At the end of a chapter on Livia, the wife of the Roman emperor Augustus, in Confronting the Classics (Liveright, $28.95), the Cambridge scholar Mary Beard reminds us that when Masterpiece Theatre first broadcast the BBC version of I, Claudius, in 1977, the host explained to the American audience that Augustus “reconciled the old nobility and the new republicans and merchants and middle classes to a system of government that was fundamentally republican.”

Although, according to Beard, this is “historical nonsense,” it transformed Livia’s (rumored) murder of Augustus into the sort of…