A 'Magister Lambertus' was affiliated with the University of Paris in the late thirteenth century and may have taught music there in some capacity. His newly edited 'Ars musica' comprises two treatises probably written in the 1270s, Musica plana and Musica mensurabilis, which together are meant to provide a step-by-step overview of the rudiments of musical practice. However, only the treatise on mensuration was attributed to 'Lambertus' in the Middle Ages (and in one notable case to 'Aristotle'), suggesting that the Musica plana may be only a report of the magister's teaching by a student or compiler, as was often the case with treatises originating from university environments. In similar fashion, the plainchant theory of Johannes de Garlandia, one of the primary sources of Lambertus's plana, has come down to us in several reportationes (see Musica plana Johannis de Garlandia, introduction, edition, and commentary by Christian Meyer (Baden-Baden, 1998)).
While the declared goal of the Musica plana is to lay out 'some essential elements of the musical art for the benefit of singers' (p. 7), the extended and learned Prologue to the treatise, based on Boethius's De institutione musica, Guido of Arezzo, and—unusually—Gundissalinus's De divisione philosophiae, betrays its possible destination for a university audience of sorts. The author begins by outlining the structure of the gamut, then moves on to explain the 'properties' and 'mutations' of solmization, the diatonic intervals from the semitone to the octave, and the eight modes of plainchant. A fairly developed tonary, illustrating the modal 'differentiae', closes the treatise.
For its part, the Musica mensurabilis offers a methodical explanation of the rhythmic figures used in the mensural notation of the ars antiqua, following the combinatorial rules of modal rhythm. The treatise is articulated in three sections: figura (introducing simple and compound figures, the latter also known as 'ligatures'); tempus (a unit of time corresponding to the recta brevis, which Lambertus further subdivides into groups of two or three semibreves); and mensura (the time principle that guarantees coherence among the various rhythmic figures and modes in a given work). The presentation is interspersed with philosophical and theological citations from Boethius's Consolation, Hugh of St-Victor, and Scotus Eriugena. Contemporaneous authors such as Johannes de Grocheo and the St. Emmeran Anonymous are criticized the last section of Musica mensurabilis for raising the number of rhythmic modes from six to nine and for the handling of the semibreve. Although Lambertus's theory of mensuration was superseded by Franco of Cologne's Ars cantus mensurabilis (c.1280), his treatise points to the growing status of mensural polyphony as a legitimate topic of intellectual engagement in late thirteenth-century Paris.
The Musica plana arguably had a more lasting impact, as it was among the first treatises (together with Johannes de Garlandia's own plana cited above) to propose an enhanced version of solmization theory that remained a staple of chant pedagogy well into the modern era. This salient point is not sufficiently emphasized in the introduction to the edition, which otherwise carefully identifies the aspects of Lambertus's opus that either link him to, or differentiate him from, other authors. In short, influential late thirteenth-century theorists such as Garlandia and Lambertus appear to have ushered in what we might call 'solfisatio 2.0' by exploring the relationship between the ut–la syllables and the seven A–G letters in far more systematic terms than ever before. In particular, the newly minted concepts of proprietas (in a 'hexachordal' sense), deductio, and mutatio conferred new theoretical weight on the six syllables and became a veritable staple of musical training for centuries to come.
Thus, if Lambertus aimed at making the case for 'the hexachordal structure of the scale', as suggested on p. xviii (a reading that is, however, called into question by the more traditional sections on intervals and modes), it is [End Page 647] important to realize that such sixfold 'structure' played a...