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  • Sylvia Rose

Ancient Greek Astrology & Astronomy

Updated: Aug 11

In the ancient Greek view, creation of astrology is attributed to the legendary sage Hermes Trismegistus. In Hellenic Greek times (323 BCE - 30 BCE), Hermes composes several important texts. The writings inspire the development of astrology from Babylon and Egypt.




starry night above trees


Initially, astronomy monitors the seasons and identifies important times of year. Astrology focuses on deciphering motions of celestial objects and associating them with different facets of earthly existence.


Many acknowledge Hermes as first to define the astrological houses and their significance, suggesting the houses originate at the inception of the Hellenic astrological tradition. The houses are key distinguishing features from Babylonian and other astrological practices.



colorful houses


Subsequently, the system of astrology is relayed to another mythical figure, the medicine god Asclepius, to whom many Hermetic writings are dedicated. Knowledge is later transmitted to an Egyptian pharaoh named Nechepso and his priest Petosiris.



They are believed author essential textbooks explaining the system, as primary sources for many later Hellenic astrologers. This system broadens the path for all subsequent forms of horoscopic astrology.



zodiac drawings


In 525 BCE Egypt is occupied by the Persians. Mesopotamia has strong influence on Egyptian astrology. Mesopotamian input includes the Balance and the Scorpion signs. These are seen in the Dendera Zodiac. In Greek versions, the Balance is known as the Scorpion's Claws.


After occupation by Alexander the Great in 332 BCE, Egypt is under Greek rule. The city of Alexandria is was founded by Alexander after the conquest. During the 3rd and 2nd centuries BCE, the Great Library of Alexandria attracts scholars from near and far.



a scroll probably Hebrew


They come seeking wisdom and inspiration in philosophy, theology, medicine, literature and natural history. Plato studies in Egypt for 13 years. Pythagoras studies medicine, philosophy and geometry for 22 years. Hippocrates studies medicine in Egypt for 7 years.


In Alexandrian Egypt, Babylonian astrology mixes with Egyptian Decanic astrology. The oldest known Egyptian Zodiac, the Dendera Zodiac originates from the 1st century BCE to create Horoscopic astrology.



Dendera Temple
part of Dendera Temple Complex, Egypt (North of Luxor)

A decan is the subdivision of a sign. To give fuller interpretation to the zodiac signs, ancient astrologers subdivide each sign into periods of about ten days. Texts from 2nd century BCE list predictions of planetary positions in zodiac signs when of the certain decans rise.


Ancient texts cover Babylonian zodiac, planetary exaltations, sign triplicities and significance of eclipses. Astrology integrates Egyptian division of the zodiac into 36 decans of ten degrees each. This identifies ascending decan, Greek planetary deities, signs and the four elements.



Greek War God Ares is conflated with Roman Mars
Greek War God Ares is conflated with Roman Mars

The decans measure time according to constellations. They're led by the constellation Sothis or Sirius the Dog Star in Canis major, the Great Dog constellation. Sirius is an exalted star, due to its brightness in the night sky and its portent of fertility, heralding the floods of the Nile.


The risings of the decans in the night divide the night into 'hours'. The rising of a constellation just before sunrise (its heliacal rising) is considered the last hour of the night. Over the course of the year, each constellation rises just before sunrise for ten days.



Dog Star Sirius is the brightest star in the night sky
Dog Star Sirius is the brightest star in the night sky

When they became part of the astrology of the Hellenic Age, each decan is associated with ten degrees of the zodiac. Texts from 2nd century BCE list predictions relating to the positions of planets in zodiac signs at the time of the rising of certain decans, particularly Sothis.


One of the key figures in the advancement of horoscopic astrology is Ptolemy, astrologer and astronomer in Alexandria, Egypt. The renowned work of Claudius Ptolemy (c. 100 - 170 AD) the Tetrabiblos, establishes the foundation of Western astrological practices.



Ptolemy, crowned, guided by Urania, muse of astrology and astronomy
Ptolemy, crowned, guided by Urania, muse of astrology and astronomy by Gregor Reisch (1508)

The Greek encounter with cultures and cosmological beliefs of Syria, Babylon, Persia, and central Asia during Alexander the Great's Asian conquest is a pivotal time in history. The Greeks learn new perspectives and astrological evolution continues.


The dominance of Greek language for intellectual exchanges marked a shift from cuneiform script. It facilitates transmission of knowledge, especially in the realm of astrology.



Ancient Greek on papyrus (fragment of Plato's Republic)
Ancient Greek on papyrus (fragment of Plato's Republic)

As astrology of the East filters into Greek and Egyptian societies, it undergoes transformation and adaptation, various forms and approaches. By the 1st century BCE, two distinct types of astrology emerge.


One is focused on interpretation of horoscopes to reveal insights into the past, present, and future. The other, known as theurgic or 'god-work,' emphasizes the spiritual journey of the soul towards the stars.



person staring up to the cosmic skies


These two branches of astrology, although not mutually exclusive, served different purposes. The first tries to provide knowledge and understanding of life's mysteries. The second is aimed at transformation and enlightenment through astrology as a way of connecting with the divine.


Astrology is a significant aspect of ancient Roman society, having been introduced through Greek influence, as are many things Roman. The connection between Babylonia or Chaldea and astrology is deeply embedded in both Greek and Roman cultures.



planetary motion


"Chaldaean wisdom" is synonymous with divination based on celestial movements. The practice of astrology gains prominence in Imperial Rome, with even emperor Tiberius seeking advice from astrologers to foresee his fate.


The influence of astrology is so profound many people don't begin their day without first consulting astrological calendars for guidance. Despite the popularity of astrology, there are contrasting views within Roman society.



big zodiac clock


While some, like Tiberius, embrace astrological predictions, others, such as Claudius, favor augury and even prohibit Roman astrologers. "Chaldaean" gradually changes meaning to deception and manipulation, leading to skepticism towards astrological practices.


One of the notable literary contributions to Roman astrology is the first-century AD poem Astronomica by Marcus Manilius. This work explores the intricacies of celestial movements and their influence on human destinies.



it's destiny


In the 4th century, Firmicus Maternus states the practice of horoscopic astrology os originally introduced to an Egyptian pharaoh Nechepso and priest Petosiris. At that time the Hermetic texts are also compiled.


Clement of Alexandria, who writes in the Roman era, highlights the importance of astrologers being familiar with these texts in his account of Egyptian sacred rituals:


This is principally shown by their sacred ceremonial. For first advances the Singer, bearing some one of the symbols of music. For they say that he must learn two of the books of Hermes [Trismegistus], the one of which contains the hymns of the gods, the second the regulations for the king's life.


charts with planetary signs


And after the Singer advances the Astrologer, with a horologe in his hand, and a palm, the symbols of astrology. He must have the astrological books of Hermes, which are four in number, always in his mouth.

The ancient Egyptian Hermetic texts focus on summoning spirits and animating statues. They influence the earliest Hellenic works on Greco-Babylonian astrology, and the emerging field of alchemy.



The Spirit of Alchemy with moon-sun symbolism, flask, containers
The Spirit of Alchemy with moon-sun symbolism, flask, tongs, compass drawing, containers

Concurrently, Hermetic philosophy provides a rationalized framework for religious rituals and a pathway for individuals to transcend their physical limitations. This philosophical tradition sometimes causes confusion with Gnosticism, which was also evolving during the same period.



Non-Fiction Books:


Fiction Books:

READ: Cult of the Fire God - Bronze Age Quest Adventure

READ: Lora Ley Adventures - Germanic Mythology Fiction Series

READ: Reiker For Hire - Victorian Detective Murder Mysteries





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