Aristotle turns his attention to epic poetry. While the mimesis of tragedy is in actions told in a dramatic form, the mimesis of epic poetry is in verse told in a narrative form. Aristotle notes that there are a number of similarities between tragedy and epic poetry.
First, epic poetry must maintain the unity of plot. In this it is allied with tragedy against history. History tells us all that happened during a certain time period or to certain people, and as such it is often somewhat disconnected. Epic poetry should focus on one particular story that remains an organic whole. Homer is an excellent example of such an epic poet, as he tells a particular, connected story in the Iliad rather than trying to narrate everything that happened during the Trojan War.
Second, epic poetry must share many of the elements of tragedy. Like tragedy, it should be either simple or complex, and it should deal primarily either with a character or with suffering. Aside from spectacle and melody, the six parts of tragedy are all present in epic poetry, and epic poetry can also feature peripeteia and anagnorisis.
There are also two notable dissimilarities between epic poetry and tragedy. The first is the length: an epic poem can reasonably last as long as a whole series of tragedies, provided it can be presented in one hearing. The plot of an epic poem can be far more expansive because it is not limited by the stage. Epic poetry can jump back and forth between events happening at the same time in different places in a way that would be impossible on stage. Second, epic poetry should be narrated in heroic meter, while tragedy is normally spoken in iambic meter.
Aristotle is clearly an admirer of Homer's, as almost all his examples of good epic poetry are drawn from Homer. He praises Homer for reducing his own voice in the narrative and letting the actions and the characters tell the story themselves. He uses Homer to show how epic poetry can recount exaggerated events in a believable manner. A tragedy could never get away with such marvels, since they are less credible when we see them performed. Having said this, he remarks that no plot should ever hinge on improbable events but praises Homer for managing through his art to make this flaw in the Odyssey seem insignificant. He also praises Homer as a master of using paralogisms (conclusions resulting from faulty or illogical arguments) to make lies seem believable.
Aristotle cautions against an overenthusiastic use of elaborate diction. While it is pleasing when there is no action to recount, and no character or thought to reveal, ornate diction can often obscure these more important elements when they are found together.