Many calendars have 13 months of 28 days. Several begin at the spring equinox. Some follow the Moon. As far as we know, the Codex is the only one that does all three, adds the Sun's eight stations and Venus's 8-year cycle, and builds a daily breath practice into the day itself.
Open today's Codex date| Calendar | 13 × 28 frame | Equinox year start | Tracks the real Moon | Eight Solar Stations | Daily practice |
|---|---|---|---|---|---|
| Codex Calendar | Yes | Yes | Yes | Yes | Yes |
| Dreamspell / 13 Moon (1990) | Yes | — | — | — | Partly |
| International Fixed (1902) | Yes | — | — | — | — |
| Positivist (Comte, 1849) | Yes | — | — | — | — |
| Igbo calendar | Yes | — | Partly | — | — |
| Ethiopian calendar | Partly | — | — | — | — |
| Solar Hijri (Iran) | — | Yes | — | — | — |
| Baháʼí calendar | — | Yes | — | — | — |
| Wheel of the Year | — | Partly | — | Yes | — |
| Gregorian | — | — | — | — | — |
“Partly” means the calendar has a version of the feature: the Igbo calendar follows lunar months, the Ethiopian has 13 months of unequal length, Dreamspell has its own spiritual practice, and the Wheel of the Year marks the equinox as one of eight festivals.
The Codex stands in a long line of timekeepers and names them openly.
| Calendar | What it shares with the Codex | Where it differs |
|---|---|---|
| Dreamspell / 13 Moon calendar José and Lloydine Argüelles, 1990 | 13 Moons × 28 days and a Day Out of Time, with a spiritual practice. | Starts on 26 July, not at the equinox. Its 260-day count differs from the traditional Maya count. It does not track the real Moon. |
| International Fixed Calendar Moses Cotsworth, 1902 | 13 × 28 + Year Day; every date on the same weekday. Used by Eastman Kodak until 1989. | A civil business calendar starting 1 January with Gregorian leap years. No sky layers. |
| Positivist calendar Auguste Comte, 1849 | The identical 13 × 28 + 1 frame. | Months honour historical figures. Never adopted. |
| Igbo calendar Nigeria, traditional | 13 months of 28 days plus one extra day. | Built on the four-day market week and local seasons. |
| Ethiopian calendar Ethiopia, in national use | A 13-month year. | 12 months of 30 days plus a short 13th month. |
| Solar Hijri and Baháʼí calendars Iran 1925; Baháʼí 1844 | The year begins at the observed spring equinox; Baháʼí days set outside the months. | Ordinary month structures. No Moon or breath layers. |
| Wheel of the Year Modern pagan | The same eight Solar Stations. | A festival cycle, not a full date system. |
| Graves's "Celtic tree calendar" Robert Graves, 1948 | 13 months of 28 days with symbolic meanings. | A modern invention, not ancient Celtic; not tied to the equinox. |
The Codex book weighs every claim in three grades: established (measured or documented, with broad agreement), contested (proposed by serious researchers but disputed) and symbolic (a meaning offered through the lens of Breath Awakens).
| Claim | Grade |
|---|---|
| The year is about 365.2422 days and the Moon's cycle about 29.53 days; neither divides evenly | Established |
| An equinox-start calendar stays with the seasons; 8 leap years in 33 tracks the equinox closely | Established |
| Thirteen 28-day Moons echo the Moon's 13 journeys around the stars each year (27.3 days) | Established |
| Venus, the Sun and the Moon return together every 8 years | Established |
| Morning light helps anchor the body clock | Established |
| Paleolithic notched bones record the Moon; some ancient sites mark the Moon's 18.6-year cycle | Contested |
| Keeping the hinge practice improves sleep or wellbeing | Untested: a pilot is proposed in the book |
| The year breathes in four phases; the Moons carry archetypes and body points; the Breath Day is a still point | Symbolic |
Both use 13 Moons of 28 days. The Codex begins at the spring equinox instead of 26 July, tracks the real Moon's phases on every day, marks the Solar Stations, and computes daily hinges for your location.
The IFC solved planning but left the sky out. The Codex keeps the same easy frame and lets the year, the Moon and the seasons show through it.
No. They are a civil frame of four exact weeks. The real Moon, whose cycle is 29.53 days, is shown on top as its own layer, so you always see both.