The seventh book of Vergil's Aeneid both mathematically and thematically launches the second half of this epic poem. Whereas some scholars regard the first six books of the Aeneid as being most comparable to Homer's Odyssey, the final six books are most comparable to Homer's Iliad. If this is the case, then Aeneas, in the second half of the poem, show begin to show similarities to Achilles. Given that Aeneas will begin to appear more like Achilles in the Iliad, we can expect that war will dominate the second half of the poem. Given this shift in tone from the Odyssean to the Achillean, Vergil offers a second invocation to the Muse:
I’ll tell of brutal war,
I’ll tell of battle action, and princes driven to death
by their courage, of Trojan armies, and all of Hesperia
forced to take up arms. (A.S. Kline translation)
This second invocation of the Muse clearly emphasizes the theme of Book 7 and the poem's second half. Thus, in Aeneid
7, madness and fervor concerning the approaching war between Aeneas and his allies and Turnus and his allies occupies the central position of the book.