Although the number of known works attributed to Ockeghem is surprisingly small in view of the length of his life and the esteem in which he was held, his masses constitute an imposing repertory. In addition to the earliest surviving polyphonic requiem and an isolated Credo, there are 13 cyclic Ordinaries, of which three appear to be partial settings. Unfortunately, it is rarely possible to date Ockeghem’s compositions with any precision, either from biographical details or from the evidence of the sources. One of the two masses for three voices may, however, be among the earliest; the cyclic structure produced by similar voice ranges, modal finals and mensural patterns recurring from one section to the next is reinforced by a head-motif rather than the tenor cantus firmus that tended to dominate continental mass composition beginning in the 1440s. Also noteworthy is a surprisingly consistent use of imitation, more so than in the presumably later four-voice masses. The implication is that if Ockeghem mastered imitative techniques early in his career, he made a conscious decision to employ them less predictably in subsequent works. The other three-voice cycle, the Missa quinti toni, which is characterized by exclusively binary mensurations and homogeneous textures, may date instead from the early 1470s, like its putative twin in the Vatican manuscript San Pietro B 80 (now attributed to Colinet de Lannoy), and reflect a renewed interest in three-voice mass composition during that decade (Wegman, 1987; Kirkman, 1997).
The remaining masses fall into two separate categories. The first and larger group consists of cyclic Ordinaries based on pre-existent material, either sacred or secular. The smaller group – equally important historically – comprises masses that seem to have been primarily freely composed. Turning first to the cantus-firmus compositions, one of the earliest is undoubtedly the Missa ‘Caput’, which Ockeghem modelled on the presumably English mass, once thought to be by Du Fay. With the exception of the Kyrie, the successive sections follow closely the structure of the earlier mass. But while Ockeghem adopted the rhythmicization of his model for the cantus firmus, he shifted it to the lowest voice, thus displaying his contrapuntal skills (and perhaps a special affection for his own voice register).
Perhaps his most straightforward treatment of a cantus firmus is deployed in the Missa ‘L’homme armé’. The mensural rhythms given to the famous tune in its polyphonic setting as a combinative chanson with Il sera pour vous are taken over into the mass with only minor differences. The borrowed tune is thus easily recognized even when, as in the Osanna and the third Agnus Dei, the values are prolonged in comparison with the movement of the other voices. The clarity of presentation of the cantus firmus makes even more effective its abandonment at the end of each major section as all four parts join to accelerate into the closing cadence. The cantus firmus is transposed (as in the ‘Caput’ mass) – to the lower 5th in the Patrem and to the lower octave in the Agnus Dei – reflecting again the composer’s tendency to favour the bass register. Ockeghem’s choice of range also provides a relatively early indication of the downward extension of the vocal registers that is one of the notable innovations of his musical style. In addition, Ockeghem appears to have imbedded into his counterpoint, as a kind of musical gloss on the pre-existent melody, references not only to the cantus of the combinative chanson but also to his own rondeau, L’autre d’antan, presumably in both cases because of the military imagery of the vernacular texts (Perkins, JM, 1984).
In what are probably later works, Ockeghem varied the treatment of the cantus firmus, assimilating it increasingly to the rhythmic and melodic activity of the other voices and thus moving towards a homogeneity of texture among the parts that was ever more characteristic of his mature style. In the Missa ‘De plus en plus’, for example, each movement opens with a literal quotation of the tenor of Binchois’ rondeau in extended values, but the borrowed melody is then paraphrased so freely as to make it virtually indistinguishable from the surrounding voices. (In this case, interestingly, Ockeghem repeated the first phrase of his cantus firmus at the end of each statement, probably in order to retain the orientation towards mode 8 on G with which the chanson opens rather than to follow its change to mode 2 on D.)
For the Missa ‘Ecce ancilla Domini’, the only surviving cyclic Ordinary by Ockeghem to use a plainchant melody as its tenor cantus firmus, the composer followed essentially the same pattern as in the Missa ‘De plus en plus’. In addition, this mass makes use of two innovative compositional procedures that anticipate the practice of following generations. One is the brief but quasi-systematic sequential treatment of the rising figure for the Amen at the conclusion of the Gloria, which helps to convey a sense of closure. The other is recourse to mimetic gestures not unlike those that were to become so common in the secular music of the next century to illustrate individual words and conceits of the text. In the Credo, for example, ‘et ascendit in celum’ is set to a steadily rising line, ‘sedet ad dexteram Patris’ to a descending one that settles into a cadence.
Ockeghem’s treatment of the cantus firmus in the Missa ‘Au travail suis’ (based on the tenor of a rondeau ascribed to both Ockeghem and Barbingant) is more original still. Whereas he presented the borrowed melody completely and with reasonable fidelity in the Kyrie (even though he altered its mensuration), in the following sections reference to it is reduced to little more than a head-motif. In addition, his extensive reliance in this work on homophonic textures removes it even further from the traditional pattern for cantus-firmus masses.
The incomplete cycle for five voices (sine nomine), which is based on plainchants for the Kyrie, Gloria and Credo, makes even more extensive use of syllabic declamation on repeated pitches (in the manner of the chants themselves). The liturgical melody is heard most frequently in the tenor, but it permeates the polyphony through imitation in the Kyrie, and in the Credo by migrating from voice to voice.
