Long Reads

The Birth of Western Astrology: A Short Story

What Asinus Teaches

  1. Astrology Makes It Into the Hellenistic World
  2. Ancient Greek Astrological Charts
  3. How Ancient Greek Astrological Charts Were Read
  4. A Glimpse Into Ptolemy’s Tetrabiblos Textual Tradition
  5. Modern Astronomic Discoveries and their Impact on Astrology

Wild Reddit Question Appears !

How similar is modern astrology to astrology as practiced by the Ancient Greeks?

This was sparked by me wondering if the Ancient Greeks thought it was odd that Aquarius the Water Carrier was an air sign, but that got me questioning if the Ancient Greeks even sorted the signs by element and mode (cardinal, fixed, ordinal).

If an Ancient Greek astrologer drew up a horoscope, would it bear any resemblance to the horoscope a modern astrologer might produce for me? Did they at least associate the same personality traits to each sign?

And if not, how did modern astrology get the way that it is? Is there an unbroken line of transmission back to Mesopotamia, or was it recreated from historical records/mostly made up? Or is the core true to ancient practices, but then a bunch of other stuff was added to it?

My Answer

Jeez! I fell down the rabbit hole fast and hard. I wonder how I ever climbed back up. Is this dust on my jacket? I’m covered with mud.

What is it?

Oh, hi! I’m sorry. I didn’t see you over there. I was so busy looking at the stars that I fell down this pit and found the most amazing things on my way down. I swear, I could have spent hundreds of years down there but I heard my wife asking me what’s for dinner tonight. Let me show you my findings. Thread lightly as we go, I don’t want you to go down as I did and break a hip or something. I barely made it out myself.

Do you mind if I buy some chicken on the way? I’m cooking a Caesar salad tonight.

Astrology Enters the Hellenistic World

When we think of the ancient Greeks, we often think of the 5th century B.C., the “peak” of Greek culture. Athens became a democracy, the Greeks fended the Persians off, Pericles high-jacked the Delian League, Athens and Sparta went to war with each other, Herodotus wrote his Histories, Thucydides the History of the Peloponnesian War and Socrates went on to pester everyone with his philosophical questions… However, this is not when astrology became the intellectual discipline that we know today.

Plato, who lived on the edge of the 5th and the 4th century B.C., made some use of Babylonian astral figures in his writings. However, the priest of Bel Marduk Berossus only taught astrology to the Greeks around 280 B.C. when he dedicated his Babyloniaca to King Antiochus I Soter. By then, the Classical era of the Greek city states was long gone. The Greeks were part of a much wider world since Alexander the Great had died and the many Hellenistic realms had claimed his military and political heritage. The Seleucid Empire, which Antiochus I Soter ruled, encompassed a good chunk of modern Turkey, most of modern Syria, pretty much all of modern Iraq and Iran and it stretched even further East, into the western borders of modern India.

According to the Roman architect Vitruvius, Berossus’ disciples deemed the moment of conception as more important than the moment of birth. This is not the case for astrologers today.

Though Berossus first taught astrology to the Greeks within the boundaries of the Seleucid Empire, it quickly caught on in Egypt, especially at Alexandria where the most advanced mathematical observations about the Earth and the stars were being made. It also found common grounds with the philosophical school of stoicism in Athens, in regards of predestination and the energetic interconnection of all things (call it “the Force” if you want ;-). The Pythagoreans also pitched it. Astrology became a whole shiny new thing and moved quite far from its Babylonian roots. Whereas Babylonian astrologers were mostly concerned with main political or meteorological prognostications, the Greeks turned astrology into a tool to investigate individual destinies. Placed at the crossroad of religion, philosophy, natural sciences and mathematics, astrology took a few centuries to look like what we know today.

A common critic today about astrology is that the twelve constellations have shifted in the sky. Every 72 years, the zodiac moves one degree “backwards” because of the precession of the equinoxes. It means that where the Aries constellation used to stand, a long, long time ago, now stands the Pisces. Critics point that out regularly to assert that astrological signs are nonsense. However, this issue had already been observed by Hipparchus, an Alexandrian mathematician and astronomer, back in the 2nd century B.C. Therefore, astrologers came up with the “tropical zodiac”: a zodiac not fixed by the actual observation of the sky, but determined by the spring equinox and the two solstices. That way, the zodiac became an abstract belt anchored and locked around the Earth. Does it make it more sense? That is a question for another day.

