Abstract
In May 1819, Percy Bysshe Shelley broke away from work on his lyric Prometheus Unbound in order to compose The Cenci —a tragedy. What precipitated this? I argue that in pausing between acts 3 and 4 of the former in order to construct the latter, Shelley was engaging in the Greco-Roman tradition of moralizing by means of sketching twinned lives. While Shelley follows Plutarch, specifically, in allowing for, among other things, the mythological and the apocryphal, I suggest that his own normative project transcends his ancestor's prototype in important ways related to both form and content.