Ptolemy's Tetrabiblos : or, Quadripartite : being four books of the influence of the stars

Ptolemy’s Tetrabiblos is the foundational classical text of Western astrology, setting out a systematic theory of planetary influence and astrological judgment. Its historical importance is immense, and readers will find a concise but influential account of natal, mundane, and meteorological astrology based on Greco-Roman natural philosophy.

The second-century Ptolemy most likely refers to Claudius Ptolemy, the Greco-Egyptian scholar whose works shaped astrology, cosmology, and mathematical astronomy in late antiquity and beyond. His Tetrabiblos became one of the most influential texts in the history of astrological theory and practice.