Meanwhile, despite the many works on astrology written and debated throughout the Hellenistic period, the earliest Greek astrological charts that we know of only date back from the 1st century B.C. Most of them, actually, were written by the time that Rome had become an Empire. O. Neugebauer and H. B. Van Hoesen made it noticeable when they published their book, Greek Horoscopes*, a scientific edition of the most ancient Greek astrological charts still at our disposal.

* O. Neugebauer & H. B. Van Hoesen (ed.), Greek Horoscopes. Philadelphia: American Philosophical Society, 1987.

Ancient Greek Astrological Charts

The most ancient surviving Greek astrological chart must be the Lion Horoscope Relief of Nemrut Dag. This massive relief depicts an actual lion bearing a crescent on his neck and standing under three stars named Pyroeis Heracleos, Stilboon Apollonos and Phaeton Dios, respectively Mars, Mercury and Jupiter.

Philip of Opus, Plato’s disciple, is the one who labeled the planets as we know them today back in the 4th century B.C. However, the Lion Horoscope, dating from the reign of Antiochus I Theos (ca. 69-ca. 40 B.C.) shows us that his taxonomy wasn’t yet universally embraced several centuries after his death.


On a side note, the “ranking” of the planets underwent many changes since the Classical era and the Hellenistic period. Anaxagoras (4th century B.C.) went for Moon, Sun, Venus, Mercury, Mars, Jupiter, Saturn; Hipparchus (2nd century B.C.) preferred Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn; Berchorius (14th century A.D.)—who wasn’t too concerned with astrology—totally reversed the classical order for the following: Saturn, Jupiter, Mars, Apollo (the Sun), Venus, Mercury and Diana (the Moon). Today, astrological ephemeris place the Sun first, then go Moon, Mercury, Venus, Mars, Jupiter, Saturn, etc.

Nevertheless, the Hellenistic period named the days of the week after planets* to answer the needs and interrogations of horary astrology—more on that later. It still survives very well in Romance languages, like French.

  • “Lundi”: Lunae dies (day of the Moon);
  • “Mardi”: Martis dies (day of Mars);
  • “Mercredi”: Mercurii dies (day of Mercury);
  • “Jeudi”: Jovis dies (day of Jupiter);
  • “Vendredi”: Veneris dies (day of Venus);
  • “Samedi”: Saturni dies (day of Saturn);
  • “Dimanche”: dies Dominicus (day of the Lord)—it used to be Solis dies (the day of the Sun) but went through a needed change with the rise of Christianism.

Not too surprisingly, this naming system also left its imprint on the English language. The Germans replaced several Latin gods by their own around the 1st century B.C. Mars became Ziu (→Tuesday), Mercury became Wuotan (→Wednesday), Jupiter became Thor (→Thursday) and Venus became Freya (→Friday). Monday and Saturday were left unchanged. So did also Sunday, the day of the Sun!

 * It is worth noting that up until the 2nd century B.C., the seven days week was totally foreign to Greeks though common among Semite people.


There’s been much conjecture about the actual day that the Lion Horoscope depicts astrologically. O. Neugebauer and H. B. Van Hoesen computed in their aforementioned book that it could be July 7th, 62 B.C., but Maurice Crijns later argued that it was rather the 14th of July 109 B.C. On either dates, however, it would have coincided with the coronation of a king of Commagene, either Mithridates I Callinicus or his son, Antiochus I Theos—once Pompey acknowledged his regal title despite his military obedience to Rome. I couldn’t find any decisive argument to solve that mystery. Anyway, a coronation placed under the omen of four planets located in Leo, including Jupiter no less, would have been a great one indeed.

The Greek astrological charts that survived on papyri (none of them is as old as the Lion Horoscope) mostly read as lists of planetary placements. There is barely any interpretation and when there is it is rather curt.

There is however one prolific astrologer, Vettius Valens, whose writings survived extensively. Vettius Valens’ Anthology is a long discussion of the various astrological doctrines of his time. He lived during the 2nd century A.D.

By then, astrology was a well-established science of prognostics. Several Roman emperors had had an extensive use of it. Nero’s odd political choices can be far better understood once we know he was educated to astrology by his mother, planned her death thanks to it and lost his mind when his reading of the stars didn’t foresee his fall. Many laws were passed in Rome since the Republic to forbid the practice of astrology but a large number of aristocrats were still hooked on it and astrology, as such, survived until the rise of Christianism and the great Migration Period (better known—sadly—as the “Barbarian Invasions”). 

