Paul, let me first reply to some points you raised.
Paul wrote:It is curious to me that my own reading of Manilius, and indeed others, seems to be the same as what BL describes here. That the houses and signs are independent, the houses static, the signs moving through them not defining them, but passing influence from one another.
Bouché-Leclercq, publishing his book in 1899, is a representative of early, partly outdated scholarship. You see that he misses acknowledging that the word
h??roscopos may also stand for the ascending sign itself, don't you? Or that the word
kentron may also denote the angular signs, not just rising, setting, culminating and anti-culminating degrees? Or that he was unable to recognize, which is perfectly understandable at the end of the 19th century, that the relevant extant horoscopes didn't use any sort of domification, only house meanings superimposed on the signs? (At the same time, you've certainly checked the modern references I gave, haven't you? Let me add Wolfgang Hübner's monograph on the subject,
Die Dodekatropos des Manilius (Manil. 2,856–970).)
But, regarding the basic claims, I can agree both with BL and you. The horizon tinges the zodiacal sections close to it with 1st and 7th-house meanings, no matter what "house system" one uses. In this respect, the houses are static indeed while the signs rotate.
Paul wrote:Nowhere in reading that section do I get the sense that he means by "horoscope" anything other than the point of the ascendant, certainly I don't think he means sign. Do you?
I think it is ambiguous; it depends what one wants to see. For me both interpretations are acceptable. This is what I really want to say: the poetic description of the pivots, quadrants, and houses allow different interpretations, from more literal ones (like yours) leading to the assumption of some sort of locally fixed quadrant system to ones that say the description is mostly symbolic and not necessarily correct in its minute astronomical details. This latter is what I claim; after all, even basic astrological concepts are idealistic approximations: the signs represent the ideal month and the degrees the ideal days, although neither is astronomically correct - and the same could be told about virtually everything else.
On the other hand, there are the two passages quoted earlier that imply that Manilius meant signs as houses. If someone takes the choice of words rigorously, which reading is based on a comparison with the usage of other authors, then it only allows the symbolic interpretation; which I do. You seem to have chosen a different approach, that is, that it is not whole signs that are dyed with house meanings but fractions; which I find quite stretched, but you may consider the symbolic interpretation of the whole description equally stretched. This would lead to a standoff.
Now, for a moment, let's assume that you are right, and Manilius intended to describe a quadrant system. But could he have computed one? I believe the answer is a definite "no," and I'll tell why.
In the first century CE, when an astrologer wanted to ascertain the ascending sign, if he knew the rising times (and most of the astrologers keep repeating them so that no-one could forget them), a gnomon or a not-too-imprecise waterclock or, on starry nights, even direct observation could yield acceptable results. If he wanted to ascertain it down to the degree, then there were sort of rule of thumb simple and not too precise arithmetic ways. If he wanted to take the meridian-MC by degree, this imprecision grew even further. (Computations like these can be found in Valens and Paulus, and if you check them, you'll see their limits.)
Of the 65 or so extant first-century horoscopes, seven calculate the ascendant to the degree. Of these, two are from Antigonus of Nicaea (writing not earlier than the late 2nd century) and two from Valens, which might have been calculated later; three are embedded in original documents. Fourteen first-century horoscopes indicate the sign of the midheaven (or the lower midheaven or both), including one original document giving the ascendant degree but only the midheaven sign; however, the sign is without exception the one in right quadrature with the ascendant. The degree of the midheaven is given only in a dozen or so horoscopes from the 1st century BCE to the 4th century CE, a third of which has imprecise or utterly wrong data.
For calculating "equal" houses, one needs the degree of the ascendant. It seems that the minority of the practicing astrologers bothered even with this calculation, except the astrologers casting so-called "deluxe" horoscopes. Neither did "15-degree rule" Dorotheus and "equal-houses promoter" Firmicus Maternus, who were both happy to use whole signs when it came to houses. "Archetypical practicing astrologer and also equal-houses promoter" Vettius Valens, the winner of the competition with his 120+ horoscopes, took up the arduous task to compute or at least publish the degree of the ascendant in five (!) cases. So even if the "equal" system(s) were originally introduced by His Thrice-Greatness, His Majesty the Wise or His Holiness of the Egyptians, when it meant labor, few astrologers were ready to make calculations; which suggests they were happy with whole signs, no matter they were philosophically (astrosophically, toposophically) sound or not.
If an astrologer is so adventurous that he wants to use a quadrant system of an easier type, that is, which slices up the quadrants on the ecliptic, he also needed the degree of the midheaven. As the numbers suggest, very few astrologers thought it was important. Even Valens, who describes Orion's system of trisecting the quadrants and who emphasizes the 10th- and 4th-house meanings of the meridian-MC and IC, gives the value only three times, of which one (Hor. gr. nat. 75.VII.19 in Val. 3.5.6-10) is fairly imprecise, and in a fourth case the degree of the MC is only implied, whereas no degrees whatsoever are given.
Ptolemy published his astronomical and astrological theories, including tables calculated using advanced methods for climes, right and oblique ascensions, in the second century. Gradually, his ideas were accepted: by the fifth century, planetary longitudes and degrees of the ascendant and the midheaven had been computed with the aid of his tables. It is probably not a coincidence the first full-fledged quadrant systems were expounded by Ptolemy's commentators, Pancharius (in the third or fourth century) and "Rhetorius" (if it was him; who knows, maybe in the fifth century). It was also Ptolemy's tables that enabled the author of the known form of Hor. gr. nat. 428.IX.8 to calculate the "Alchabitius" houses: you just do some simple arithmetics, and you'll get nice results.
Ptolemy's tables were calculated using the so-called Menelaus theorem, which was either developed by Menelaus of Alexandria around 100 CE or somewhat earlier. Actually, this theorem made the spherical trigonometry of the upcoming nine centuries possible. Perhaps there were a few forgotten astrologers who made tiresome calculations for quadrant houses in single horoscope or for constructing tables, but available historical data shows the spread of "house systems" from about 800 CE onward, probably not independently from the fact that around this time was Ptolemy's astronomy and astrology rediscovered.
So, can a first-century astrologer be imagined as someone making exhausting calculations? The answer, theoretically, is a "maybe" (provided the Menelaus theorem was available); however, historical data suggest that astrologers of this era were by far lazier. For me, a Manilius-like figure, who mixes System A data with System B data, uses the climes of Babylon, Alexandria, and Rome indiscriminately, and so on - and, alas, the majority of the Hellenistic astrologers was this sort of folks -, is more similar to an averagely informed modern astrologer who knows what buttons to press toget the horoscope but has very limited astronomical knowledge than to someone who not only knows exactly where the north is found (there was no polar star that time) but can visualize position circles dividing the prime vertical, or, Thot forbid!, even calculate them.
For my part, the debate on "house system issues in Hellenistic astrology" is over for forever. I've used all the relevant historical data from extant horoscopes, writings published and unpublished but available to me, the applicable philological, historical, and astronomical arguments drawn from these sources in this and previous threads, and I really don't have anything more to say.
So, Paul, if you feel like, after a little break, we can return to the titular topic of the thread.