After classical antiquity, the Italian Renaissance raised the portrait, whether literary or pictorial, to the status of an important art form. Among sixteenth-century Renaissance painters, Titian made his reputation, and much of his living, by portraiture. Titian's portraits were promoted by his friend, Pietro Aretino, an eminent poet and critic, who addressed his letters and sonnets to the same personages whom Titian portrayed. In many of these letters...