Waybread, I'm pretty sure the numbering pattern is Tropical in origin. So each Tropical sign has a number, a ruler, a mode, an element and at least one image, as well as a key expression like "I See" for Sag. and "I Use" for Cap. I realize you already know this; just suggesting it came into widespread use though Ptolemy, who chose Tropical over Sidereal, in the 2nd Century A.C.E. The base-10 system, which led to the decimal system is even more recent (as, again, I'm sure you know already).
Um, care to weigh in on the qualities of Jupiter in a chart, especially when it's in Scorpio? My Jup. in Scorp. is in the 9th H. (Whole Sign method).
David, if you're interested in the history of astrology I can suggest some readings, depending upon what you want to know. Back when horoscopic astrology was developed (around 200 BCE) there was no real distinction between tropical and sidereal. The Babylonians didn't use houses. Different ancient Near Eastern societies used different dates to start their calendars. I agree that Ptolemy popularized the tropical zodiac calendar, using 0 degrees Aries as the starting point, even though the equinox had already slipped back into Pisces by then.
The key words for each sign ("I am, I have, I see, I know, &c) are probably modern. They weren't part of Hellenistic astrology. Maybe someone else can say if they were used in medieval or Renaissance astrology.
Signs' qualities were also related to the perceived characteristics of the constellations for which they were named. Leo gives pride, the Virgin gives barrenness, the Ram gives a headstrong disposition.
The sexagesimal (base 60) system was in use in Mesopotamia as a very flexible arithmetic system, due to its large number of factors-- including the astrologically significant number 12. The number 60 lends itself to a division by many numbers, thus facilitating the calculation of fractions. Base 60 is really the basis of our hours, minutes, and seconds; 360 degrees in a circle and compass bearings; and I believe our lines of latitude and longitude.
The Babylonians developed 30-degree astrological signs (also base 60) out of the zodiac constellations (which are of varying widths along the ecliptic) to make it easier to predict eclipses.
Of course, 10 divides into 360 handily enough, but historically base 10 did not originate with the arithmetic system that informed ancient astrology.
In terms of Jupiter in Scorpio in the 9th, it is hard to say without seeing the entire chart, because you'd want to consider how it is aspected and the situation of its house ruler/s within the horoscope.
But a good way to consider a placement is that a planet gives you the "what" in a sentence, what we would call the subject. In a natal chart, Jupiter is the principle of optimism, luck, and/or expansion. It is a planet of panoramic thinking, vs. Mercury's attention to immediate facts.
The sign says how or in what manner a planet operates, like an adjective or adverb in a sentence. Scorpio is about the most complex sign going, but superficially, it is fixed water. So a planet in Scorpio operates primarily out of your feeling nature, and it tends to be constant and consistent. The Scorpion with its stinger tends to have a retaliatory streak, which may seem a little out-of-place with idealistic Jupiter. Thanks to its Pluto nature, Scorpio will channel Jupiter into life's deeper mysteries.
An aspect operates in a "how" or "what manner" mode as well, but here we think about pairs or stellia of planets. How do they get along with one another?
A house says where or in what domain of life a planet operates, like a prepositional phrase in a sentence. The 9th deals with activities that expand your mental horizons, such as foreign travel, higher education, theology, and developing a life philosophy. There is no consistent match-up between planets, houses, and signs; but the Jupiter-Sagittarius-9th house connection is one of the better ones.
So to put these components together in a sentence: you exercise your powers of faith and panoramic thinking through probing life's mysteries in a persistent and feeling way. If I understand your chart correctly, you have Pisces rising, which would tend to reinforce the significance of your Jupiter in your life, because it rules your ascendant.
