Re: Ibn Ezra and House System

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carriere.francois wrote:I have quite a short question ;-) Does anyone know which house system Ibn Ezra used? I suspect either whole sign houses or Alcabitius. But I may be wrong!...
I just returned North's Horoscopes and History to the library, so I can't recount the details, but there is evidence (an astrolabe? a description of an astrolabe?) that ibn Ezra favoured what we know as the Placidus system. Whether he did so for all of his astrological career I can't say. Alcabitius would have been the 'default option' in his day. Perhaps someone else can give a more detailed answer.

Re: Ibn Ezra and House System

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carriere.francois wrote:Hello,

I have quite a short question ;-) Does anyone know which house system Ibn Ezra used? I suspect either whole sign houses or Alcabitius. But I may be wrong!...

Dear Francois,

Alain Cablais in 1986 wrote for CieloeTerra this article about IbnEzra preferences about house system, with Latin quotes from his text and examples, which is the source for many other articles about the same subjiect.

http://www.cieloeterra.it/articoli.cablais/cablais.html

Margherita
Traditional astrology at
http://heavenastrolabe.wordpress.com

Re: Ibn Ezra and House System

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Gjiada wrote:Alain Cablais in 1986 wrote for CieloeTerra this article about IbnEzra preferences about house system, with Latin quotes from his text and examples, which is the source for many other articles about the same subjiect.
Hello Margherita,

Thank you for the link. Unfortunately I do not understand neither Latin nor Italian (not in regular cursus in school at the time I went :, )... However, with an awful French Google translation ("Girolamo Diedo" becomes "J?r?me is Dead" or "Medio cielo" is "Middle East"... :-cry ), I think I understand that Grigoryev and Cablais have a different source: the latter used Ibn Ezra's astronomical tables (Liber de rationibus tabularum)... and that the calculation iterations would have been lost in some way with Alcabitius (although Ibn Ezra came latter then Alcabitius!?)...

I wished Cablais had written the paper in French or English also...

Update: Alta Vista's Babel Fish gives a little better translation...
Regards,
François CARRIÈRE

Re: Ibn Ezra and House System

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Martin Gansten wrote:
carriere.francois wrote:I have quite a short question ;-) Does anyone know which house system Ibn Ezra used? I suspect either whole sign houses or Alcabitius. But I may be wrong!...
I just returned North's Horoscopes and History to the library, so I can't recount the details, but there is evidence (an astrolabe? a description of an astrolabe?) that ibn Ezra favoured what we know as the Placidus system. Whether he did so for all of his astrological career I can't say. Alcabitius would have been the 'default option' in his day. Perhaps someone else can give a more detailed answer.
Fortunately, I did make some notes from this book. It says (p. 23) Ibn Ezra seems to have invented the 'hour circles (fixed boundary)' method, that is popularly known as 'Placidus system'. It's his reconstruction of Ptolemy's system (which turns to be erroneous, however, as Ptolemy probably used simple whole-image system, except for the special purposes of obtaining the length of life) and his ideas may have found their route to Placido via Magini. The description is in his Book of the Fundaments of Astronomical Tables and the relevant sections are quoted by Cablais on Cielo e Terra website as Margherita points to.
Things being so, one wonders that, although Ibn Ezra vehemently criticises the 'standard method' (that is, the 'Alchabitius' system) and attributes it to al-Khw?rizm? and Ibn al-Muthann?, in the only surviving chart cast by him he uses this very method (p. 109). It's dated 29 October, 1136. It is to be found in a separate work of his.
(A final word: there are several charts in the later version of his Book of Nativities, but they appear to have been supplemented by the printer, Erhard Ratdolt, since the dates are from between 1462 and 1485.)

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Hi Osthanes
It's his reconstruction of Ptolemy's system (which turns to be erroneous, however, as Ptolemy probably used simple whole-image system, except for the special purposes of obtaining the length of life)
As that text reads, it sounds like you are passing on what North wrote, but it would surprise me if J.D. North made that remark about Ptolemy probably using simple whole-sign, so could you clarify for me if that is part of your paraphrase of what North wrote, or whether it is your own remark based upon more recent suggestions?

And thanks for your interesting post,
Deb

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Deb wrote:From what I can see, this is essentially the same calculation that Ptolemy explains in the Almagest II 9 & 10.
I believe that this is the idea Cablais wants to highlight, in fact.
Cablais implies the idea that Placidus was just an heir of IbnEzra, and both took from Ptolemy.

About the language, yes it's a pity they have the site just in Italian, but last Sunday I went in Milan for Giuseppe Bezza's lecture and I understand they desire having some of their articles translated in English too, so people can read directly their site. I believe they will do very soon,


