Why thirteen
The earth makes one circuit of the sun in roughly 365 days. The moon completes 13 sidereal cycles in that same span — 13 × 28 = 364, plus one day for the gap. Twelve was a number imposed by emperors and accountants. Thirteen is the number the sky was already using.
A 13-month calendar with 28-day months was proposed publicly by Moses B. Cotsworth in 1902, championed in the 1920s by George Eastman of Kodak, and used internally at Kodak from 1928 until 1989. The League of Nations seriously considered it as a world standard in 1928. The same structure exists in older form across Indigenous lunar reckonings on every continent — the Pleiades calendar of the Aboriginal Yolŋu, the 13-moon traditions carried in many Native American tribes, the Druidic Coligny calendar. The earth knew this rhythm long before anyone wrote it down.
Twelve is a number imposed. Thirteen is the number the sky was already using.
The shape of the year
Every moon is exactly 28 days. Every moon begins on a New Moon Day (Sunday) and ends on a Settle Day (Saturday). The 8th and the 22nd are always Sundays. The 1st of every month, forever, is a Sunday. Once you learn one moon, you have learned them all.
The thirteen moons
The names come from the traditional Native American moon calendar — pre-colonial, agricultural, in tune with what each part of the year was actually doing. FRQNCY keeps them. Each is paired with the consciousness phase the body and field tend to move through at that time. The Gregorian dates are approximate — the system is a fixed grid, not seasonal drift.
Conversion
If you want to read your Gregorian date in moons: take the day-of-year (Jan 1 = 1, Feb 1 = 32, etc.), subtract 1, divide by 28. The integer is your moon number minus one. The remainder + 1 is your day inside the moon.
| Gregorian | Moon | Day | Weekday |
|---|---|---|---|
| Jan 1 | I — Wolf | 1 | New Moon (Sun) |
| Mar 21 (Equinox) | III — Worm | 24 | Tuesday |
| Jun 21 (Solstice) | VII — Sun | 4 | Wednesday |
| Sep 23 (Equinox) | X — Harvest | 14 | Full Moon eve |
| Dec 21 (Solstice) | XIII — Cold | 19 | Thursday |
| Dec 31 | — | Beyond Time | Day of Rest |
How to use it
For practice. Move through the moon. Notice what's seasonal in you on Wolf Day 12 versus Flower Day 12. The same numeric date hits you at different points of the year because the moon is different. You start to feel it.
For planning. Anything you ship on Day 14 of any moon ships on a Saturday — forever. Recurring meetings, salaries, retreats, releases all lock to the same weekday across years. The administrative overhead of the Gregorian calendar drops by a third.
For belonging. Each moon has a name your great-grandmother would have known. Tracking time this way is a small, quiet way of stepping out of the empire's clock and back into the earth's.
Sources & lineage
- — Cotsworth, M. B. (1902). The Rational Almanac. The original 13-month proposal.
- — George Eastman / Kodak — adopted internally, 1928–1989.
- — League of Nations Committee on Calendar Reform — final report, 1937.
- — Traditional Native American moon names — carried by the Algonquian-speaking peoples, popularised by the Farmer's Almanac.
- — Coligny Calendar (Gaulish, c. 200 CE) — a 5-year cycle of 62 months including intercalary months. The earliest known European lunisolar reckoning.