Some just use stamped leather, but for others the material used is variously described as "a sort of gesso mixed with varnish",Diehl, 83 or just "gesso",Marks, 40 but these plaquettes can have extremely fine detail. What may have been Grolier's first such binding has a plaquette with 11 human figures and an architectural setting in a scene about two inches (50 mm) wide, showing Marcus Curtius leaping into the hole, the same subject as on the British Museum casket illustrated at the start of the article.BL G 9026, De Medicina, by Aulus Cornelius Celsus; British Library Bindings database , with good images. Marks, 40 and Hobson, 18 both illustrate the cover.
