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House Division Calculations in Astrology Explained

The Astrology Podcast・155 minutes read

Chris Brennan and Luís Ribeiro delve into the historical and mathematical aspects of house divisions in astrology during the Medieval period, emphasizing the importance of understanding various systems for informed choices. The debate over different house systems, like Whole Sign, Placidus, and Regiomontanus, showcases the complexity and historical evolution of astrology, with scholars like LR continuing to research and educate on these topics.

Insights

  • Historical and mathematical rationale behind house division is crucial for astrologers, even with the availability of modern tools.
  • Astronomers and astrologers historically shared intertwined disciplines, showcasing the close relationship between the two fields.
  • The debate on whether manual chart calculations should be a requirement for astrology certification remains ongoing.
  • Preferences for house systems can vary due to astronomical, mathematical, cultural, and historical reasons, impacting astrological interpretations.
  • The evolution of house division systems highlights the historical shifts in popular methods, such as the reemergence of the whole sign system in the late 20th century.
  • Different quadrant systems like Porphyry, Alcabitius, and Campanus present unique approaches to house division, influencing astrological interpretations.
  • The revival of traditional astrology in the 1980s led to a resurgence of specific house systems like Regiomontanus, particularly in horary astrology.
  • Academic research and historical texts provide valuable insights into the development and debates surrounding house division systems in astrology.

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Recent questions

  • What are some common house division systems in astrology?

    House division systems in astrology include Whole Sign, Placidus, Regiomontanus, Alcabitius, and Koch houses. Each system has its unique way of dividing the chart based on different astronomical and mathematical principles, influencing the interpretation of astrological charts.

  • How did the whole sign house system evolve historically?

    The whole sign house system, originating in the first century BCE, was one of the earliest documented systems in Western astrology. It faded by the end of the Medieval period but reemerged in the late 20th century in the Western tradition. Despite its decline, the whole sign system continued to be used in Indian astrology throughout history, showcasing the system's enduring influence and resurgence in modern astrology practices.

  • What is the significance of the Ascendant in astrology?

    The Ascendant, or rising sign, is a fundamental concept in astrology, representing the zodiac sign that was rising over the eastern horizon at the time of an individual's birth. It marks the beginning of the first house in an astrological chart and plays a crucial role in determining the overall structure of the chart. The Ascendant influences an individual's outward personality, appearance, and approach to life, making it a key point of analysis in astrological interpretations.

  • How did the use of astrolabes impact astrology in the Medieval period?

    Astrolabes, complex devices used for astronomical and time-telling purposes, played a significant role in astrology during the Medieval period. They facilitated the calculation of celestial positions, including the Ascendant and Midheaven degrees, aiding astrologers in chart calculations. The availability and ease of use of astrolabes contributed to the popularity of quadrant systems of house division, influencing the practice of astrology and the accuracy of chart interpretations during that time.

  • Why is understanding different house division systems important in astrology?

    Understanding different house division systems in astrology is crucial for astrologers to make informed choices and interpretations. Each system, such as Whole Sign, Placidus, Regiomontanus, Alcabitius, and Koch houses, offers unique perspectives on chart analysis based on varying astronomical and mathematical principles. By comprehending the historical and mathematical rationale behind house division, astrologers can enhance the accuracy and depth of their interpretations, adapting to different preferences and approaches in astrology practice.

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Summary

00:00

Medieval Astrology: House Division and Astrolabe

  • Chris Brennan and Luís Ribeiro discuss the mathematics and astronomy behind house division and the use of the astrolabe in astrology during the Medieval period.
  • Luís Ribeiro is the author of "On the Heavenly Spheres: A Treatise on Traditional Astrology" and teaches astrology through academyofastrology.eu and the Astra project on YouTube.
  • They delve into the celestial mechanics and mathematics underlying house division, emphasizing the importance of understanding different systems for informed choices.
  • Luís Ribeiro has extensively researched the astronomical structures and calculations behind various house systems, including Placidus, to make informed decisions.
  • Understanding the historical and mathematical rationale behind house division is crucial for astrologers, even though modern tools have made manual calculations less common.
  • Historically, many astronomers were also astrologers, showcasing the intertwined nature of the two disciplines.
  • The debate on whether knowing how to calculate charts by hand should be a requirement for astrology certification is ongoing.
  • While the number of house systems has proliferated, common ones include Whole Sign, Placidus, Regiomontanus, Alcabitius, and Koch houses.
  • Preferences for house systems can vary over time due to astronomical, mathematical, cultural, and historical reasons.
  • A historical overview of house divisions shows the evolution of popular systems, with the Whole Sign system being the oldest and simplest form of division based on the Ascendant's degree.

