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For and Against: The Zodiac Debate

One topic that is sure to cause controversy amongst astrologers is that of whether the Tropical or Sidereal zodiac is most effective in practice. A recent forum debate revealed how passionately astrologers cling to alternate views. In 1997 the Traditional Astrologer magazine asked two expert astrologers to justify their own choice by reference to history, philosophical logic and the results of their own experience. Their responses have been reproduced here and allow us to consider the historical influences upon this 'astrological complication' in-depth.

This debate assumes a knowledge of the issues connected to precession. For a more detailed explanation of precession and the early refinement of zodiacal signs refer to the article Heavenly Imprints.

For The Sidereal Zodiac - Kenneth Bowser

The tendency of many western astrologers to make assumptions about the past born of contemporary usage, indeed to insist upon them, has confounded the tropical-sidereal argument for the past 50 years. Endless would-be refutations, polemics, even an appendix riddled with gross errors, have sought to contravene the life work of the most learned men and women in Assyriology and Near Eastern Studies to impose the tropical zodiac on the Babylonians and their neighbours. In order to do that one must turn a blind eye to the material, plus adopt implausible explanations to account for how the patently obvious, to all but tropical astrologers, is something else.

The material at the root of the problem has been available for many decades, beginning with the seminal work of J. Epping who in 1881, with help from J. Strassmaier, published a modest article, On Deciphering the Chaldean Astronomical Table, which solved the problem of dating the Seleucid and Parthian eras. A larger study followed in 1889 with Father Epping's book Astronomy out of Babylon. Epping died in 1894 but the work was continued by his younger colleague, F.X. Kugler, who published Babylonian Lunar Reckoning in 1900 and the monumental Starlore and Starwork in Babel [Babylon] in 2 volumes and 3 supplements from 1907-1935, the last of which was completed by J. Schaumberger.

The floodgate of information opened primarily by Epping, Strassmaier and Kugler has been substantially augmented by 20th century scholars on both sides of the Atlantic, such that the question is no longer if the ancients used a sidereal zodiac, but rather if the Hellenistic Greeks used a tropical one before Hipparchus or very much afterward in view of the absence of extant tropical horoscopes before the Roman Imperial period. Moreover the Babylonian norm of System B (vernal point = 8° Aries) persisted contemporaneously with Ptolemy and so long after him, that its use gives rise to questions about the currency of the tropical zodiac, and at the very least constitutes proof of the pervasiveness of Babylonian influence in the Roman world. It is a moot point whether the tropical zodiac would ever have persisted if the west had not become an intellectual backwater after Roman power was broken in the 5th century AD, coincident with both the rise of Christianity which discouraged inquiry, and the near confluence of tropical and sidereal reckoning in the 3rd century AD.

Significantly, the Almagest was not translated into Latin until the late 12th century AD. Since, as the editors of Martianus Capella suggest, there was not a man alive in the west who could compute a geometric proof when the best qualities of the Classical world fell into desuetude, it us no surprise that nobody questioned why the cardinal points should not be reckoned as the beginning of things when one could look up into the sky and see that it was so, even if only for a few lifetimes, but by then it was too late. The inertia of tradition coupled to the remarkable achievement of the Almagest had founded the tropical zodiac: most people then displayed the right trait characteristics because the sidereal signs were not far out of alignment with their bogus tropical namesakes.

Hipparchus, the discoverer of precession, apparently did reckon longitudes from the vernal point, although it looks like he didn't have much company; yet his wholesale adoption of the Babylonian lunar and planetary theories speaks volumes about the accuracy of Babylonian mathematical models, and ostensibly his regard for them. Much has been made about whether the Babylonians were aware of precession or not; Kugler was confident that they were not except 'perhaps' (his word) very late in their history. Neither the vaunted Neugebauer nor anybody I have ever read, whose views are corroborated by evidence, and who has examined the material first hand, claims the Babylonians used the cardinal points except as a means to intercalate their lunar calendar and as a schematic argument to determine the length of daylight. The argument then, that the Babylonians didn't know the difference between the tropical and sidereal appears wanting. What tropical? What difference? For the Babylonians there was only one zodiac.

Neugebauer stated that in his experience the norm:

0° Aries = vernal point

exists nowhere in the Babylonian astronomical/astrological material. Examining the same for themselves, van der Waerden concurs, Huber concurs, Aaboe concurs, etc. Neugebauer is still more explicit in his History of Ancient Mathematical Astronomy (p.594) about the Babylonians:

"Longitudes were not counted from the vernal point but from the sidereally fixed end points of the zodiacal signs"

Cyril Fagan came to the same conclusion 30 years before Neugebauer published his magnum opus. They had corresponded during the 1940s but on other subjects as far as I know.

While there is abundant evidence that the Babylonians were assiduous observers and chroniclers of celestial events from early in the 2nd millennium BC, detractors contend that what they were doing was not 'real' astrology, as though a model T Ford was something other than a 'real' car. The nay-sayers contend further that Babylonian data were not sufficiently accurate to be astronomically or astrologically useful, but the eclipse data were good enough for Ptolemy who mentioned these in the Almagest (III) as the oldest data available to him. They are from the first regnal year of the Babylonian king Nabonassar (747 BC). Fagan's greatest achievement, the solution of the exaltation degrees, is even older (786 BC). The Babylonians wrote about the intrinsic natures of the planets and the sidereal signs centuries before the Greeks: the Babylonians developed the doctrine of the four triplicities, (and the trine aspect taken over by the Greeks), in addition to furnishing the entire zodiac eventually adopted by the Greeks. What is this if not divination by the sky? Could an astrologer do otherwise, even if he styles himself 'counsellor', 'therapist' or psychologist'?

