Podcast episode

Episode 41: Fate and Foreknowledge: Toward Hellenistic Astrology

The Dendera Zodiac, c. 50 CE. Looted by the French and now in the Louvre.The history of astrology is one of the central stories of the history of western esotericism. This episode is loosely centred on the birth of western astrology proper in Hellenistic Egypt, but takes in lots of other important matters. We start with a few notes on the importance of astrology as a defining science, not only of western esotericism, but of the west more generally, looking at a few of the general ways in which it has been accepted, rejected, or domesticated down the ages. We then take a look at the Chaldæans, a.k.a. Mesopotamian diviners as received by the Græco-Roman world, and their contributions to the final transformation of Near Eastern omen-traditions into horoscopic astrology (not to mention their invention of the zodiac), at the Egyptians and their own contributions, in particular the fertile cultural breeding-ground of Hellenistic Alexandria and the role which its milieu played in the birth of western astrology, and at the Greek contribution in terms of the geocentric cosmologies discussed in the previous episode.

The result of the complex synthesis of all these elements was something easily recognisable as ‘astrology’: a system of divination based in a geocentric cosmos where the heavenly bodies, moving through the zodiac (and sometimes the Egyptian decans), determine or indicate events on earth, and the astrologer’s job is to read them to discern how these events are going to take place.

We make a quick, tantalising reference to the earliest known astrological manuals and related texts, such as treatises on the occult powers of stones and plants and on numerology. These works, now lost except in fragments, are significant in that they are the earliest manifestations of a genre which was of defining importance to western esotericism: the Hermetica.

Corrigendum: I attempt a working definition of astrology in this episode involving the idea of astral causation. However, as Chris Brennan points out in Episode 42, not all ancient (or modern) astrologers thought in terms of causation – for some, the stars simply give signs or omens, with no causal link being assumed. I have thus revised my typology, framing it instead in terms of ‘correspondence between stellar and earthly phenomena’. Thanks, Chris.

Works Discussed in this Episode:


  • Astrologers (and Zeus-Sabazius-worshipping-Jews!) expelled from Rome in 139 BCE: Valerius Maximus I.3.3.
  • Berossus: see Josephus Ap. 1.129; Vitruvius de arch. 9.2; 9.6.3; 9.8.1.
  • Eudoxus of Cnidos: We have evidence of the Babylonian zodiac in the lost works of Eudoxus, via the third-century verse-translation of one of his works by Aratus, which gives a list of stars rising and setting with the zodiacal signs, the paranatellonta. Eudoxus’ dismissal of Babylonian natal astrology (or omen-interpretation) is cited at Cicero Div. 2, 88.
  • Nechepso and Petosiris: the fragments of these early Egyptian astrological writers can be found collected in Reiss 1892 (see below).
  • Sudines: see Strabo Chr. 16.1.16.

Wise barbarian alert! Our classical authors agree that either the Chaldæans, the Egyptians, or both, were the founders of the discipline of astrology: Diodorus Siculus II 31, 8-9; cf. Pliny 7, 193. Diodorus also reports a claim from the Egyptians that the Chaldæans were in fact colonists in Mesopotamia from Egypt, and so the Egyptians could claim primacy as the founders of the art of astrology (I 81, 4-6).


  • Said, E. W., 2003. Orientalism. Penguin, London.
  • Von Stuckrad, K. (2000). ‘Jewish and Christian Astrology in Late Antiquity: A New Approach’, Numen 47 : 1-40. We quote p. 5.

Recommended Reading:

Chris Brennan, whom we interview in the next episode, maintains the Hellenistic Astrology website, where you can find an excellent timeline of ancient astrology which may be helpful in orienting oneself among all these dates and cultures. Marilynn Lawrence’s article for the Internet Encyclopedia of Philosophy is an excellent introduction.

  • Barton, T., 2002. Ancient Astrology. Routledge, London.
  • Juan Antonio Belmonte and José Lull. Astronomy of Ancient Egypt: A Cultural Perspective. Springer Nature, Cham, 2023.
  • Bouché-Leclercq, A., 1899. L’Astrologie grecque. Leroux, Paris. The classic study.
  • Cumont, Franz, et al (eds.), Catalogus Codicum Astrologorum Graecorum, 12 vols. in 20 parts, Lamertin, Brussels, 1898–1953. Now available, and searchable, online here!
  • Freudenthal, G. (2009).’ The Astrologization of the Aristotelian Cosmos: Celestial Influences on the Sublunar World in Aristotle, Alexander of Aphrodisias, and Averroes’. In: Bowen, A. C. & Wildberg, C. (Ed.), New Perspectives on Aristotle’s De cælo, Brill, Leiden.
  • Hans G. Gundel. Dekane und Dekansternbilder. Ein Beitrag zur Geschichte der Sternbilder der Kulturvölker. Wissenschaftliche Buchgesellschaft, Glückstadt, 1936 [if you are really interested in the decans and know German, this book is for you].
  • Hegedus, Tim. (2007) Early Christianity and Ancient Astrology, Peter Lang, New York, NY.
  • Jones, Alexander. (1999) Astronomical Papyri from Oxyrhynchus, 2 vols. bound in one, American Philosophical Society, Philadelphia, PA.
  • Neugebauer, O. (1943). ‘Demotic Horoscopes’, Journal of the American Oriental Society 63 : 115-27.
  • Neugebauer, O. and van Hoesen, H.J. (1959). Greek Horoscopes. American Philosophical Society, Philadelphia, PA. The standard work, with a wealth of papyri, pottery shards, and other unlikely sources for ancient horoscopes.
  • Pingree, D., 1997. From Astral Omens to Astrology, from Babylon to Bitkner. Rome.
  • Reiss, E. (1892). ‘Nechepsonis et Petosiridis fragmenta magica’, Philologus Supplementband 6 : 325-94.
  • Rochberg-Halton, F. (1989). ‘Babylonian Horoscopes and their Sources’, Orientalia : 102-23.
  • Sachs, A. (1952). ‘Babylonian Horoscopes’, Journal of Cuneiform Studies 16 : 49-75.
  • Sachs, A. and Hunger, H., 1988-2006. Astronomical Diaries and Related Texts from Babylonia. Österreichische Akademie der Wissenschaften, Vienna. Six volumes of Babylonian stargazing. Enter if you dare.
  • Swerdlow, N. M. (Ed.), 1999. Ancient Astronomy and Celestial Divination. MIT Press, Cambridge, MA.
  • von Bomhard, A.-S. Ludwig von Bomhard (trans.), 2008. The Naos of the Decades: From the Observation of the Sky to Mythology and Astrology. Oxford Centre for Maritime Archæology, Oxford.
  • Williams, C. (2008). ‘Some Details on the Transmission of Astral Omens in Antiquity’. In: Ross, M. (Ed.), From the Banks of the Euphrates: Studies in Honor of Alice Louise Slotsky, Eisenbrauns, Winona Lake, IN. This article traces omens from the Enuma Anu Enlil in the works of Petosiris, showing just how much later astrology owed to Mesopotamian omen-literature.



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