Aristotle's Poetics IV

Aristotle begins the fourth part by explaining how poetry even began. He goes on to say that imitation is a purely natural thing for humans to do, adopting it as small children and ceasing not from there. Not only is it natural, but we learn things through imitation and delight in works of imitation. What poetry does is takes this imitation to levels of rhythm, making heavy emphasis on its innate aesthetic beauty.  

Tragedy draws imitation from the parts of reality that are filled with misfortune; dramas derived from poetic Dithyrambs. He mentions that Tragedy has drastically changed from what it was in that it included far more many actors than intended due to Aeschylus and Sophocles' innovations. Also the metre changed from a satyric trochaic tetrametre to simplistic iambic hexametre. The iambic stanzas are far too similar to how people normally speak to be very aesthetic. His final complaint is how long and how many acts the plays contain, granted details are important. 

Aristotle's Poetics II and III

Aristotle in his brief second part of the Poetics describes the three different levels of agency in poetry. There are, in other words, three different ways to present a character to an audience. In relation to the 'average man' a character can be presented in a standard better or worse than us, or else the same as. He gives three examples: Homer shows his character's better, Cleophon (Athenian politician) presents them on 'our own level', and finally Hegemon of Thasos presents his character lower than a standard.

In the third part of the Poetics, Aristotle furthers his segregation of the elements to good literature/poetry. He points out that there are three ways to deliver the story and go as follows:
1. A narrative with elements of monologue and dialogue mixed in. Homer often does this. The narrator and the character[s] don't necessarily need to interact, however.
2. The poem remains in one voice for its entirety, certainly no dialogue is allowed here. 
3. In this form, dialogue is superfluos, and the events of the story are 'acted' out. What we   call now 'playwrights' would fall under this category.

Aristotle's Poetics I

In this part of the Poetics, Aristotle begins by defining what poetry is. He notes that there are four genres of poetry that may be written in three 'styles'. The four genres that Aristotle notes are epic poetry, comedy, tragedy, and Dithyrambs. Each of these can differ however in that they can be expressed through these three ways: the medium, the objects, or the mode of imitation. These make up what poetry is, and how it can be expressed as an art form. Another aspect of poetry Aristotle speaks of is the importance of both metre and 'harmony' in poetry. Through imitation it is important to add rhythm and metre, otherwise it cannot be considered poetry. All art however also contains elements of tune, rhythm, and metre, or else all its structure is ambiguously messy.

Summary of Aeschylus's The Libation Bearers

Greek Mosaic depicting a Libation

Agamemnon has been murdered by his own wife, Clytemnestra as soon as he returned from the Trojan War. Many feel this act is unjust, and strongly wish for Justice to be enforced, especially Agamemnon's son, Orestes. Orestes has been placed in exile by Clytemnestra for quite sometime, she claims that this was done for his own protection. Orestes, having heard about his father's murder, rushes to Agamemnon's corpse incognito to mourn. As he bitterly mourns, his sister, Electra, followed by the Chorus of enslaved Trojan women, see Orestes in disbelief. Evidently the two hadn't seen each other since they were quite young; proper identification is difficult followed by a joyous reunion. Electra discusses the nature of their father's murder and begin to plot vengeance.
Orestes plots to disguise himself as a traveler to penetrate the heavily guarded palace walls. Then as soon as he enters he kills both Aegisthus (Clytemnestra's lover) and Clytemnestra. The Chorus and the olympian Apollo support his plan, easily creating sympathy toward the two orphaned children. His plan changes, however, when Clytemnestra unexpectedly answers to disguised Orestes' knocking. To further conceal his identity, Orestes pretends to be a messenger announcing Orestes' death. Clytemnestra mourns and sends Orestes' old nurse for Aegisthus and his bodyguard to hear of the news. The Chorus convinces the nurse to just send Aegisthus alone, and so he does. Aegisthus meets Orestes off stage and is killed, his death is announced by a messenger to the audience.
Chaos breaks out in the palace, and Clytemnestra sense something is wrong, she finds Orestes by Aegisthus' corpse. It was her turn to receive Justice. Cunning Clytemnestra puts herself at Orestes' knees, begging him to remember their familial connection. He is nearly convinced to spare her life, but when one of Orestes' friends, Pylades arrives, he reminds Orestes of Apollo's will. He stabs his mother to death, in an act of Justice.
The Furies are enraged, seeing Clytemnestra's murder as an act of injustice.