Decan 3 of Gemini

This is the third ten-degree segment of Gemini, the mutable air sign, spanning 20 to 30 degrees. Its ruler in the Chaldean order of faces is the Sun, reached by continuing the sequence of the seven planets around the thirty-six decans. The decan is the most ancient part of this material, the thirty-six having begun as Egyptian stars used to divide the year into ten-day weeks and the night into hours, absorbed into the Greek zodiac as ten-degree arcs only when Babylonian astrology reached Egypt.

The Golden Dawn of 1888 assigned the thirty-six minor arcana to the decans in zodiacal order; this segment bears the Ten of Swords, titled Ruin, its Sun-in-Gemini planet taken from the face ruler, the tens marking the fullest, and here the most exhausted, expression of the airy suit. The tarot correspondence is a modern overlay on the older decan scheme rather than a feature of the ancient tradition.

The third decan of Gemini runs from 20 to 30 degrees of the sign and is ruled, in the scheme this atlas records, by Sun.

The card on the decan

In the Golden Dawn's assignment this decan carries the Ten of Swords. The mapping is one to one and exhaustive: the thirty-six small cards numbered two to ten across the four suits match the thirty-six decans exactly, taken in order from the Two of Wands at the first decan of Aries. The suit follows the sign's element, so Gemini is a Air sign and takes a card of Swords, and the rank follows the position in the sequence, which puts the ten here.

Why the rulers carry over between signs

The thirty-six rulers run in the Chaldean order, the seven planets arranged from slowest to fastest as Saturn, Jupiter, Mars, Sun, Venus, Mercury and Moon, applied one after another right round the circle beginning with Mars at the first degree of Aries. Because thirty-six is not divisible by seven, the sequence does not restart at each sign. It runs straight through the boundaries, which is why the rulers of a sign's three decans are not the sign's own planets and why the pattern only closes after the whole zodiac.

What the atlas is recording

The degrees and the ruler are the attributions this atlas holds for this decan, and the card is the Golden Dawn's. All of them are traditions with variants rather than settled facts, and the decan itself, as a ten degree segment of a sign, is the only part that is simply arithmetic.