Tetrabiblos
Tetrabiblos (Greek: Τετράβιβλος, lit. 'Four books'), also known as Apotelesmatiká (Greek: Ἀποτελεσματικά, lit. 'On the effects') and in Latin as Quadripartitum (lit. 'Four Parts'), 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). Ptolemy's Almagest was an authoritative text on astronomy for more than a thousand years, and the Tetrabiblos, its companion volume, was equally influential in astrology, the study of the effects of astronomical cycles on earthly matters.