16:18

Evolution of House Systems in Astrology

  • The sign equals house system, also known as the whole sign house system, originated in the first century BCE and was one of the earliest documented systems in Western astrology.
  • By the ninth and 10th centuries, the whole sign house system began to fade as other quadrant systems gained dominance, disappearing completely by the end of the Medieval period.
  • The whole sign system reemerged in the late 20th century in the Western tradition, while it continued to be used in Indian astrology throughout history.
  • The rise of more accurate astronomical instruments and the need for precision in astronomical measurements influenced the development of mathematical systems in astrology.
  • The equal house system, which appeared parallel to the whole sign system, was described by Ptolemy in the Tetrabiblos and seemed to fade out around the ninth and 10th centuries.
  • Renaissance authors debated the use of the equal house system, with some attempting to revive it based on earlier texts like those attributed to Asclepius and Firmicus Maternus.
  • The equal house system was sometimes viewed as a simplistic form of house division, potentially used for economic reasons in printing charts more easily.
  • In the mid-20th century, there was a revival of the equal house system in the UK, with authors like Margaret Hone advocating for its use.
  • The porphyry house system, attributed to Porphyry in the late third century, was one of the earliest quadrant systems that accounted for the Midheaven and Ascendant in house division.
  • The simplicity of the porphyry system suggests it may have been used earlier than documented, with attributions to Porphyry possibly due to historical lore or lack of evidence for earlier origins.

33:05

Alcabitius: Standard Quadrant House System in Astrology

  • The first quadrant system discussed is Porphyry, which divides the four quadrants between the Ascendant, Midheaven, Descendant, and the degree opposite the Midheaven.
  • Alcabitius, also known as Al-Qabisi, is the next system mentioned, with the earliest example found in Rhetorius in the fifth century, despite Alcabitius living in the 10th century.
  • Alcabitius wrote a popular Introduction to Astrology text, critiquing Abū Maʿsar's lengthy work, aiming for a middle ground between concise and extensive texts.
  • Alcabitius' system became the standard quadrant house approach during the Medieval period, attributed to him due to his outline of quadrant house systems in his text.
  • Historians of mathematics and astronomy study the historical problem of house system calculation, noting the ambiguity in sources due to similar results in different systems.
  • Alcabitius' system is considered the standard system due to its widespread use during the Medieval period, with John D. North's book being a seminal work on house systems.
  • Alcabitius' system remains popular until the early 17th century, eventually being replaced by other systems like Regiomontanus.
  • Alcabitius' system is the preferred quadrant house system for the speaker, chosen based on experimentation and results.
  • Recent academic work by scholars like Julio Samsó and E. S. Kennedy focuses on different systems of house division, with Kennedy's work on Medieval Islamic astronomers being notable.
  • The debate over whole sign houses as a legitimate form of house division in the Greco-Roman tradition is discussed, with some scholars like J. D. North focusing more on quadrant systems due to mathematical complexity.

