Isorhythm

Isorhythm (from the Greek for "the same rhythm") is a musical technique using a repeating rhythmic pattern, called a talea, in at least one voice part throughout a composition.

[1] Although 14th-century theorists used the words talea and color—the latter in a variety of senses related to repetition and embellishment[2]—the term isorhythm was coined in 1904 by musicologist Friedrich Ludwig, initially to describe the practice in 13th-century polyphony.

Discarding modal-rhythmic limitations, isorhythm became a significant organizing principle of much of 14th-century French polyphony by extending the talea of an initial section to the entire composition in conjunction with variation of a corresponding color.

[7] "The playful complexity of ...[taleae] that mixes mensuration and undergoes diminution by half—became a typical, even a defining feature of motets in the 14th century and beyond".

[6] A 15th-century mass by a composer known only as Pycard found in the Old Hall manuscript (named for the English town in which it was eventually discovered), demonstrates the high sophistication and complexity of panisorhythmic techniques.