
The myth behind Seven Against Thebes begins with another very famous myth portrayed by Greek tragedy, that of Oedipus. Oedipus unknowingly kills the kings of Thebes, and later becomes its king when he defeats the Sphinx. As a reward, he gets to marry the queen of Thebes, Jocasta. Unbeknownst to him however, Jocasta is his biological mother. Their incest bears him four children; sons Polynices and Eteocles, and girls Antigone and Ismene. Upon discovering the nature of his marriage, Oedipus blinds himself and his wife/mother Jocasta commits suicide. Oedipus relinquishes the throne of Thebes and leaves in exile with his daughters, Antigone and Ismene.
This is where the two main protagonists in Seven Against Thebes come into frame. Eteocles and Polynices, the sons of Oedipus, are now the rightful heirs to the throne of Thebes. However, they disagree about who should become King. In the course of their quarrel, Oedipus lays a curse upon his two sons: not only will they fail in dividing the Kingdom amongst themselves, but they will unavoidably kill each other in their fight for the throne of Thebes. Accounts differ at this point, but most have Eteocles becoming King for the first year, with the agreement that the two switch off every year as Kings. However, Eteocles refuses to relinquish the throne after the first year. In other versions, Eteocles was always agreed upon as the permanent King, while Polynices received a large share of movable property and riches as compensation. Both accounts however have the same end result: Polynices marries the daughter of the Argive King, Argeia, and persuades the Argives to provide him with an Army for him to conquer Thebes with.
Thus, our play begins with Polynices and Eteocles preparing for battle. Polynices and the six "champions" (think extremely proficient warriors) are about to attack the city at its seven gates with their army. Meanwhile, Eteocles is busy organizing the city's defense. The play's plot moves in a simple linear progression: as a messenger describes each of the six opposing champions in turn, Eteocles dispatches six Theban champions to counter them, one at each gate. In the end, he ends up selecting himself as the seventh champion, knowing this will result in him facing his own brother Polynices. While the Argive invasion is defeated, the two brothers nevertheless end up killing each other.
Most academics believe that this is where the play properly ends. However, an additional scene is added where the sisters of the two brothers appear. Antigone and Ismene arrive with the new ruler of Thebes, Creon, who declares that while Eteocles will receive a proper civil burial, Polynices (by order of the king) will be left out to rot. Antigone denounces Creon and states regardless of his actions, she will bury her brother. This sets the stage for another play by Sophocles, Antigone, but does not add anything further to our play here. Furthermore, all of the characters that appear in the end have not been mentioned at all beforehand. Even more telling is the way in which it interrupts Aeschylus' unique style. His plays are always (with a telling exception here) carried forward by a single protagonist and dilemma. The Aeschylean tragedy universally moves forward in an intractable trajectory towards its final end. Thus, to suddenly introduce new characters and a new dilemma (to bury Polynices against the King's orders or not) indicates what is most likely a later interpolation.
Therefore, we must carefully consider the ending's role in our interpretation of the play. Should we disregard it entirely in our analysis? Or should its role only be minimized given our lack of knowledge as to the true origin of the later alteration? Several generations have read the play as it stands today, and thus, an argument can be made for at least considering it in our interpretation, given its primacy to 18th and 19th century readers.
Regardless of the interpretive issues this creates, Seven Against Thebes is admired for presenting the earliest and most defining archetype example of a "tragic choice", one in which the hero must choose between two morbid choices. In this archetype, the tragic hero always ends up accepting, and eventually embracing his predetermined path to a grim fate. One must keep aware in Eteocles seven speeches this tragic choice and the ultimate ruin it creates for his and his brother. Does Eteocles make up his mind "as he goes", and is only forced to put himself out as the seventh champion against his brother? Or has his mind already been made up, given the fate handed to him and his brother by Oedipus? To what extent do the heroes themselves create this fate, and to what extent do the Gods create this fate through circumstance, just as they did for their father, Oedipus? These questions are not only relevant and defining for our play, but more importantly are ones we find ourselves asking in introspection. To what extent does circumstance control our lives versus choice? Seven Against Thebes does not profess to answer that question, but most tragically and profoundly presents it to us.