In Hellenistic astrological literature, there’s a chart that’s said to be set for the creation of the world. A planetary nativity – that is much more than what it seems or is claimed to be – floated around in the Hellenistic world and was a wonderful tool for anyone who could learn to interpret it. This chart was called the Thema Mundi. It should be obvious that no chart could really claim to be set for the beginning of the world, as logic dictates finding the moment for when the Earth was created would take some pretty awesome powers. In truth, the chart was a completely made up concept, however, this is one of those rare occasions when something being made up isn’t useless. The truth behind the Thema Mundi is that it was used as a teaching tool for certain Hellenistic principles. First, though, we should discuss the structure of the Thema Mundi itself.
As you can see, the Thema Mundi looks like a pretty decent horoscope, aside from the fact that some of its placements can’t really happen. The Ascendant on the chart is 15° of Cancer, which might seem like a random placement, but there is a logic behind it. One of the more obvious ones would be that it’s linked to the beginning of the Egyptian New Year. The New Year started at the helical rising of Sirius, and while that star is obviously the alpha star of Canis Major, it is zodiacally placed in Cancer. Another interesting correlation is that there’s a Hellenistic belief that all souls descend to earth through the Gates of Man which is said to be located in the nebula in the middle of Cancer. It would seem only logical that the soul of the world would descend from the same gate.
The Thema Mundi was used as a Hellenistic teaching tool, the first thing it teaches is obviously the planetary domiciles as the planets within the chart are all set in one of their domiciles. Something else the chart teaches are exaltations with differing rules depending on the sect of the planet. The nocturnal planets all sextile their sign of exaltation, while the diurnal planets trine their exaltations. Luna in Cancer sextiles Taurus, Venus’s domicile of Taurus sextiles to Pisces, and Mars’ domicile of Scorpio sextiles Capricorn, in the diurnal sect Sol in Leo Trines to Aries, Jupiter’s domicile Pisces trines to Cancer, and Saturn’s domicile of Aquarius trines to Libra. Mercury gets to be the oddball here – as Mercury usually is – already being within its sign of exaltation and domicile.
Something else about the exaltations: they are all configured to the Thema Mundi ascendant. Moon’s exaltation of Taurus sextiles Cancer, Mercury’s exaltation of Virgo also Sextiles Cancer, Venus’s exaltation Trines Cancer, Sun’s Squares it, Mars’s exaltation Opposes it, Jupiter’s conjoins it, and Saturn is Square to it. I find it interesting that the benefic planets are all in harmonious aspects to the Thema Mundi ascendant, whereas the malefics are all in a harsh aspect to it. This would, of course, mean we have to consider the Sun a functional malefic planet given his tendency to severely debilitate planets he conjoins with.
The chart also teaches aspects based on the concept of planetary natures of benefic and malefic planets. Saturn opposes the Moon, so the opposition aspect is of the nature of Saturn, the greater malefic which by the law of association makes the opposition the most hostile of the aspects. Jupiter – the greater benefic – trines the sun, which makes the Trine share in Jupiter’s benefic nature. Mars Squares the sun, making the square share the conflicting and lesser malefic nature with Mars. Venus performs a sextile to the sun, and the sextile echoes the helpful attitude of the lesser benefic. The oddball nature of Mercury is reflected in the semi-sextile – which it performs to the sun – which is described as “minorly helpful”.
So you can see the Thema Mund is a great tool to understand and observe some of the basics of Hellensitic astrology!