Decan 2 of Aquarius

This is the second ten-degree segment of Aquarius, the fixed air sign, spanning 10 to 20 degrees. Its ruler in the Chaldean order of faces is Mercury, following the continuous sequence of the seven planets around the thirty-six decans. Historically the decan is the most ancient layer of the tradition: the thirty-six were Egyptian star groups, a calendar and a night-clock older than the zodiac, folded into the twelve signs three to a sign only after Babylonian astrology reached Egypt.

The Golden Dawn, from 1888, mapped the numbered minor cards onto the decans; this segment carries the Six of Swords, to which they gave the title Science or Earned Success, its Mercury-in-Aquarius attribution taken from the face ruler, Mercury in the airy sign of the mind matching the card's theme of hard-won clarity and passage to calmer water. That tarot layer is a modern Western construction over the ancient decan scheme rather than part of the inherited astronomy.

The second decan of Aquarius runs from 10 to 20 degrees of the sign and is ruled, in the scheme this atlas records, by Mercury.

The card on the decan

In the Golden Dawn's assignment this decan carries the Six 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 Aquarius is a Air sign and takes a card of Swords, and the rank follows the position in the sequence, which puts the six here.

Three layers, three periods

The decans are Egyptian: thirty-six star groups whose successive risings told the hours of the night, attested on coffin lids from the Middle Kingdom onward. The division of the zodiac into thirty-six ten degree segments with planetary rulers is Hellenistic, several centuries later, and it is a different object that inherited the name and the number. The tarot assignment is later again, and belongs to the Hermetic Order of the Golden Dawn in the late nineteenth century. None of it is Egyptian, and this atlas records the three as three.

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.