Podcast episode

Episode 88: Claudius Ptolemy and the Tetrabiblos

Claudius Ptolemy (c. 90 to c. 168 CE) was an Alexandrian astronomer/astrologer and geographer whose work – for whatever reason – became the standard textbooks on matters astral and geographic throughout the west until the modern period. In this episode we pretty much ignore his geography, and don’t even pay that much attention to his great summing-up of Hellenistic astronomical science, the Almagest, concentrating instead on his equally-authoritative astrological work, the Tetrabiblos.

The theory of astral causation outlined in the Tetrabiblos was not the only theoretical framework available to ancient astrologers – indeed, it may have been a minority opinion – but it became the one that stuck, informing thought on how the stars shape life and events here on earth for more than a millennium. In this episode we introduce some of its overarching themes, the cosmos it envisages, and discuss in a general way the significance of all this for western esotericism.

Recommended Reading:

The best available edition of Ptolemy’s Almagest (under the title Syntaxis mathematica) remains J. L. Heiberg, Claudii Ptolemaei opera quae exstant omnia, vols. 1.1 and 1.2 (1898, 1903). A much more up-to-date edition of the Tetrabiblos (under the title Apotelesmatika) is now available in Wolfgang Hübner, editor. Claudii Ptolemaei opera quae exstant omnia 1, Apotelesmatika. Teubner, Stuttgart, 1998.

For English, there is a Loeb translation of the Tetrabiblos (Frank E. Robbins ed. and trans. Cambridge, MA: Harvard University Press 1940, available online here) and several stand-alone translations of the Almagest, notably G.J. Toomer, editor. Ptolemy: Almagest. Duckworth, London, 1984. A recent book of essays, mostly on the medieval reception of Ptolemy, Ptolemy’s Science of the Stars in the Middle Ages, David Juste, Benno van Dalen, Dag Nikolaus Hasse, and Charles Burnett edd. (Turnhout: Brepols 2020), is available online through open access.

Also relevant and interesting:

  • Tamsyn Barton. Ancient Astrology. Routledge, London, 2002.
  • Chris Brennan. Hellenistic Astrology: The Study of Fate and Fortune. Amor Fati, Denver,
    CO, 2017.
  • Nicola Denzey Lewis. Cosmology and Fate in Gnosticism and Greco-Roman Antiquity:
    Under Pitiless Skies. Number 81 in Nag Hammadi and Manichæan Studies. Brill,
    Leiden, 2013.
  • Jaqueline Feke and Alexander Jones. ‘Ptolemy’. In Lloyd Gerson, editor, The Cambridge
    History of Philosophy in Late Antiquity, Vol. 1, pages 197–209. Cambridge University
    Press, Cambridge, 2010.
  • Gerd Grasshoff. The History of Ptolemy’s Star Catalogue. Springer Verlag, New York,
    NY, 1990 [a useful discussion of the aftermath of all the errors to be found in Ptolemy’s astronomical data].
  • Alexander Jones, editor. Ptolemy in Perspective: Use and Criticism of his Work from
    Antiquity to the Nineteenth Century. Springer Verlag, Dordrecht/New York, NY,
    2010 [a collected volume on the reception-history of Ptolemy’s work].
  • Daryn Lehoux. ‘Tomorrow’s News Today: Astrology, Fate, and the Way Out’. Repres-
    entations, 95:105–22, 2006.
  • Anthony A. Long. ‘Astrology: Arguments Pro and Contra’. In J. Barnes, J. Brunschwig,
    M. Burnyeat, and M. Scholfield, editors, Science and Speculation; Studies in Hellen-
    istic Theory and Practice, pages 165–92. Cambridge University Press and Éditions
    de la Maison des Sciences de l’Homme, Paris, 1982.
  • Olaf Pedersen. A Survey of the Almagest: With Annotation and New Commentary by
    Alexander Jones. Springer, New York, NY, 2010.
  • Mark Riley. ‘Theoretical and Practical Astrology: Ptolemy and his Colleagues’. Trans-
    actions of the American Philological Association, 117:235–256, 1987 [Available online here].
  • Idem. ‘Science and Tradition in the Tetrabiblos’. Proceedings of the American
    Philolosophical Society, 132(1):67–84, 1988 [Available online here].
  • George Saliba. A History of Arabic Astronomy: Planetary Theories During the Golden
    Age of Islam. New York University Press, New York, NY, 1994.
  • Idem. ‘Greek Astronomy and the Medieval Arabic Tradition’. American Scientist,
    90(4):360–67, July-Aug. 2002.



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