Most important, the purposes of oral and literary epics are greatly distinct, a difference that has a profound effect on the epics's contents and the ways in which their stories develop. Oral epic was intended primarily to provide diversion and entertainment to its audience, although it also embodied much of the history and folk-wisdom of the culture in which it was created. For example, although the Iliad has a serious theme with many important moral lessons, these teachings are only a by-product of Achilles's story, which is the main reason for the poem's existence. Literary epic, on the other hand, always has a didactic purpose that is foremost in the poet's mind when he composes his work. Poems like the Aeneid communicate serious philosophical, moral, and patriotic messages that subordinate their narrative stories. Because of this subordination, literary epic has a higher degree of unity and coherence than oral epic, but its human characters are less believable and oftentimes less admirable in human terms, for they lack many important human qualities. To the poet and his readers, the underlying national theme is the epic's main element.
Aeneas, the hero of the Aeneid, is plainly a personification of the most respected Roman virtues, and we are frequently reminded that Augustus is his descendent. The implication of this association between Aeneas and Augustus to Virgil's contemporary readers is clear: They would infer that Augustus shares many of his ancestor Aeneas's fine qualities; their full confidence in the emperor's judgment would be justified; and they would be foolhardy and pretentious to criticize Augustus's new government.
