Books of Hours are amongst the most exquisite of all medieval manuscripts. Small enough to be carried inside a sleeve or attached to a belt and illustrated with brightly coloured, painstakingly executed miniature paintings and marginal illuminations, they are much sought after as works of art. Imagine, then, the bafflement of librarians and curators when Eamon Duffy ordered the photographs for Marking the Hours: he did not want pictures of the most beautiful folios in their collections but of those which had been disfigured by scratches, erasures and scribbling. The reason, he explains in his preface, was that the object of his study was not the Books of Hours themselves, but rather the hand-written prayers, charms, financial records, requests for remembrance, holy pictures and pilgrim souvenirs inserted into them by generations of owners. These additions customised and personalised what would otherwise be simply standard devotional works and, as Duffy brilliantly demonstrates in this absorbing book, they are ‘an extraordinary archive providing unexpected windows into the hearts and souls of the people who used them to pray’. His book is, he tells us, ‘a tribute to scribbles, an attempt to trace a history written, quite literally, in the margins’.