In the contemplation of the constellations/signs of the zodiac, a further defining which describes the interiority or inner qualities of each of these vast regions proves to be helpful. This is offered by the subdivisions of the zodiacal signs which are called decans. The 36 decans are 10░ subdivisions of the zodiac, three decans in each sign of thirty degrees.
The decans originated with the Egyptians and are referred to in an ancient text ascribed to the legendary teacher of the Egyptians, Hermes Trismegistus.1 In this text the planetary rulers of the decans are indicated (Saturn ruling the first decan of Pisces, Jupiter ruling the second decan of Pisces, Mars ruling the third decan of Pisces, etc.). The planetary rulerships describe the quality or mood of the subdivisions. These planetary rulerships assigned to the decans by Hermes were confirmed as valid by Rudolf Steiner.2 These same planetary rulerships are used in hermetic astrology, with the exception of the interchange of Mercury and Venus.
To understand this, let us consider the example of the sign of Taurus. Mercury, the Moon, and Saturn are indicated as the rulers of the three decans of Taurus. For Hermes, and also for Rudolf Steiner, esoteric Mercury was understood to be the ruler of the first decan of Taurus (having to do with the cosmic unfoldment of planetary evolution).
However, in astronomical science Venus and Mercury are interchanged. This signifies that the planet called Venus in astronomical science is considered - from a modern standpoint - as the ruler of the first decan of Taurus. On this account, Mercury and Venus are interchanged throughout the decanal descriptions used in hermetic astrology and indicated below, as we seek to discover the relational qualities of the inner work of the decans. Therefore references to these planetary names are the same as those assigned to Mercury and Venus by modern astronomy.3
Careful study of the mythology associated with the stars in each decan reveals the accurancy of this interchange. For example, as we have seen, Aldebaran (15 Taurus) is at the center of the second Taurus decan ruled by the Moon, and the star cluster of the Pleiades (5 Taurus) is located at the center of the first Taurus decan ruled by Venus (esoteric Mercury). Since the Pleiades are called the Seven Sisters, the rulership (influence) of this Pleiades decan by Venus can be felt as an experiential reality.
Apart from this detail of the interchange of Venus and Mercury, the planetary rulerships of the decans referred to in hermetic astrology are the same as those indicated by Hermes and confirmed by Rudolf Steiner.
As we come into a greater awareness of the cosmic realm as a relational field, we can begin to have an understanding of the relationship of the constellations which inhabit the region that surrounds the zodiacal belt as an expression of the subtle body of the zodiac. Just as the human being has a subtle body of life energy which extends beyond the physical form, the images which present themselves as constellations surrounding the zodiac bring to expression the qualities of the inner work of the decans.
According to an ancient tradition researched by Frances Rolleston in her work Mazzaroth, each of the 36 decans is associated with one or other of the 36 extra-zodiacal constellations as recorded in Ptolemy's star catalogue in the Almagest.4 The association is given by virtue of the constellation being located above or below the corresponding ten degree division (decan) of the sidereal zodiacal sign. However, it is only now, with the application of modern astronomy in determining the longitudes in the sidereal zodiac of the stars in our cosmos that the precise determination of an association of each decan with an extra-zodiacal constellation is possible. The methodology underlying the alignment of each star in the heavens with a particular location or meridian - given by the star's longitude in the sidereal zodiac - is described in detail in the section on mega stars (click here). Applying this method, it is evident that the decan associations with extra-zodiacal constellations given by the ancient tradition referred to by Frances Rolleston are by and large correct. Only in a few instances is it necessary to refine and update the ancient tradition of decanal associations with extra-zodiacal constellations. The updated associations are listed below, as far as it is possible to assign only one decan to an extra-zodiacal constellation, given that it often occupies an area (longitudinally in the sidereal zodiac) much larger than simply one decan (10˚) of the zodiac.
Thus, as the outer body of some constellations often comprises such a vast expanse in the heavens, their regions sometimes expand beyond a single decan. In several cases there are shared regions of influence - for example Auriga the Shepherd extends above the third decan of Taurus and the first decan of Gemini. Likewise, Orion the Hunter extends below the third decan of Taurus and the first decan of Gemini. Therefore, these two decans are associated with both Auriga and Orion. In the light of cosmic correspondences, however, Auriga is associated primarily with the third decan of Taurus and Orion is associated primarily with the first decan of Gemini, because these are the regions whose cosmic stories most magnify their unique influences.
Modern astronomy has made it possible to more accurately define this relational aspect through recording the light emanations from the individual stars. Recent research findings concern the relationship of the greater cosmos to the signs of the sidereal zodiac. This research reveals the reality of the greater cosmos as a living productive working body of spiritual significance, and this comes to expression in the connection of the extra-zodiacal constellations with the decans.
