Every history of astrology must necessarily begin with the Babylonians, who are commonly thought to have invented astrology. The Babylonians left us one of the earliest overtly astrological documents, the Enuma Anu Enlil. This document may date as far back as 1600 B.C., and it enumerates astronomical omens and their interpretation.
The focus of Babylonian Astrology was to predict events that affected the entire nation and its cities, whether it was war, famine, or meteorological events. The fate of the King was also a major concern. Astrologers employed by the King were expected to explain astronomical omens, and advise the King accordingly.
It is thought that in about 400 B.C., the Babylonians started working out the mathematical means of predicting astronomical events. This information was quickly disseminated throughout the Middle East and India. Information was recorded on clay tablets, which was particularly helpful as the Babylonians started working with individual natal horoscopes.
Historically, the Greeks have been credited as the inventors of horoscopic astrology, which is the notion of representing the horoscope of a moment as a chart of the heavens at that moment. Horoscopic astrology was used for the natal horoscopes of individuals, as well as those of questions or actions, or horary Astrology and electional astrology, respectively.
The Greeks added many concepts to Babylonian Astrology, such as the notion of sect, and the related concept of signs being male or female.
Since the Romans looked to Greece for all matters cultural and scientific, they adopted Greek Astrology about 100 B.C. This is how we know that Caesar Augustus had the Moon in Capricorn, as Augustus was a great believer in the truthfulness of astrology.
The Romans did not introduce very many innovations to Greek Astrology, but they documented it very well, such as the famous Astronomica by the poet Marcus Manilius. This is a comprehensive work covering many aspects of astrology.
Another important Roman-era work is by Dorotheus of Sidon, who composed a five book poem about astrology. This is a handbook, which just happens to be in verse. The concept of Triplicities, that is, that each sign is ruled by three planets, the day ruler, the night ruler and the participating ruler, comes from Dorotheus’s book.
Perhaps the most influential astrological writer of this era was Claudius Ptolemy, who wrote the famous Tetrabiblos, a kind of summary of the Greek Astrology of his day. This book is filled with various observations and aphorisms, and abbreviated methods of astrological prediction in various fields.
Finally, there is equally important Vettius Valens, who, unlike Ptolemy, was a practicing astrologer. He fills in many of the gaps left in Ptolemy’s work, and includes over a hundred horoscopes in his book, titled Anthology.
Much of the history of medieval astrology is actually the history of Arabian astrology, as the newly prosperous and victorious Islamic empire actively.
