first half (“my beginning”) relates to its second half (“my end”), the rondeau being the one fixed form
whose two halves, unlike those of the ballade, are played straight through, and whose final cadence,
unlike the virelai’s, comes at the end of the second half.
The piece is notated in two parts, but the text refers to the “third part,” so we know that there is an
unnotated part. That third part is labeled contratenor, so we know that the unnotated part is the tenor, of
which we read that its end is its beginning. The contratenor is only half as long as the other notated part
(the cantus), and we are told that it reverses itself. So we have a hint that it must double back on itself for
“complete” statements of the two halves (AB) within the rondeau form, of which (the text reminds us)
there are three. So this doubling-back or going backwards must also be the way the unnotated tenor is to
be derived from the notated cantus. (Proceeding backward was known as cancrizans motion after the
word for “crab,” an animal evidently thought in those days to walk backward rather than sideways.) Thus
the whole song can be “realized” from the rubric: Accompany the cantus with its own cancrizans (and
note that when this is done, the tenor actually behaves like a tenor at the final cadence), and supplement
the contratenor with its cancrizans to fill out the required length.
FIG. 9-4 Guillaume de Machaut’s rondeau Ma fin est mon commencement, as it appears on folio 136 of Paris, Bibliothèque
Nationale, MS Fonds Français 9221, a manuscript containing the collected works of Machaut, copied for Jean Duc de Berry (d.
1416). The song begins on the fourth notated line. Only two of its three parts are written down: one without text (incorrectly
labeled “Tenor” in this source; it should read “Contratenor,” as it does in other manuscripts); the other with the text upside
down and to be read backward (forming the tenor), while another performer reads it normally (forming the cantus). Only the first
half of the (contra)tenor is given. At the point where it ends (the three-note ligature at the beginning of the fifth notated line),
the musician reading it is to reverse direction and perform it again from back (fin) to front (commencement).
EX. 9-18 Guillaumede Machaut, Ma fin est mon commencement in transcription