49:35

Evolution of House Systems in Astrology

  • Academics like J. D. North initially overlooked the concept of whole sign houses, leading to a blind spot in their understanding.
  • The primary academic reference text for Greco-Roman astrology, L'Astrologie Grecque by Bouché-Leclercq, published around 1899, hinted at whole sign houses but did not explicitly recognize them as a form of house division.
  • Neugebauer's Greek Horoscopes provided examples of whole signs, indicating an early awareness of the concept.
  • Dr. Walter Koch and Wilhelm Knappich's German book from 1959, Horoskop und Himmelshäuser, discussed the signs as houses, predating James Holden's work by three decades.
  • The Campanus system, attributed to Al-Biruni in the 10th century, gained popularity in the 15th century through Johannes Gazulus.
  • Regiomontanus, described by an author in the 10th-11th century, was popularized by Regiomontanus in the early modern period and remained prevalent into the early 20th century.
  • Regiomontanus, a German mathematician, astronomer, and astrologer, engaged in a regional competition with Campanus, ultimately becoming the favored system.
  • William Lilly's endorsement of Regiomontanus in the 16th and 17th centuries solidified its widespread usage, particularly in English astrology.
  • The revival of traditional astrology in the 1980s led to a resurgence of Regiomontanus, especially in horary astrology, following Lily's approach.
  • Historically, astrologers typically used the same house system across all branches of astrology, with little debate on using different systems for various purposes until the late 20th century.

01:05:41

House Systems in Astrology Charts and Celestial Motion

  • Astro.com or Astrodienst offers various house systems for astrology charts, including Placidus, Koch, Campanus, Regiomontanus, equal houses, and more.
  • Solar Fire, another astrology software, provides house division options like Campanus, Koch, meridian, Placidus, Porphyry, and more.
  • Placidus is a complex house system believed to have origins in the 8th century but popularized by Placidus de Titis in the 17th century.
  • Placidus is also known as the hour line system and is considered the standard system in the English-speaking world.
  • The celestial equator, a projection of Earth's equator into space, influences the movement of celestial objects parallel to it.
  • Celestial objects, including planets and stars, rise, culminate, set, and anti-culminate in a 24-hour period due to Earth's rotation.
  • The signs of the zodiac also follow this daily motion, with variations due to Earth's orbit tilt causing seasonal changes.
  • The Ascendant, Descendant, Midheaven, and IC points in astrology charts correspond to specific degrees of the ecliptic based on rising, setting, culminating, and anti-culminating positions.
  • The concept of the rising sign or Ascendant stems from the zodiac signs rising over the eastern horizon daily.
  • The motion of celestial objects and signs in astrology charts mirrors the daily movement observed in the sky, influencing the structure of house divisions in astrology.

01:21:22

"Understanding Astrology: Rising Signs and Houses"

  • The rising sign concept is fundamental in astrology, starting with identifying the sign emerging on the eastern horizon.
  • The Ascendant is determined by the sign rising, like Gemini in the example provided.
  • Diurnal motion moves clockwise, while planets move counterclockwise through the zodiac signs.
  • Houses are numbered based on the direction of sign movement and planet motion.
  • The Ascendant marks the first house, followed by the second, third, and so on.
  • The numbering of houses follows the sequence of rising signs.
  • Early astrology traditions focused on the zodiac and planet movement, while Egyptians emphasized decans.
  • The synthesis of zodiac signs and diurnal movement occurred in the first century BCE.
  • House division methods and the use of the Ascendant and Midheaven are crucial in astrology.
  • The ecliptic path of the Sun and planets is essential in understanding astronomical and astrological concepts.

01:36:54

Celestial Power at Meridian: Planetary Significance

  • Saturn and Jupiter have passed over the meridian, which is the quadrant Midheaven.
  • The Moon is now passing over the meridian, reaching its highest elevation for the day.
  • The highest elevation of any point in the sky occurs when it hits the meridian.
  • The degree of the quadrant Midheaven is considered a point of power for planets.
  • The ecliptic can sometimes be higher in elevation than the planets.
  • Planets reaching their highest point symbolize power and significance.
  • Planets overpower others when they are at a superior square position.
  • The debate arises between zodiacal culmination and the meridian's power observation.
  • The meridian marks the due south-north axis halfway between east and west.
  • Historical chart displays varied from simple lists to complex diagrams, with zodiac depictions evolving over time.

