ABSTRACT
This chapter describes both musical and historical features are used to evaluate such hypothetical chronologies. The other tracts are classed separately, despite the fact that the dates of origin of their Feasts are intertwined with those for which chronological strata are posited. The Advent Project took place in the late-seventh century, according to J. McKinnon, and it is probable that the eighth-mode tracts were revised and fixed by the Roman schola at this time. The transmission of the Easter Vigil tracts, which is rather different from that of the rest of the eighth-mode tracts, has prompted speculations that these tracts are either very much older than the rest of the corpus, or that they are very much younger. The suggestion of Jean Claire and his followers that these chants represent the most ancient state of the eighth-mode tracts must be approached with circumspection.
