Horoscopes & Omens: Astrology in the Hellenistic World

The origins of astronomy are so closely intertwined with those of astronomy as to make it impossible to speak of one without the other. Astrology held an important place in the scientific and philosophical inquiry of Classical Antiquity. It is even fair to say that astronomy was one of the catalysts behind astronomical inquiry and observation.

The Farnese Atlas, depicting the Zodiac on a celestial sphere. By Sailko, CC-BY

While astronomy is one of the more prominent scientific fields today and astrology is understood to be pseudo-science, the distinction between the two was not nearly as important in antiquity. To ancient observers, the heavenly bodies appeared to be immortal, unchanging, and therefore divine forces in a cosmos that was otherwise largely unstable and hard to define. This perception of the heavenly bodies as divinities, even gods, persisted well into the early Middle Ages when it was supplanted by belief in monotheistic religions.

The cradle of Western astrology in the ancient Near East

Astronomers in the Near East first developed the mathematical tools to accurately predict the movements of the stars and planets. This allowed observers to make accurate predictions about the stars, and to develop more refined lunar and solar calendars. To these astronomers, it was an obvious jump to attempt to understand unexplained occurrences and predict the unknowable based on their complex knowledge of the divine.

Omen astrology attempted to predict future events based on dramatic astrological and meteorological phenomena such as eclipses and thunder. This particular kind of astrology dates back to 8th Century BCE Babylon, and reflects the concerns of the time. These astrological predictions made warnings about famine, civil strife, and the wellbeing of the royal family.

Babylonian astrologers did not limit themselves to reading dramatic omens about the fate of the land, they soon began to draw relationships between astronomical phenomena and individual outcomes. Much like today, the fates and fortunes of individuals were captivating.

The Sun’s annual journey and the seasonal cycle of death and rebirth inspired the idea of reading the course of a man’s life in the heavens. Genethlialogy, or “natal astrology” was practiced in Babylon by the 5th Century BCE, but did not reach the height of its popularity until a few centuries later, during the Hellenistic period.

It was not usually possible for exact astrological conditions at the moment of a person’s birth to be recorded. To answer this, astrologers made charts which could be used to determine planetary positions against the zodiac at the time and place of a person’s birth. This enabled the creation of individual horoscopes.

Ancient horoscopes differed from modern horoscopes in many ways. While modern horoscopes tend to offer insight into personal life and emotional well-being, ancient horoscopes focused on the most important circumstances in an individual’s life, and were especially concerned with death.

The birth of Hellenistic astrological traditions

During the Hellenistic period, after Alexander the Great’s conquest of the Near East in the 4th Century BCE, Graeco-Macedonian dynasties ruled the remnants of the Achaemenid Persian Empire. The most important of these were the Seleucid Empire in Mesopotamia and the Ptolemaic Kingdom in Egypt. The strong ties between Greece and the Near East led to Greek culture increasingly influencing and being influenced by Eastern cultures. As a result, Greek astronomy and astrology was based on the Babylonian and Egyptian traditions that influenced it.

Hellenistic authors claimed that astrology was first introduced to Greece by Berossus, a Babylonian priest who established a school of astronomy and astrology in Kos around 280 BCE. In all likelihood, Berossus was just one of many who contributed to the transmission of astrological traditions to Greece.

Hellenistic astrology developed in tune with the religions, philosophies and medical theories which prevailed in the ancient Mediterranean. While we tend to view Greek society as rational and ordered, Greek culture placed significant weight on the immaterial. From protective amulets to magical incantations, individuals looked for ways to make sense of, and ultimately control, their fates.

Hellenistic astrologers often drew from Platonic, Pythagorean, Stoic, or Gnostic philosophy, and any combination thereof. No unified astrological theory was ever accepted, and many different interpretations of astrological significance existed based on varying cosmologies, philosophies and personal convictions. A multiplicity of syncretic belief systems characterized Hellenistic religious and philosophical thought, and this worldview left plenty of room for astrology.

Astrology emerged in antiquity as one of many means of explaining the unknowable in a world that was torn apart by conflict and natural disasters. Even for those who did not place faith in astrology, it was not out of the question that the heavenly bodies might exert influence over daily life or contain hidden meaning.

The effort to better understand the world is expressed in Manilius’ c. 14 CE Astronomica, the earliest major surviving treatise on Hellenistic astrology:

“Truly, since many are the signs in which men are born for discord, peace is banished throughout the world, and the bond of loyalty is rare and granted to few; and just as in heaven, so too is earth at war with itself, and the nations of mankind are subject to a destiny of strife.”

(2.603-7, translated by Goold)

One of the most significant influences on astrology was the 1st Century BCE philosopher Posidonius’ theory of “cosmic sympathy”. Posidonius believed that all elements of the universe influenced one another. This cosmic sympathy meant that celestial bodies could exert influence over earthly phenomena and human behaviour. This was criticized by some philosophers who agreed that the planets could be used for divination, but maintained that they were not the causes of events.

The importance of fate vs free will was as heated a controversy in Antiquity as it is today. Some ancient philosophers questioned the efficacy of astrology, while others considered the prediction of future events to be unethical because of the fatalistic outlook that it encouraged. As a whole however, astrology was taken just as seriously as the other forms of divination which were practiced in the ancient Mediterranean.

Greek medical theory and the origins of the zodiac

It was in the Hellenistic period that astrology began to develop into a form that is more familiar to modern readers. Hellenistic astrologers singled out a few bodies as particularly significant and associated them with deities. These included the fixed stars and the Seven “Planets”; Helios (the Sun), Selene (the Moon), Aries (Mars), Hesperos (Venus), Hermes (Mercury), Zeus (Jupiter), and Kronos (Saturn). In terms of characteristics and personality, planetary gods took after the Greek deities they were named for. The 12 Western zodiac signs also took their familiar forms and associations at this time.