For example, if we read the starry script that supports the region of the heavens identified as the central ten degrees of Aries, i.e. the middle decan of the Ram, which is said to be ruled by the Sun, we find an amazing correspondence. For Cassiopeia,5 "The Enthroned Woman" stretches her starry body out as protectress of this region. Known in antiquity as the "queenly woman, matchless in beauty and exalted in dignity", Cassiopeia is revealed as a symbol for Sophia, "the woman clothed with the Sun", described in chapter 12 of the Book of Revelation.
The following - including the above example of the relationship between the second decan of Aries, the Sun, and Cassiopeia - is a complete list of the decans and their planetary rulers (allowing for the interchange of Mercury and Venus), and also the extra-zodiacal constellations they are associated with, which are above or below the respective decans in terms of sidereal longitude.6
Aries, the Ram
first decan - Mars - the Girdle of Andromeda
second decan - Sun - Cassiopeia
third decan - Mercury - the Throne of Cassiopeia
Taurus, the Bull
first decan - Venus - Perseus
second decan - Moon - Eridanus (the River)
third decan - Saturn - Auriga (the Shepherd, also called the Charioteer)
Gemini, the Twins
first decan - Jupiter - Orion
second decan - Mars - Canis Major (the Greater Dog)
third decan - Sun - Canis Minor (the Lesser Dog)
Cancer, the Crab
first decan - Mercury - Argo Navis ( the Ship Argo - Puppis, the Stern)
second decan - Venus - Ursa Minor (the Lesser Bear - the Neck of the Bear)
third decan - Moon - Ursa Major (the Greater Bear - the Flank of the Bear)
Leo, the Lion
first decan - Saturn - Leo Minor (the Lesser Lion)
second decan - Jupiter - Ursa Major (the Tail of the Great Bear)
third decan - Mars - Canes Venatici (the Hunting Dogs)
Virgo, the Virgin
first decan - Sun - Crater (the Cup)
second decan - Mercury - Corvus (the Raven)
third decan - Venus - Hydra (the Serpent - Tail of the Serpent)
Libra, the Scales
first decan - Moon - Bo÷tes (the Ploughman)
second decan - Saturn - Corona (Northern Crown) and Crux (Southern Cross)
third decan - Jupiter - Centaurus (the Centaur)
Scorpio, the Scorpion
first decan - Mars - Lupus (the Wolf - the Sacrifice)
second decan - Sun - Hercules
third decan - Mercury - Ophiucus (the Serpent Bearer)
Sagittarius, the Archer
first decan - Venus - Ara (the Altar)
second decan - Moon - Corona Australis (the Southern Crown)
third decan - Saturn - Lyra (the Lyre)
Capricorn, the Goat
first decan - Jupiter - Aquila (the Eagle)
second decan - Mars - Sagitta (the Arrow)
third decan - Sun - Delphinus (the Dolphin)
Aquarius, the Waterman
first decan - Mercury - Piscis Australis (the Southern Fish)
second decan - Venus - Cygnus (the Swan)
third decan - Moon - Pegasus (the Winged Horse)
Pisces, the Fishes
first decan - Saturn - the Square of Pegasus (the Body of the Winged Horse)
second decan - Jupiter - Cepheus (the Crowned King)
third decan - Mars - Andromeda
1 Wilhelm Gundel, Neue astrologische Texte des Hermes Trismegistos ("New Astrological Texts of Hermes Trismegistus") (Gerstenberg Verlag: Hildesheim, 1978).
2 Rudolf Steiner, Ancient Myths, (Rudolf Steiner Press: London, 1971), pages 57-58.
3 Robert Powell, Hermetic Astrology, volume I (Sophia Foundation Press: San Rafael, CA, 2007), pages 103-112, discusses the interchange of Venus and Mercury, and pages 238-261 elaborates upon the decans and their planetary rulers.
4 Frances Rolleston, Mazzaroth (Weiser Books: York Beach / ME, 2001). The tradition of decans associated with extra-zodiacal constellations referred to by Frances Rolleston, who first published her work in 1865, has been expanded upon by the following authors: Alice A. Bailey, The Labours of Hercules (Lucis Press: New York and London, 1974), and Ethelbert W. Bullinger, The Witness of the Stars and Joseph A. Seiss, The Gospel of the Stars both published by Kregel Publications: Grand Rapids / MI, 1967, 1972.
5 Cassiopeia's main stars create a large "W" in the night sky or an "M" according to one's viewing perspective (location) on the earth.
6 Cosmic Dances of the Zodiac by Lacquanna Paul & Robert Powell (Sophia Foundation Press: San Rafael, CA, 2007) offers further material relating to the decans and the mythologies of the corresponding extra-zodiacal constellations, and also gives indications of historical personalities born in the various decans.