Porphyry arranges the Enneads

Thirty years after his teacher's death, Porphyry sorts fifty-four unrevised treatises into six groups of nine — a number chosen because six times nine is fifty-four and because both numbers pleased him.

The shape of the source text is an editorial decision. This app says that about the Golden Dawn's colour scales and about Kircher's wiring; it says it here too, about the book it treats as a headwater.