01:52:24

"Sun's Movement and House Division in Astrology"

  • The Sun rises quickly from the east and sets rapidly towards the west.
  • In regions like Scotland, there is an inclination due to the celestial equator's angle in relation to the Earth's equator.
  • Stellarium, a free astronomy program, can visually represent the celestial movements and angles based on different latitudes.
  • At higher latitudes, like in Norway or Denmark, the Sun's rising angle is lower, causing it to take longer to rise.
  • The ecliptic's movement can complicate house calculations at high latitudes, leading to distorted or collapsed house divisions.
  • Whole sign houses divide the chart based on the rising degree of the zodiac sign, with each house being a full sign.
  • Equal houses method establishes house cusps in 30-degree increments from the Ascendant degree, creating a different house division system.
  • In equal houses, the nonagesimal degree (90 degrees from the Ascendant) plays a role in determining house cusps.
  • The Midheaven in whole sign houses floats around the top half of the chart, while in equal houses, it does not act as the starting point for the 10th house.
  • Understanding the differences between whole sign and equal houses is crucial for accurate house division in astrology.

02:07:42

"House Division Methods in Astrology Explained"

  • The highest point of the ecliptic is at five degrees of Aquarius, holding symbolic significance.
  • Equal houses are the last non-quadrant house system discussed, dividing the ecliptic into three equal parts based on the Ascendant and Midheaven degrees.
  • Porphyry, the first quadrant system, divides the quadrants into three equal parts based on the Ascendant and Midheaven degrees.
  • Alcabitius method incorporates the Ascendant and meridian degrees, dividing the celestial equator into 12 parts to determine house cusps.
  • Alcabitius method accounts for heavenly movement by tracking the Ascendant degree parallel to the equator.
  • Campanus method, known as the prime vertical method, divides the prime vertical into 12 parts using the poles to establish house cusps.
  • Campanus method is considered ingenious for its intuitive division of space into 12 parts, but more complex than Alcabitius due to the use of the prime vertical.
  • Campanus method does not consider the equator, focusing on the prime vertical and directionality of north and south for house cusp calculations.
  • Campanus method results in a major shift in intermediate house cusps, with significant differences in house placements compared to previous methods.
  • Campanus charts typically show a distinct configuration with small 10th and 9th houses and large 1st and 12th houses, along with specific placements for other houses.

02:23:40

House Division Methods in Traditional Astrology

  • Different astronomical reference points can lead to varied results in house computations.
  • Dividing something into 12 parts can be done in various ways, affecting the zodiac.
  • Regiomontanus divides the celestial equator into 12 parts, focusing on the equator's motion.
  • Regiomontanus and Campanus divide space differently, affecting house sizes.
  • Placidus uses hour lines to divide houses, with each part representing an hour on the equator.
  • Tropic of Cancer and Tropic of Capricorn mark the extremes of the ecliptic, affecting daylight hours.
  • Placidus connects hour lines to create house cusps, with each house representing two hours.
  • Placidus' complex calculations were simplified with pre-calculated tables of houses.
  • Regiomontanus gained popularity due to available tables and primary direction calculations.
  • Primary direction calculations were crucial in traditional astrology, tied to house division discussions.

02:40:37

Historical Astrology: House Division Debates and Traditions

  • The method of directions, along with profections, has been a longstanding tradition in astrology, with directions and progressions being key methods for prediction.
  • Astrolabes, particularly complex ones, have divisions to calculate directions directly on them, saving time in calculations.
  • Early texts like Hermes, Asclepius, and Nechepso and Petosiris introduced concepts of house divisions and significations, influencing later astrological traditions.
  • The Nechepso and Petosiris text introduced the length of life technique using primary directions, impacting quadrant house divisions in Hellenistic astrology.
  • Interpretations of Ptolemy's work led to debates on house division systems, with varying opinions on equal houses versus quadrant systems.
  • Astrologers debated the mathematical logic behind house divisions, considering the significance of planetary angles from the horizon.
  • The historical debate on house divisions reveals different motivations, including textual arguments, astronomical reasons, and practical chart placements.
  • Research projects are suggested to explore the representativity of different house systems in practice and the discrepancy between theoretical and practical use.
  • Some house systems were developed as theoretical exercises rather than for practical application, adding complexity to the understanding of historical astrology.
  • Regional differences in house division preferences and biases in academic interpretations highlight the need for a comprehensive study of historical house systems.

