A Brief History of Astrology
© 2002 Curtis Manwaring
Most people know that astrology is a discipline that is several thousands of years old. Some have said that it is as old as Atlantis (about 12,000 BC), while others say that it is only about 3000 years old. Because of the changes in the sky and cultures over the ages, the form of theory and practice that astrology took has varied greatly. For this reason, it is important to establish the principles upon which it was practiced through historical records. The scholastic record only dates back 2000 - 3000 years in the west, however, eastern astrology claims to have records dating back about 7000 years into the past.  Investigating history is like looking into the fog: the farther you look, the more hazy the evidence, even if we know it exists.
Before we get started in examining the historical record, we need to have some idea of what the sky looks like and define terms so we know what we are talking about.
Basic Celestial Mechanics:
The sky is represented as a celestial sphere in figure 1.1. You can see the two poles with the "N" and "S" representing north and south poles respectively. The earth is located in the center of the sphere at "O". The great circle that is perpendicular to the poles is the celestial equator represented by [A B Aries Libra]. The other great circle is the ecliptic which has the 4 strange symbols representing Aries (vernal equinox), Cancer (summer solstice), Libra (autumnal equinox), and Capricorn (winter solstice). The ecliptic is defined by the Sun's apparent path against the background stars during the course of one year. The two great circles intersect at the equinoxes. When the Sun happens to be on them, the day and night are of equal length. When the Sun is on the summer solstice, daylight is the longest in the northern hemisphere, and shortest in the southern hemisphere. When the Sun is on the winter solstice, the daylight is shortest in the northern hemisphere, and longest in the southern hemisphere. These two great circles are also known as the circle of the Same (celestial equator), and the circle of the Other (ecliptic) in Plato's Timaeus because the motions of these two circles are contrary to eachother. As you will see, this strange fact will become crucial later.
While to beginners it might not be obvious, it is important to know that the ecliptic circle defines one of the types of zodiacs known as the tropical zodiac. The other type of zodiac is known as a sidereal zodiac, where the background stars define the signs. Because there are no well placed boundaries in the heavens between the stars to mark where one sign ends and another begins, there are several types of sidereal zodiacs, whereas there are only 4 (possible) different tropical zodiacs. The main tropical zodiac is defined by the vernal point which begins the first degree of Aries, the Ram. The two types of zodiacs were roughly coincident about 2000 years ago, but because of the precession of the equinoxes (explained below), there is a noticable difference today. This angular difference between the beginning of the tropical zodiac and the beginning of the sidereal zodiac is known as the ayanamsa.
The Precession of the Equinoxes:
There is one astronomical phenomena that has wreaked more havoc, controversy and confusion than any other and it is known as the precession of the equinoxes. Precession is the backward motion of the equinoxes with respect to the background stars over a period of about 25,960 years for one complete circle of 360 degrees. This backward motion is caused by the gravitational pull of the Moon on the earths equatorial bulge (helping to gradually shift the polar axis) while it revolves around the earth. In the span of one person's lifetime this is barely noticeable, and only amounts to about 1 degree in 72 years, but in the 2200 years since the time of Hermes Trismegistus, this has amounted to a difference of about one sign!
The problem lies in coming to terms with what constitutes a sign. Is it the background stars? Or the space in between them and the earth? The Vernal equinox, sometimes called the first point of Aries is now in the area of sky called the constellation Pisces by astronomers. Tropical astrologers use this point to define the zodiac of the 12 signs as we know them. Sidereal astrologers (most of them vedic practicioners) say it is the background stars that define the zodiac. The zodiac signs that we see in newspaper horoscopes in the west are tropical. The argument for using a tropical zodiac stems primarily from keeping in sync with the seasons and elemental attributions of Aristotle (I'll get to that later). For instance, the Sun is exalted (lifted up) in Aries when it crosses the vernal equinox. This is because in the northern hemisphere, the Sun now has a greater amount of time above the horizon each day than it does below, causing the days to be longer than the nights.
