House Systems in Western Astrology

Whole Signs

The houses are sections of a natal chart that map the different areas of life and are fundamentally connected to an individual in the way the zodiac signs are fundamentally connected to the path of the Sun. Whole Signs is undoubtedly the oldest house system in astrology, having been used in ancient Hellenistic astrology and Indian astrology. There is evidence of its use in Hellenistic astrology dating to the 1st century BC and from the 2nd century CE in Indian astrology, and while Whole Signs is still used in Vedic astrology today it has a much more checkered history in the Western tradition. 

It is not hard to see why Whole Signs was used in a time when the ability to make complex calculations was limited. In this system the Ascendant is determined by the sign on the eastern horizon at the moment of birth and the rest of the signs progress in order to fill the rest of the 12 houses. There are no complicated mathematical procedures and they are remarkably easy to calculate based on the Ascendant. The houses are determined by the signs of the ecliptic with no consideration for the actual placement of the zodiac.  

By the time of Ptolemy and Valens in the 2nd century CE Hellenistic astrologers were using a hybrid approach with Whole Signs houses and quadrant zones determined by the birth time being used to evaluate dynamic division, length of life treatment, and planetary influence. Quadrant zones are determined based on the horizon and the meridian. The Ascendant is the point on the east horizon, the Descendant on the western horizon, the Midheaven is the noon point where the meridian crosses the south, and the Imum Coeli (IC) is the midnight point where the meridian crosses the north. 

Hybrid systems of whole signs and quadrant zones were used by Rhetorius of Egypt in the 6th-7th centuries, and Arabic astrologers Masha’alla and Abu Ali al-Kayyat in the 8th and 9th centuries. However quadrant houses completely displaced Whole Signs houses in Western astrology during the 9th century under the influence of Abu Ma’Shar. Quadrant house systems begin the first house at the Ascendant, the fourth house at the IC, the 7th house at the Descendant, and the 10th house at the Midheaven. Whole Signs would not become popular again in Western astrology until the 21st century. 

Placidus

Placidus is the most popular quadrant house system in use today. It was published by its namesake, a monk from Perugia, Italy and a professor of mathematics, astronomy, and astrology, in 1650. His house system was heavily influenced by the 11th century Spanish Jewish scholar Abraham Ibn Ezra and the middle ages interpretation of Ptolemy’s chapter on house division. How this chapter is translated is controversial but it has undoubtedly had a substantial impact on house systems in Western astrology. 

Ptolemy viewed astrology as a celestial sphere and Placidus was focused on recreating this three dimensional approach. Placidus delineates the houses based on time by trisecting each quadrant based on the time that the Sun takes to pass through that zone. This of course varies by the time of year, but also creates radically different sized houses at high latitudes. 

The Placidus house system cemented its place in Western astrology when Old Raphael published Placidus tables in his 1820’s almanac. Throughout the 19th and 20th centuries Placidus was the only set of astrological tables that was readily available at an affordable price to astrologers. While these calculations are more complex than Whole Signs, they are still relatively easy to delineate based on the horizon, meridian, and length of the day.  

Campanus

I use the Campanus house system, which was introduced by the mathematician Johannes Campanus in the 13th century. He also studied Ptolemy but as opposed to Placidus trying to create the cosmic sphere through time, he connected it to space using the prime vertical. Campanus houses use the pole of the meridian and project the houses onto the ecliptic by giving each house the same volume of the celestial sphere. I primarily focus on the effect that astrology has on our lived experience, and I’ve found that transits as interpreted through the areas of life drawn by the Campanus system carry the most relevance.

Like other quadrant house systems the Ascendant, IC, Descendant, and Midheaven mark the beginning of the 1st, 4th, 7th, and 10th houses. These can be compared to the cardinal cross in western astrology which begins each season at an equinox or solstice. Like with Placidus the angles of the prime vertical and the zodiac signs increase as you move away from the geographic equator, but not to the same degree. To be honest, I think that there is a psychological impact that comes with our experience of the seasons so it makes sense to me that you see intercepted signs when this experience is more severe. While the calculations required to draw Campanus houses may have once been difficult, that has changed with the algorithms of the modern age. 

Ultimately astrology is a tool. These are systems that have been built over millennia based on theory and observation. As we develop more advanced tools and are able to more accurately study the cosmos we’ve been introduced to new planets, asteroids, and systems to map our place in it. While I believe there are set aspects in astrology that create the fundamental theoretical base, how tightly we cling to certain elements should be in alignment with the overall theory. The houses drawn by space and time are an area where we can and should embrace advancements enabled by technology. 

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