The introduction outlines the polyphonic and interactive character of Pliny the Younger’s Epistles by first looking at how Pliny constructs time and space of literary interaction in his social environment. The chapter then moves on with a discussion of interdiscursivity and generic interaction in Pliny’s letters and a review of scholarship on intertextuality. A case study of the triptych of letters 4.26-28 demonstrates how various forms of textual and non-textual interaction are combined in Pliny’s Epistles. Whereas the centrepiece of this series, Ep. 4.27 on the recitation of Sentius Augurinus’ poetry, focuses on oral exchange and mnemonic skills, the preceding letter (4.26) foregrounds the materiality of literature by playing with the motif of books as companions (comites) on journeys. The third letter (Ep. 4.28), on the other hand, emphasizes the visibility of famous writers whose portraits were placed and looked at in libraries. In addition to staging various forms of literary interaction, the triptych of Ep. 4.26-28 also showcases the letters’ intermediality. The introduction concludes with a key to the volume’s chapters.