The West Apse at the Mausoleum of Galla Placidia: Detail, St. Lawrence or St. Vincent
The bookcase on the left contains the four gospels, labeled by their purported authors. In the center is a gridiron such as the ones on which the deacon saints Lawrence and Vincent were martyred. A figure runs in from the left wearing a dalmatic with long vertical stripes such as a deacon would wear in 6th-century Ravenna. He carries a processional cross and a gospel book on a stand. These most likely refer to some of the liturgical duties of a deacon during the fifth century: leading the faithful to their place, maintaining order, and reading the assigned passages from the Gospel.
For a long time most scholars believed that this deacon was St. Lawrence, whose death by gridiron was being portrayed as early as the 4th century. However, Gillian Mackie has argued that he is St. Vincent. His Passio speaks of his rushing to the gridiron "with quick step. Joy gives him speed." And his punishment is specifically for refusing to lead the authorities to the church's books, which they sought to burn. Further, although he was martyred in Spain Vincent had a widespread following, especially in Ravenna, where he was invoked in the Litany of the Saints and is among the martyrs in the great procession mosaic at Sant'Apollinare Nuovo (Mackie, 54-58).
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Photographed at the site by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.