The “prince of liturgists,” Edmund Bishop (1846–1917), likened historians who busy themselves with “external criticism,” the verification of what primary sources can be made to say and what they cannot, to an army of “burrowing earth-worms”:
[I]t is well to remember that by their quiet, steady, persevering, and in the long run unerring labour, they have undermined more than one stately looking edifice which there can now be no question of shoring up or buttressing any more. Down it has, or inevitably must, come.1
Henry Parkes is less an earthworm than a blasting engineer, and the edifice he has demolished has been, until now, an axiomatically accepted datum of modern liturgical scholarship, the so-called Pontifical romano-germanique (PRG).
Standard textbooks on the medieval liturgy (e.g., Vogel's Medieval Liturgy: An Introduction to the Sources and Palazzo's A History of Liturgical Books) tell the story of the PRG and its reconstruction from some forty surviving manuscripts by Michel Andrieu.2 According to Andrieu, the PRG was created at Mainz in the middle of the tenth century as a “standard edition” of the bishop's liturgical book, complete with a guide to ordering the entire ecclesiastical year,3 in an attempt to unify liturgy under the Ottonians. Parkes has shown elsewhere that the PRG, as represented in its classic edition, never actually existed: the same texts are indeed encountered in some forty manuscripts, but seldom all together and often with significant alterations.4 In …