Valperga: or, The Life and Adventures of Castruccio, Prince of Lucca was a novel surprisingly long in its gestation. Although not published until 1823, its inception actually dates from six years earlier. “I first thought of it in our library in Marlow,” Mary Shelley wrote as she was completing it in 1821 (L I 203), thus placing its beginnings at some point in 1817. She does not stipulate what book in the library which she and Percy Bysshe Shelley had assembled in Marlow prompted her to conceive the idea of this new novel, nor is there anything in either's correspondence that would further elucidate her claim. But among the components of an ideal library P. B. Shelley later enumerated to his cousin Thomas Medwin were the writings of Nicolo Machiavelli, the Italian Renaissance political theorist. Beginning with the first English translations of The Prince in the early seventeenth century, it became a common practice to append to that work Machiavelli's admiring biographical account of Castruccio Castracani dei Antelminelli, the warlord of fourteenth-century Lucca, whom Machiavelli, in 1520, looked back on as an exemplary Italian “prince.” This is the work that Mary Shelley denigrates in the first sentence of her Preface to the novel as a mere “romance” (V i 5). One might therefore infer that Mary Shelley's original idea for the novel centered on simply setting the record straight about Castruccio; her original title - The Life and Adventures of Castruccio, Prince of Lucca - focusing on him alone, would seem to substantiate that inference. The change in title by which Valperga became centered was owing to Mary Shelley's father, William Godwin, who reconfigured the novel's balance by emphasizing its female protagonist, the Countess of Valperga, a fictional Tuscan duchy.