Source books · Astrology
Tetrabiblos
Ἀποτελεσματικά
How this book fits
- Traditions
- Astrology
- Role in the tradition
- Primary source Written from inside the tradition: scripture, revelation, a grimoire, a manifesto or a practical treatise.
- Public attention
- Major Wikipedia has an article about it in 17 languages.
Read it
- Ashmand's translation ↗ sacred-texts.com checked against the Internet Archive's copy of January 24, 2026, because the site refuses scripts · archived copy
- Read at gutenberg.org ↗ gutenberg.org checked September 11, 2026
- Read at penelope.uchicago.edu ↗ penelope.uchicago.edu
From Wikipedia
Tetrabiblos, also known as Apotelesmatiká and in Latin as Quadripartitum, is a text on the philosophy and practice of astrology, written by the Alexandrian scholar Claudius Ptolemy in Koine Greek during the 2nd century CE (c. 90 CE – 168 CE).
From the Wikipedia article Tetrabiblos, revision 1368458905, under CC BY-SA 4.0. Wikidata Q1879027: “essay by Ptolemy”.
In this study
The most influential astrological text ever written, and the reason Western astrology has the shape it has. It sets out the signs, their elements and modalities, the houses of the planets, aspect, and the interpretation of nativities — as a defensible natural philosophy rather than as divination.
Book I chapter 17 supplies the rulerships now called traditional. Later schemes are measured against them, including the modern reassignment of three signs to planets unknown to Ptolemy.
Cited for 61 sourced claims here, among them correspondences of Aquarius, Aries, Cancer, Capricorn, Gemini, Leo, Libra and Pisces.