The confusion with regard to which zodiac to use does not end there however. Valens is said to have used a zodiac where 8 degrees of Aries was considered the vernal point.  Still some others use 10 degrees Aries.  Because we do not know if these 2 variations were tropical or sidereal, we have to include them as being possible definitions for a tropical zodiac. The 4th type of tropical zodiac is based upon the position of the Nodes (Draconic). However, some would not call this a tropical zodiac, so we have one standard tropical zodiac and two possible variations of the tropical zodiac. Suffice it to say that I use a tropical zodiac of 0 degrees Aries for the vernal point as do most western astrologers, though I encourage experimentation in this area.
While it is a terrible problem and brings many techniques into question, without it we would not have as firm a basis for the zodiacal ages. It is because the vernal point has backed up to the beginning of constellational Pisces and is about to enter constellational Aquarius that we are said to be living in the "dawn of the age of Aquarius".
It is both very interesting and suspicious that the two zodiacs coincided roughly 2200 years ago. It could be that the names for the constellations were derived at that time and did not exist before that. I am not saying that astrology did not exist before that - we clearly have examples of oracular astrological warnings from earlier times, just that the names or meanings of the zodiac signs may have somehow been different. On the other hand, there are some references to Nechepso and Petosirius who come from a time much earlier than 200 BCE. Valens  attributes the use of the lots to them, and it is hard to see how they might have made good use of the lots without some clear boundaries by sign.
Historical Astrological Timeline:
The earliest records in the west show references to Nechepso and Petosirius who lived at about 1000 BCE , known as the King and his high preist. The works of these two are lost for the most part so we do not know for certain if they had their source from Babylon or Egypt, or both. We know about them because we see Vettius Valens making several references to the work of these two.
The next major figure to appear on the astrological map was Hermes Trismegistus. Hermes was a very mysterious figure; so much so that we are not even sure if he was an individual or a sect of astrologers. Schmidt has stated on numerous occasions that this individual (or group) is probably the focal point of hellensitic astrology. He also says that he believes that Hermes deliberately founded an astrology based upon the Athenian philosophical disciplines as a response to a challenge from Athenian philosophers who said that the contingent was ultimately unknowable, and therefore not the proper object (of study) of philosophy.  Hermes work is dated at about 160 BCE. The Liber Hermetis is the main body of his work, though it is likely that the majority of his works are lost.
It seems that the beginning of the split between the Hermetic school and what is now known as the medieval school of astrology may have had their root in the debate that was taking place between Plato and Aristotle. Plato was an idealist in the original sense of the word. He regarded the realm of the noetic or eidetic forms to be the most real and permanent and that the study of these things would lead man to the truth of his being. By contrast, Plato considered the material inconsistencies in the world to be an imperfect representation of what is happening within the realm of the pure forms (or the mind of God). As such, the exact measurements of material variations is not necessary to get at the truth. Aristotle believed that the material in the world was also capable of causing changes in other parts of the world, just as the change of seasons bring changes in the weather, or the push of one's hand is capable of opening a door. He was interested in the nature of cause and effect among other things and because of this he focused his mind upon the material causes of nature.
Claudius Ptolemy (about 100 CE) seems to represent Aristotle's line of reasoning. Many of his observations are still held today by astrologers. It was Ptolemy who formulated a theory for celestial mechanics according to natural laws, and who inadvertently started several controversies because of the difficulty medieval astrologers had in translating his style of Greek. We still live with these controversies to this day, especially in the area of astrological house division.  His methods tended to stress a material cause based upon the philosophy of Aristotle and as such are not really compatible with the original conception of Hellenistic astrology. By contrast, Hellenistic astrology tended to emphasize a noetic (spiritual) cause.
Dorotheus of Sidon was a contemporary of Ptolemy's who also wrote on astrological matters at about 100 CE. He was widely known for his use of the trigons in astrological forcasting. He was probably in touch with the mainstream of the Hermetic tradition and most of his writings seem to reflect a platonic line of reasoning.
Vettius Valens was an astrologer who lived in the 2nd century. His works are the most extensive we have available that detail the practice of Hellenistic astrology at the time and most of the charts that he worked on were dated between 100 CE and 150 CE. His work was very thorough and he was not afraid to be critical of the results of astrology when it was warranted. By his time, there is the sense that the original system was beginning to lose it's philosophical cohesion, because he wrote:
"This theory is now dishonored and banished ... But once it possessed a name which was looked upon with envy, when those before us were proudly confident in this and were made blessed [by it]." 
