• Search
  • Lost Password?

How Did Placidus Become the Most Popular House System?

Why Is Placidus the Most Popular House System?

Episode 244 features an interview with Anthony Louis about the history of how Placidus became the most popular system of quadrant house division used in western astrology in modern times.

In late 20th and early 21st century astrology Placidus is the most popular house system, and it is usually the default house system in most software programs, which makes it the system that most people begin their studies of astrology with.

The question is: how did this come to be the case? Especially since there are other forms of quadrant house division that are available, such as Porphyry or Alcabitius houses, what led to the widespread acceptance of Placidus?

It turns out, the origins of the Placidus house system and its popularization lie in the 17th century, and it was partially based on an an attempt to reinterpret a controversial passage from the work of the 2nd century astrologer Claudius Ptolemy.

The genesis of this discussion was an article on Anthony’s blog titled Why are Placidus Houses so Popular?

Our goal here was to talk about some of the arguments outlined in that post, and go into some areas in greater detail, to understand the history of house division.

While our previous episode on the origins of the different forms of house division in ancient astrology covered the early history of house division, the purpose of this episode is to fill in some missing pieces about the later history from the Renaissance era forward into modern times.

You can find out more information about Anthony on his website:


Below you will find an extensive set of show notes that we used as the outline for our discussion.

This episode is available in both audio and video versions at the bottom of the page.

Episode Outline and Show Notes

Here is part of the outline we created in preparation for this episode:

