Podcast episode

Episode 42: Chris Brennan on Hellenistic Astrology

The right -hand side of the diptych sketched above. Courtesy Musées grand est.

In this episode we discuss the nitty-gritty of Hellenistic astrology, trying to get at how it might have actually been practised in the Hellenistic and Roman periods. But it would be silly to interview an experienced astrologer like Chris Brennan without taking full advantage of his expertise, so a lot of material is covered which makes this episode an excellent introduction to technical astrological matters more generally. The conversation has four main sections:

  • We cover basic terminology – how do you tell your natal astrology from your inceptional astrology?
  • We look at the fourfold typology for Hellenistic astrology laid out in Chris’ book (see below), discussing the implications of each of the four components of the schema.
  • We take a look at the practicalities of ancient astrology. It’s the first century and I am visiting an astrologer with my newborn baby to get its chart read. What happens next? Astrology is unique among ancient occult sciences in that we have procedural texts (as well as some fascinating artefacts!) which give us a pretty solid glimpse into what must have gone on in an ancient astrological consultation.
  • I put my own proposed definition of astrology from Episode 41 to Chris, defining astrology as 1) the belief in astral causation and the resultant ideas about human action coupled with 2) Hellenistic cosmology, the zodiac, and 3) the horoscopic and/or electional modes of divination, and he takes me to school in a big way, resulting in an on-the-spot definitional refinement which will stand the podcast in good stead for many episodes to come.

Interview Bio:

Chris Brennan is a practical astrologer and historian of astrology on a mission to resurrect the Hellenistic astrological tradition. He maintains a website devoted to exploring the subject, as well as hosting the long-running weekly Astrology Podcast. His work also includes an extraordinary book, a survey of the history, philosophy, and techniques of Hellenistic astrology, much-discussed in this episode:

  • Brennan, C., 2017. Hellenistic Astrology: the Study of Fate and Fortune. Amor Fati, Denver, CO.

Works Discussed in this Episode:



  • Dorotheus of Sidon: Dorothei Sidonii Carmen Astrologicum, Interpretationem arabicam in linguam anglicam versam una cum Dorothei fragmentis et graecis et latinis, ed. and trans. David Pingree, Teubner, Leipzig, 1976.
  • Firmicus Maternus: Iulii Firmici Materni Matheseos libri VIII, ed. Wilhem Kroll, F. Skutsch, and K. Ziegler, 2 vols., Teubner, Leipzig, 1897–1913.
  • Ptolemy: Claudii Ptolemaei opera quae exstant omnia, vol. III, 1: ΑΠΟΤΕΛΕΣΜΑΤΙΚΑ, Wolfgang Hübner, Teubner, Stuttgart/Leipzig, 1998.
  • Vettius Valens: for the great Vetius, we have the edition of Wilhelm Kroll (Vettii Valentis Anthologiarum Libri, Weidman, Berlin, 1908), but also a working English translation by Mark T. Riley, which is still the best English-language resource for this important astrological writer (Anthologies, trans. Mark T. Riley, originally released online in December 2010).


  • Adamson, Peter, ‘Plotinus on Astrology’, Oxford Studies in Ancient Philosophy, vol. 35 (2008), pp. 265–91.
  • Evans, James, ‘The Astrologer’s Apparatus: A Picture of Professional Practice in Greco-Roman Egypt’, Journal for the History of Astronomy, vol. 35, part 1, no. 118 (2004), pp. 1–44. Check out this article for fascinating insights into the material culture of ancient astrology, including the horoscope-boards discussed in the episode, one of which is pictured above.
  • Fowden, Garth, The Egyptian Hermes: A Historical Approach to the Late Pagan Mind, Cambridge University Press, Cambridge, 1986.
  • Holden, James Herschel, ‘Ancient House Division’, American Federation of Astrologers Journal of Research, vol. 1, no. 1 (August 1982), Tempe, AZ, pp. 19–29.

