This paper examines Siena’s reliquary for the right arm and hand of John the Baptist, completed in 1466, with particular emphasis on the way its decoration helped to authenticate and promote the Eastern provenance of the relic held inside. Details of the saint’s severed head on a platter, rendered in mother of pearl, are related for the first time to similar devotional sculptures and ultimately the famous relic head of the Baptist in Amiens, implying a shared Constantinopolitan pedigree. Aspects of the reliquary’s relief narratives of the saint’s vita are also compared to similar Baptist cycles in Siena, especially those that evidence Byzantine influence.
Prato was the birthplace of a great merchant, Francesco di Marco Datini, who lived there when a remarkable relic, the Sacred Belt of Mary, was honoured with a chapel frescoed by Agnolo Gaddi. This relic became attached to a unique civic iconology. Gaddi gives us a specific and recognizable Prato as well as scenes from the life of Mary. Shortly after Datini’s death in 1410 a lesser artist, Pietro di Miniato, created another fresco, this one in the Palazzo Communale. With Mary hovering above, the fresco centres on another portrait of Prato (including Datini’s new palazzo), and inserts Datini himself as a kind of secular saint. Instead of holding the martyr’s gridiron or wheel, the evangelist’s pen or book, Datini holds a curious object, a reified signum: the symbol he used to sign documents in his Europe-wide trade. The painting renders Datini’s written and abstract commercial device as a material object, just as then-new letters of exchange rendered material wealth as the conventional abstraction of a bit of writing. The development of Datini as a figure in this and other civic art in Prato seems to parallel the earlier fabrication of the Sagra Cintola, and to trace the new mercantile globalization of the late Middle Ages.