  • Based on Anthony’s November 2019 blog article Why are Placidus Houses so Popular?
    • Follow-up to original article: “Placidus: The Default Darling of Domification”, in Federation of Australian Astrologers Journal, Vol 49, No 2 (June 2019), pp. 21-26.
  • Premise of the discussion:
  • In late 20th and early 21st century astrology Placidus is the most popular house system
  • In modern western astrology.
  • It is the default house system in most software programs, like Astro.com
  • As a result of that it is the system that people usually start with
  • One of the questions that comes up is why is Placidus the default quadrant system?
  • Holden makes a passing remark that Placidus became the default due to availability:
    • “It has become a cliche in the 20th century that the Placidus system later became the 19th and 20th century standard because it was the only one for which affordable tables were readily available. This is partially true, but the same thing could be said for the initial success of the Regiomantanus system.” Holden, A History of Horoscopic Astrology, p. 150.
  • Anthony took some issue with this because Placidus had been popularized earlier.
  • While it was the primary system available by the 20th century, this was because it had been promoted widely since the 17th century.
  • So how did this get started?
  • Placidus published his book in 1650.
  • Focused on primary directions and house division.
  • He was interested in reconstructing Ptolemy’s approach.
  • Part of the general back to Ptolemy movement.
    • Also evident in Lilly and others.
    • Ptolemy was the oldest Greek author available
    • Viewed as the most authoritative.
  • Ptolemy has a discussion of house division in his length of life chapter (3, 11).
    • This is also where he introduces primary directions.
  • The method of house division he advocates here has long been the subject of dispute.
    • “This one chapter has occasioned more astrological controversy than any other ever written.” Holden, A History, p. 47.
  • Ptolemy was like the Einstein of his day
  • Even in the early Greek authors after Ptolemy there were different interpretations about what system of house division they thought he was trying to introduce in this chapter.
  • Some of the later forms of houses came from trying to interpret Ptolemy.
  • Regiomantanus was one of the authors that did that.
    • “Regiomontanus claimed that his method was what Ptolemy had in mind when he wrote Tetrabiblos, iii. 10 This is certainly false, but Regiomontanus’s arguments were accepted by the majority of astrologers.” Holden, Ancient House Division II.
    • “His house tables, accompanied by auxiliary tables for calculating primary directions, were very likely the first extensive set of mathematical tables of any kind ever printed, appearing as they did scarcely four decades after the invention of printing.”
    • “Three things combined to make the Regiomontanus system a success. First, it provided a convenient printed set of house tables. Second, it was modern and scientific. And third, it substituted a system with alleged classical Greek sanction for a system supposed to have been invented by a medieval Arab. But these arguments would have been equally applicable to the Campanus or Placidus systems. Thus, it is fair to say that the success of the Regiomontanus system was due to external circumstances rather than to any inherent superiority.”
  • Placidus was another author who popularized a system based on what he thought Ptolemy meant
  • What was unique about Placidus is that he is thought to have been one of the first in centuries to correctly understand Ptolemy’s system of primary directions.
    • However he misunderstood Ptolemy’s intended system of house division.
    • At least, according to Holden.
  • Holden and Schmidt thought that Ptolemy was describing equal houses essentially.
    • With ranges that begin 5 degrees above the cusp of the Ascendant.
    • This is how Hephaistio describes it at first
    • But then an earlier commentator named Pancharius interpreted it differently
    • Introduced a modified “Alchabitius” style (Holden says “modified Porphyry”).
    • So interpretations of Ptolemy have generated multiple house systems.
    • This is why Holden called this the most controversial chapter ever in the history of astrology.
  • Even though the Placidus system bears his name, it may not have been the first time it was introduced.
    • Ibn Ezra describes the same approach in the 12th century
    • Holden says on p 162 that Magini “is said” to have described it, and that Placidus “presumably” could have got the idea from reading his book.
    • So there was precedent, but Placidus popularized it.
  • Impact of Placidus
  • Didn’t impact Lilly’s Christian Astrology because it was published after Placidus.
    • Lilly (1602-1681) used Regiomantanus houses as did his disciples John Gadbury (1627-1704) and Henry Coley (1633-1707).
  • Placidus’ work was forbidden by the Catholic Church late in his life.
    • Placidus was placed on the Index of Church’s Index of Forbidden books in 1687 (the same year that Kirby & Bishop published their abridged translation of Placidus) and the ban was renewed in 1709.
    • Therefore Placidus mainly became available and popular in Protestant England
  • By the end of the 17th century, Placidus became popular among English astrologers.
    • Maybe because it was seen as a new or radical reinterpretation and innovation.
    • Recovering lost wisdom that had been obscured, to improve the techniques.
    • “According to his perhaps most famous statement, Placidus ‘desired no other guides but Ptolemy and Reason’.” Gansten, Primary Directions, p 19.
    • Rapidly (?) became popular
    • Similar in many ways to recent popularization of whole sign houses in our time
  • There was an early translation of Placidus’ work into English.
  • In 1687 Kirby and Bishop published The Marrow of Astrology, an abbreviated English translation of the magnum opus of Placidus (1650).
  • John Partridge (1644-1715) became the biggest proponent of Placidus houses
    • Wasn’t initially in his first book An Astrological Vade Mecum (1679) which includes tables of Regio houses, but in his second Opus Reformatum (1693) in which “he rejected the doctrines of the medieval astrologers in favour of Ptolemy and Placidus” (Gansten, Primary Directions, p. 21).
    • A very vocal proponent
    • He was the last major English astrologer of the 17th century
  • R.C. Smith (‘Raphael’) published a popular astrological almanac with tables of Placidus houses in 1821, making the Placidus system widely available to the public.
    • Ralph William Holden (1977) speculates that “it seems likely that his doing so was that the Placidus method produces cusps which are complicated to calculate when referred to any one given sidereal time, but which on the other hand are very straightforward to produce in table form.” (The Elements of House Division, p.91).
  • After this point Placidus became the most popular system among English-speaking astrologers
  • Lilly’s book was republished in an abridged form, without the Regiomontanus house tables
    • The Zadkiel edition (1852)
    • As the original version of Lilly fell out of print, Zadkiel became more important
  • Alan Leo used Placidus, as it was the standard of practice in England in the late 19th century
  • The early 20th century astrologers tended to use Placidus
  • Placidus became the primary system that tables of houses were available for.
    • When calculating a chart by hand, you need a table of houses to calculate cusps
    • It simplifies some of the mathematics involved.
    • In what is already a tedious process.
    • Additionally astrologers tend to not be highly skilled in astronomy.
  • With the advent of computerized astrology and websites Placidus was often the default.
    • For Chris’ generation, Placidus being the default on Astro.com was a big deal.
    • It means that this is the first system you start with
    • The accuracy or inaccuracy of the interpretations then depend partially on it
    • To go against this then often means rejecting what you first learned.
  • These are some of the reasons why Placidus became the most popular houses system in modern times.
  • The end.


