This chapter focuses on the cultural transformations of Late Antiquity, using poems and letters produced between 300–600. Late Antique poets used rivers as ways of addressing changing religious, political, and religious identities, and to help them create new images of self and country. These early writers were responding to both literary and cultural rivers and to real encounters with river ecosystems. They shaped a sense of place and community alongside the rivers of Gaul, and their poetry reflects not only a sensitivity to the aesthetics of these riverscapes but also an awareness of the non-human world of river ecosystems. All told, Gallo-Roman poetry highlights an appreciation for the natural beauty of rivers, an awareness of their ecological abundance, and a recognition of the manifold ways in which human cultures, histories, and economies were drawn up in their watery webs.

The visual and intertextual effects of Ausonius’ versified riverscape, the Mosella, make it a prize specimen for modern study of late antique Latin poetics and aesthetics. What kind of performance – and then what kind of a book – would this poem originally have been, in the empire of Valentinian and his sons, in the 370s and ’80s? The chapter measures the oddity of the Mosella, and of the poet’s oeuvre, against the background of prior fourth-century Latin opuscular poetizing, to argue that Ausonius’ “poetical fame” (Gibbon) was at once enabled by his profile as an imperial officeholder and an effect of his deliberately stepping aside from it. A following generation of Latin writers, many of whom would style Christian literary careers for themselves, may be seen reprising – if not emulating – the trick that Ausonius performed in improvising a personal poetic subjectivity at the edge of the cognitive ecology of Roman empire.