A Medieval Latin Prayer in English Dress

The Collect for Purity predates the Reformation considerably, circulating in medieval Latin sacramentaries as a private prayer said by the priest while vesting or approaching the altar before Mass, well before Thomas Cranmer translated and repositioned it as the opening prayer of the entire English communion service in the sixteenth-century Book of Common Prayer. That repositioning changed its function significantly: what had been a priest's personal preparatory prayer, said quietly and not necessarily heard by the congregation, became a public prayer spoken aloud at the very start of the service, asking on behalf of the whole gathered community that God cleanse the thoughts of their hearts through the inspiration of the Holy Spirit. Its opening address, to whom all hearts are open, all desires known, and from whom no secrets are hid, sets a tone of complete divine knowledge of the worshipper's inner life before a single petition is even made, a structure liturgical scholars have noted gives the prayer unusual theological weight for its brevity. Cranmer's English translation has remained remarkably stable across nearly five centuries of subsequent prayer book revision, unlike many other texts from the same original 1549 book that were later altered, shortened or removed entirely.