Why did Guillaume de Machaut believe that “in my end is my beginning, and in my beginning”?

Question

Source: The Master and His Emissary (2009). p. 448 Middle.

  The individual life was seen in the past as more than just a line leading to — what? Its shape had the qualities of a circle: in my end is my beginning, and in my beginning is my end. Like many complex and apparently paradoxical dispositions to the world, this belief is better expressed in music than in words. Guillaume de Machaut's rondeau Ma fin est mon commencement, et mon commencement ma fin, written in the mid-fourteenth century, is not only remarkable for its beauty, but images its spiritual meaning in the form of the piece, in that the second voice part is the reverse of the first part, and the third is a palindrome. Reverting to an earlier discussion, this is something that is not merely clever, but is appreciable by the listener and taken up (aufgehoben) into the whole, where it adds to the meaning. The text expresses a truth about life in this world as well as in the next, death being a gateway to life; for our relationship with the world leads us constantly back to what was already known, but never before by us understood, circling and searching our own origins.
  This reflected the shape of the cosmos, the universe, and ultimately of the Divine. The idea that God is a sphere whose centre is everywhere and circumference nowhere has a long history. It as at least as early as the w, a body of early Christian texts from Hellenic Egypt dating back to the third century. After an interval of a thousand years, it was picked up by a thirteenth- century bishop, Alain de Lille, and is found throughout the Hermetic tradition in

the Renaissance, notably in Nicholas of Cusa in the fifteenth century and Giordano Bruno in the sixteenth, who wrote of 'an infinite sphere whose centre is everywhere and whose circumference is nowhere', an idea that was given its most famous expression by Pascal in the seventeenth century'.⁴⁴

Notwithstanding the last para. overhead, I still don't understand this medieval belief. I know that religion predominated the medieval era, but how'd even believers in the afterlife, believe that the end of their earthy life is the start of their spiritual life? These lives obviously happen in different realms and with different people (e.g. mortals on earth vs. angels in heaven).

Afterword: I first chanced on this phrase while reading p. 8 of the liner booklet to this CD:

These characteristics and preoccupations have certainly not vanished from his more recent orchestral works — on the contrary, his labyrinthine Exody (1997-98), composed during the upswing to the millennium, comprises his definitive realization of time as circular: 'In my end is my beginning, and in my beginning is my end,' as the medieval tag has it.

Answer 1

Simply stated, this is a three-voice chanson in which the second voice is the first voice sounded backwards, while the second half of the lowest voice is its first half sounded backwards. The sung text (by Machaut?) explains this somewhat enigmatically, in slightly old French:

Ma fin est mon commencement
Et mon commencement ma fin.
Et teneure vraiement
Ma fin est mon commencement
Mes tiers chans trois fois seulement
Se retrograde et einsi fin
Ma fin est mon commencement
Et mon commencement ma fin.

Here is a performance, with musical graphic: Machaut Rondeau 14, "Ma fin est mon commencement" (crab canon over a palindrome)

Answer 2

Like many ancient philosophical concepts, this was probably never meant in the literal way that a modern audience might experience it. There are overtones here of the mythical Phoenix, which dies, and is reborn, eternally, and of the Biblical description of God as the "Alpha and the Omega, the beginning and the end," but at root it's a very simple idea: The end of anything is connected to its beginnings. The old man is present, in some sense, in the baby, and the baby in the old man. They aren't two separate things, they are one thing, across the span of time.

In this case, however, there's little reason to assume that de Machaut might not have simply selected the title as a well-known phrase that was a good match for the structural games he wanted to play with the music.