Claudius Ptolemy

KLAU-dee-uhs TOL-uh-mee

Definition

Claudius Ptolemy (c. 100–170 CE) was a Greek-speaking scholar in Alexandria who worked across astronomy, mathematics, geography, and astrology. You meet him most often through two books: the *Almagest*, antiquity's standard treatment of an Earth-centred cosmos, and the *Tetrabiblos*, his four-book astrological synthesis (also titled *Apotelesmatika*). He also wrote the *Geography*, the *Optics*, and the *Harmonics*. His astrology went on to shape Hellenistic, Arabic, and modern Western practice for more than a millennium and a half.

In Tradition

Scholars of Hellenistic astrology count the *Tetrabiblos* as one of the two great surviving Greek textbooks of the art, the other being Vettius Valens' *Anthologiae*. Holden cautions, though, that Ptolemy gives a deliberately trimmed version of the astrology of his day — he leaves out much of the working material on lots, derived houses, and sign-by-sign readings that other Hellenistic writers kept.

In Practice

Traditional astrologers today turn to Ptolemy for several core teachings: the four humoral qualities, essential dignities (the terms in three versions, and triplicities sorted by sect — whether the chart is a day or a night birth), the aspects, his case for the tropical zodiac (*Tetrabiblos* I.22), the doctrine of length of life (III.10), and the framework for mundane and weather prediction in Book II. Because he leaves out so much that his contemporaries used, you'll usually see the *Tetrabiblos* read alongside Dorotheus, Valens, and Paulus Alexandrinus, which together restore the fuller Hellenistic picture.

Historical Origin

Ptolemy worked in Alexandria under the Roman Antonines (c. 100–170 CE). Holden notes that his astrological writings did not circulate widely until the end of the third century — Vettius Valens, in Alexandria a generation later, shows no sign of knowing them. The *Tetrabiblos* passed down through Late-Antique commentaries by Hephaestio and Porphyry, reached medieval Europe through twelfth-century Latin translations from the Arabic (Plato of Tivoli, *Quadripartitum*, 1138), and was first put into English by J. M. Ashmand in 1822 (PD).

Etymology

Origin: Greek. Meaning: From Ptolemaios, meaning "warlike" or "aggressive".

Definition

In Tradition

In Practice

Historical Origin

Etymology

Further Reading