Grandes chroniques de France Jean Fouquet: Caligula Stephen, illuminated manuscript

Caligula Troper, British Library Cotton MS Caligula A XIV; St Stephen as a Deacon, in the Caligula Troper, British Library: [1],
Per BL: "The illumination for the feast of St Stephen refers to the book's liturgical use, depicting the saint who, as one of the original deacons, would have sung the chants of the mass. By the 11th century deacons still sang some of the most beautiful chants such as the Exultet (the blessing of the paschal candle). The white stole (maniple) in his left hand indicates his grade as deacon, and the book and smoking censer (thurible) symbolise his duties as lector and assistant at the sacraments. His red dalmatic symbolises the Eucharist and martyrdom, while the branch represents the palm of martyrdom or the rod of Aaron, a reference to priesthood."