Some medieval texts have barely survived. Beowulf , the Old English masterwork, exists today because of a single manuscript – one that narrowly escaped combustion in 1731. For such texts, the single manuscript is all important. The discovery of another copy would transform our understanding. By contrast, a work like Bede’s Historia Ecclesiastica Gentis Anglorum (Ecclesiastical History of the English People) survives in more than 160 manuscripts . This volume of material has meant that scholars have tended to focus on just a few of the earliest copies, since these are most likely to preserve a text close to what Bede originally wrote. The result is that many later or less well-known manuscripts have received little detailed attention. Now, however, computational methods that make it possible to analyse millions of words are changing that picture. Instead of relying on a narrow selection of manuscripts, we can begin to take the full breadth of the tradition into account.…