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From Sassanian to Tropical Zodiac

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Joined: 26 Jun 2007
Posts: 104

Posted: Fri Nov 10, 2017 9:27 pm    Post subject: From Sassanian to Tropical Zodiac Reply with quote


At mark's suggestion, I repost a question I had post in the Philisophy and Science Forum, with Therese Hamilton answer:

carriere.francois wrote:

I am looking for the moment when the Sassanian passed from a sidereal Helleno-Sassanian zodiac to a tropical zodiac. Early writings (Masha'Allah or Abu'Mashar, as translated by Dr Benjamin Dykes in Persian Nativities I-III) seem to show it was based on sidereal zodiac. About al-Qabisi, I can't tell. In any case the reference was the star zeta Piscium. James Holden (A History of Horoscopic Astrology) seems to have same opinion. Perhaps I think it was around the 9th or 10th century and because sidereal tables (the "zij") may have not been available anymore. Am I correct? Maybe Martin Gansten will want to briefly comment on this issue?

Therese Hamilton wrote:
I had this exact same question. When I looked into this question a while ago, I think I came to the conclusion that the change-over began during Al-Qabisi's time period since Masha'Allah was clear in using a sidereal zodiac. (Persian Nativities I, p. 16) Of course if we had the dates when specific tables were introduced we would have our answer. I'll see if I can find my notes on this and post my findings a little later.

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Martin Gansten

Joined: 05 Jul 2008
Posts: 1242
Location: Malmö, Sweden

Posted: Sat Nov 11, 2017 7:52 am    Post subject: Re: From Sassanian to Tropical Zodiac Reply with quote

As my name has come up, let me say at once that I don't know the exact answer to this question, but my impression is that it was a process rather than a moment in history. In any case, it was later than many seem to think! I'm fairly sure that Rob Hand mentions somewhere (in a PH or possibly ARHAT publication) that some charts include both tropical and sidereal positions (indicating that different kinds of tables were used), but I couldn't say where; it's been too long since I read it.

I had expected Pingree to discuss this, but, as I have searchable PDFs of several of his books and articles, I just did a quick search (for 'sidereal' and 'tropical') and came up with nothing -- not even in his From Astral Omens to Astrology. This was so surprising that I have to wonder if he was shirking the issue for some reason (perhaps it is just very hard to determine). But it may be that I just haven't looked in the right places.
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Joined: 30 Sep 2005
Posts: 4910
Location: Edinburgh, Scotland

Posted: Sun Nov 12, 2017 12:43 am    Post subject: Reply with quote

A few references worth following up on this issue:

1. Raymond Mercier's 65 page article/booklet "Studies in the medieval concept of precession" which is cited by Juan Revilla. However, I have been unable to find any reference to this text anywhere on the internet. Instead I have found a text by Raymond Mercier ''Studies on the Transmission of Medieval Mathematical Astronomy'' 2004 – Routledge. This may be a later update to this earlier work and is 334 pages long. So I am assuming Mercier's earlier work is incorporated here.

2. David Pingree's article: ''The Greek influence in early Islamic mathematical astronomy'', Journal of the American Oriental Society, 93: 32-43, 1973.

3. James Holden's ''"A History of Horoscopic Astrology". The section on Arabian astrology is reproduced on the CURA site. I have placed a link below:

This link below is to a forum piece by the Costa Rican astrologer Juan Revilla which helpfully covers these and some other sources discussing the foundational chart for the city of Baghdad in 762 CE.

Juan Revilla points out these early Perso-Arabic horoscopes seem to be using sidereal tables for planetary longitudes but the tropical positions for the houses.

This may seem initially paradoxical but when you consider the culturally eclectic astronomical sources the early Islamic Caliphate was relying on this is not so bizarre. The sidereal astronomical tables for planetary positions no doubt came from Persian sources and were bolstered by Indian thinking. The use of tropical positions is quite possibly an adaption of Ptolemy's Handy Tables.

The real question though was what were these astrologers thinking? Were they aware of these contradictions? If not it suggests they were not aware of precession at this point. So their astrology cannot be described as a conscious selection of a sidereal or tropical zodiac since they were probably unaware of the distinction at this point.

From what I have read it seems Islamic astronomy made great strides in the 9th century and superceded the Greek, Indian or Persian traditions. At this point it moved from being purely derivative to genuinely innovative.

‘’As thou conversest with the heavens, so instruct and inform thy minde according to the image of Divinity…’’ William Lilly
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Joined: 13 Apr 2006
Posts: 246
Location: Chicago, IL

Posted: Thu Nov 16, 2017 3:09 am    Post subject: Reply with quote

given that nuroz is celebrated with the vernal equinox, the ancient (pre-sassanian) iranians seem to be of the solar dynasty to cop a concept i believe is in the puranas ... rather than lunar dynasty qua vedic
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