Hellenistic astrology

Almost everything that makes up Western astrology came into being within a few centuries in Hellenistic Egypt — roughly from the second century before our era to the seventh after it.

What was there before

From Mesopotamia came the observation of the planets, the interpretation of omens and the zodiac as a division into twelve equal sections. That is the Babylonian layer, and it is well attested.

What it lacked was the core of the later practice: the birth chart of one individual person, with an ascendant, houses and interpretation by fixed rules.

What the Hellenistic period added

The list is remarkable. These centuries produced:

• The ascendant and with it the twelve houses — the division of the sky above one place at one time. This is the step that turns knowledge of the heavens into a reading for a single person.
• The doctrine of dignities — domicile, exaltation, triplicity, term, face.
• Sect — the distinction between day and night births.
• The doctrine of aspects in its geometrical form.
• The lots, among them the Part of Fortune.
• The time-lord techniques — profections, circumambulations, the lords of the times.

Anyone working classically today works with this stock.

The authors

Among those preserved are Dorotheus of Sidon, Vettius Valens, Ptolemy, Paulus Alexandrinus and Hephaistio of Thebes. They contradict one another regularly — Ptolemy, for one, gives a different table of terms from all the rest — and those contradictions teach more than any smoothed-over summary.

Valens is the most interesting case: not a systematiser but a working astrologer, whose book is full of real charts, along with what became of the people in them.

What happened afterwards

The system passed into Persian and Arabic, was developed further there — the firdaria and much of the technique of mundane astrology come from there — returned to Europe in the Middle Ages through translations, and shaped practice down to the seventeenth century.

The break came only around 1900, when astrology was reorganised, in part by people who could not read the sources. Much of what is now being rediscovered as “traditional” is simply what was lost then.

See also: Indian astrology, which comes from the same Hellenistic root and has developed separately for nearly two thousand years.