Here are some timestamps for topics covered at different points in the episode:

00:00:00 Intro
00:00:30 Anthony’s background
00:01:30 Overview of Placidus house system
00:04:06 Why the house debate gets intense
00:04:39 Why Placidus is the default
00:12:05 Who was Placidus?
00:17:20 Ptolemy’s influence
00:22:16 Ptolemy’s difficult chapter on house division
00:24:40 Primary direction and house division
00:25:34 James Holden’s papers on house division
00:28:06 Regiomontanus and Ptolemy
00:35:11 Placidus misunderstood Ptolemy on house division
00:40:30 Different interpretations of Ptolemy
00:44:27 The impact of Placidus
00:45:58 Placidus’ book forbidden by the Catholic church
00:51:25 Placidus house division popular by end of 17th century
00:54:20 Text of Ptolemy’s paragraph on house division
00:55:50 Placidus house division was seen as innovative
00:59:40 John Partridge was a proponent of Placidus
01:01:50 Infighting among astrologers
01:07:15 Lilly removed Regiomontanus tables
01:09:00 US astrologer Luke Broughton used Placidus
01:14:20 Other major astrologers that endorsed Placidus
01:16:15 20th century timing techniques replaced primary direction
01:20:05 Positive developments that come from misunderstanding ancient astrologers
01:22:19 Computerized astrology and Placidus
01:26:50 The house system Anthony uses
01:31:08 Porphyry houses
01:32:40 Chart changes based on house divisions
01:35:10 Indian astrology and Placidus
01:36:55 Other points about Placidus and Whole Sign
01:39:08 Anthony’s blog
01:40:39 Anthony’s book on horary
01:43:05 Closing remarks

Watch the Video Version of This Episode

Here is the video version of our discussion about the history of Placidus houses:


A full transcript of this episode is available: Episode 244 transcript

Listen to the Audio Version of This Episode

You can either play the audio version of this episode of the podcast directly from the website or download it as an MP3 to your device by using the buttons below:

Leave a reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

  • Another very informative podcast. Thanks. As your podcasts are unveiled I continue to add layer upon layer of astrological knowledge, both current and historical. I am struck by how current deeper research in the history of astrology lays out a clearer and clearer picture of how human astrological knowledge grows over the centurys. I think that your podcasts have helped to clarify astrological history as things come into focus. The house division debate is intriguing but, for me, adds to my confusion about analysing charts. As I have followed Chris podcasts a few years ago I switched from Placidus to Whole Signs which gave me an “ah ha” period where I felt I could sense my personality and events more clearly. As I listen to this podcast I am now making an attempt to use both Placidus and Whole Signs. It seems that valid information comes from both somehow. I am also struck by how personalities in the astrological community clash in the debate and wonder how this could also be demonstrated astrologically somehow. I see it as part of the dynamic of the human project to constantly advance understanding of the Cosmos. However, mostly it helps me put in perspective that knowledge and the truth are not static but are continually advancing…..or more appropriately are moving cyclically like the planets.

    • Bryan – I know this sounds unfounded but from my experience, if you use a system in house division it starts to speak to you and especially in the reading, the element of divination comes into play. This is the same for Tarot. If you are used to using an assigned meaning or two for a card, that is what it is for that reading. This is not to suggest that there are not rules and technique that must be followed in astrology. When I switched to Whole Signs there was more flow for me. It made things clearer. I find having intercepted houses and sub-rulers (the second sign of a house) is over-complicating. And besides, there are astrologers that firmly believe the planet in a house trumps house rulers-hip anyway. In Placidus I have 4 intercepted houses. For expample, House 5 starts with Sagg wholly encloses Capricorn, and ends in AQ. This means Jupiter rules that house and the subtone is Saturn. Using Whole Signs, the ruler is Saturn which natally resides in Sagg and answers to Jupiter. We get to the same place. I saw this too when switching from using outer planets and rulers to the traditional rulers alone. Maybe I am ready to venture back to some other house division – for transits maybe Koch, but I truly love Wh Signs and always use the MC and IC to read into H10 and H4 regardless of where there end up being. These to me are critical points, so critical that if I am understanding, Placidus was intent on getting to the appear exactly at the top (MC) with mathematical precision. I still read it with that kind of importance.