Ockeghem’s two other partial cycles, the Missa ‘Ma maistresse’ and the Missa ‘Fors seulement’, are both based on chansons of his own and appear to be late works as well. In these masses the voices take over material from more than one part of the model simultaneously and keep the borrowed lines in their original relationship to one another as other voices weave new counterpoints against them. Ma maistresse, a virelai, begins with a short mensuration canon between cantus and tenor that becomes a head-motif between superius and contratenor in the mass. The Kyrie is based primarily on the tenor of the chanson, carried by its bass, while its tenor quotes short excerpts from the cantus of the model. By contrast, the Gloria (the only other surviving section) borrows from the cantus for its contratenor, while its bass draws upon the virelai’s tenor. The resulting permeation of the part-writing by material derived from the chanson is greater than in any other of Ockeghem’s masses except the Missa ‘Fors seulement’. Here the tenor of the chanson has been adopted as a fundamental cantus firmus throughout, but the other voices are quoted extensively as well. Ockeghem may not have been the first to have quoted from several voices of a polyphonic model at once, but his ingenious and original use of these procedures clearly helped to prepare the way for the widespread adoption of similar procedures in the ‘imitation’ or ‘parody’ masses of the 16th century.
Ockeghem’s polyphonic Requiem has special historical significance as the earliest surviving setting. Each section is based on the corresponding plainchant, and the melodies, which are carried in the superius and only lightly embellished, are treated in the manner that had become conventional early in the 15th century for liturgical polyphony such as hymns, Magnificats and psalm settings. The numerous subsections for two or three voices give an impression of sober simplicity, but their skilful alternation with full four-voice textures achieves the cumulative effect that is characteristic of much of Ockeghem’s music. The work culminates with the offertory in which a more consistent use of full textures, together with more recondite mensural schemes and contrapuntal procedures, contributes to a sense of climax and closure.
The small group of masses that were apparently freely composed includes the compositions made famous over the centuries by the recurring discussions of fascinated theorists. Each is unique in its own way and without clear historical precedent; consequently their place in the development of the genre, individually and collectively, is difficult to determine. The Missa cuiusvis toni is not unduly complex in its contrapuntal style despite the practical problems involved in reading the work as notated with each of several modal finals as the determinant of scalar structure and modal orientation. The mass is designated by the composer as ‘in any mode’; Glarean categorized it as a ‘catholicon’, meaning it ‘might be sung in many modes, almost at the will of the singers’. Most discussions interpret the mass as intended to exemplify the four regular finals, re, mi, fa and sol (see Houle, 1992; Perkins, 1993), but an interpretation on three finals, ut, re and mi, was suggested by Glarean (see van Benthem, 1996; Dean, 1996). Since such a mass could have been used repeatedly and, if performed from changing finals, still have sounded somehow different from one time to the next, it may have been intended for ferial use. By contrast, the Missa prolationum may well be the most extraordinary contrapuntal achievement of the 15th century; using all four of Philippe de Vitry’s prolations simultaneously, it presents a series of canons whose interval of imitation expands from the unison progressively through to the octave in accordance with a complex combination of verbal instructions, rests and mensural signs. Surprisingly, the result is a graceful, euphonious composition that gives the listener no hint of the intricate technical problems it embodies.
Ockeghem’s purpose in writing such a pair of masses may have been didactic as well as musical. Taken together, they constitute a practical exemplification of the modal and mensural doctrine of 15th-century theory, a musical counterpart to treatises such as those written by Tinctoris. If the (much more modest) canonic chanson, Prenez sur moi, is seen in a similar light as a thorough-going exercise in solmization, the three compositions cover in a comprehensive and engaging way the fundamentals of music as taught at the time: hexachordal and modal systems, notation, mensural usage and of course composition (Perkins, 1990).
Perhaps nowhere does Ockeghem show more clearly his mastery of the cyclic mass as a polyphonic genre, nor the genius of his own style, than in the Missa ‘Mi-mi’. Here he has reduced the head-motif to the most concise of gestures, the falling 5th (E to A, mi in the natural and soft hexachords, respectively) in the bassus. If that figure refers at the same time to the tenor of his virelai, Presque transi, as has been claimed (Miyazaki, 1985), the allusion is both brief and characteristically subtle; for most of its substance the work seems to be essentially freely composed. Ockeghem deployed a typical pattern of changing mensurations throughout, mostly involving perfect and (diminished) imperfect tempus, coupled with skilfully wrought contrasts in texture and sonority. Internal cadences are often concealed by the continuous flow of interlocking melodic lines, and the ends of major sections are approached with lively rhythms and dotted figures that generate a strong sense of climax. This mass also has a surprising number of text-related compositional devices, such as contrasting registers – low for ‘suscipe deprecationem nostram’ and high for ‘Qui sedes ad dexteram Patris’ (Gloria); superius and altus for ‘Pleni sunt celi’ followed by tenor and bassus for ‘et terra’ (Sanctus) – strict imitation for ‘Et unam sanctam catholicam’ and black notes in extended values for ‘mortuorum’ (Credo). It exemplifies in full measure the ‘varietas’ and ‘subtilitas’ that characterize Ockeghem’s artistic aesthetic. It may also give some indication of the extent to which the humanistic passion for epideictic oratory – intended more to move than to persuade – had begun to influence Ockeghem’s compositional manner. A close relationship with Cardinal Jean Jouffroy, as is suggested by the shared embassy to the court of Castile and by the cardinal’s central role in procuring papal benefices for Ockeghem and his companions in the royal chapel, could have acquainted Ockeghem with the growing enthusiasm for rhetorical studies in humanistic circles. Jouffroy completed his education at the University of Pavia, where he studied rhetoric with Lorenzo Valla (who became his lifelong friend), and was himself both a scholar and an accomplished orator (Perkins, 1997).