He was not afraid to be critical of astrological techniques and tinkered with some of the methods when he felt it was warranted. His works are noted for their epistolary style and their sense of humanity.
At about 380 CE, Hephaistio of Thebes wrote a treatise on the "Apotelesmatics" which is the Greek word for "effects" or "outcomes". Because he was about 280 years after Ptolemy and about 540 years after the start of the Hermetic tradition, he was in a period where the Ptolemaic/Aristotilean and Platonic/Hermetic traditions were the dominant forms of astrological thought. Hephaistio tried to unify these two schools, but it did not stick because he wrote his treatise just before the onset of the dark ages.
There is a large gap where there is little information about various astrologers between 400 CE and about 750 CE corresponding to the dark ages. During this time, western astrology seems to have been idle, but some time during this period it was making it's way into the Arabic language. From here, the translation of the material was less than perfect, but they did make an honest effort to do the best they could. The doctrine of sect was subtly changed in a few ways, and the list of lots/arabic parts grew enormously. They were the first to institute and formalize orbs for aspects. Al-Kindi was the first major figure to appear in the Arabic world. He was known for his theory on astrological magic. Abu-Mashar (About 800 CE) was a successor to Al-Kindi and was widely known for his work on large mundane cycles such as the Jupiter/Saturn cycle, and his work on solar returns.
Eventually, at around 1150 CE, the material that was translated into Arabic was translated again into Latin, and this is the period in which we have the most material from. The most famous astrologer from this time was Guido Bonatti (13th century). He was among the last astrologers to understand the use of sect in a birth chart.
In the early Renaissance period, there are several well known astrologers: Antonio Montulmo, Ramon Lull, John Dee, Darius, and several others. At the end of the Renaissance, the most notable astrologer was William Lilly who is still reknown for his work on horary. By this time several changes had taken place in astrological technique. Astrology fell out of favor again at the beginning of the Enlightenment and didn't begin to become popular again until the latter half of the 19th century.
A little over a century ago, some astrologers attempted to make sense out of the mess of translations, and also felt a need to include the newly discovered outer planets into astrology. By this time, the confusion was exceedingly great, and there are several techniques that just didn't make it due to the lack of a good overview of all of the works. Because astrology had been severely discredited by the discovery of the outer planet Uranus and several philosophical developments such as reductionism (Descartes), few qualified individuals were even interested in the subject, so it became the domain of Gypsies and charlatans. It is at this point that astrology became lumped in with psychism, and shortly afterwards, psychology with the work of Dane Rudhyar. While Rudhyar did something very innovative with astrology (In his book, "The Astrology of Personality"), he himself was not familiar with most of the techniques of the ancients. Hellenistic astrology is not person centered, but puts the cosmic soul (or Plato's anima mundi) as the center of focus and concern.  However, it is important to realize that because of the inconsistencies in the transmission of the art, that it is certain that there is room for improvement in all the various schools of thought. It is my opinion that we should let philosophical first principles decide ambiguous issues in astrology, because astrology came about through philosophy.
1. As G. Kumar states in his article about the history of Vedic astrology elsewhere on this website (X-File Cabinet).
2. As Rob Hand stated in the 1995 PHASE Conclave.
4. Vettius Valens, Hellenistic astrology, Anthology, Bk II aprox. 160 A.D. © 1994 Robert Schmidt, through Project Hindsight, Published by The Golden Hind Press. See pt. 1, pg. 6-7.
5. Schmidt says the dating of the works of Nechepso and Petosirius are uncertain, and their works may have been as recent as 250 BCE.
6. The contingent in astrology represents Man as either tall or short, brilliant or dullard, etc... I have heard Schmidt say that philosophers would prefer to study the beingness of man or its eidos which is not contingent or variable. He says they prefer this because to study the contingent is to embark upon a path of illusions based upon the dyadic qualities in nature.
7. Schmidt says that the controversies in house division and other areas are possibly the result of his style of writing Greek.
8. Vettius Valens. Anthology, Bk II aprox. 160 A.D. © 1994 Robert Schmidt, through Project Hindsight, Published by The Golden Hind Press. See Book VI. pg 62.
9. Robert Schmidt said this in July 2000 in his lecture series in Cumberland, MD.