The problem of modally ambiguous chants – which received much attention from medieval theorists – is most clearly demonstrated by juxtaposing different readings of a particular chant. This procedure often reveals transpositions (partial or complete), and other differences, many of which affect the final cadence. For example, the offertory Justitiae Domini, in the Vatican edition and various manuscript sources (e.g. F-Pn lat.776, 780, 1132) ends on E (deuterus); but the St.Yrieix gradual (F-Pn lat.903) and some other early sources (e.g. I-BV VI.34, GB-Lbl Harl.4951) emend the final cadence to end on F (tritus). This changes the maneria of the chant. A critical study of such mode-change is the primary task of this paper.

At the Third Colloquium of Scandinavian Liturgists assembled at Hanaholmen in May 1975, I distinguished two categories of liturgical chant book: (i) the books emanating from the first Carolingian renaissance – sacramentary, antiphoner, etc.; (ii) the books extracted from the preceding in the course of the second renaissance of letters and arts under Charles the Bald (840–877) and later – pontifical, troper-proser, processional.

Genetical factors cannot be excluded from the forces which determine vocal colour. There is no reason to suppose, therefore, that English singing should resemble that of any other nation in all respects. The facility for falsetto singing (by adult male, boys' and women's voices), the paucity of ‘true’ tenor voices and the ‘duller’ tone production all may be cited as characteristic of English singing, and might have a genetical basis. Vocal quality would also be affected by the time at which boys' voices changed, and if Latin were superseded by the somewhat duller English language.