A Companion to Hildegard of Bingen

hearing the heavenly symphony 181
from the larger structure. It seems possible that Hildegard’s fairly frequent
recourse to large ranges reflects not only her theory of human musical capability
before the Fall but also the neo-Platonic context that informed discussions
of mode in South German theory.61
However, like much of Hildegard’s music, O vos angeli also contains
prominent cadences on the fourth note above the fijinal (a) for the phrases
animas iustorum, et throni, sigillum secretorum Dei, and Sit laus uobis; in
Dendermonde all of these cadences are clearly signaled by the use of
soft-b (b-flat). This copious use of soft-b distinguishes Hildegard’s music
from that of some other South German composers, notably Hermannus
Contractus. Nevertheless, regional theory did allow for a fijifth tetrachord
named the synemmenon (G-a-b-c) to be used as an alternative for the “tetrachord
of the superiores” (a-h-c-d). According to the Musica of William
of Hirsau’s protégé, Theoger of Metz (d. 1120), two synemmena tetrachords
(Gamma-A-B[flat]-C and G-a-b-c) were widely used in South German
chant style: “It ought to be known that these two tetrachords, although
they are not regular, are nonetheless excessively common in practice.”62
Although Theoger acknowledged a lower synemmenon tetrachord, most
theorists did not accept soft-B in this octave, and notated sources of
Hildegard’s music never sign this lower soft-B. However, Hildegard’s music
frequently cadences with soft-b in the upper octave, so there is good reason
to consider the structural use of the upper synemmenon tetrachord
(G-a-b-c) as a feature of her style.
In O vos angeli, the synemmenon tetrachord allows the cadences made on
the note “a” to carry full deuterus quality, since the soft-b allows “a” to be
approached from the semi-tone above and the tone below. This also allows
the perfect intervals on “a” to be of second species, with deuterus quality:
the diatessaron a-b-c-d, the diapente a-b-c-d-e, and even the diapason a-bc-d-e-f-g-aa.
The systematic use of the synemmenon tetrachord therefore
brings all of the perfect intervals that are stressed in O vos angeli (the work’s
harmonia) into complete modal agreement (the work’s symphonia).63
61 McCarthy’s Music, Scholasticism and Reform, pp. 147–74, treats South German music
theorists’ use of neo-Platonic thought. Hildegard’s familiarity with the same key sources
(e.g. Calcidius and Macrobius) can be traced in the “Index auctorum” of Diu. operum, and
in Peter Dronke, “Platonic-Christian Allegories in the Homilies of Hildegard of Bingen,” in
From Athens to Chartres: Neoplatonism and Medieval Thought: Studies in Honour of Edouard
Jeauneau, ed. H. J. Westra (Leiden, 1992), pp. 381–96.
62 “Sciendum tamen, quod haec duo tetrachorda, quamvis non sint regularia, tamen
nimium sunt usitata.” Theoger of Metz, “De Musica,” in Scriptores ecclesiastici de musica
sacra potissimum 2, ed. Martin Gerbert (1784; repr. Hildesheim, 1963), p. 187.
63 The version in the Riesenkodex is less systematic than in Dendermonde and weakens
the cadential structure through its less coherent (and sometimes clearly erroneous)