One particularly fine American astrologer contends that the earliest horoscope extant, dated to 410 BC, could be tropical because it has no degrees (although other Babylonian horoscopes have them with sidereal degrees), and that there is no proof that the Babylonians used twelve equal length sidereal signs that early; but since the Greeks had not even adopted the Babylonian sexagesimal degree notation as early as 410 BC, the degree objection seems to be without merit. In addition, somehow it has been overlooked that the oldest text with twelve equal length sidereal signs dates from 475 BC. This also mentions the 31 Babylonian 'normal stars' but does not deal with the cardinal points or a tropical zodiac.

It has been claimed that there are too few sidereal horoscopes from which to draw reasonable conclusions, because Fagan, using Sachs' work from 1952 described only six, but 24 more have been recovered since then. Early Greek and Roman horoscopes and inscriptions, (the coronation of Antiochus I of Cammagene at Nemrud Dagi in 62 BC for example), are commonly reckoned from fiducials other than 0° Aries= vernal point, (including all of the horoscopes attributed to Vettius Valens), with decreasing values versus time which Neugebauer and van Hoesen show correspond roughly with precession. Many of them are close sidereal fits.

A Greek lunar ephemeris (Papyrus Rylands no. 27) from 250 AD, which was recovered only slightly damaged and later translated by Neugebauer in 1949, proved to be entirely sidereal. Why then is there the incessant claim that the sidereal zodiac is a fiction? The only way out for the tropical apologists is to claim that the demonstrably incorrect notion of the 'trepidation' of the zodiac was widespread in the ancient world. It is noteworthy then that Neugebauer said explicitly that the evidence points to Hipparchus (whose last known date for works is 127 BC) as the inventor of trepidation. Ptolemy (whose last observation was recorded in 141 AD) disregarded it, perhaps because their values for precession were significantly different. Grasshoff points out that this discrepancy suggests that the matter was not seriously entertained during the interval between their lifespans, when the difference between sidereal and tropical reckoning decreased from 5° to 1°.

The real question is if the tropical zodiac is invested with meaning. Obviously I think not. McCann asks for us to look at our ascendants and other positions when addressing such questions. I wholeheartedly concur. Beside the tradition invoked by Hipparchus and Ptolemy that longitudes be reckoned from the vernal point, the bleed-over from sidereal sign to tropical sign is what has caused the problem. A good example is Scorpio, the sign that gets the most attention because it is considered the most sexual. From the standpoint of a siderealist, Scorpio is not a love-maker, sweet, alluring, the complex, tortured artist or inclined to press for a resolution of a problem; rather, Scorpio imposes solutions and brooks no resistance. It doesn't bargain; it is aggressive, insistent, penetrating and intense, likes to fight and is often loud, coarse, vulgar and utterly graceless, other things not considered. Scorpio isn't like Libra, yet 5 out of 6 tropical Scorpios are sidereal Librans during the current era.

Since the Librans are genuinely agreeable and attractive people, other things not considered, astute tropicalists who notice what the trait characteristics of the people in their experience really are, which deviates from the old lore, trot out profound esoteric explanations about how the deeper occult significance of Scorpio (choose one) is actually in accord with their contemporary observations. That is how tropical Virgo becomes strong and overbearing, Aries gentle and sensitive or Capricorn formal and ambitious, etc. They are Leo, Pisces and Sagittary misnamed, which corruption eventually produces a meaningless hodgepodge to the great detriment of Art.

 Read: The Case for the Tropical Zodiac by David McCann

If you wish to comment on this debate, you can add to the thread in the forum where the tropical v. Sidereal issue is being discussed.

Kenneth Bowser has a B.A. in history and has studied both astrology and ancient history for over thirty years. He began his astrological studies as a tropicalist, but within two years switched to the sidereal camp. He is known for his careful scholarship in the field of ancient astrology and is widely regarded as one of the major figures in western sidereal astrology today.

Ken was a personal service astrologer and long time columnist for American Astrology magazine. His articles have also appeared in The Mountain Astrologer, The Siderealist, The Traditional Astrologer, Continuum, Realta, and The NCGR Newsletter. He lectures at astrological conferences in the US and Europe, regularly teaches classes on a variety of astrological subjects, and works as a full-time astrologer in Minneapolis, Minnesota, providing a full range of astrological services from natal interpretations to business-related predictive work.

Ken has created the first comprehensive course on western sidereal astrology and is at work on a book on western sidereal techniques. For more details visit his website at

© Kenneth Bowser. Published online February 2005. First published in The Traditional Astrologer magazine, (Ascella), Issue 14, May 1997, pp.23-27

For the Sidereal Zodiac: Kenneth Bowser

  Now read the case for the Tropical Zodiac by David McCann