William Langland's "Piers Plowman" is one of the most important poems of the English Middle Ages. It is also a poem that gains in an exceptional way from the study of its manuscript sources. There is no need to emphasise what a vital part "Piers Plowman" has played in debates about textual criticism and editing during the last 30 years. The poem, in its three versions, has been the focus of intense and occasionally impassioned debate. The copy of "Piers Plowman" which forms the only contents of Bodleian Library MS Douce 104 is a version of the C-Text, and has its part to play in the debate. The present facsimile is the first of either of the two longer versions of the poem to appear for over 50 years. But Douce 104 has a unique claim on our attention. It contains 72 marginal illustrations which provide a record of the response to the poem of an early 15th-century reader. The pictures are not elaborate, but from the literary point of view this adds to rather than detracts from their interest, since it means that they are closer to the text and to the perceptions and thinking of the illustrator, or the person who gave him his instructions. For the art-historian, the pictures are interesting as an exercise in the eclectic adaptation of pictorial traditions to a special interpretative purpose. For the literary scholar, the manuscript is an opportunity to examine an authentic early and near-contemporary response to a great poem of the English Middle Ages.