The Aeneid appears to have been a great success. Virgil is said to have recited Books 2, 4, and 6 to Augustus; and Book 6 apparently caused Augustus' sister Octavia to faint. Although the truth of this claim is subject to scholarly scepticism, it has served as a basis for later art, such as Jean-Baptiste Wicar's Virgil Reading the Aeneid.

Which book supposedly caused Augustus' sister to faint?