From about the thirteenth to the sixteenth century, anyone who could afford it owned a ‘book of hours’ and kept it close at hand for daily use. It contained the prayers of the divine offices to be said at appointed hours, as well as psalms, lists of saints and a calendar, often tailored to the particular place in which it was used. My diary, the only book I use many times a day, is a paltry thing beside these medieval books, some of which are made visually beautiful with illuminations, and all of which are conceptually beautiful in their weaving of the hours of each day with the arc of the whole year.