Symbolism, Imagery, Allegory
In the Aeneid, fire symbolizes unbridled energy, for good or ill. On a literal, instead of symbolic, level, fire imagery features prominently in the destruction of Troy. As a symbol, the "fire" in Dido's veins represents her passionate desire and love – which ultimately leads to her destruction. That said, when Aeneas is "enflamed" by the images of Rome's future shown to him by Anchises in the underworld, this symbolizes his newfound enthusiasm for his mission.