  • I noticed there was mention of other astrologers who use both quadrant house cusps together with whole signs. There are many tropical Jyotish practitioners who have been influenced by Ernst Wilhelm to practice using both whole sign houses and quadrant house cusps (usually Campanus) – Ryan Kurczak, Corey Dowds, Levi Cosijn, Carmina Anza, Nicole Brenny, and Laura Barat all come to mind. If you do produce an episode that addresses this subject of delineating using both house systems Ernst (or maybe one of the other astrologers listed above) would probably be a good addition to the episode.

    • Kevin,
      Good point. My understanding of the way Ernst Wilhelm and his students interpret the combination of Whole Signs and quadrant house cusps is as follows:
      As in Hellenistic astrology, the whole signs are “places” numbered in order from the ascending sign as Number One or the First Place. Each “place” has a specific set of significations which always have reference to the Ascendant, which symbolizes the native. If I understand him correctly, Ryan Kurczak says that the whole sign “places” represent our relationship to the aspect of our life symbolized by the numbered place.
      The cusps of the quadrant houses, on the other hand, symbolize the concrete area of life. Thus, the 4th Place would show us how we relate to our mother (if we take the 4th to be the house of the mother) whereas the 4th cusp would be the concrete embodiment of the mother. For example, difficult planets in the 4th place can show problems in the native’s relationship with the mother, but the 4th quadrant cusp may be in an adjacent sign with a benefic so that the mother herself is quite fortunate and as a person, she displays the quality of the sign in which the 4th cusp is placed.
      This idea is consistent with Morin’s precept that the beginning degree or cusp of a quadrant house is the most powerful or robust point of that house (Book 17, Ch 2): “domus principium esse punctum ipsius domus robustissimum.” Morinus uses the Latin word “domus” to refer to what we call “houses” in English. In Latin “domus” means the home, household, family dwelling place or house where the family lives.
      In Jen’s comment (above) she says that she “always uses the MC and IC to read into H10 and H4 regardless of where they end up being.” Morin would extend this thinking and he claims that for every quadrant house the cusp represents the concentrated power and essence of that house. Just as the MC can be read as H10, the 11th cusp can be read as H11, the 12th cusp as H12, etc., regarding of which Whole Sign Place they fall in.
      Finally, to add to your suggestion for a future podcast, it would be useful to trace the history of the word “house” to describe out divisions of the zodiac. Originally the Greeks called the whole signs “places” rather than houses. In Latin the translators used words like “domus” and “domicilia”. I don’t read Arabic or Persion, so I don’t know what words those authors chose to describe divisions of the zodiac. Our choice of words strongly colors how we conceptualize an idea. I wish we would get rid of the term “house” altogether and return to calling the whole sign system one of “places” rather than houses and calling the quadrant systems “quadrant divisions” of the zodiac. I think the better translation of “house” is “home”, which I would reserve for the homes or domiciles of the planets, as in the Thema Mundi.

  • Hi Chris,
    In our discussion I quoted Luke Broughton’s reference (1898) to a translation of Placidus by E. Sibly in 1789. Afterward I checked wikipedia, which attributes that translation of Placidus into English to his brother Manoah, who was a linguist. In any case, E. Sibly had studied Placidus and used Placidus houses in his famous chart of the USA Independence of 4 July 1776. For those who are interested, I summarized these findings with a copy of Sibly’s original chart in a blog post at https://tonylouis.wordpress.com/2020/02/26/ebenezer-siblys-use-of-placidus-houses-in-the-late-1700s/