This is the twelfth of a multi-part post. (Please see previous posts below for earlier installments.)
Example 13, Miserere by William Shelbye (d. 1584, of Canterbury Cathedral) is in three parts. It has the plainsong in the top part with each note repeated (a kind of plainsong figuration). In the first half of the verset the descant in the lowest part is labelled with the proportion 9:2 and the descant in the middle part is labelled 3:2. In the second half, the proportions of the two descants are exchanged (a process also used in Ex. 15).
One kind of plainsong figuration has been discussed in earlier posts (see Ex. 5b, Burton’s Tibi omnes, Ex. 7c, Redford’s Te prophetarum, and Ex. 11, Blitheman’s Eterne rerum I), involving breaking a simple note into two or more notes of shorter duration that equal its note-value. This can be done in a basic way (two minims replacing a semibreve, for example), or elaborately, to the extent that the plainsong is made into a melody like the descant, as described by Morley (Introduction, p. 90): ‘making your plainesong as [i.e. like] your descant notes, and so making [counterpoint] vpon it’. Another kind of plainsong figuration is ‘making it [each note of the plainsong] two long, three long, et cetera. Or three minimes, fiue minimes, or so forth, two minimes and a crotchet, three minimes and a crotchet, fiue minimes and a crotchet, et cetera’ (Morley, Introduction, p. 90).
In Shelbye’s Miserere each note of the plainsong is made two semibreves. Without the repetition of each note of plainsong the proportions against the two descants below would be 3:1 and 9:1. However, Shelbye, like other Tudor composers, enjoyed syncopation, and by repeating each note he creates the effect of the proportion ‘sesquialtera perfect’ (2:3) against the middle part, and ‘quadrupla sesquialtera’ (9:2) against the lowest part.
According to Morley (Introduction, pp. 91-92) ‘sesqui altra [3:2] and sesquitertia [4:3] they [the old descanters] denominated after the number of blacke semibriefes set for one note of the plainchant’. His example of ‘sesquialtera perfect’ is shown in Fig. 4 (bars 1-2); ‘in the third barre you have broken sesquialtra, & the rest to the end is Quadrupla sesquialtra, or as they termed it, nine to two’. A contrapunctus of Morley’s example, in which bars 3-7 are reduced to the basic 3:2 (‘sesquialtera perfect’), is shown in Fig. 5.
Figure 4 Morley, ‘sesquialtra’: three notes of descant (three black semibreves, in the top staff) to two semibreves of the plainsong (lower staff):
Figure 5 A contrapunctus of Morley’s example of sesquialtera (Fig. 4):
Note that the only dissonance in Fig. 5 is a 7-6 suspension in bar 2. In bars 4-6 of Fig. 4 (9:2) the descant comprises stepwise motion (creating several passing-tones) and consonant leaps.
Fig. 6 gives an example of 2:3 (subsesquialtera), Burton’s Te ergo, which has two descant notes for every three of the plainsong (a faburden), which is in the lower part. The dissonances are as follows: at plainsong notes 5, 17, 26, a 4-3 suspension; at note 8, a 7-8 bass suspension; at 29 a 7-6 retardation (a bass suspension resolving upwards).
Figure 6 Avery Burton, Te ergo (Te Deum, 29996, fol. 24r):
Example 13 William Shelbye, Miserere (30513, fols 47v-48v):