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Domification and House Systems in Astrology

What is Domification?

Domification in astrology is the process of dividing the sky into twelve segments called "houses" based on a person's birth location and time.

Each house represents a different aspect of life, such as career, relationships, money, family, or health, etc. The method used for this division influences the interpretation of the astrological chart.

The houses are divisions of the plane of the ecliptic (a large circle containing the orbit of the Sun, as seen from Earth), at the time and place of the natal chart being studied. They are numbered counterclockwise starting from the beginning (this beginning is called the tip or the cusp) of the first house.

The methods of dividing houses in Western astrology vary based on their mathematical interpretation, related to space and time. All use twelve houses aligned with the ecliptic.

If the division is based on space, a plane (such as the ecliptic, the celestial equator, or another great circle) is divided into equal segments of 30°, and then projected onto the ecliptic.

If the division is based on time, the houses can represent either equal hours (each house equates to two hours of apparent solar movement per day), or variable hours depending on the seasons and latitude (day and night are divided into six equal parts).

Despite these differences, certain characteristics are common to all house divisions in Western astrology: the twelve cusps (starting points) of the houses are projected onto the ecliptic, the beginning of the first house is close to the eastern horizon, and each house is opposed to another (the 1st to the 7th, the 2nd to the 8th, etc.).

Description of the Most Commonly Used Domifications

On Astrotheme, three domifications are active on the natal chart application, the comprehensive portrait, the career and vocation report, and the child portrait. On the upcoming website within a few weeks, the following nine domifications will be offered.

Placidus Domification

Placidus is the most widely used house system in modern Western astrology. To determine the cusps of houses 2, 3, 11, and 12, the paths drawn from each degree of the ecliptic to the Imum Coeli (IC), then from the horizon (DS) to the Midheaven (MC), are divided into three parts. The cusps of houses 8, 9, 5, and 6 are directly opposite these.

The Placidus system has limitations at latitudes above 66°N or 66°S (polar circles), as some degrees of the ecliptic never touch the horizon, making it difficult to assign planets to houses in these regions. This characteristic is considered a weakness of the Placidus system, particularly due to the very unequal proportions of the houses at high latitudes.

This system is named after the 17th-century astrologer, Placidus de Titis. Although first mentioned in Arabic literature in the 13th century, the system's first confirmed publication dates back to 1602, in Giovanni Antonio Magini's work "Tabulae Primi Mobilis, quas Directionem Vulgo Dicunt". The first documented use in Czech dates back to 1627. Placidus remains the most popular system among English-speaking astrologers.

Equal Houses Domification

In the Equal Houses system, the ecliptic is divided into twelve sections of 30 degrees each, but the houses are measured in 30-degree increments from the degree of the Ascendant.

Thus, the Ascendant serves as the cusp or starting point of the 1st house. The 2nd house then begins exactly 30 degrees further in the zodiacal order, the 3rd house starts 30 degrees after the 2nd, and so on.

Proponents of this system claim that it is more accurate and causes less distortion at high latitudes (especially above 60 degrees) compared to the Placidus system and other quadrant-based house systems.

Whole Sign Houses Domification

In the Whole Sign Houses system, each astrological house covers an entire zodiac sign and measures exactly 30 degrees. The Ascendant marks the start of the ascending sign, and the first house begins at zero degrees of this sign, regardless of the exact position of the Ascendant within the sign. The next sign becomes the 2nd house, and so on, with each house corresponding to a whole sign.

This system was commonly used in Hellenistic astrology and is also present in Indian astrology and some forms of ancient medieval astrology, considered one of the oldest house division systems.

The Whole Sign Houses system might have been developed in Hellenistic astrology around the 1st or 2nd century BC and could have influenced Indian and medieval astrology. While its exact origin is debated, this system was continuously used in India and was rediscovered and reintroduced into Western astrology in the 1980s and 1990s.

The main difference between Equal Houses and Whole Sign Houses lies in that, in Whole Sign Houses, the top of the 1st house is the beginning of the sign containing the Ascendant, whereas in Equal Houses, the degree of the Ascendant is the top of the 1st house.

The Whole Sign Houses system is subject to debate, with some claiming it was the original form of house division and others suggesting it is not explicitly mentioned in the texts of ancient astrologers.