Margherita
Traditional astrology at
http://heavenastrolabe.wordpress.com

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Hi Deb
Deb wrote:As that text reads, it sounds like you are passing on what North wrote, but it would surprise me if J.D. North made that remark about Ptolemy probably using simple whole-sign, so could you clarify for me if that is part of your paraphrase of what North wrote, or whether it is your own remark based upon more recent suggestions?
Well, the words in parenthesis are not North's, it's an addition by me. But I see I should clarify my statement.
As it appears, places doesn't play an important role in Ptolemy's astrology. In fact, he doesn't speak about domification matters, and the rare usage of traditional names of places ('Hour-marker', 'Midheaven', 'Good Spirit' etc.) doesn't seem to differ from standard astrological practice of that time.
The only 'exception' (which is not an exception, though) is his own method concerning the length of life (III. 11). There are two crucial parts: the allocation of segments for the possible releaser and the detailed method of the releasing itself. Although this section is by no means about domification, generations did read it as a key for Ptolemy's understanding of division. It might have begun with Porphyry but I'm far from being sure, for his so-called Introduction to the Apotelesmatics of Ptolemy is in fact not a commentary to his work, as the title suggests, and its extant form comes from Demophilus who added and perhaps inserted new chapters. In any case, I saw Hephaestio making no implication that could be perceived as he and his predecessors interpreted Ptolemy's description pertaining for domification matters.
Therefore, it seems to have come later, possibly from al-Khw?rizm?. It's not sure, but I'm convinced it began with the Arabs, since I found no definitive example in Greek literature, except for a case which I describe later.* The terminus post quem is the first Arabic translation of Ptolemy: it was made by al-Bi?r?q on the request of ?Umar al-?abar?, thus at about 810. The terminus ante quem is, I think, the time of Ab? Ma?shar whose On Solar Revolution shows a prime example of 'Alchabitius'-style domification; it means the years between 834 and 886. All the other attempts to establish place-division (Ab? 'l-Hasan ?Al?, al-B?r?n?, Ibn Ezra, al-Jayy?n? and the later re-inventors and advertisers, like Roger of Hereford, Gil Gazul, Regiomontanus, Cardano, Magini and Placido) are going on the same way, interpreting Ptolemy.

*The only, however often cited example of a Greek nativity with 'Alchabitius'-style division is the one dated 8 September, 428 that is attributed to Rhetorius. As a matter of fact, it appears (as far as I know) at three places: in the [Smaller] Book of Nativities of M?sh??all?h, in the Book of Nativities of Ab? ?Al?, and in Epitome IV of Rhetorius. It's curious that the division differs: while the 'Rhetorius' text contains an elaborate treatment of 'Alchabitius'-style division, the M?sh??all?h version gives different cusps which appear to have been computed for the latitude of Provence and the Ab? ?Al? version doesn't give cusps at all. It's clear that the cusps of the M?sh??all?h version come neither from M?sh??all?h, who lived at a rather lower latitude, nor from Rhetorius whose nativities are from the Eastern Roman Empire. Moreover, the Epitome IV of Rhetorius comes from the same Demophilus who edited the Introduction of Porphyry, and this very section (chapter 12) has no parallel with other epitomae of Rhetorius (although chapters 1-11 and 24-28 do so). To sum up, I suspect it was Demophilus who introduced 'Alchabitius'-style division for this nativity and in this move he could well rely upon Arabic sources as the existence of a selection of Arabic astrological works available to him definitely proves.

And a final remark: I think there were three steps which led to the confusion of domification matters. First, the invention of the quadrant trisection method by Orion, possibly in 1st century CE, as Valens reports. Second, its idiosyncratic application by Valens which was echoed also by early Arabic astrologers, like ?Umar and Sahl ibn Bishr. (I mean the statement that the MC falling on the 9th image infers meanings pertaining to both 9th and 10th place.) Third, the Arabic discovery of Ptolemy and his sophisticated releasing method which was interpreted as a key for divisions too. After that, the history of favoured and unfavoured methods are only a history of interpreting Ptolemy and a history of fashion.

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carriere.francois wrote:Martin,

Indeed! I have found out late yesterday that apparently, according to Anton Grigoryev, there are two manuscripts of Ibn Ezra's The Book of Reasons, "A" and "B". The one called "A" has a text that would describe what we now know as Placidus and he shows how to get the results:

http://www.antonblog.net/astrology/ibn- ... carnation/
Interesting, the method reminds me of an equation formula with spherical trigonometry in it. Except that in this case no sine cosine etc is used because the tables already have done this part. Since Placidus cusps cannot be calculated directly, such an equation formula is needed to approximate it till the desired exactness is attained. This calculation is a constantly repeating of calculations and can be a bit tedious. This may have restrained the popular use of it in Ibn Ezra's days.

In his introduction to an article on Placidus' method, Michael Wackford mentions Ibn Ezra as someone who ascribed the method to Ptolemy.
http://www.skyscript.co.uk/placido.html
Osthanes wrote:Hi Deb
Deb wrote:As that text reads, it sounds like you are passing on what North wrote, but it would surprise me if J.D. North made that remark about Ptolemy probably using simple whole-sign, so could you clarify for me if that is part of your paraphrase of what North wrote, or whether it is your own remark based upon more recent suggestions?
Well, the words in parenthesis are not North's, it's an addition by me. But I see I should clarify my statement.
As it appears, places doesn't play an important role in Ptolemy's astrology. In fact, he doesn't speak about domification matters, and the rare usage of traditional names of places ('Hour-marker', 'Midheaven', 'Good Spirit' etc.) doesn't seem to differ from standard astrological practice of that time.
In an article on house division in the Hellenistic astrology, Robert Schmidt mentions something similar that Ptolemy doesn't appear to use his own system but may have used whole sign houses. http://cura.free.fr/quinq/02schmi.html

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Hello Osthanes,
Osthanes wrote:
Well, the words in parenthesis are not North's, it's an addition by me. But I see I should clarify my statement.
As it appears, places doesn't play an important role in Ptolemy's astrology. In fact, he doesn't speak about domification matters, and the rare usage of traditional names of places ('Hour-marker', 'Midheaven', 'Good Spirit' etc.) doesn't seem to differ from standard astrological practice of that time.
The only 'exception' (which is not an exception, though) is his own method concerning the length of life (III. 11)..
True, I believe that supporters of Placido - like in CieloeTerra- take as reference Almagest, the chapters quoted by Deborah,

Margherita
Traditional astrology at
http://heavenastrolabe.wordpress.com