The only copy of Beowulf to survive is found in the manuscript with the modern shelf-mark London, British Library, Cotton Vitellius A. xv. It is known to critics as 'the Beowulf manuscript' or 'the Nowell codex'. In its modern form, the volume consists of several separate medieval manuscripts, which were very likely only bound together in the eighteenth century. The manuscript was damaged in the Cotton fire of 1731, which makes its structure difficult to discern. However, it is likely that the following texts comprised a single volume:
A fragment of a Life of St Christopher
The Marvels of the East
Letter of Alexander to Aristotle
Beowulf
Judith
All these texts are in Anglo-Saxon. The volume was the work of two scribes, who changed over halfway through Beowulf. It is difficult to discern the principles by which the codex was arranged, which is basically, to quote Sisam, 'a collection in verse and prose of marvellous stories' (see Orchard 1995). It is thought the manuscript was produced around the turn of the eleventh century.
In recent years, two studies of the manuscript have reached controversial conclusions. Kiernan 1996 argues that the Beowulf portion of the Nowell Codex was originally a separate manuscript and that the second scribe was the author of the poem, with his authorial corrections visible on fol. 179. Kiernan infers that Beowulf was composed during the reign of Cnut. More recently, Lapidge 2000 argued that the errors made by both scribes in copying certain letters suggest that the poem was at one stage written in a type of script not used after c. 750. The poem therefore was composed early in the Anglo-Saxon period. However, neither of these theories have achieved a consensus of support and both should be cited with caution.