What was billed as a special multimedia event, “Capturing Music: Writing and Singing Music in the Middle Ages,” took place Sunday afternoon at First Church in Cambridge, Congregational. The music in question was chiefly a chanted alleluia for Easter Sunday, in versions from the centuries on either side of 1000, sung by the vocal ensemble Blue Heron under the direction of Scott Metcalfe. Their performances illustrated a lecture by Thomas Forrest Kelly, the Morton B. Knafel Professor of Music at Harvard; among the event’s sponsors was the Harvard Department of Music.

Blue Heron seems to be unusually busy this season, having just performed last week both in concert and in their role as de facto resident early-music ensemble at Boston University. As explained on their website [here], Sunday’s event was a preview of Kelly’s forthcoming book-cum-CD of the same title (it has been announced for publication later this year by W. W. Norton). To judge from Sunday’s presentation, the book is likely to live up to its advertised description on the publisher’s website as “an entertaining history of how musicians learned to record music for all time.” Given Blue Heron’s long association with Harvard, their collaboration with Kelly on the project comes as no surprise, though Sunday’s performance was no less beautiful and polished for that.

The media at Sunday’s presentation were not particularly multi: apart from Blue Heron themselves, just a standard computer and video projector. But the color photos from numerous medieval manuscripts, displayed on a screen set up at the front of the church sanctuary, were well chosen and beautifully detailed, if possibly too small for many in the audience to see clearly.

Kelly is a terrific lecturer, and at moments I felt as if I were in school again, experiencing a type of teaching that, unfortunately, is more common in films than in reality, and which is frowned upon by educators who underestimate students’ capacity to learn from something that is not interactive or simplistically entertaining. Kelly is lively and infectiously enthusiastic about his subject, even when, as in this case, it is one that is potentially quite dry: the beginnings of musical notation in Western Europe. This topic, although one of the hoariest in musicology, is far from settled in all details. While Kelly stuck close to traditional subject matter and examples, specialists will have appreciated his personal takes and reinterpretations of various issues. (For instance, he points out that the earliest notation was concerned with musical lines or “gestures,” not individual notes, and he questions the notion of the so-called substitute clausula, preferring to see examples of the latter as keys to the rhythm of motets whose notation did not yet indicate the durations of most notes.)

Although the ancient Greeks had a form of musical notation, they used it rarely, and by the early middle ages it had been completely forgotten in Western Europe. Thus the monks whose job descriptions included singing what we call Gregorian chant had to memorize it until the re-invention of notation around 800 or 900. (The date and place are somewhat controversial, and throughout the event Kelly avoided giving dates or pinning developments to particular places.)

Kelly focused on three crucial developments, starting with the invention of graphic signs to suggest the general shape of a melody—what makes it beautiful, rather than its individual notes or pitches. The latter came to be fixed in notation only at a second stage, to be followed by the specification of durations or rhythms for those notes. Blue Heron sang examples of music representing each of those developments, beginning with the chanted introit “Ad te levavi” for the first Sunday in Advent—the first text in many medieval chant books—and the Alleluia “Pascha nostrum” for Easter Mass.

These were sung beautifully and imaginatively. Most musicians today think of chant as simple, but it poses many questions, both interpretive and technical. Who shall sing it? how many singers? all male? where shall they stand? how to direct it? Beyond these fundamental questions comes the more substantial one of what sort of rhythm and phrasing to use in music whose notation indicates neither.

Metcalfe’s solution, at least in presenting these examples of early notated chant, was to use seven male singers, not counting himself; he stands facing the others, discretely conducting. The chants in question belong to two of the more florid types in the repertory, and Metcalfe had them sung in a somehwat more lively fashion than one usually hears. This allowed embellishments within the melodies to be sung as such, rather than simply intoned with the same unchanging weight as other notes. The latter became the norm by the fourteenth or fifteenth century, and the group demonstrated this as well, as an illustration of subsequent practice, which was beautiful in its own familiar way but far less engaging or expressive.

Rhythmically, Metcalfe’s approach is distinct from both the Romantic but somewhat amorphous style pioneered in the early twentieth century by the monks of Solesmes and the heavily metrical, almost dancelike approach made familiar to many listeners in the US by R. John Blackley and Schola Antiqua beginning in the 1970s. Recent years have seen various groups tending toward one or the other of these extremes, but I have heard few performances as convincing or as well thought out as these. Characteristic of Blue Heron’s chant is a tendency to move quickly at the heart of a melismatic phrase, then to relax as it reaches a cadence, sometimes leaving a substantial silence before moving on. This gives the music a beautiful, expressive shape, and it must be the product of much rehearsal and careful listening to one another by the singers. You can’t fake this; lacking harmony, chant leaves no room for error, and this was sung with perfect ensemble.

Of course, we have no idea whether this was what one heard historically. Certainly most medieval churches and monasteries could not have heard such beautiful singing, but, as Kelly suggested through comments made at various points, what we were hearing was not merely functional service music. This was music sung by specialists for the elite, becoming even more so when monks in the great cathedrals of Paris and other centers began adding harmony to chant.

Kelly’s second step in the development of notation, the fixing of pitches, was illustrated by the hymn “Ut queant laxis.” A very different (and less interesting) type of music when compared to the two opening chants, this made little musical impression. But it is fitting to include the hymn in presentations such as this, as it was the source of those famous syllables ut, re, mi, fa, sol, la, used for singing scales (“ut” was later replaced by “do,” which, as Kelly observed, made possible “Do, a deer” in the Sound of Music).

Musically the high points of the afternoon were the examples of two- and three-part polyphony or organum constructed upon the Alleluia “Pascha nostrum.” Like chant, organum raises problems that scholars and performers have addressed in various ways, particularly in the two-part variety attributed to the Parisian musician Leonin. Here Jason McStoots sang Leonin’s upper line, with several others doubling on the notes of the original chant melody, now stretched out to many times their original duration. This too was done beautifully, the upper part executed with much the same freedom as the chant, but with greater flexibility and virtuosity than one hears in less successful efforts to make sense of this music. This performance left no doubt that, as arcane as two-part organum or its notation may be, this is exciting stuff when executed with imagination.

I felt similarly about the three-part setting of the same alleluia ascribed to the follower of Leonin known as Perotin. This is an immensely lengthy re-imagining of the original chant, now with two lively upper parts—in this performance each doubled by two singers—intertwining kaleidoscopically. Here Kelly suggested a parallel to the American minimalism of the late twentieth century, and there is perhaps a common focus on simple repeated patterns, not to mention the extended time frame in which both types of music take place. But hearing this music performed in a great space, rather than through loudspeakers or headphones, I was struck by the incessant variety, the absence of simple patterning, in Perotin’s counterpoint. No doubt this variety was deepened by the acute sensitivity of both singers and director to the sounds they were producing and to the changing rhythms of the three parts.

I would have been glad to hear more of that music. But because this was, after all, a lecture, Kelly continued to the third step in his history of notation, which was illustrated by somewhat later sorts of medieval polyphony. The sustained nature of chant and organum makes it taxing to sing, and both he and the singers may have lost some of their energy by the time it came to deal with the clausula and the motet. But I sensed no fatigue in the performance of the final selection, the 13th-century English song “Sumer is icumen in.” This had little to do, stylistically or in the subject matter of its text, with what had preceded it. But it is an old favorite, and its echoing cuckoo calls made for a lively ending to a beautifully conceived demonstration not only of music history but also of how to teach it.