6th Century AD Byzantine zodiac. Beth Alpha synagogue, Israel. Photo by Talmoryair, Public Domain

In the 5th Century BCE, the Greek physician Hippocrates hypothesized that human personality, gender, and physical well-being was determined by an individual’s proportion of hot, cold, wet, and dry qualities. These Hippocratic qualities were eventually attributed to the zodiac which was divided into four elements; air signs which were hot and wet (Libra, Aquarius, Gemini), fire signs which were hot and dry (Aries, Leo, Sagittarius), earth signs which were cold and dry (Taurus, Virgo, Capricorn), and finally water signs which were cold and wet (Cancer, Scorpio, Pisces).

Medical manuals describe the impact of astrological conditions on physical health and personality, illustrating the intersection between Greek medical and metaphysical theory. The four elements were further identified as active and masculine (air and fire), or passive and feminine (earth and water). People were said to take on the qualities of their birth sign, and Greek manuals list ideal occupations for each sign based on their traits. For example, people born under Pisces were supposed to be good sailors and fishermen.

Horoscopes and arcane knowledge in Ptolemaic Egypt

Ptolemaic Egypt was the centre of intellectual pursuits in the Hellenistic period. Scholars from around the Hellenistic world studied at the Museion and Great Library in Alexandria. Because of this, Ptolemaic Egypt was the crucible of Hellenistic astrology, where scholars refined Greek and Babylonian astronomy, and applied it to new styles of astrology. Some of the oldest surviving Greek horoscopes have been found in Egypt, and were written on papyri and ostraka (potsherds) in the 1st Century CE.

The oldest Greek horoscope discovered so far was carved in relief near the top of Mount Nemrud in modern-day Turkey. This relief, which shows the constellations in Leo, is a horoscope for the coronation of Antiochus I of Commagene on 6 or 7 July 62 BCE.

Mt Nemrud Horoscope. From Reisen in Kleinasien und Nordsyrien by Carl Humann & Otto Puchstein.

Horoscopes and omens were the most widely used, but not the only forms of astrology in the Hellenistic world. Katarchic astrology attempted to predict the opportune moment for a given enterprise or action. Katarchic astrology was also employed to reveal events which had already occurred. This was used by some to recover lost or stolen items, or to understand past events.

Most early Hellenistic astrological texts come from the surviving Hermetic literature, a Ptolemaic genre of esoteric writing. Hermetic texts encompassed magical, astrological, and scientific treatises. Many of these texts claim to reference impossibly ancient Egyptian or Near Eastern astral lore. In reality, the genre is a product of the Hellenistic period which combined contemporary Greek ideas with bits of Egyptian and Babylonian cosmology. The desire to attribute these texts to ancient Eastern knowledge reflects Hellenistic reverence for archaic Eastern knowledge when it came to matters of theology and science.

Astrology and astronomical discovery

In 127 BCE, Hipparchus had noted that the orientation of the Earth’s axial rotation was gradually shifting. Because of this slow precession, the Classical zodiac was slowly falling out of alignment with the observed positions of the stars. To compensate for the precession of the equinox, Hipparchus designed a zodiac which began at the vernal equinox rather than one of the constellations. Despite the importance of Hipparchus’ astronomical discovery, his work was ignored by contemporary astrologers until Claudius Ptolemy included it in his Tetrabiblos in the 2nd Century CE.

The two most important surviving Greek texts pertaining to astronomy and astrology are the Almagest and the Tetrabiblos respectively. Both texts were authored by Claudius Ptolemy, a prominent Graeco-Roman scientist active in Egypt during the 2nd Century we CE.

Reconstruction of a Ptolemaic armillary sphere from the 2nd Century. Photo by Gts-tg CC-BY-SA

The Almagest concerns itself mainly with the hard science of astronomy as it was understood at the time. The Tetrabiblos, its sequel, details the rules and history of astrology. The Tetrabiblos was often treated as the essential work of Hellenistic astrology during the Middle Ages, and modern Western astrology draws heavily on Ptolemy’s work. Although Hipparchus’ discovery was ignored by his contemporaries, his modified zodiac, transmitted through Ptolemy, is still used in Western astrology.

Hellenistic Astrology in the Roman Period

Silver Tetradrachm of Augustus, c. 24 – 20 BC. By EttuBruta CC-BY-SA

Ptolemaic astrological tools were exported to the rest of the Mediterranean, where they helped shape Graeco-Roman astrology. Much of modern historians’ understanding of Hellenistic astrology derives from the works of Roman authors like Vettius Valens and Plutarch, who lived long after the Hellenistic period.

Sources & Bibliography

Barton, Tamsyn. Ancient Astrology. Routledge, London and New York. 2003.

Hegedus, Tim. Early Christianity and Ancient Astrology. Peter Lang. 2007.

Beck, Roger. A Brief History of Ancient Astrology. Blackwell Publishing. 2007.

Oestmann, Günther, and Rutkin, H. Darrel, and Von Stuckrad, Kocku. Horoscopes and Public Spheres: Essays on the history of astrology. Walter de Gruyter. 2005.

Thorndike, Lynn. “The True Place of Astrology in the History of Science”, Isis, Vol. 46. No. 3, (Sep. 1955), pp. 273-278.

Manilius. Astronomica, ed. and trans. G. P. Goold, Loeb Classical Library, Harvard University Press, Cambridge, MA, 1977 Lawrence, Marilynn. “Hellenistic Astrology”, Internet Encyclopedia of Philosophy.

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