Horoscopes of the moon: weather prediction as astrology in Ptolemy’s Tetrabiblos

Journal article

Ptolemy’s Tetrabiblos is not usually considered as a meteorological text. I examine the sections of the Tetrabiblos that deal with weather prediction and argue that Ptolemy considers it part of astrology. I show that the way Ptolemy categorises weather prediction differs significantly from other Greco-Roman writers, including Cicero (On Divination) and Sextus Empiricus (Against the Astrologers). I argue for these conclusions: first, that Ptolemy considers weather prediction to be part of astrology – i.e., a scientific practice which includes giving an account of the causes of phenomena with reference to the stars; to give such an account for the weather requires a practitioner to go beyond the observation and cataloguing of weather signs. Secondly, I argue that understanding weather prediction as astrology means that the distinction between horoscopic and general astrology is more fluid than is sometimes thought. Finally, I will show that Ptolemy’s views on weather prediction provide a case study for his view of astral causation.

Authors: Hall, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Brill Academic Publishers
• Journal: Early Science and Medicine
• Volume: 26
• Issue: 3
• Pages: 231-253
• Publication date: 2021-08-18
• DOI: 10.1163/15733823-02630018
• EISSN: 1573-3823
• ISSN: 1383-7427
• Language: English
• Keywords: Ptolemy; astrology; weather prediction; meteorology; signs; causes; Tetrabiblos; Phases; astrometeorology; divination