Ordo Romanus Primus (ORP) is a descriptive account in Latin of the papal mass at Easter in Santa Maria Maggiore, probably at some time in the seventh or eighth century. It is the first such account, and differs from earlier evidence of the Roman rite by its relative disregard for the spoken text, which is usually only cited in ORP as providing cues for the ceremonial action. The 'action', however, is detailed, is often surprising, and gives a three-dimensional...