A History of Simile
A simile is a poetic comparison between two things, often phrased using the words "like" or "as." You distinguish an epic simile from a standard simile in two ways. First, an epic simile is much longer than a standard simile, which may consist of only a few words. Second, an epic simile elevates the importance of the event discussed. Rather than referencing common or earthly elements, an epic simile references to mythological events to emphasize the heroic nature of the events, which is a critical part of Virgil's goal in creating "The Aeneid."
The Calming Words of "Neptune"
Virgil deviates from the standard construction of a Homeric simile at times. Early in "The Aeneid," Virgil compares the riotous ocean to a rioting crowd of people. Like Homer, Virgil references a divine figure, in this case, Poseidon, who controls the seas with "his sov'reign trident." In contrast to Homer, who used epic similes to highlight the glory of Greek heroes, Virgil describes the calming of the sea as being akin to a noble man convincing a horde to calm themselves, poetically humanizing the god.
Like the God of Light
Virgil often deployed the epic simile in the manner Homer intended. The beautiful Queen of Carthage Dido falls in love with Aeneas immediately, likening his form and grace to that of the god Apollo. While any comparison to a god would indicate admiration, a comparison to Apollo, the god of light notable for his beauty and heroism, is particularly complimentary. By using the epic simile in this manner, Virgil indicates the intensity of Dido's infatuation.
The God and Oak
When the anguished Dido begs Aeneas to choose her as his romantic partner, he "shoots his tow'ring head on high, / So deep in earth his fix'd foundations lie." Here, Virgil notes that Aeneas is as impervious to Dido's pleas as an oak's roots are to the winds. However, as the winds are themselves controlled by the gods, Virgil utilizes the hyperbole inherent to epic simile to emphasize Aeneas' powers of self-control.