Plenarium of Duke Otto the Mild from the Guelph Treasure

A note in Latin on the inside of the cover announces that ‘This plenarium was prepared in the year of Our Lord 1339 […]’. The inscription refers to the completion of the cover. The plenarium itself, a liturgical text containing the complete readings of the Mass (Latin: ‘plenus’, complete) was probably completed a few years before. A Venetian chessboard was used in the front cover of the book. The back cover displays an artistically significant engraved depiction of St. Blaise, the primary patron saint of the Guelph ‘home church’ in Brunswick. Duke Otto the Milde of Braunschweig-Göttingen (r. 1318–1344) and his second wife Agnes of Brandenburg (1297–1334) are kneeling beside him as donors of the book reliquary.