Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
Serious, Elegiac, Ironic
Despite the hope it expresses for the future, the Aeneid is also very focused on the transitory nature of human affairs. In keeping with this emphasis – and with its subject matter of struggle and warfare – the tone of the Aeneid is generally serious and dignified. Even when describing, for example, the beauties of the countryside, Virgil conveys a subtle sense of sadness at a way of life that will vanish. Even the poem's lighter moments, such as the athletic contests in Book 5, often give way to disaster, as when the Trojan women set fire to the ships. After enough experience with this sort of shift, you might start to pick up on a sense of irony every time things seem too quiet – you just know something's going to come along to throw things out of whack.