02:56:31

Insights and Biases in Astrology and Academia

  • Astrologers sometimes have insights into older texts that academics may miss due to their practical experience.
  • However, astrologers may also introduce biases based on their preferences, which can affect their interpretations.
  • Academic research is prone to bias, necessitating vigilance to present facts objectively.
  • Errors in historical and mathematical descriptions of house systems are prevalent on the internet.
  • The concept of houses in astrology has historically been murky, leading to confusion and debates.
  • Terminology in Hellenistic texts can be ambiguous, with words like Ascendant and Midheaven having multiple meanings.
  • The use of incorrect terms can mislead the understanding of house systems.
  • Clear and precise writing is crucial to avoid misinterpretations that could lead to the formation of new traditions.
  • The astrolabe is a complex device used for various astronomical and time-telling purposes.
  • The astrolabe consists of a base, plate, rete, and pointer for measuring celestial objects and calculating positions like the Ascendant and Midheaven.

03:13:01

Astrolabe: Key Tool in Medieval Astrology

  • Fixed star positions help determine rising degree and Midheaven at night when the Sun is not visible.
  • Astrolabe is useful for calculating Ascendant and Midheaven degrees but not planetary positions.
  • Astrolabe simplifies calculating Ascendant and Midheaven degrees, especially for horary or electional charts.
  • Houses are calculated using the astrolabe by considering the horizon, meridian, and hour lines.
  • Alcabitius method on the astrolabe aids in calculating intermediate house cusps based on hour lines.
  • Regiomontanus method on the astrolabe involves a separate plate for calculating house cusps.
  • Astrolabe's ease of use led to its widespread adoption by astrologers in the 8th to 9th centuries.
  • Astrolabe's emergence influenced the shift towards quadrant systems of house division in the Medieval period.
  • Astrolabe's availability facilitated quick chart calculations, potentially aiding the rise of horary astrology.
  • Astrolabe's role in astrology's popularization varied based on astrologers' mathematical knowledge and tools available.

03:28:51

Evolution of Astrology Through History and Academia

  • Astrologers have operated at various societal levels throughout history, serving kings, presidents, and common people.
  • Astrologers used elaborate boards made of ivory, stone, wood, and gold to display charts, while others drew charts in sand for a simpler method.
  • Theon of Alexandria wrote a commentary on Ptolemy’s Handy Tables to help astrologers calculate charts.
  • Different levels of astrologers existed, some focusing on interpreting charts while others excelled in mathematical calculations.
  • Simplified forms of astrology were practiced in certain books or manuscripts, reflecting popular practices.
  • Astrologers entering academia in recent decades have brought valuable historical knowledge to the field.
  • Academic involvement allows for peer review, leading to more precise conclusions and the development of astrology.
  • Different house division systems are based on various astronomical reference points, complicating the choice of a singular system.
  • Traditional debates focused on better describing the universe rather than attributing qualities to specific authors or systems.
  • The 20th and 21st centuries have seen the application of different house systems for various purposes, influenced by different schools of astrology.

03:44:25

Reviving Hellenistic astrology and honoring astrology history.

  • Project Hindsight in 1993 and 1994 revived Hellenistic astrology, with Rob Hand and Robert Schmidt promoting whole sign houses, previously discussed by James Holden in 1984.
  • The guest, LR, plans to revise his book "On the Heavenly Spheres" and continues to teach astrology through academyofastrology.eu, with a collaboration on theastraproject.org focusing on the history of astrology.
  • LR's partner, Helena Avelar, recently published "An Astrologer at Work in Late Medieval France" before her unexpected passing, prompting a future episode to celebrate her life and work.
  • The Astrology Podcast, where LR was a guest, is supported by patrons on patreon.com and sponsors like The Mountain Astrologer Magazine, offering discounts on astrology software and almanacs.
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