Little attention has been paid to the implications of the form of the ancient book for literary, as opposed to textual, criticism until very recently. The Arethusa volume entitled ‘Augustan Poetry Books’ (13.1.(1980)) has begun to plug that gap and has provided the impetus for the present article. The ancient book as known to the Classical authors was very different from the vellum codex which superseded it under Christian influence in the Early Empire and in turn formed the model for the modern printed book. We wish to draw attention to one aspect of the papyrus roll which has important implications for the ancient writer and reader.