Back on the topic of Vettius Valens. He recorded hundreds of actual astrological charts from 37 A.D. till his own era and flavored them with unique biographic information. He specified when someone encountered a violent death (beheaded, drowned, hanged, eaten by wild beasts, etc.). He also added when someone was faced with a peculiar destiny regarding the loss or gain of personal fortune, all that kind of things. He actually build what could be the most ancient surviving astrological database!

How Were Ancient Greek Astrological Charts Read ?

The Hellenistic Period laid the ground rules of astrology. Those notions survived very well and are still found in today’s astrological treatises.

The zodiac was already charted and arranged around the concept of cosmic harmony. This is why the constellations, despite their actual placement in the sky, divide the Sun’s course beyond the clouds into twelve sectors of equal dimensions. The Egyptians did count no less than thirty-six constellations. The Hellenistic astrologers therefore adapted their constellation system by splitting every astrological constellation into three decans.

The Sun and the seven planets, amounting for eight astrological bodies/deities, were already invested with their traditional meaning. The geometrical angles they drew within a chart were also imbued with a great significance. They were called apects—among which trines were especially considered as important.

The Houses were also already implemented. The Ascendant (Rising Sign) was called Horoscopos and gave its name to modern horoscopes. The meaning of the Houses turned into a mnemonic Latin verse during the Middle Ages: “Vita lucrum fratres genitor nati valetudo uxor mors pietas regnum benefactaque carcer.” (Life, wealth, siblings, parents, birth, health, spouse, death, rectitude, authority, profits, prison.) Also, planets were assigned as rulers of various Signs or Houses. In effect, planets had a domicile, a state of detriment, exaltation or fall depending on where they were placed on the natal chart. This was referred as the system of dignities.

This sophisticated system gave birth to at least two schools of interpretation. The “Egyptian” school rather focused on planet’s dignities whereas the “Babylonian” school centered more on planet’s aspects. However, astrology was used for far more than the mere study of individual destinies.

The old Babylonian practice of computing political prognostics was still popular, so were annual predictions. Horary astrology—predictions made for a specific event—was rather ubiquitous as was the use of astrology for medical purposes. The idea of a close relationship between the universe and the human body, often displayed in medieval manuscript, was already in effect. Each astrological sign was assigned a part of the human body. There were also attempts to connect and bind everything together into one monumental system, which gave birth to “magical astrology” and would later grow close ties with alchemy.

Astrology really became an overall system, a scientific paradigm of its own. However, its high degree of sophistication and the long years of study it demanded were snubbed by con artists and frauds who only pursued astrology for money or power. Those people indulged into hemerology; they casted predictions and identified propitious days only with the placement of the Sun or the Moon, drawing what would be considered as astrological oversimplifications.

The Tetrabiblos Plays Hide and Seek

Contemporary to Vettius Valens, Claude Ptolemy wrote the most comprehensive synthesis on Hellenistic astrology, the Tetrabiblos.

Contrary to Valens, Ptolemy didn’t view himself as a “soldier of destiny”. He didn’t think that individual destinies were unequivocally shaped by the stars. He argued that here on Earth, change was paramount, so much that it couldn’t always be predicted. Astrology was a guide, at best.

As mentioned before, the rise of Christianism and the Migration Period saw an end to erudite astrology in Europe. Astrology books were burned. Astrologers were hunted down. They even had to flee the Byzantine Empire when Justinian closed the School of Athens in the early 6th century. Actually, everything that vaguely resembled mathematics was prohibited. In medieval Latin, the word “mathematicus” was used to describe sorcerers, wizards and madmen. Geometry was barely tolerated for its practical applications.

As astrologers and other philosophers fled the Roman and Byzantine empires, they sought refuge east. They opened new schools in Persia, India and the Muslim states, where their knowledge grew and matured, to ultimately find its way back to Europe through Spain, like many other Greek intellectual treasures. Those treasures were now augmented with critical and scholarly commentaries or “glosses”. Aristotle was read alongside the running commentary of Averroes and so was Ptolemy’s Tetrabiblos with the additions and corrections of Haly Albohazen, a Tunisian astrologer of the 10th and 11th century.

Ptolemy’s Tetrabiblos augmented with Haly’s glosses found its way in many European book collections, including Charles V of France’s royal library. Charles V had at least two independent French translations of the astrological volume, still contained today in the manuscripts Paris, BnF, fr. 1348 and fr. 1349. But wait, there’s more. Since we’re on the topic of textual transmission—and since I’m a sucker for it—I’ll shortly explain how Haly’s commentary of Ptolemy’s Tetrabiblos found its way into Charles V’s royal library.