Concerns have been raised that this system may undermine the value of the angularity of houses. Martin Gansten suggested that although houses were often approximately defined by the signs alone, precise calculation by degree was always considered more accurate and useful.

Topocentric Domification

The topocentric system, a relatively recent astrological model originating from Argentina, was developed empirically. Its creators, Wendel Polich and A. Page Nelson, determined the geometry of houses by observing people's life events and seeking a house system that fits these observations.

The cusps of the houses in this system are generally located close to those of the Placidus system.

The topocentric system can thus be seen as a method of approximating the Placidus system. It is also known as the Polich-Page system, named after the inventors of this house system.

Koch Domification

The Koch system is a slightly more complex variant of the Placidus system, based on equal increments of Right Ascension for each quadrant.

Developed by the German astrologer Walter Koch (1895-1970), this system is applicable only to latitudes between 66°N and 66°S.

It is particularly favored by astrological researchers in the United States and especially in German-speaking countries. However, in Central Europe, its popularity is continually decreasing.

Porphyry Domification

The Porphyry house system is one of the oldest methods of house division and is based on quadrants.

In this system, each quadrant of the ecliptic is divided into three equal parts, between the four cardinal points.

Although attributed to Porphyry of Tyre, this system was actually first described by Vettius Valens, a 2nd-century astrologer, in the third book of his astrological work titled "Anthology."

Campanus Domification

The Campanus house system divides the prime vertical, a great circle passing through the zenith and the eastern point of the horizon, into twelve segments.

These divisions are then projected onto the ecliptic along great circles encompassing the north and south points of the horizon.

Although this system is attributed to Campanus of Novara, it is known that this method was used before him.

Regiomontanus Domification

In the Regiomontanus house system, the celestial equator is divided into twelve equal parts. These divisions are then projected onto the ecliptic using great circles that pass through the north and south points of the horizon.

This system is named after the German astronomer and astrologer Johann Müller of Königsberg, better known as Regiomontanus.

Although the Regiomontanus system was widely used, it was later supplanted by the Placidus system.

Alcabitius Domification

The Alcabitius system of astrological house division begins by dividing the diurnal arc of the Ascendant into six equal parts.

Through these segments, meridian circles are drawn, and their intersections with the ecliptic define the cusps of the Alcabitius houses. To find the cusps of the other houses, simply add 180° to those already calculated. This same method applies to the nocturnal arc for the remaining six segments.

In this system, the positions of the Ascendant and the Midheaven (MC) correspond to the cusps of the first and tenth houses.

The Ascendant/Descendant axis plays a key role in the Alcabitius system, as the size of the divisions depends on the diurnal arc of the Ascendant at the time of birth.

This system is named after the Arab astrologer Al-Qabisi, known in the West as Alcabitius, who lived until 967 AD.

Advantages and Disadvantages of Different House Systems

No domification is "perfect." The choice depends on the astrologer's preferences, the context of the analysis, and the birth latitude. Each house system has its advantages and disadvantages, so it is up to the practitioner to form their opinion through the experimentation of a large number of themes.

The Placidus system, the most used in modern Western astrology, offers great accuracy in mid-latitudes but encounters difficulties at extreme latitudes, where houses can become disproportionate.

In contrast, the Equal Houses system stands out for its simplicity, with each house measuring exactly 30°, although it may lack the nuance of more complex systems.

The Whole Sign Houses system (each house corresponding to a sign) is appreciated for its clarity, with each zodiac sign constituting a house. However, it can lack precision for temporal events.

The Topocentric system, less known, is particularly accurate for specific study purposes but is more complex.

The Koch system, similar to Placidus, works well for mid-latitudes, but like Placidus, it is less reliable at extreme latitudes.

Porphyry, one of the oldest systems, offers equitable divisions and is easy to understand, though it is less precise than time-based systems.

Campanus, interesting for the analysis of planetary aspects, is less suited for psychological interpretations. Like Porphyry, it does not take into account temporality in addition to space, as do more complete systems like Placidus or Koch.

The Regiomontanus system is accurate for aspects and transits but shares the same limitations as Placidus and Koch at high latitudes.

Finally, the Alcabitius system, which gives particular importance to the Ascendant/Descendant axis, is historically significant although less used today.