The Thema Mundi ("World Theme", with 'theme' being a word that also means chart) was a mythical horoscope used in Hellenistic astrology that shows the supposed positions of the seven visible planets (including the Sun and Moon) at the beginning of the universe. It purports to exemplify the logic behind the sign rulerships, exaltations, and meanings of the aspects, among other things. The purely symbolic nature of the chart is readily perceived from the impossible positions of Venus and Mercury in it. In the late Middle Ages there has been a confusion between a horoscope of the world and the thema mundi.
The chart significantly diverges from the theory that the houses and the signs are directly correlated. Modern astrology assumes that Aries, the first sign, conveys its character to the first house. Instead the thema mundi has Cancer in the ascendant, suggesting that nature, rather than being aggressive (in correspondence to Aries and Mars), is nurturing (in accord with the symbolism of Cancer and the Moon).
|Diagram by Won Brain.|