At this church whose patron was Galla Placidia (died 450), paired rectangular chambers flanking the apse, accessible only from each aisle, have been interpreted as paired (Latin and Greek) libraries and perhaps scriptoria [REF].
The individual traditions of scriptoria developed in incomplete isolation, to the extent that the modern paleographer learns to identify the product of each scriptorium and date it approximately by comparison with other, datable productions of that scriptorium.