Ptolemy wrote in Greek. Manuscripts containing his Tetrabiblos still survive to this day, among which Paris, BnF, gr. 2425 and Città del vaticano, Bibl. Apostolica Vaticana, Vat. gr. 1038, which were used for the scientific edition of the text according to modern rules of philology. Franz Boll and Emilie Boer gave a critical edition of the Tetrabiblos in 1940* and according to Simonetta Feraboli** they relied on the aforementioned Vatican manuscript as their model. However, whoever translated the Tetrabiblos into Middle French for Charles V didn’t have access (either materially or intellectually) or knowledge of such manuscripts.

What happened is that Haly’s commentary of Ptolemy’s Tetrabiblos, which was written in Arab—and fully translated the Tetrabiblos from Greek—, was translated into Old Castellan. That Old Castellan translation was in turn translated into Latin by Gilles de Tebaldis (Francis J. Carmody counted 55 manuscripts containing this translation***, among which would be the following: Paris, BnF, lat. 16653). Then, and only then, was Haly’s commentary translated into French by two independent translators, one being identified as Guillaume Oresme (for the manuscript BnF, fr. 1348) and the other remaining anonymous (for the manuscript BnF, fr. 1349). Anyway, both of these translations were found among Charles V’s books.

The textual tradition of Ptolemy’s Tetrabiblos is quite the maze and I’ve only touched on the surface of it. However, all these layers of transmissions and translations rendered the text almost unintelligible in Middle French. We find many astronomic mistakes. It is only with the Renaissance, the rediscovery of genuine Greek manuscripts and the advances of astronomy that Ptolemy’s work became clear and properly understood. Astrology became a legitimate science—it was taught at the university—until it was fully discredited in the 17th and 18th centuries and viewed as the epitome of superstitions.

* Franz Boll & Emilie Boer (ed.), Claudii Potlemaei opera quae exstant omnia, vol. 3-1. Apotelesmatica. Lipsiae: Teubner, 1940. | ** Simonetta Feraboli, Claudio Tolomeo. Le Previsioni astrologiche (Tetrabiblos). Roma: Fondazione Lorenzo Valla, 1985. | *** Francis J. Carmody, Arabic astronomical and astrological sciences in Latin translation: a critical bibliography. Berkeley: University of California Press, 1956.

New Astronomic Discoveries and Modern Astrology

The continued advancement of astronomy in the 18th century forward shaped new concepts and rules for astrology. The discoveries of Uranus (1781), Neptune (1846), Pluto (1930) and their inclusion in the astrological system literally changed the way natal charts are read and predictions are made. Mars used to be the ruler of Scorpio, it is now said to be Pluto.

Astrology underwent many shifts and turns through the centuries. Its uses and schools of interpretation have varied greatly. Nonetheless the mathematical system had stayed relatively unchanged if not for the great divide between tropical and sidereal zodiac—the latter being preferred and still used by Vedic astrologers, in India. Planets, aspects, dignities, houses, it remained rather unscathed by the passing of time until Uranus, Neptune and Pluto made their “entry” into the Solar system. Pluto is still considered as a planet by astrologers though it was demoted by astronomers but it shouldn’t come as a surprise. Vedic astrologers, in their own cosmic understanding of the universe and their symbolic love for the number nine, had promoted the Lunar Nodes to the rank of planet and their position is still computed in ephemeris tables.

Astrology has also been challenged by the rise of new human sciences. Carl Gustav Jung, Swiss psychiatrist and psychoanalyst, wrote quite a deal about astrology. As a matter of fact, his psychological theories have been implemented into astrological interpretations by modern astrologers. It gave way to brand new methods on how to interpret native charts.

Therefore, not only because the mindset and cultural background of Hellenistic astrologers would be totally foreign to us, but also because astrology as an intellectual practice has gained new layers through the ages, there would be very little to no chance for anyone to practice astrology today as the Ancient Greek did back then. On the surface, it would look the same. There would be mention of planets, their placements and their aspects, how they’re located into one Sign or one House and how it affects them. The mathematical structure of a natal chart would look quite familiar at first. That is until you consider how much progress was made in astronomy since Copernic, how much was written on and about astrology since Ptolemy and how well astrology actually answers to social interrogations that reflect their own era.  

General reference

Willelm Knappich, Histoire de l’astrologie. Translated from German into French by Henri Latou. Originally published in 1967. Paris: Oxus, 2008.

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