Forty years ago, in the introduction to what remains today the largest and most detailed commentary on Pliny's epistolary corpus, Sherwin-White claimed that Pliny rewrote or edited a selection of his Gebrauchsbriefe “according to the rules of the literary genre” (ⅹⅵ). Sherwin-White's assessment is both true and potentially misleading. It is true because Pliny certainly did rewrite and edit his letters before publishing them; it is misleading because it implies Pliny's observance of rules without spelling out what those rules were. In fact, Pliny did not conform to the rules of a genre because there was no genre to conform to. As I have shown, Pliny inherited a variety of letter-writing practices, ranging from the quotidian and the matter-of-fact to the highly refined and extremely formalized, from the personal and private to the philosophical and poetic. His nine books of epistles did not so much reproduce a received paradigm as they contributed to shaping a tradition into one. By engaging in a constant dialogue with other literary texts and genres, Pliny imported into the confines of the still fluid practice of literary letter-writing principles of composition and organization drawn from more canonical neighboring traditions. In so doing, Pliny created a new form of literary epistolography at the same time as he inscribed himself into an established but eclectic literary tradition.