Yang

The Western tradition divides the twelve signs into two alternating groups, beginning with Aries. Ptolemy treats them in the first book under the heading of masculine and feminine signs, and the division is mechanical: Aries belongs to the first group, Taurus to the second, and so on round the circle without exception.

The result is that the six fire and air signs form one group and the six earth and water signs the other. Aries, Gemini, Leo, Libra, Sagittarius and Aquarius are the active, projective, outward group this entry records as yang. They are the diurnal or masculine signs in the classical terminology, and the two elements they comprise, fire and air, are the two the classical physics counts as light and rising.

The property matters chiefly through the planets. A planet in a sign of its own charge is at ease in a way the tradition notices, and the doctrine of sect, which sorts the planets into a day team and a night team, runs on the same underlying distinction. Ptolemy classifies the planets themselves as masculine or feminine as well, so a full reading of any placement weighs the charge of the planet, the charge of the sign and the sect of the chart together.

The alternation is one of the small number of structural facts about the zodiac that no branch of the Western tradition disputes.

Sources TetrabiblosClaudius Ptolemy with A History of Western AstrologyNicholas Campion

The name this entry carries is not the tradition's own, and the reason for the change is worth setting out plainly.

The classical terminology is masculine and feminine, and in the sources it is doing two jobs at once. It is a technical label for an alternating property of the signs, and it is a live piece of the period's gender thinking with the evaluations of that thinking attached. Ptolemy and his successors move between the two senses without marking the transition, and the resulting text reads very differently depending on which sense a reader supplies.

Modern astrology has substituted several alternatives. Positive and negative were common earlier in the twentieth century and have largely been dropped, because negative reads as a judgement rather than as a charge. Active and receptive, projective and magnetic, and yang and yin are all in current use. The atlas uses yang and yin, which is what the underlying data carries, and states here that they are a modern substitution for a classical pair.

The substitution has a cost as well as a benefit. Yang and yin are a genuine and central pair in Chinese cosmology, with their own long history, their own texts and their own technical uses in the Yijing, in medicine and in calendrics. Borrowing the words to relabel a Greek category invites a reader to assume the two systems describe the same thing, and whether they do is a question of comparative scholarship rather than a settled fact. The atlas holds the Chinese material under its own entries and does not treat the two as equivalent.

Sources The Contemporary Astrologer's HandbookSue Tompkins with A History of Western AstrologyNicholas Campion