Recommended Reading:

  • Amand, David, Fatalisme et liberté dans l’antiquité grecque. Recherches sur la survivance de l’argumentation morale antifataliste de Carnéade chez les philosophes grecs et les théologiens chrétiens des quatre premiers siècles, Bibliothèque de L’Université, Lovain, 1945.
  • Beck, Roger, A Brief History of Ancient Astrology, Blackwell Publishing, Malden, MA, 2007.
  • Bobzien, Susanne, Determinism and Freedom in Stoic Philosophy, Clarendon Press, Oxford, 2001.
  • Brennan, Chris, ‘The Planetary Joys and the Origins of the Significations of the Houses and Triplicities’, ISAR International Astrologer Journal, vol. 42, no. 1 (Apr. 2013), pp. 27–42. You can read the article here.
  • Campion, Nicholas, A History of Western Astrology. Volume 1: The Ancient and Classical Worlds, Bloomsbury, London/New York, 2008 (repr. 2012).
  • Denzey Lewis, Nicola, Cosmology and Fate in Gnosticism and Graeco-Roman Antiquity: Under Pitiless Skies, Nag Hammadi and Manichaean Studies 81, Brill, Leiden, 2013.
  • Dieleman, Jacco, ‘Stars and the Egyptian Priesthood in the Greco-Roman Period’, in: Prayer, Magic and the Stars in the Ancient and Late Antique World, eds. Noegel, Walker, and Wheeler, 2003, pp. 137–53.
  • Hand, Robert, ‘Signs as Houses (Places) in Ancient Astrology’, Culture and Cosmos, vol. 11, nos. 1 and 2, 2007, pp. 135–162.
  • Holden, James H., A History of Horoscopic Astrology, American Federation of Astrologers, Tempe, AZ, 1996 (3rd rev. ed. 2013).
  • Jones, Alexander (ed.), Ptolemy in Perspective: Use and Criticism of His Work from Antiquity to the Nineteenth Century, Archimedes vol. 23, Springer, Dordrecht/New York, 2010.
  • Komorowska, Joanna, Vettius Valens of Antioch: An Intellectual Monography, Ksiegarnia Akademicka, Kraków, 2004.
  • Lawrence, Marilynn, ‘Who Thought the Stars are Causes? The Astrological Doctrine Criticized by Plotinus’, in: Metaphysical Patterns in Neoplatonism, ed. John Finamore and Robert Berchman, University Press of the South, 2007, pp. 17–31.
  • Lehoux, Daryn, ‘Tomorrow’s News Today: Astrology, Fate, and the Way Out’, Representations, vol. 95 (2006), pp. 105–122.
  • Long, Anthony A., ‘Astrology: Arguments Pro and Contra’, in: Science and Speculation: Studies in Hellenistic Theory and Practice, ed. J. Barnes, J. Brunschwig, M. Burnyeat, and M. Schofield., Cambridge University Press and Editions de la Maison des Sciences de l’Homme, Paris,1982, pp. 165–92.
  • Pérez Jiménez, Aurelio, ‘Pseudepígrafos de la astrología griega’, in: Mundus vult decipi: Estudios interdisciplinares sobre falsificación textual y literaria, ed. Javier Martínez, Ediciones Clásicas, Madrid, 2012, pp. 271–284.
  • Riley, Mark, ‘Theoretical and Practical Astrology: Ptolemy and his Colleagues’, Transactions of the American Philological Association, vol. 117 (1987), pp. 235–56.
  • Sharples, Robert, ‘The Stoic Background to the Middle Platonist Discussion of Fate’, in Platonic Stoicism – Stoic Platonism, ed. M. Bonazzi and C. Helmig, Leuven University Press, Leuven, 2007, pp. 169–188.
  • Tarrant, Harold, Thrasyllan Platonism, Cornell University Press, Ithaca, NY, 1993.


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