Welcome back to Between the Barlines AND another episode of Music Theory Friday!! We’re diving into a concept that might not be on your radar 24/7 when we are talking about analyzing music in general, but this concept has played a vital role in the evolution of Western music. This concept is called isorhythm. 

Teoria.com describes isorhythm as “a compositional technique developed in the 13th century and [was] in use up to the 15th century.” The term comes from the Greek words isos, meaning "equal," and rhythmos, meaning "rhythm." There are two different parts of isorhythm: the talea and the color. A repeating rhythmic pattern, known as the talea, is combined with a repeating melodic pattern, known as the color. These two facets of isorhythm don’t necessarily have to be the same length rhythmically and melodically. It’s actually really fascinating that these two patterns don’t necessarily align perfectly; it creates intricate texture in the music.
Isorhythm emerged in the late Middle Ages, particularly in the 14th and 15th centuries, as a foundation of the Ars Nova movement. Composers that we have spoken about like Guillaume de Machaut and Philippe de Vitry used isorhythm to structure their motets, creating pieces that were not only complex but also intellectually engaging. It was a revolutionary step toward organizing music in a systematic way, influencing later compositional techniques.
I’d love to take some time today to break down and analyze an example of an isorhythmic motet. When we talk about analyzing a piece of music this old, we aren’t referring to analyzing the harmonies. There was this cool time when I got a really awesome comment on my doctoral comps after having analyzed a piece in the form of a virelai (WE WILL TALK ABOUT THIS AND OTHER FORMES FIXES NEXT EPISODE!) because I said something about the “interesting harmonies.” Folks back then didn’t really care too much about that. What they did care about was consonance versus dissonance, and they tended to side with the former when composing music. Hence - why we will be talking more about the specific features, color, talea, and other things when analyzing this piece. 
The isorhythmic motet we are going to chat about today was composed by Guillaume de Machaut, and it is called “Quant en moy/Amour et biaute/Amara valde.” I have attached a score, both annotated and unannotated, in the episode notes for your visual perusal while we chat about analyzing this piece. Just a disclaimer about the annotated score: I am just now noticing some spelling mistakes of the word talea, so that’s cute. Also, this is obviously in modern notation, so take the large bar lines with a grain of salt. I have deciphered that this motet is in a compound triple feel, which comes from those modernized bar lines but also the placement of the talea which we will talk about soon.
Notice the three different labeled parts: the bottom part or tenor, is from an existing piece of music, labeled as Amara valde. The text is not sung here, but the melodic content is taken from a Gregorian chant typically sung on Holy Saturday. The two upper parts, both with different texts in French, are the motetus and the triplum. When I try to analyze something like this, I like to dig right in and find the talea because I find it easy to discover a repetitive rhythmic pattern first before finding some melodic outline that might start on a different note than its first iteration. With that being said, the tenor line is so slow that you can tell the entirety of the first page encompasses one talea statement. The next talea statement starts at the bottom of the first page. Throughout the entire piece of music, there are 11 talea statements. What I did was just followed the pattern set forth on the first page and mark the rest. That was easy! Next order of business is to find our color. This is the more challenging step of the two, I think, because you’ll notice on the marked score that the color is about the size of 6 full taleas. I neglected to highlight the whole first color, but when the diminution of the talea happens in the second half of this motet, the color also restarts and takes us to the end of the motet. 
Something else that we might look at, especially if you’re asked to analyze a piece like this on some sort of comprehensive exam, is what the text means. I am not going to go into that today for the sake of time, but it is important to consider the complexities of the text; sometimes the tenor, which is usually a sacred-based melody or chant, is paired with two completely secular pieces of text, creating an interesting juxtaposition of feelings.
A ton of these isorhythmic motets are present in a special work called the Roman de Fauvel, which was a 2-book collection of works in the early 14th century. This work was a collection of poems with musical interspersions, mostly consisting of works like these isorhythmic motets and other complex polyphony. As I stated earlier, the use of isorhythm continued well into the 15th century. Although isorhythm faded from mainstream use after the Renaissance, its influence can be traced to later composers, including Olivier Messiaen, who applied similar rhythmic cycles in his 20th-century works. Even in contemporary genres, the principle of looping different rhythmic and melodic patterns can be seen in minimalist music, electronic music, and even jazz improvisation.