The 'arm' can be said to illustrate how the 'seasons' of waxing and waning moon are divided into weeks.

Hb9-23 has 7 'spines' at the back and Hb9-25 has 6. Furthermore, 7 * 28 = 196 and 6 * 28 = 168, which results in 196 + 168 = 364 = 13 * 28.

Waxing moon is lean (hungry and growing) while waning moon is fat. Waxing moon has a little black eye and waning moon a rather big white eye. The beginning of creation (also of a month) happens in the dark (as in the night of new moon).

The eye of waxing moon cannot be anything else than black, because that is her beginning. What is at the beginning will continue for 'life'. Therefore the eye of waning moon may be depicting full moon. Waxing begins with new moon and waning with full moon - Omotohi, when the 'sucking', omo, period is broken off, tohi, and she must be weaned.

Moon is waxing during half a month and 9 * 23 (in Hb9-23) = 207 = half 414.

In Hb9-25 we can count 9 * 25 = 225 = 15 * 15, alluding to how waning moon is beginning with full moon (the 15th night of the month).